Histo

Front 1

Red Blood Cells

Back 1

Deliver oxygen to tissues and pick up carbon dioxide for transport to the lungs. Derive their energy from fermentation of glucose to lactate. Anucleate, biconcave discs in the adult human.

Hint 1

anucleate cells devoid of typical organelles. Function only within the bloodstream to bind O2 for delivery to the tissues and in exchange bind CO2 for removal from tissues. Shape is biconcave disk with a diameter of 7.8microns, edge thickness of 2.6microns and central thickness of .8microns. Shape maximizes cells surface area (140microns squared). Membrane strength and flexability is important. Life span is about 120 days. Hemoglobin is carrier protein (4 chains).

Front 2

Lymphocytes

Back 2

These are the key players of the immune system. There are many different categories of lymphocytes. Unfortunately in the LM with ordinary staining methods they all tend to look alike. Typically they have a large nucleus with little cytoplasm.

Hint 2

20-30% of leukocytes in peripheral blood, small, most are 6-10 microns in diamerter, undifferentated lymphocytes leave marrow and travel to lymphoid organs and tissues (T, B, NK cells)

Front 3

Eosinophil

Back 3

Peripheral blood leukocytes that emigrate and are particularly prominent in the respiratory tract. They are filled with eosinophilic granules containing major basic protein (MBP). MBP is parasitolytic, but can destroy respiratory epithelium in asthma

Hint 3

Bilobed nucleus, 10-12 micron diamerter. Large eosinophilic (pink-red) "specific" granules: major basic protein (forms crystals), Eisnophilic peroxidase, Histaminase (neutralizes histamine) Arylsufatase (neutralizes slow reacting sugstance of anaphalaxis secreted by basophils), collagenase. Located in connective tissue underlying skin, bronchi, GI tract, Uterus, vagina.Causes respiratory burst (faster more effective killing). Eosinophilia is an indicator of allergic reactions, helminthic infections. Few mitochondria. Crystals at center of granules contain MBP.

Front 4

Basophil

Back 4

A specialized peripheral blood leukocyte. Originates from bone marrow. The term basophil is also used for cells of the hypophysis (which do not originate in the bone marrow, as far as we know).

Hint 4

0-1% of leukocytes, 12-15 micron cell diamater. Function= release mediators of inflammation: histamine, SRS-A (a group of leukotrienes). Display Ige bound to Fc receptors- reaction with antigen leads to activation_degranulation. .5 micron basophilic specific granules contain histamine, SRS-A, and heparin sulfate (role not clear, negative charge makes specific granules basophilic (basophilic granules almost obsucre the multi-lobed nucleus (different from eosinophils))

Front 5

Neutrophil

Back 5

Most frequently-occurring leukocyte in blood. Avid phagocytes, but usually die in the process. First defense against bacterial infection. Lobulated nucleus. Migrate into other tissues. Granules contain various substances.

Hint 5

Recognized by multi lobed nucleus, 10-12 micron diameter. Specialized phagocyte- changes from smooth shape to lots of pseudopods upon diapedesis. Has "specific" granules, small (at LM resolution limit). Azurophilic granules (deep purple) = lysosomes. Granule size = small compared to eosinophil and basophil. Few mitochondria (uses glycoloysis instead of aerobic metabolim - good for anerobic conditions). Release IL-1 (induces prostaglandin synthesis= produces fever).

Front 6

Platelets

Back 6

Round or oval biconvex, anucleate corpuscle involved in blood clotting. Fragment of megakaryocytes. Produces growth factors and other factors.

Hint 6

Platelets are cell framents involved in clot formation, 2-4 microns in diameter. 200K-400K per microliter, No nucleus, cytoskeleton is a marginal band of microtubules, lots of actin and myosin (useful in clot retraction). Delta granules (very electron dense, contain elements picked up from other cells and stored temp. Ca ions, ADP, ATP, Serotonin absorbed by platelets from plasma) Alpha granules (platelet factor 4: vascular permeability, Ca mobilization from bon, chemotaxis of monocytes and neutrophils, Coagulation factors: fibrinogen, factor V, factor VIII) Lysosomes (contain hydrolytic enzymes) Dense tubular system (may be site of prostablandin synthesis) Derived from Megakaryocyte.

Front 7

Megakaryocyte

Back 7

The mother cell of platelets. Located in the bone marrow. Very large cells

Hint 7

Large polyploid cell with multilobed nucleus, cell extensions fragment into platelets, one cell can make appx 8000 platelets.

Front 8

Monocytes

Back 8

Peripheral blood leukocyte originating from bone marrow. After leaving blood and entering other tissues it can differentiate into macrophages or dendritic cells depending upon the stimulus.

Hint 8

3-8% of leukocytes, 12-20 micron cell diameter, agranular blue-gray cytoplasm. Granules: azurephilic= lysosomes for phagocytosis. Nucleus is oval, horseshoe, kidney shaped. Chromatin: delicate distribution, stains less intensely than in large. Act as macrophages (goes systemic)- secondary lymphoid tissue, liver, lung, connective tissue, interacts with lymphocytes to regulate immune response )antigen presentation), major cell type at inflammation site after neutrophils are spent.

Front 9

neucleus

Back 9

Prominent membrane-bound organelle in a eukaryotic cell containing DNA. Site of Synthesis of various RNA's

Hint 9

Nucleus of a nondividing cell consists of the following components: Chromatin (nuclear material organized as euchromatin and heterochromatin. It contains DNA, histones, and various nuclear proteins that are necessary for DNA to function) Nucleolus (small dense area within the nucleus that contains RNA and proteins. The nucleolus is the site of rRNA synthesis) Nuclear envolope (the membrane system that surrounds the nucleus of the cell. Cinsists of inner and outer membranes separated by a perinuclear cystenral space and perforatedby nuclear pores. The outer membrane of teh nuclear envolope is continyous with that of the rER and is often studded with ribosomes) Nucleplasm (the nuclear contents other than the chromatin and nucleoslus).

Front 10

neucleolus

Back 10

The nucleolus is the site of rRNA synthesis and is especially prominent in neurons

Hint 10

Nonmembranous, intranuclear structure formed by fibrillar material and granular material. Varies in size but is particularly well developed in cells active in protein synthesis. Consists largely of DNA loops of different c-somes containing genes for rRNA clustered together, large amounts of rRNA, and proteins.

Front 11

centriole (triplet microtubules)

Back 11

Organizes the microtubular system and the mitotic apparatus

Hint 11

Visible in the LM are paired short, rod like cytoplasmic cylinders built from nine microtubule triplets. In resting cells, centrioles have an orthogonal orientation. Usually found in close proximity to the nucleus, often partially surrounded by the golgi apparatus and assoiated with a zone of amorphous, dense pericentriolar material. CENTROSOME.

Front 12

Golgi

Back 12

Membranous stacks receiving proteins from RER. Proteins may be decorated with carbohydrate residues in the Golgi. Packages proteins into vesicles for further transport or secretion.

Hint 12

ER> pre-golgi intermediates (PGI), cis-median-trans cell membrane via bulk flow. Microtubule tracks- motors appear to be involved, Sorting=major function (Anterograde movement: cargo moves with flattened sack as it goes from cis to trans position, Retrograde movement: processing and targeting factors are recycled/retrieved along with membrane). CopI= coat protein complex I (moves things from pre-Golgi to ER, retrograde), CopII= coat protein complex II (exports cargo from ER, anterograde). Clathrin= forms coated vesicles at trans Golgi network and endocytosis. Hard to see in LM (negative staining), in EM = Sack of flattend membrane sheets, often adjacent to one side of nucleus

Front 13

mitochondria (cristae)

Back 13

Spherical or cigar-shaped organelles, bounded by a double membrane, associated with aerobic energy (ATP) productions from oxidation of fuels. Can sometimes be seen in the LM. Semi-autonomous with their own DNA, RNA and ribosomes. Accumulate calcium.

Hint 13

Outer membrane/intermembrane space/inner membrane. Foldings in inner membrane called cristae, contains enzymes of oxidative phosphorylation and ETC. Matrix xpace = enclosed by inner membrane (TCA, electron dense granules high in calcium, used for caclium sequestration.) Mt division derived from endosymbiotic prokaryotes, have own genome, inherited maternialy. Hard to see in LM can be seen in liver cells, EM shows 2 membrane system.

Front 14

microvilli

Back 14

Surface specializations to increase absorption. Glycosylated proteins are abundant. Actin forms the core.

Hint 14

Tightly packed, microscopic projections of the apical surface of intestinal absorptive cells. They further increase the surface available for absorption.

Front 15

rough endoplasmic reticulum

Back 15

A system of intracellular membranes studded with ribosomes. Contains newly-synthesized proteins. May be continuous with the Golgi Complex.

Hint 15

Engaged chiefly in protein sytnthesis. Stains intensly with basic dyes (because of RNA). With EM appears as a series of interconnected, membrane- limited flattened sacs called cisternae, with particles studding the exterior surface of the membrane (ribosomes attached with ribosomal docking proteins)

Front 16

smooth endoplasmic reticulum

Back 16

Endoplassmic reticulum lacking polyribosomes. Cisternae are often tubular and branching. Contains some enzymes reqired for steroid synthesis. Also serves as a site for oxidation and detoxification reactions. Perticularly in hepatocytes.

Hint 16

Membranous network in cell, no ribosomes, cisternae are more tubular with profusion of interconnected channels. Steroid producing cells: has enzymes involved in steroid sythesis. Liver: SER has enzymes anchored to membrane that are related to cytochrome p450, degrade hormones and noxious substances like -OH and barbituates. Typically not visable in LM, in EM flattened sheets, sacs and tubes of membranes without attached ribosomes.

Front 17

cilia

Back 17

Active in moving fluid. The cilium is the most common motor in the world.

Hint 17

Made of actin.

Front 18

basal bodies

Back 18

Sites of attachment (and production) of cilia.

Hint 18

each cilium requires a basal body. Repeated replications of centrioles and the migration of the newly replicated centrioles to the apical surface of the cell are responsible for the production of basal bodies. Serves as the organizing center for the assembly of the microtubules of the cilium. Look at the base of cilia. The thin dark staining band is usually seen extending across the cell at the base. This dark staining band represents structures know as basal bodies.

Front 19

lysosomes

Back 19

Intracellular vesicles containing hydrolytic enzymes. Segregation of their contents prevents damage to the cell itself.

Hint 19

organelles rich in hydrolytic enzymes such as proteases, nucleases, glycosidases, lipases, and such phospholipases. Responsible for degradation of macromolecules derived from endocytotic pathways as well as from the cell itself in a process known as autophagy (removal of cytoplasmic components, particularly membrane bounded organelles, by digesting them within lysosomes). Lysosomes have membranes that are resistant to the bad stuff inside them.

Front 20

free ribosomes

Back 20

Seen as dark separated dots in this fairly low-power TEM. Synthesize protein.

Hint 20

Ribosomes not attached to anything in cytoplasm. Approximately spherical bodies often arranged in strings or spirals (because they are strung together by messenger RNA)

Front 21

polysomes

Back 21

Not on atlas, but check out this link instead.

Hint 21

Essentially the same as free ribosomes. Polysomes are variable in length and are strings of ribosomes joined by messenger RNA. As the mRNA feeds through these ribosomes, so proteins are synthesised. The proteins synthesised by these free ribosomes pass into the cytoplasm.

Front 22

euchromatin

Back 22

Uncoiled chromatin, active

Hint 22

Extended/dispersed chromatin; transcriptionally active; lightly staining material compared to heterochromatin

Front 23

heterochormatin

Back 23

Clumped chromatin. Less active in transcription. Stains more densely than EUCHROMATIN

Hint 23

Condensed chromatin; transcriptionally inactive; appears electon dense in electron micrographs; an example of heterochromatin is the Barr body (inactive X chromosome)

Front 24

nuclear pore

Back 24

Channel through the NUCLEAR envelope that allows selected molecules to move between nucleus and cytoplasm

Hint 24

70-80 nm openings in the nuclear envelope; formed from fusion of inner and outer membranes; allows passage of molecules between the nucleus and cytoplasm; 3000-4000 per cell; mediate the active transport of proteins, ribonucleoproteins, and RNAs between the nucleus and cytoplasm; each pore contains many different proteins arranged in an octagonal symmetry (nuclear pore complex, NPC); NPC acts as a close-fitting diaphragm to mediate bidirectional nucleocytoplasmic transport

Front 25

nucleus

Back 25

Prominent membrane-bounded organelle in a eukaryotic cell containing DNA. Site of synthesis of various RNA's

Hint 25

Membrane limited compartment that contains the genetic information in eukaryotic cells; includes the nucleolus, chromatin, nuclear envelope, and nucleoplasm

Front 26

nuclear envelope

Back 26

N/A in atlas

Hint 26

Formed by two membranes with a perinuclear cisternal space between them; encloses the chromatin, defines the nuclear compartment, and serves as a membranous boundary between the nucleoplasm and the cytoplasm; possesses an array of openings called nuclear pores

Front 27

nucleolus

Back 27

The NUCLEOLUS is the site of rRNA synthesis and is especially prominent in neurons

Hint 27

Site of rRNA synthesis and initial ribosomal assembly; nonmembranous, intranuclear structure formed by fibrillar material (pars fibrosa) and granular material (pars granulosa); consists largely of DNA loops of different chromosomes containing genes for rRNA clustered together, large amounts of rRNA, and proteins

Front 28

secretory granules

Back 28

Storage vesicles containing zymogens and other substances. Appear as GRANULES in LM

Hint 28

Secretory cells which produce specialized substances used for digestion and degradation of matter; found in pancreas, goblet cells, exocrine and endocrine tissues

Front 29

plasma membrane

Back 29

Delimits cell and regulates exchange of materials between the cell and the extracellular fluid. Contains receptors for hormones and other signals

Hint 29

A lipid-bilayered structure composed of phospholipids, cholesterol, and protein molecules; amphipathic character: hydrophilic (polar) head and hydrophobic (nonpolar) tail; 8-10 nm thick; lipid component reflects asymmetry (phosphotidylcholine and sphingomyelin in outer leaflet; phosphatidlylethanolamine and phosphatidlylserine in inner leaflet); phospholipids diffuse laterally within the lipid bilayer; protein component consists of integral and peripheral proteins, receptor proteins (ion channels, G-protein linked receptors, enzyme-linked receptors)

Front 30

basal lamina

Back 30

Produced by epithelial cells. Not usually seen in LM. In LM the underlying reticular LAMINA is included in what we term BASAL LAMINA. In most texts the terms BASAL LAMINA and basement membrane are used interchangeably.

Hint 30

Structural attachment site for overlying cells and underlying connective tissue; specialized extracellular matrix produced mainly by epithelial cells; type IV collagen acts as the basic scaffolding; role in structural attachment (integrin adhesion; important for apoptosis and cellular signalling), compartmentalization of tissues, regulation of substances to and from connective tissues (ex: basal lamina in glomerulus in kidney acts as a molecular filter), guide or scaffold during regeneration; typically consists of collagen, proteoglycans, glycoproteins (entactin, fibronectin); also called lamina densa; the basal membrane (thinner, only visible in TEM, SEM) and the lamina reticularis comprise the basement membrane (visible in LM)

Front 31

brush border

Back 31

Surface specialized to increase absorption. Glycosylated proteins are abundant.

Hint 31

A distinctive border of vertical striations at the apical surface of the cell; has closely packed microvilli for increased absorption

Front 32

glycocalyx (on intestinal absorptive cell brush border)

Back 32

The polysaccharide coating of some cells. Particularly abundant on the mucosal surface of cells lining the small intestine.

Hint 32

Glycoproteins that project from the apical plasma membrane of epithelial absorptive cells; provides additional surface for adsorption; includes enzymes secreted by the absorptive cells that are essential for the final steps of digestion of proteins and sugars

Front 33

actin filaments

Back 33

The thin FILAMENT of muscle. Most cells contain ACTIN

Hint 33

A type of filament found in the cytoskeleton; thinner, shorter, and more flexible than microtubules; actin molecules assemble spontaneously by polymerization into a linear helical array of filaments 6-8nm in diameter; polarized structures with fast-growing end (plus or barbed end) and slow-growing end (minus or pointed end); participate in a wide variety of cell functions: anchorage and movement of membrane protein, formation of structural core of microvilli, locomotion of cells (push plasma membrane ahead of growing actin filiment), extension of cell processes (filopodia, cytoplasmic streaming)

Front 34

microtubules

Back 34

Tubular structures composed of tubulin. Involved in mobility and in the maintenance of cellular integrity

Hint 34

Nonbranching and rigid hollow tubes of protein that can rapidly disassemble in one location and reassemble in another; create a system of connections within the cell (i.e. railroad tracks) along which vesicular movement occurs; microtubules are elongated polymeric structure composed of of 13 circularly arrayed globular dimeric tubulin molecules (alpha tubulin and beta tubulin); the alpha and beta tubulin dimers are added to a gamma tubulin ring in an end-to-end fashion=length of microtubule changes dynamically as tubulin dimers are added or removed (dynamic instability); involved in numerous processes, including: intracellular vesicular transport (movement of secretory vesicles, lysosomes); movement of cilia and flagella; attachment of chromosomes to the mitotic spindle and their movement during mitosis and meiosis; cell elongation and movement (migration); maintenance of cell shape, particularly its asymmetry; dyneins move along the microtubules toward the minus end of the tubule (retrograde transport) while kinesins move along the microtubules toward the plus end (anterograde transport) [during mitosis and meiosis]; microtubules coordinate the movement of dynein (cilia & flagella beating) and kinesin (axonal transport)

Front 35

intermediate filaments (e.g., keratin filaments in epidermis)

Back 35

A subgroup of intermediate FILAMENTS. Provide structural protection for cells

Hint 35

Rope-like filaments with 8-10 nm diameter located between actin filaments and microtubules; organized into four major classes: keratins, vimentin, neurofilaments, lamins; intermediate filaments are essential for the integrity of cell-to-cell and cell-to-extracellular matrix junctions

Front 36

tight junction

Back 36

Zonula occludens. Forms an impermeable seal between two cells. In the GI tract TIGHT JUNCTIONs prevent the escape of digestive enzymes from the lumen into the intracellular space. Also prevent lateral migration of proteins of the apical cell membrane.

Hint 36

Form the intercellular diffusion barrier between adjacent cells; their impermeable nature allows epithelial cells to function as a barrier; also called occluding junctions; limit the movement of water and other molecules through the intercellular space; maintain physical-chemical separation of tissue compartments; located at the most apical point between adjoining epithelial cells; prevent the migration of specialized membrane proteins between apical and lateral surfaces and thus segregates certain internal membrane proteins on the apical surface while restricting others to the lateral or basal surfaces; maintain the mechanical integrity of cell; essential role in the selective passage of substances from one side of epithelium to the other; the tight junction is not a continuous seal, but rather a series of focal fusions between the cells

Front 37

desmosomes

Back 37

Disk-like intercellular attachments between neighboring cells. Abundant in epidermis

Hint 37

Anchoring cell-to-cell junction that provides lateral spot-like adhesion between epithelial cells; occupies small, localized sites on the lateral domain of the cell (like spot welds); occurs at small discrete sites; mediate calcium-dependent cell adhesion; cadherin is the adhesion molecule

Front 38

Clathrin coated pit/vesicle

Back 38

Pinocytotic vesicles arise from indentation of the plasma membrane at CLATHRIN-COATED pits. Thought to be active in imbibing liquids and in intracellular and transcellular transport.

Hint 38

Coated vesicles formed at the plasma membrane which fuse with cytoplasmic endosomes during exocytosis; fusion is mediated by specific surface receptors (receptor mediated endocytosis); the formation of the coated pit aids in forming invagination and pinches off the membrane, typically directed toward the Golgi apparatus

Front 39

hemidesmosomes

Back 39

Half of a desmosome. Attachment of epithelial cells to underlying basal lamina. Abundant in the skin

Hint 39

Anchor the intermediate filaments of cytoskeleton into the basement membrane; a type of anchoring junction which helps to maintain the morphological integrity of the epithelium-connective tissue interface; hemidesmosomes occur in epithelia that require strong, stable adhesion to connective tissue, such as cornea, skin, oral mucosa, esophagus, bagina; found on the the basal cell surface; provide increased adhesion to the basal lamina; contain integrin as the adhesion molecule and type XVII collagen

Front 40

zonula adherens

Back 40

N/A in atlas

Hint 40

A type of anchoring junctions that provides lateral adhesions between epithelial cells, using proteins that link into the cytoskeleton of the adjacent cells; interacts with the network of actin filaments inside the cell; occurs in a continuous band or belt-like configuration around the cell; composed of transmembrane adhesion molecule E-cadherin; extends around the entire perimeter of cell

Front 41

mitotic figures (in crypts of Lieberkuhn, thymus, epidermis...)

Back 41

It is important to recognize MITOTIC FIGURES because they are abundant only in epithelia ( especially of the GI tract), lymphoid tissue, and reproductive tissues of a healthy human adult. Abundant MITOTIC FIGURES elsewhere may indicate a malignancy.

Hint 41

Dividing cell found in renewing cell populations such as epithelial, mucosal, reproductive, lymphoid tissue; slow or rapid regular mitotic activity is expected in healthy dividing cell populations, as opposed to static cell populations which exhibit post-mitotic cells; mitotic figures found in non-dividing cell populations may be indicative of disease (cancer)

Front 42

simple cuboidal epithelium

Back 42

Simple - One layer thick. Cuboidal - Composed of cells resembling a cube in shape

Hint 42

Where? Small ducts of endocrine glands(absorption), surface of ovaries(barrier) and kidney tubules(absorption and secretion).

Front 43

simple squamous epithelium

Back 43

Composed of simple squamous cells. The cells look like scales, hence the name

Hint 43

Where? Vascular system(exchange), repiratory spaces in the lung(exchange)

Front 44

simple columnar epithelium

Back 44

EPITHELIUM composed of cells taller than they are wide. Typically found in the intestine

Hint 44

Where? Intestine (absorption and secretion)

Front 45

pseudostratified columnar epithelium

Back 45

Type of epithelium composed of tall columnar, ciliated cells, GOBLET cells, and nondifferentiated basal cells. All cells reach the basal lamina even though this epithelium may appear to be stratified

Hint 45

appears stratified, and although some of the cells do not reach the free surface, all the cells rest on the basement membrane. Where? Trachea, bronchial tree, ductus deferens, efferent ducts of epididymus

Front 46

transitional epithelium

Hint 46

Also called urothelium. Epithelium lining the lower uninary tract (bladder, ureters, urethra), stratified epithelium with specific morphologic characteristics that allow it to distend

Front 47

stratified cuboidal epithelium

Back 47

Stratified - many layers. Cube shaped cells

Hint 47

Where? Sweat gland ducts, large ducts of exocrine glands - barrier

Front 48

stratified squamous epithelium

Back 48

Multi-layered EPITHELIUM. Nomenclature refers to the shape of the surface cells only

Hint 48

Where? Epidermis, oral cavity, esophogus, vagina - barrier, protection

Front 49

keratinized stratified squamous epithelium

Back 49

The superficial (outer) layer of skin consisting of STRATIFIED squamous, keratinized EPITHELIUM

Hint 49

keratinocytes originate in the basal epidermal layer, they produce keritin that is a major structural protien of the epidermis and participates in the formaiton of the epidermal water barrier

Front 50

mucosa

Back 50

Composed of EPITHELIUM, glands, lamina propria, and muscularis mucosa. Often referred to as mucous membrane

Hint 50

mucosa is the side closest to/ in the lumen

Front 51

submucosa

Back 51

Connective tissue layer beneath the mucosa. In the GI tract it is located between the mucosa and the muscularis externa

Hint 51

dense connective tissue found below the mucosa containing variable amounts of adipose tissue, blood vessels, and nerve fibers

Front 52

basal lamina

Back 52

Produced by epithelial cells. Not usually seen in LM. In LM the underlying reticular LAMINA is included in what we term BASAL LAMINA. In most texts the terms BASAL LAMINA and basement membrane are used interchangeably

Hint 52

specialized extracellular matrix produced mainly by epithelial cells; continuous thin mat - type 4 collagen fibers, laminin and proteoglycans; cells attach via integrins. Integrin adhesions give intracellular signals needed for survival - loss of adhesions leads to programmed cell death; also acts as a filter

Front 53

brush border

Back 53

On Another list

Front 54

goblet cell (+ secretory granules)

Back 54

unicellular exocrine gland that secretes mucin.

Hint 54

Nucleus is located at the basal part of the cell; majority of the cell is filled with mucinogen granules at the apical end (much fuller than the basal end). Microvilli of golblet cells are restricted to a thin rim that surrounds the apical surface.

Front 55

intestinal absorptive epithelial cells

Hint 55

Microvilli increase surface area, apical membranes specialized for absoption

Front 56

mitotic figures in intestinal crypts

Back 56

It is important to recognize MITOTIC FIGURES because they are abundant only in epithelia ( especially of the GI tract), lymphoid tissue, and reproductive tissues of a healthy human adult. Abundant MITOTIC FIGURES elsewhere may indicate a malignancy

Hint 56

Replicating cells

Front 57

lamina propria

Back 57

The connective tissue under the epithelia

Hint 57

loose connective tissue of mucous membranes such as those of the respiratory system and alimentary systems, contains a large number os these cells

Front 58

plasma cells

Back 58

Specialized end state of a B lymphocyte. Produces antibodies. A given CELL produces only one kind of antibody

Hint 58

Prominent constituent of loose connective tissue where antigens tend to enter the body; derived from its percursor, the B lymphocyte, a plasma call has only limited migratory ability and somewhat short life span of 10-30 days. Cell is relatively large(20 microm) with a large amount of cytoplasm; resembles a clockface - heterochromatin resembles to numbers. Cell functions to synthesize large amounts of protien - one specific antibody from a cell

Front 59

mast cells

Back 59

Initiators of the inflammatory response. Produce histamine and other compounds. Have early origins in bone marrow, but migrate to other tissues during development and specialize in response to stem CELL growth factor. Most of body's IgE is on them

Hint 59

large, connective tissue cells with a spherical nucleus and cytoplasm filled with large, intesly basophilic granules; the cell surface exhibits numerous microvilli and folds, the cytoplasm displays small amounts of ER, mitochondria, and Golgi. Ganules contain heparin.

Front 60

dense connective tissue

Back 60

Typically has more fibers than cells, as opposed to loose CONNECTIVE TISSUE

Hint 60

Collagen fibers are more numerous and desley packed; cells are relatively sparse and limited to fiberblasts; abundant where only strength is required.

Front 61

loose connective tissue

Back 61

Has numerous cells and few fibers. Cells readily migrate through loose CONNECTIVE TISSUE

Hint 61

located beteath the epithelia that covers the body sufaces and line the internal surfaces of the body; associated with the epithelium of glands and surrounds the smallest vessels; this tissue is the initial site where pathogenic agent such as bacteria have breached an epithial surface can be challenged and destroyed by cells of the immune system - site of inflammatory and immune responses - loose connective tissue can swell a lot

Front 62

macrophages in loose connective tissue

Back 62

Regulates the immune response. Presents antigens to lymphocytes. Originates from blood monocytes. The best phagocyte in the body. Closely related to dendritic cells of immune system

Hint 62

derived from monocytes - monocytes migrate from the bloodstream into the connective tissue where they differentiate. Easiest to identify if there is evidence of phagocytic activity, kidney shaped nucleus; may contain endocytotic vesicles, phagolysosomes, and other evidence of phagocytosis; regulated secretions can be regulated by phagocytosis, immune complexes, complement, and signals from lymphocytes

Front 63

lymphocytes in loose connective tissue

Back 63

These are the key players of the immune system. There are many different categories of LYMPHOCYTEs. Unfortunately in the LM with ordinary staining methods they all tend to look alike. Typically they have a large nucleus with little cytoplasm

Hint 63

Effector cells in the response of the immune system to harmful substances. 30% of lymphocytes to do not circulate and can be found in the loose connective tissue - these cells are often immature cells or activated cells designated for a specific area

Front 64

hyaline cartilage

Back 64

Most abundant CARTILAGE type in the body. Called hyaline because of its glassy appearance. Matrix contains type II collagen and glycosaminoglycans

Hint 64

Characterized by matrix containing type III collagen fibers, proteoglycans, and hyaluronic acid. Throughout the cartilage matrix spaces are called lacunae. Provides low friction surface, lubrication in synovial joints, distributes applied forces to underlying bone; produced by chondrocytes

Front 65

perichondrium

Back 65

Surrounds the cartilage like a capsule. Contains chondrogenic cells

Hint 65

Dense connective tissue composed of cells that are indistinguishable from fibriblasts; serves as a source of new cartilage

Front 66

collagen fibers (in dense connective tissue)

Back 66

Type I COLLAGEN molecules are organized in fibrils. Several fibrils, in turn, comprise a COLLAGEN fiber

Hint 66

Flexible and have high tesile strength; Type I is found in dense connective tissue and makes up roughly 90% of the body's collagen. If functions to provide resistance to force, tension and stretch

Front 67

cilia (cross section, longitudinal section, 9 + 2)

Back 67

Active in moving fluid. The cilium is the most common motor in the world

Hint 67

The cross section is arranged with an outter ring of 9 microtubule doublets and a central pair of microtubules. The microtubules are composed of tubulin dimers; each microtubule has dynein arms - motor protien. Dynein uses ATP hydrolysis. The bottom of the cilia - basil body - cross section = 9 microtubule triplets nad none in the center

Front 68

neutrophils in loose connective tissue

Back 68

Not exactally found in atlas, check this out

Hint 68

Sometimes sneak into the loose connective tissue. Involved in immune defense and inflammation.

Front 69

keratinized stratified squamous epithelium

Back 69

The superficial (outer) layer of skin consisting of STRATIFIED SQUAMOUS, KERATINIZED EPITHELIUM. Epidermis of the skin, but may occur in some other places, e.g. tongue and palate.

Hint 69

Keratinocyte is the predominate cell type of the epidermis. These cells originate in the basal epidermal layer. On leaving this layer, kerationcytes assume two essential activities (1) produce keratin, the major structural protein of the epidermis. Keratin cinstitutes almost 85% of fully differentiated kerationcytes. (2) they participate in the formation of the epidermal water barrier.

Front 70

fibroblast

Back 70

Protein-synthesizing factory of the connective tissue. Produces both fibers (collagen and others) and ground substance.

Hint 70

responsible for the synthesis of collagen, elastic and reticular fibers, and the complex CH2O of the ground substance. Reside in close proximity to collagen fibers. Mostly nucleus is the only thing visable. Fibroblasts in some locations constitute a replicating population of cells that have a particularly close physical relationship within the overlying epithelium. They are believed to interact with the epithelium in normal renewal and differentation in the ault organism.

Front 71

adipocytes (fat cells)

Back 71

Cells active in the synthesis and storage of triglycerides, and in the release of fatty acids and glycerol.

Hint 71

individual fat storing cells and groups of adipocytes are found throughout loose connecctive tissue. Tissues in wich adipocytes are the primary cell type are designated adipose tissue. They function as fat storage containers. Fat is an efficient form of calorie storage because it has about twice the calorie density of the CH2O and protein.

Front 72

myoepithelial cells (sweat glands)

Back 72

Specialized cells which are contractile and aid in secretion of glandular fluids.

Hint 72

Contractile cells with numerous processes. They lie between the basal plasma membrane of the epithelial cells and the basal lamina of the epithelium. They also underlie the cells of the proximal portion the they duct system. In both locations, the myopeithelial cells are instrumental in moving secretory products toward the excretory duct. The nucleus of the cell is often seen as a small round profile near the basement membrane. The contractile filaments stain with esin and are sometimes recognized as a thin eosinophilic band adjacent to the basement membrane.

Front 73

thymus

Back 73

Divided into lobules, which are separated by connective tissue septa. Each lobe has peripheral dark zone, the cortex, and a central light zone, the medulla. There is no sharp border between the two parts.

Hint 73

Lymphoepithelial organ that is fully functionaly at birth, but regresses after puberty when T-cell differentiation and proliferation has slowed. Thymus has a connective tissue capsule and trabeculae that contain blood vessels, efferent lymphatic vessels and nerves.

Front 74

thymic cortex

Back 74

Darkly staining due to large number or lymphocytes. Look for Mitotic figures, reticular epithelial cells, and macrophages. The Thymic Cortex produces more lymphocytes than any other lymphoid tissue. No Afferent lymphatics exist

Hint 74

Positive T-Cell selection takes place here. T-Cells here have a high mitotic rate because most of them fail to recognize self MHC. These reject T-cells are cleaned up by Macrophages. NO AFFERENT LYMPHATICS.

Front 75

thymic lobule

Back 75

Lobule contains both a cortex and medulla and is separated by connective tissue.

Hint 75

Domains established by the trabeculae. They are cortical caps over portions of the highly convoluted but continuous inner medually tissue.

Front 76

lymphocytes in the thymic cortex

Back 76

Just like any other lymphocyte.

Hint 76

These T-cells are also called thymocytes. Abundant in cortex of thymus and give dark staining appearance to cortex.

Front 77

epithelial reticular cells of the thymic cortex

Back 77

Form 3-D framework of the thymus. Probably have a role in T-Cell development.

Hint 77

Associated with basal lamina. They form a sheath around a capillary. Provide a framework for developing T-cells. 3 types located in cortex. Types II and III have both MHC I and II molecules and are involved in T-cell education. Type I separates thymic parenchyma from the connective tissue of the organ.

Front 78

macrophage of the thymic cortex

Back 78

Regulate immune response. Present antigens to lymphocytes.Originate from blood monocytes. The best phagocytic cells in the body, and is closely related to dendritic cells.

Hint 78

Phagocytose T-Cells that do not fulfill thymic education requirements.

Front 79

lymphocyte mitotic figues, thymic cortex

Back 79

Abundant in epithelia, lymphoid tissue, and reproductive tissue of healthy human adult. Abundant mitotic figues elsewhere in the body may indicate a malignancy.

Hint 79

They are numerous in thymic cortex. Evidence of rapidly dividing lymphocytes due to selection.

Front 80

thymic medulla

Back 80

Lighter than cortex. Fewer lymphocytes are present, but more epithelial cells are present. Mature T-Cells exit through Efferent lymphatics and venules via the medulla. NO Afferent lymphatics exist in the thymus.

Hint 80

Negative T-Cell selection takes place here, mediated by macrophages and dendritic cells. Fewer lymphocytes. More macrophages and epithelioreticular cells. Venules and Efferent lymphatics present for exiting educated lymphocytes.

Front 81

Hassall's corpuscles

Back 81

Formed by epithelial reticular cells of the thymus. Thought to produce various cytokines.

Hint 81

Epithelial cells wrapped around eachother. They are the DISTINGUISHING FEATURE OF THE THYMIC MEDULLA. They are made up of concentrically arranged type VI epithelioreticular cells with flattened nuclei. May produce thymic hormones. Function not fully understood.

Front 82

lymph node

Back 82

Have abundant type III collagen fibers, which act as scaffold.

Hint 82

Small encapsulated organ that serves as a filter through which lymph percolates on its way to the blood. Supporting elements are capsule, trabeculae, and reticular tissue. Lymph node is an important site for phagocytosis and initiation of immune responses.

Front 83

Peyer's patch

Back 83

A lymphoid aggregation in the ileum.

Hint 83

Lymphocytes enter via high endothelial cell postcapillary venules and exit via blood vessels. Consist of numerous aggregations of lymphatic nodules with T and B cells. Important in mucosal defense of small intestine.

Front 84

lymph node cotex

Back 84

Look for capsule, subcapsular sinus, high endothelial cell postcapillary venules, and lymphoid follicles. Usually contains several germinal centers.

Hint 84

Outer portion of lymph node. Consists of a dense mass of lymphatic tissue, lymphatic sinuses and lymph channels. Lymphocytes here are organized into nodules. These nodules are called primary nodules if they consist of mostly small lymphocytes and secondary nodules if they have a germinal center.

Front 85

lymph node medulla

Back 85

Contains lymphatic sinuses and cellular cords.

Hint 85

Inner part of the lymph node. Contains cords of lymphatic tissue separated by lymphatic sinuses called medullary sinuses. Medullary cords contain lymphocytes, macrophages, and plasma cells.

Front 86

type III collagen (reticular) fibers (silver stain)

Back 86

More delicate than type I. Abundant in cardiovascular tissue and lymphoid tissue. They provide structural support.

Hint 86

Reticular cells secrete collagen (reticular fibers) and ground substance. Form a fine, supporting meshwork throughout the lymph node.

Front 87

high endothelial cell post-capillary venules

Back 87

Found in lymphoid tissue, Ecluding the thymus. Endothelial cells are tall and lack tight junctions. This fascilitates entry of lymphocytes into lymphoid tissue from the blood.

Hint 87

MAJOR site of lymphocyte entry. Located in lymph node medulla. Lined by columnar or cuboidal endothelial cells. Have specialized receptors for antigen-primed lymphocytes. They signal lymphocytes to leave circulation and migrate into lymph node.

Front 88

primary and secondary lymph nodule in lymph node

Back 88

A ball having a lighter staining center. A place for B-Cell production.

Hint 88

A lymphatic nodule consisting chiefly of small lymphocytes is a primary nodule. Most nodules are secondary nodules and have germinal centers.

Front 89

lymphocytes in lymph node

Back 89

Key players in the immune system. Most of them have a large nucleus and little cytoplasm.

Hint 89

Leave via Efferent lymphatics. Antigen presentation to lymphocytes allows for differentiation of B-Cells into memory B-cells or plasma cells to make antibodies.

Front 90

germinal center

Back 90

A place where B-Cells are produced in lymphoid tissues other than the thymus. Appears as a lighter-stained center of a ball of lymphocytes (lymph nodule).

Hint 90

Located in center region of nodule. Appears lightly stained. Germinal center develops when a lymphocyte that has recognized an antigen returns to the primary nodule. It is a morphologic indication of lymphatic tissue response to the antigen. Mitotic figures are often prevalent.

Front 91

lymphatic vessel

Back 91

Transport lymph and macromolecules from the tissues. Lymphatic vessels are an important supplement to the veins in returning fluids to the heart.

Hint 91

Begin as networks of blind capillaries in loose connectice tissue. Remove substances and fluid from extracellular spaces of the connective tissue, thus producing lymph. They are the route by which cells and large molecules pass from the tissue spaces back to the blood. Afferent lymphatics are possible entry sites for lymphocytes.

Front 92

lymphatic vessel with valve

Back 92

Lymphatic vessels typically have frequent valves to help prevent backflow. The presence of valves provides a convenient way of identifying small lymphatics.

Hint 92

Help direct flow of lymph, prevent backflow.

Front 93

sinusoids of lymph node medulla

Back 93

The medulla of lymph node is composed of sinuses, or sinusoids, and cellular cords. Sinuses eventually lead into the efferent lymphatic vessels.

Hint 93

Drain into efferent lymphatic vessels.

Front 94

lymph node capsule

Back 94

An envelope of variable thickness surrounding an organ, or part of it. Usually, but not always, composed of connective tissue.

Hint 94

composed of dense connective tissue that surrounds the node

Front 95

lymph node subcapsular sinus

Back 95

In lymph nodes, the area immediately beneath the capsule. Lymphocytes enter here via the afferent lymphatics.

Front 96

appendix

Hint 96

arising from the cecum, contains many lymphatic nodules and is heavily infiltrated with lymphocytes. In early life functionally associated with bursa equivalent organs, but tissue regresses with age.

Front 97

lymph nodule in appendix

Back 97

A ball having a lighter-staining center. This is a place for B-cell production.

Front 98

spleen

Hint 98

about the size of a clenched fist, largest lymphatic organ, located in Upper left abdominal quadrant

Front 99

splenic capsule with connective tissue trabeculae

Back 99

splenic capsule -Connective tissue capsule covering the spleen./trabeculae - Blood filter. In the red pulp of the spleen the trabeculae are composed of numerous cells, including macrophages, dendritic cells, fibroblasts, (and all cells of the blood traveling through).

Hint 99

Contain Myofibroblasts - contractile cells that also produce connective tissue fibers.

Front 100

spleen, red pulp, sinusoids, white pulp

Back 100

Red pulp - Composed of the sinusoids of the spleen. The sinusoids are normally filled with blood and appear red in fresh spleen, thus the name. The white pulp refers to the lymphoid tissue of the spleen. In Fresh spleen one can see white roundish areas embedded in the red pulp.

Hint 100

In slides red pulp is white and white pulp is red. Old RBCs recycled by Macrophages & if fragile break while squeezing through sinusoid lumen. Sinusoid basal lamina is fenestrated. Endothelial cells like barrel staves, actin controls gaps between cells.

Front 101

spleenic central artery with lymphocyte sheath

Back 101

The central artery in the spleen is surrounded by lymphocytes. Most of these are T-cells.

Hint 101

central arteries are branches of splenic artery

Front 102

splenic sinuses, spindle shaped endothelial cells

Back 102

Endothelial cells prevent thrombus formation. By producing NO and endothelin they help regulate intravascular pressure. Some regard the endothelial cells as constituting the largest endocrine organ in the body.

Hint 102

long rod shaped endothelial cells stain with silver. No continuous basal lamina. No smooth muscle or pericytes present in wall o splenic sinuses

Front 103

epidermis

Back 103

The superficial outer layer of the skin consisting of stratified squamous, keritinized epithelium

Hint 103

specialized apoptosis occurs in which cells do not rupture

Front 104

desquamating cells of epidermal nonkeratinized stratified squamous epithelium

Back 104

cells that are sloughing off

Front 105

dermis

Back 105

The connective tissue layer in the skin located between the epidermis and hypodermis.

Hint 105

Pappilary layer just beneath the epidermis, nervous and vascular papillae, extensive network of collagenous, reticular and elastic fibers.

Front 106

Pacinian corpuscle

Back 106

encapsulated sensory receptors. Composed of several layers of concentric fibroblasts and a centrally-located unmyelinated nerve ending. Believed to sense vibration and pressure.

Hint 106

Onion like structure

Front 107

stratum basale

Back 107

lowest and stem-cell layer of stratified epithelium

Front 108

stratum spinosum

Back 108

Prickle cell layer. Second innermost layer of the epidermis. Neighboring cells have many desmosomes between them

Hint 108

Keratinocytes and Merkel cells are joined by numerous desmosomes. Cells are polyhedral.

Front 109

stratum lucidum

Back 109

Is present only in thick skin. The transparent-appearing layer between the stratim corneum and the stratum granulosum

Hint 109

3 to 5 layers of flattened cells, translucent, indistinguishable cell boundaries, lost all organelles (including keratohyalin granules). Tonofibrils arranged parallel to surface of the skin and contain semifluid keratohyalin.

Front 110

stratum granulosum

Back 110

The third innermost layer of the epidermis. Keratin appears in the form of granules.

Hint 110

3 to 5 layers of cells, mostly keratinocytes. Produce filagrin which causes the aggregation of keratinfilaments in stratum corneum. Cells die in this layer.

Front 111

keratohyalin granules

Back 111

Basophilic, irregularly shaped structures without membranes. Present mainly in stratum granulosum in epidermis.

Front 112

sweat gland

Back 112

Simple tubular coiled gland of the skin. Produces and excretes a hypotonic sodium chloride solution. Involved in thermoregulation.

Hint 112

Eccrine, duct opens at surface, non viscous secretion; Apocrine duct opens into hair follicle, viscous secretion, located in axillary, areolar and anal regions.

Front 113

myoepithelial cells

Back 113

Specialized cells which are contractile and aid in the secretion of glandular fluids.

Front 114

sebaceous glands

Back 114

Pluristratified alveolar glands with holocrine secretion. Scattered in dermis except in palms and soles.

Hint 114

cells differentiate, accumulate lipids, pushed from apex of gland. Cells rupture to produce sebum, a protective fat material.

Front 115

hair follicle, papilla

Back 115

site for production of hairs, papilla is connective tissue core of hair follicle.

Hint 115

connective tissue sheath derived from dermis, hair root and sheath merge at papilla

Front 116

hypodermis (with adipocytes)

Back 116

Layer of skin beneath the dermis. Deepest layer of skin.

Hint 116

loose connective tissue contains varying amounts of adipose tissue, provides mobility of skin over underlying body parts

Front 117

cardiac muscle

Back 117

A specialized, striated, MUSCLE. The MUSCLE fibers anastomose to form a complex three-dimensional network

Hint 117

Striated, mono-nucleated, involuntary muscle cells with prominent intercalated disc interconnections. Nucleus at center of cell distinguishes cardian from skeletal muscle. Exercise induces hypertrophy.

Front 118

skeletal muscle

Back 118

Functional unit composed of large number of SKELETAL MUSCLE fibers grouped in MUSCLE fascicles and enveloped in successive connective tissue sheaths. Usually under voluntary control.

Hint 118

Striated, long, multi-nucleated fiber (cells) voluntary muscle cells. Cylindrical multi-nucleated, up to 30 cm long, and 10-100 micron in diameter. Multi-nucleation result of fusion of embryonic myoblast precursors. Nuclei at periphery. Exercise induces hypertrophy (increased cell volume without an increase in cell number)

Front 119

smooth muscle

Back 119

Long spindle-shaped cells arranged so that the thin end of one cell is adjacent to the thickest portion of another cell. Usually involuntary. An aggregation of many smooth MUSCLE cells forms the contractile portions of various organs.

Hint 119

Non-Striated, mono-nucleated slow, involuntary muscle cells (e.g. peristalsis of the gut). Capable of Hyperplasia (e.g. uterus)

Front 120

endocardium

Back 120

The innermost layer of the heart. Lined with endothelium. Equivalent to the tunica intima of blood vessels.

Hint 120

Inner layer of endothelium and subendothelial connective tissue (a middle layer of connective tissue and smooth muscle cells and deeper layer of connective tissue also called subendocardiac layer which is continuous with connective tissue of the myocardium) The impulse conducting system of the heart is in the subendocardial layer.

Front 121

myocardium

Back 121

Middle layer of the heart. Composed of cardiac muscle. Equivalent to the tunica media of blood vessels.

Hint 121

Mostly cardiac muscle, principal component of the heart. The myocardium of the ventricles is substantially thicker than that of the atria because of the thick cardiac muscle in the walls of the two pumping chambers.

Front 122

epicardium

Back 122

Composed of simple squamous epithelium and connective tissue. Delimits the heart. The pericardium has two layers, EPICARDIUM, which covers the myocardium, and the pericardial sac.

Hint 122

layer of mesothelial cells on the outer surface of the heart and its underlying connective tissue. The blood vessels and nerves that supply the heart lie in the epicardium and are surrounded by adipose tissue that cushions the heart.

Front 123

cardiac muscle cells

Back 123

Typically cardiac MUSCLE cells have a single nucleus located in the middle of the cell. (SKELETAL MUSCLE cells are multinucleate with the nuclei located peripherally.)

Hint 123

Up to 40% of volume is mitochondris using lipid droplets as an energy source. Not as well organized as skeletal muscle, only one T-tubule per sarcomere at level of Z-line.

Front 124

cardiac muscle cell nucleus

Back 124

Typically cardiac MUSCLE cells have a single nucleus located in the middle of the cell. (SKELETAL MUSCLE cells are multinucleate with the nuclei located peripherally.)

Hint 124

single nucleus near the middle of each muscle cell.

Front 125

intercalated disks

Back 125

In cardiac muscle these are the sites of end-to-end attachments of individual muscle cells.

Hint 125

Highly specialized junctional complexes between cardiac muscle cells with transverse and lateral portions. Transverse portions have fascia adherentes ("hemi-Z-bands") anchoring sites of actin filaments from terminal sarcomeres. Also have macula adherentes (desmosomes). The lateral face has Gap Junctions to provide ioninc coupling whick allow the signal to move as a wave across chains of cells. This allows cells to act like a synctium.

Front 126

sarcomere

Back 126

Fundamental functional unit of muscle. Extends from one Z-line to the next

Hint 126

Basic contractile unit of the striated muscle between adjacent Z-lines. 2-3 micron in relaxed muscles. Interdigitating Thin and Thick Filaments.

Front 127

A-bands

Back 127

In striated muscle the A (anisotropic) BAND is the BAND formed by overlapping thin and thick filaments. Appears dArk in LM and TEM.

Hint 127

Demarks the extents of the myosin filaments. See the Diagram from Lecture

Front 128

I-bands

Back 128

The light BAND in striated muscle. Contains thIn filaments

Hint 128

Thin filament region, shrinks with contraction of muscle fibers. See Diagram from Lecture

Front 129

Z-lines

Back 129

Border between two sarcomeres. The area at which the thin filaments of adjacent sarcomeres attach. Named from the German Zwischenscheibe meaning the BAND in between

Hint 129

Anchor sites of actin filaments which extend from the Z-line into the A-band region. See the Diagram from Lecture

Front 130

H-zone

Back 130

The light BAND in striated muscle. Contains thin filaments

Hint 130

Thick filament regions, shrinks with muscle fiber contraction. See the Diagram from Lecture

Front 131

endomysium

Back 131

Thin connective tissue capsule surrounding individual muscle fibers. In heart it is part of the so-called cardiac skeleton.

Hint 131

delicate tissue, surrounds each skeletal muscle fiber (innermost layer of muscle fiber organization)

Front 132

perimysium (not paramecium or paramyosin...)

Back 132

After linking, go to Item 2 (good for endo, peri, & epimysium)

Hint 132

septa of connective tissue surrounding bundles of skeletal muscle fibers (intermediate layer of muscle fiber organization)

Front 133

epimysium

Back 133

After linking, go to Item 2 (good for endo, peri, & epimysium)

Hint 133

dense connective tissue surrounding entire muscle in skeletal muscle (outermost layer of muscle fiber organization)

Front 134

tendon

Back 134

Strong bundle of collagen fibers connecting muscle to bone

Front 135

myotendenous junction (from atlas and lecture slides)

Back 135

After linking, go to Item 3.

Hint 135

a.ka. Muscle-Tendon Junction…specialized dense connective tissue continuous with surrounding muscle fibers which help transmit the force. Collagen fibers of the tendon insert into complex infoldings of the cell membrane. This allows for the contractile activity of the muscle fibers to be translated into useful work by moving or stabilizing parts of the body.

Front 136

lipofuschin pigment

Back 136

Brown PIGMENT present in many kinds of cells. Represents indigestible material. Prominent in neurons and cardiac muscle cells that do not divide and disperse their cytoplasmic contents.

Hint 136

Adult cardiac muscle cells do not normally divide and are not replaced, during long life accumulate residual bodies - aka lipofuscin granules = digested cellular components in lysosomes

Front 137

Purkinje fibers

Back 137

Highly-specialized cardiac muscle cells designed for conduction. Contain much glycogen (which dissolves during tissue preparation).

Hint 137

large myocytes (modified muscle cells just under the endocardium) in cardiac muscle which pass the conduction signal through the cardiac muscle. Conduct action potentials more rapidly then cardiac muscle cells (3-4 meters/sec vs. 0.5 meters/sec

Front 138

smooth muscle cell dense bodies (from lecture slides)

Back 138

After linking, go to Item 14

Hint 138

Dense bodies (both membrane and cytoplasmic) are Z-line analogs in that they crosslink the myofilament bundles that form the lattice-like network of the smooth muscle contractile unit.

Front 139

elastic artery (aorta)

Back 139

Composed of elastic laminae and smooth muscle. It is difficult to distinguish between the tunica intima nad media.

Hint 139

Diameter >1cm, Inlcudes the aorta, common carotids, brachiocephalic, subclavians, and most of pulmonary arteries. Composed primarily of elastic lamina and smooth muscle. Intima layer has endothelium, connective tissue and smooth muscle; media has smooth muscle and elastic lamenae; adventitia layer has connective tissue, elastic fibers, and is thinner than media layer. With age, the elasticity is lost, leading to increased peripheral resistance and BP.

Front 140

elastic lamellae of elastic artery media

Back 140

The elastic sheaths found in arteris and some veins

Hint 140

Part of tunica media - interposed elastic fibers and lamellae

Front 141

smooth muscle in media of elastic artery, muscular artery, etc.

Back 141

Long spindle shaped cells arranged so that the thin end of one cell is adjacent to the thickest portion of another cell. Usually involuntary. An aggregation of many smooth muscle cells forms the contractile portions or various organs.

Hint 141

Also part of tunica media, which is made up of concentric layers of smooth muscle cells (interposed by elastic fibers and lamellae).

Front 142

muscular artery

Back 142

A distrubuting artery. The thickest layer of the wall ist he media, composed of smooth muscle.

Hint 142

2-10 mm in diameter, main distributing branches or arterial tree (radial, femoral, coronary, and cerebral arteries). Same basic structure as elastic artery, but elastic tissue is reduced to prominent, fenestrated elastic sheet, the internal elastic lamina. The presence of a muscular artery can be distinguished from a large vein by comparing the relative wall thickness compared to lumen diameter. Note that the prominent internal elastic lamina which is seen in the artery is in fact, missing in the thinner walled vein.

Front 143

arteriole

Back 143

The smallest of arteries.

Hint 143

10-100microns in diameter. 1-2 cell layers thick of smooth muscle in media layer. Prominent elastic membrane in small arteriole. Single layer of flattened epithelial cells make intima. Adventitia merges with surrounding tissue.

Front 144

tunica intima

Back 144

The innermost layer of blood vessels.

Hint 144

layer of endothelial cells lining interior surface (1% turnover per day); basal lamina; subendothelial layer = loose connective tissue, smooth muscle (optional) both with longitudinal fibers; contains internal elastic lamina (in arteries) = elastin with fenestrae to allow diffusion of substances deep into vessel wall. Tunica intima of the heart is called the endocardium.

Front 145

endothelial cells, endothelial cell nuclei

Back 145

Endothelial cells prevent thrombus formation by producing NO and endothelin - they help regulate intravascular pressure.

Hint 145

Flat layer of polygonal cells lining lumen, esp. blood vessels and lymphatics. Connected to neighbors via junctional complexes; numerous pinocytotic vesicles; act as permeability barrier; produce interleukins and cell adhesion molecules; synthesize growth factors (FGF, PDGF).

Front 146

tunica media

Back 146

middle layer lining a blood vessel - difficult to tell difference between intima and media in aorta (elastic artery)

Hint 146

Intermediate muscular layer of vessels - concentric layers of smooth muscle cells; interposed elastic fibers and lamellae, reticular fibers, proteoglycans; in capillaries and postcapillary venules media is replaced by pericytes. Tunica media layer of heart is myocardium.

Front 147

tunica adventitia

Back 147

The outermost of the three layers of the blood vessel wall. It contains collagen, some elastic fibers, and some fibroblasts.

Hint 147

Outer, supporting tissue layer of vessels - Longitudinally oriented collagen (mostly type I) and elastic fibers; gradually becomes continuous with enveloping connective tissue of organ through which vessel runs. Tunica adventitia of heart is the epicardium (also visceral pericardium)

Front 148

elastic lamina

Back 148

Border between intima and media in a muscular artery

Hint 148

made of elatic tissue - it is a well defined, fenestrated elastic sheet, separating tunica intima from tunica media. (there is also sometimes a external elastic lamina separating media from adventitia layers).

Front 149

skeletal muscle cell

Back 149

Functional unit composed of large number of skeletal muscle fibers grouped in muscle fascicles and enveloped in successive connective tussue sheaths. Usually under voluntary control.

Hint 149

Sarcomere is smallest functional, contractile unit. Cross section shows "beautiful" crystalline array. Sarcomere stretches from Z-line to Z-line, has A band, I band, H band, M band. Has interdigitating thick (myosin) and thin (actin) bands.

Front 150

vas vasorum

Back 150

vessels of the blood vessel wall. Literally, vasa vasorum means vessels of a vessel.

Hint 150

"Vessels of vessels" = nourish deeper cells (further from lumen in media and adventitia); more prominent in veins (deoxygenated blood in lumen); penetrate the vessel wall and branch profusely.

Front 151

veins

Back 151

carries (usually deoxygenated) blood towards the heart.

Hint 151

Smaller wall thickness compared to artery with same lumen diameter.

Front 152

venous valves

Back 152

At point where a small vein enters a larger one or along a vein to prevent backflow of blood.

Hint 152

Valves consist of delicate semilunar projections of tunica intima of vein wall. Projections are composed of fibroelastic tissue. 2 leaflets per valve w/ free ends projecting in direction of blood flow. Valves only occur in veins >2mm in diameter, esp in extremities.

Front 153

venules

Back 153

Smallest vein. The postcappilary venule is the smallest of venules.

Hint 153

Nerves can act on smooth muscle layers to cause vasoconstriction. Release norepinephrine in adventitia layer (nerves usually don't penetrate to media). NE diffuses in and causes contraction - gap juntions allow contraction in whole layer.

Front 154

lymphatics

Back 154

Transport lymph and macromolecules from the tissues. Lymphatic vessels are an important supplement to the veins in returning fluids to the heart.

Hint 154

Drain excess fluid (lymph containing water and electrolytes and some plasma proteins) from extracellular spaces and returns it to blood vascular system. Lymph from hydrostatic pressure of blood exceeding colloidal osmotic pressure from plasma proteins. Walls of vessels even thinner than veins of similar size.

Front 155

lymphatic valve (leaflets)

Back 155

Lymphatic vessels typically have frequent valves to prevent backflow. The presence of valves provides a convenient way of identifying small lymphatics.

Hint 155

Numerous delicate valves in small and medium sized vessels. Structure similar to venous valves.

Front 156

capillaries (continuous, fenestrated - TEM's from lecture)

Back 156

Smallest vessels in vascular system.

Hint 156

Continuous cap's have no interuptions and are found in most tissues. They exchange contents between lumen and tissue by 3 ways: passive diffusion (gases), pinocytosis (proteins/lipids) across cell, or some WBC's squeeze through intercellular space. Fenestrated cap's are found where there is extensive molecular exchange (small intestine, endocrine glands, and kidneys) and have numerous pores or fenestrae 60-80nm in diameter (most have diaphragms except in kidney glommerulus). Vascular endothelial cell growth factor (VEGF) involved in growht of fenestrated blood vessels from endocrine glands.

Front 157

pericytes

Back 157

A pluripotential cell surrounding blood vessels, particularly numerous around post-capillary venules.

Hint 157

Occasional flattened cells that embrace the capillary endothelial cells and may have a contractile function.

Front 158

Discontinuous (sinusoids) (from atlas and lecture slides)

Back 158

Specialized capillaries in the liver. The endothelium is fenestrated and discontinuous. They lack a basal lamina to facilitate exchange of materials.

Hint 158

Enlarged diameter, irregular shape, large fenestrae that lack diaphragms, basal lamina also discotinuous. This is found only withing the sinusoids of the liver.

Back 159

Stuff that's good to know:

Hint 159

There are 2 portions of the respiratory tract-- the conducting portion (which moves and conditions air) and the exchange portion (which is where gas exchange by diffusion happens). The conducting portion consists of (in this order): oral cavity, nasopharynx, larynx, trachea, bronchi, terminal bronchioles. The exchange portion consists of (in this order): respiratory bronchioles (yes, after the terminal bronchioles), alveolar ducts, alveoli.

Front 160

olfactory epithelium

Back 160

Contains olfactory receptor cells and supporting cells

Hint 160

Specialized sensory epithelium; pseudostratified; cell types are basal stem cells, sustentacular (supporting) cells, and olfactory receptor cells. Also have Bowman's glands producing fluid on epithelium surface; ducts of Bowman's glands run from the glands.

Front 161

olfactory mucosa

Back 161

Composed of olfactory epithelium and underlying glands and nerve fibers.

Hint 161

Mucus serves to condition (inhaled) air by moistening it.

Front 162

respiratory epithelium (ciliated cells, goblet cells, basal cells) also see * below

Back 162

Ciliated cells: active in moving fluid; the cilium is the most common motor in the world. Goblet cells: unicellular exocrine gland producing mucus; abundant in GI and respiratory tracts. Basal cells: sites of attachment and production of cilia.

Hint 162

"Resp. epithelium lines most of the conducting part of the respiratory tree. It moistens and filters air.

Front 163

*goblet cells

Hint 163

In an SEM, they look like a bald spot with a rim of short microvilli.

Front 164

*brush cells

Back 164

don't confuse brush cell with basal cell!

Hint 164

A goblet that a released granules and has more extensive microvilli; some of them also receive afferent nerve endings.

Front 165

*ciliated epithelial cells, trachea

Back 165

Active in moving fluid; the cilium is the most common motor in the world.

Hint 165

Microtubules are "9+2" pattern; dynein is the motor; they have gap junctions for coordination. Kartengeners syndrome: genetic mutations in dynein genes, so patients can't move mucus up, sperm can't swim, and you often also see situs inversus in these patients.

Front 166

elastic fibers (in broncus mucosa)

Back 166

Long, branched, anastomosing fibers occurring in variable amounts in different supporting tissues. They stretch and return to their orginal shape.

Hint 166

The bronchi are part of the "conducting portion" of the resp. system.

Front 167

olfactory receptor cells (olfactory knobs, modified cilia from lecture slides)

Back 167

Dendritic processes of the olfactory receptor cells from which the cilia containing molecular receptors extend.

Hint 167

The olfactory organ is on the roof of the nose, extending into the superior chonchae (which are the turbinate bones intruding from the lateral walls of the nasal cavity) and nasal septum. The olfactory organ has specialized epithelium; it is pseudostratified and includes basal stem cells, sustentacular (supporting) cells, and olfactory receptor cells. For the olfactory knobs, you can see cilia coming out of the knobs. The cilia are in fluid that is produced by Bowman's glands (see below).

Front 168

olfactory epithelium supporting cells (sustentacular cells)

Back 168

Sustentacular cells of the olfactory epithelium. (that's all he says here)

Hint 168

Have microvilli.

Front 169

olfactory epithelium basal cells

Back 169

Basal lamina: produced by epithelial cells. Not usually seen in LM. In LM the underlying reticular lamina is included in what we term basal lamina. In most texts, the terms basal lamina and basement membrane are used interchangeably.

Hint 169

Basal cells replenish other cell types

Front 170

Bowman's glands, ducts (see also *)

Back 170

Bowmans glands and Bowmans gland ducts are two different things! (you can see both at this link) Bowmans glands are glands of olfactory epithelium and Bowmans gland ducts are ducts of glands of olfactory epithelium.

Hint 170

Bowman's glands are branched tubulaoalveolar glands that secrete watery fluid that is probably essential for solubilization of air-borne odorants.

Front 171

*Bowmans glands

Back 171

see them at different magnifications

Hint 171

see directly above.

Front 172

epiglottis

Back 172

An unpaired, spoon-shaped organ representing the cover of the larynx; is composed largely of elastic cartilage. This and the outer ear are the main examples of elastic cartilage.

Hint 172

"Fibrocartilage" The epiglottis is flexible because it has elastic fibers. The anterior surface is covered with stratified squamous epithelium; toward the base, this transitions to pseudostratified.

Front 173

hyaline cartilage (matrix, chondrocytes, lacunae)

Back 173

Most abundant cartilage type in the body. Called hyaline because of its glassy appearance. Matrix contains type II collagen and glycosaminoglycans.

Hint 173

There are 16-20 C-shaped rings of hyaline cartilage in the trachea.

Front 174

perichondrium

Back 174

Surrounds the cartilage like a capsule. Contains chondrogenic cells.

Front 175

vocal cords

Hint 175

"True vocal cords have elastic fibers (vocal ligament) and vocalis muscles. The anterior surface is covered with stratified squamous epithelium. False vocal cords have an anterior surface that is stratified squamous, with mixed mucous-serous glands in lamina propria.

Front 176

thyro-arytenoid muscle

Back 176

Skeletal muscle located between thyroid and arytenoid cartilages in the larynx. Regulates the tension of vocal cords. Innervated by the laryngeal branch of the recurrent vagus.

Front 177

lung parenchyma

Back 177

The respiratory portions of the lung.

Front 178

alveoli (air space, septum)

Back 178

Respiratory portions of the lung active in gas exchange.

Hint 178

Part of the "exchange portion" of the resp. system. Alveolar ducts come off of the respiratory bronchioles (see below) and contain elastic fibers. The bronchial wall at this level is completely composed of alveolar openings. Alveolar ducts and alveoli are lined by simple squamous epithelium. Smooth muscle and lamina propria form sphincter-like bundles at the rim of the alveoli. These open into atria communicating with 2 or more alveolar sacs. Alveoli themselves are "small outpocketings of respiratory bronchioles", 250 micron in diameter. Exchange of CO2 and O2 takes place at this level; total surface area is equal to about 140 square meters.

Front 179

pore of Kohn (alveolar pore)

Back 179

A small opening between two alveoli. Provides communication between neighboring alveoli; but also an avenue for infection.

Hint 179

8 to 60 microns large, serves to equilabrate pressure between neighboring alveoli.

Front 180

alveolar capillaries (endothelial cells, fused basa lamina at air/blood interface)

Back 180

The interalveolar wall is composed of capillaries and two layers of type I pneumocytes and their basal laminae.

Hint 180

Alveolar capillaries are found in the interalveolar septum that separates adjacent alveoli. Capillaries are drained by veins initially running through the lung away from the bronchiole branches, but then associating closely with larger bronchi and the pulmonary artery at the hilum.

Front 181

type I alveolar cell (=type I pneumonocyte)

Back 181

This is actually pointing to a type I pneumonocyte nucleus. Type I pneumonocytes are simple squamous cells lining the alveoli. Their cytoplasm is so thin it is difficult to distinguish them from endothelial cells (in the LM).

Hint 181

Type I are squamous alveolar cells, they line the surface of the alveoli and share the basement membrane with capillary endothelium. When you look at an SEM, the thin surface that looks like a blanket are the type I cells.

Front 182

type II alverolar cell w/secretory granules containing surfactant

Back 182

Type II pneumonocytes line alveoli, but are much less numerous than type I cells with which they share tight junctions. The type II cells produce surfactant (antiatelectatic factor). In fixation the surfactant is lost, leaving small holes behind.

Hint 182

Type II are "great alveolar" or "septal" cells; they contain multilamellar bodies that contain surfactant precursors, they are more cuboidal than type I. Have secretory granules (aka lipoprotein vesicle, lamellar body), which extrude to produce surfactant. They also have occluding junctions (tight junctions) with type I cell neighbors. Type II may be able to differentiate into type I to serve as a source for replacement.

Front 183

respiratory bronchiole

Back 183

see description at right.

Hint 183

Bronchiole gives off terminal bronchiole, which then gives off the respiratory bronchiole (which then gives the alveolar ducts). Resp. bronchioles are the region of transition between conducting and respiratory regions of the resp. system (these 2 regions are important! make sure you know what all is in each! it's listed at the beginning of this section); they are like terminal bronchioles except that they have alveoli in their walls. The pulmonary artery branches to follow branches of the bronchi and bronchioles to the level of the respiratory bronchiole.

Front 184

bronchiole

Back 184

see description at right. **Remember that bronchiole, terminal bronchiole, and respiratory bronchiole are each something different.**

Hint 184

Bronchioles are the terminal branches of lobar (secondary) bronchi (see below). Each enters a pulmonary lobule and branches 5 to 7 times. After 10 to 15 branches, the bronchiole is ~1 mm diameter. Have CLARA CELLS: cuboidal, spherical in shape, not ciliated, contain secretory granules that are important for defense and in breaking up mucous, e.g. surfactant to keep airway open, antibodies, lysozyme. The bronchiole is the area most susceptible to blockage due to disease (chronic bronchitis due to smoking, spasmotic contraction of smooth muscle in asthma). The pulmonary artery branches to follow branches of the bronchi and bronchioles to the level of the respiratory bronchiole.

Front 185

air-blood barrier

Back 185

In the lung; composed of type I epithelial cells, endothelial cells, and their combined basal lamina.

Hint 185

Consists of (going from out to in) the alveolar lumen, the alveolar epithelium, the capillary endothelium and the capillary lumen. The alveolar epithelium and capillary endothelum have a fused basal lamina; surfactant lines the alveolar epithelium.

Front 186

terminal bronchiole

Hint 186

Part of the "conducting portion" of the resp. system. Comes off of bronchiole and gives off respiratory bronchioles.

Front 187

bronchus, (smooth muscle, elastic fibers)

Hint 187

Part of the "conducting portion" of the resp. system. Primary bronchi enter lung at hilum, the pulmonary root (it has dense connective tissue, arteries, veins, and lymphatics). For lobar (secondary) bronchi, there are 3 in the right lung and 2 in the left, each supplying a pulmonary lobe. They continue to branch repeatedly. The bronchus is made of: cartilage, connective tissue, smooth muscle (which contracts toward the end of inspiration to squeeze out more air) elastic fiber, folded mucosa, and submucosa with serous and mucous glands. The pulmonary artery branches to follow branches of the bronchi and bronchioles to the level of the respiratory bronchiole.

Front 188

respiratory epithelium (ciliated cells, goblet cells, basal cells) also see * below

Back 188

Ciliated cells: active in moving fluid; the cilium is the most common motor in the world. Goblet cells: unicellular exocrine gland producing mucus; abundant in GI and respiratory tracts. Basal cells: sites of attachment and production of cilia.

Hint 188

"Resp. epithelium lines most of the conducting part of the respiratory tree. It moistens and filters air.

Front 189

hyaline cartilage

Back 189

Most abundant cartilage type in the body. Called hyaline because of its glassy appearance. Matrix contains type II collagen and glycosaminoglycans.

Hint 189

Appears at articular surfaces such as the walls of respiratory passages (nose, larynx, trachea, bronchi), end of ribs and at the epiphyseal plates. Contains cells, fibers, ground substance. NO VESSLES OR NERVES. LOW METABOLIC RATE.

Front 190

perichondrium

Back 190

Surrounds the cartilage like a capsule. Contains chondrogenic cells.

Hint 190

As perichondrial cells differentiate they become round and secrete matrix proteoglycans which bine water and resist compression. Fibers are mainly collagen.

Front 191

chondrocytes

Back 191

Cells of cartilage.

Hint 191

Look active. Lots of ER. Secreting matrix composed of collagen and proteoglycans (mainly aggregan). Aggregan is a core protein with GAG sidechains. It binds water and forms a gel but still allows nutrient transport.

Front 192

elastic cartilage

Back 192

A kind of cartilage characterized by a network of elastic fibers in the matrix. Also contains collagen.

Hint 192

Found in outer ear and epiglottis. Contains type II collagen.

Front 193

hyaline cartilage without perichondrium at articular suraces

Back 193

A specialized avascular connective tissue composed of chrondrocytes and specialized intercellular matrix.

Hint 193

No perichondrium, therefore poor repair. Smooth articular surface facilitates sliding. Nutrients travel with water entering and leaving bone through cycle of compressions. Therefore moderate exercise is good for joints.

Front 194

compact (cortical) bone

Back 194

Usually surrounds outer parts of bones. Composed of Haversian systems.

Hint 194

Comprises 30% of skeleton, but 80% of total bone mass. Contains Haversian systems (structural unti of compact bone), interstitial lamellae (remnants of old osteons), cicumferential lamellae (outermost and innermost layers of cortical bone) and blood vessels (in Haversian and Volkman canals). Collagen in successive neighboring lamellae is perpendicular to each other.

Front 195

cancellous (trabecular, spongy) bone

Back 195

Usually fills the central portion of bone. More metabolically active than compact bone.

Hint 195

Comprises 70% of skeleton, but 20% of total bone mass. Consists of rods and plates. Best strength per weight. Arranged as lamellae, but no Haversian systems present. Large interconnecting cavities, cavity walls call traveculae (aligned along stress lines). Contains bone marrow. Bone formation/ absorption occurs here. Lots of matrix is exposed. Highly cellular. Sensitive to hormones and to immobility.

Front 196

bone marrow

Back 196

A richly vascularized connective tissue specialized for production of all formed elements of blood (and more).

Hint 196

Defined by the trabeculae of the spongy bone. Produces and contains all bone cell types.

Front 197

Haversian unit (osteon)

Back 197

Stuctural unit of compact bone. Composed of concentric bone lamellae with osteocytes located in between.

Hint 197

Haversian system is the structural unit of compact bone. Collagen in successive neighboring lamellae are perpendicular to one another.

Front 198

Haversian canal

Back 198

Center of an osteon in the bone. Contains blood vessels.

Hint 198

Located in the central part of osteon. Haversian canals are longitudinal and parallel to the developing bone with Volkman canals are perpendicular to the direction of bone growth. Both canals contain blood vessels.

Front 199

lamellae of bone

Back 199

Successive layer of calcified bone matrix.

Hint 199

Concentric circles of osteocytes in the compact (cortical) bone layer. Contain rings of lacunae where osteocytes resided when the bone was still functioning.

Front 200

trabecula of bone

Back 200

Thin, anastomosing spicules, beams, or threads of bone devoid of Haversian canals.

Hint 200

Present only in cancellous (spongy) bone. Consists of rods and plates. Provides the best strength per weight.

Front 201

interstitial lamellae

Back 201

These are leftovers from previously existing haversian systems (osteons).

Hint 201

Old osteons leftover after remodelling of bone. No loner complete. Only remnants.

Front 202

osteocytes

Back 202

Mature bone cells surrounded by bone matrix. Spider-shaped.

Hint 202

Osteoblasts trapped in the matrix. May repair internal matrix damage. Actively involved in turnover. Maybe be mechnosensory cells-remodel bone to match stress. Communicate with bone lining cells via gap junctions on cell processes. Cell extensions may have actin pumping effect--possibly initiate bone remodeling.

Front 203

osteocyte lacunae and canaliculli in ground specimens

Back 203

In a ground specimen the spaces formerly occupied by osteocytes and their processes are clearly seen.

Hint 203

Lacunae="Holes" in tissue sections where osteocytes reside Cannaliculli= canals that allow the extension of osteocyte cell processes.

Front 204

intramembranous bone

Back 204

In developing long bones the first (intramembranous) bone is formed around the cartilage model in a fasion suggestive of a collar.

Front 205

intramembranous bone collar, developing bone

Back 205

SAME AS ABOVE

Front 206

osteoblasts

Back 206

Bone-forming cells. Originate in bone marrow stroma.

Hint 206

Bone forming cells. Originate from stromal cells in bone marrow. High alkaline phosphatase activity, probably important for bone mineralization. Rich in organells. Make OSTEOID (initial non-mineralized collagen and proteoglycan matrix). Mineralize the matrix. Regulate the minute by minute calcium leves in body.

Front 207

osteoclasts

Back 207

Multinucleated cells active in bone removal. Originate from bone marrow hematopoetic stem cell. Play an important role in bone turnover. Travel to bone as a mononuclear precursor.

Hint 207

Main resorbers of bone. Gian, multinucleated cells. Actin zone near ruffled border=SUBOSTEOCLASTIC COMPARTMENT. Inhibited by Calcitonin and Estrogen. Attach to any bony matrix in a pit underneath the cells.High proton concentration in pit dissolves hydroxy apatite. Lysosomal enzymes released into pit activated by low pH, digest collagen and proteoglycans.

Front 208

periosteum

Back 208

Contains cells that orginiate in bone marrow stroma and that give rise to osteoblasts.

Front 209

Howship's lacunae (from lecture slides)

Hint 209

site where osteoclast resorption in trabecular bone.

Front 210

endochondrial bone formation (cartilage model, interstitially growing cartilage, hypertrophic cartilage, calcifying cartilage...)

Back 210

Occurs at the end of long bones. Requires a cartilage model. Active in extending bone length.

Hint 210

Mesenchymal cells specialize and produce a hyaline cartilage model for bone. The perichondrium in the middle of the shaft of the model transforms into osteoprogenitor cells and forms a bone collar by intramembranous ossification. Blood vessels penetrate the bone collar and bring more osteoprogenitor cells and osteoclast precursors to the inside of the cartilage model (the so called "primary ossification center"). The cartilage cells hypertrophy and die. Osteoclasts form tunnels in the cartilage, and bone is laid down by osteoblasts on the remnant cartilage spicules. Bone grows in length by endochondral ossification at the epiphyseal (growth) plates. The bone grows in thickness by intramembranous ossification. The growing bone is constantly modeled by the closely coupled action of osteoclasts and osteoblasts to achieve the final adult shape