Histology #1

Front 1

simple squamous epithelium

Back 1

where there is a need to create a barrier that is easily penetrated and a need to maintain a slippery smooth surface
eg: inner lining of blood vessels (endothelia), outer linings of visceral organs (mesothelia), lining of lung aveoli

Front 2

simple cuboidal epithelium

Back 2

where there is a need for more substantial barrier but allowing significant movement across cells
eg. kidney tubules, exocrine gland ducts (small)

Front 3

simple columnar epithelium

Back 3

(GI) where a more substantial barrier is needed but transport across is still facilitated, microvilli common
eg: stomach & intestine, some exocrine gland ducts, gall bladder, some lung airways

Front 4

stratified squamous epithelium

Back 4

where there is a need to resist physical abrasion

Front 5

keratinized stratified squamous epithelium

Back 5

where tissue must be resistant to abrasion and be relatively water-proof
eg: epidermis

Front 6

non-keratinized stratified squamous epithelium

Back 6

where tissue must have modest resistance to abrasion & water-proofing isn't much of an issue
eg: oral cavity, esophagus, and anal canal, vagina

Front 7

stratified cuboidal epithelium

Back 7

uncommon strategy
eg: some exocrine glands and their ducts, fetal epidermis, follicular cells surrounding ovum

Front 8

stratified columnar epithelium

Back 8

rare type
only eg: male prostatic urethra (vas deferens, epididymis)

Front 9

pseudostratified columnar epithelium

Back 9

uncommon but important, appears to be stratified & of mostly columnar cells that form a single layer. Almost always ciliated, interspersed with goblet cells
eg: larger airways, some nasal epithelium (respiratory epithelium)

Front 10

transitional epithelium

Back 10

uncommon, looks stratified, when stretched is relatively thin, when relaxed the cells can pile up to make a thicker-looking layer, usually lacks basement membrane. Cuboidal sometimes and other times stratified squamous, unique to urinary system (urinary epithelium)
eg: urinary bladder ureter, parts of kidney

Front 11

glandular epithelia

Back 11

derived from membranes (during embryological/fetal development)

Front 12

exocrine glandular epithelia

Back 12

with ducts, a smost common type of many forms and classified many ways

Front 13

serous secretory material

Back 13

thin, water (stains darker)

Front 14

mucous secretory material

Back 14

thick, sticky (stains lighter)

Front 15

unicellular

Back 15

single cell secreting into a space
eg: goblet cell

Front 16

multi-cellular ducts

Back 16

(exocrine) most of them, classified by shape of secretory portion of gland: tubular or acinar

Front 17

tubular

Back 17

secretory portion shaped as a tube (often simple cuboidal or columnar)

Front 18

acinar

Back 18

secretory portion shaped like a grape, lumps (often a kind of stratified cuboidal ball of cells)

Front 19

simple vs. compound

Back 19

one vs. many, branched

Front 20

endocrine

Back 20

without ducts and rely on blood vasculature. Seen as primitive glands of "internal secretion," very well vascularized, responsible for hormone secretion, of a few forms and crudely classified

Front 21

cord/clump forms (endocrine)

Back 21

example of cord type seen in: adrenal gland, columns of cells bordered by blood capillaries. Masses of cells with penetrating blood capillaries
eg: anterior pituitary gland, pancreatic islets, gonads

Front 22

follicular forms (endocrine)

Back 22

hollow ball of cells filled with fluid and surrounded by blood capillaries
eg: thyroid gland

Front 23

parenchyma

Back 23

functional epithelial aspects of a gland

Front 24

stroma

Back 24

the non-function connective tissue, or support parts, of a gland

Front 25

capsule

Back 25

the CT covering of some glands

Front 26

septa

Back 26

CT ingrowths from the capsule that compartmentalize the parenchyma

Front 27

lobes

Back 27

segments of glands discernible macroscopically

Front 28

lobules

Back 28

segments of gland discernible microscopically

Front 29

matrix of CT

Back 29

composed of amorphous ground substance (water and GAGs) and fibriller proteins, depending on exact composition, physical property vary from a gel to a fibrous mass to a fluid

Front 30

glycosaminoglycans (GAGs)

Back 30

unbranched polysaccharides that are highly hydrophilic, good at resisting compressive forces, often covalently bonded to other proteins, 4 broad subtypes: hyaluronic acid, chondroitin & dermatan sulphate, keratin sulphate, each with unique properties

Front 31

collagen

Back 31

most important, holds tissues together, most common protein in body, synthesized by fibroblasts, often assembled into bundles and can take on a variety of forms and physical properties, white to naked eye, pink with stains
eg: bone, cartilage, sclera, teeth, dermis

Front 32

elastin

Back 32

assembled into cables, a very stretchy fiber bound together as cables, stains brigher red, uncommon but critical in areas
eg fibrillin, fibronectin

Front 33

fibroblast/fibrocyte

Back 33

very common stellate-shaped cell, prime builder of general CT matrix (collagen & GAGs), fully mature form - fibrocyte

Front 34

mast cell

Back 34

uncommon eosinophilic cell, derived from blood basophils, granules of histamine and heparin, mediate inflammatory response: cause capillaries to become leaky

Front 35

macrophage

Back 35

highly phagocytic cell, derived from blood monocytes, powerful scavenger that can move tissues

Front 36

plasma cell

Back 36

antibody producing cell, derived from a blood B-lymphocyte

Front 37

adipocyte (adipose cell)

Back 37

fat cell, subtypes of white (unilocular, common) and brown (multilocular, rare), lipid droplet usually washed out during preparation

Front 38

chondroblast/chondrocyte

Back 38

cartilage cell, makes and maintains cartilage matrix

Front 39

osteoblast/osteocyte

Back 39

bone cell, makes and maintains bone matrix

Front 40

dense regular CT

Back 40

type 1 collagen tightly in a chaotic arrangement, excellent at resisting tensile forces in a particular orientation, poorly vascularized and have minimal cells other than fibrocytes
eg: tendons, ligaments, periosteum

Front 41

dense irregular CT

Back 41

type 1 collagen tightly in a chaotic arrangement, excellent at resisting tensile forces in multiple directions, well vascularized and innervated, has many cells though fibroblast the most common
eg: dermis of skin, submucosa of GI tract

Front 42

loose/areolar non-dense CT

Back 42

very loose array of collagen, most common, lots of open spaces and with many cell types, well vascularized and innervated, serves as a kind of filler, may appear dense when cellular
eg: hypodermis of skin, lamina propria of GI tract

Front 43

elastic non-dense CT

Back 43

containing elastic cable, uncommon, important in select areas (arterial walls)

Front 44

reticular non-dense CT

Back 44

made of a reticulum of mostly type 3 collagen, seen in lymphatic tissue and bone marrow, serves as a loose supportive framework, very cellular

Front 45

adipose non-dense CT

Back 45

common in globules in select places, essentially cellular, some consider a special CT: minimal matrix, well-vascularized, storage of lipid, insulation and shock absorption

Front 46

cartilage

Back 46

semi-rigid matrix of type 2 collagen and chondroitin GAG, which appears homogeneous and smooth, only cell is chondrocyte, most covered by a perichondrium of dense CT, avascular and aneural, found in: joint articulations, rib-to-sternum attachments, walls of larger airways, nose, ear, fetal bones

Front 47

hyaline cartilage

Back 47

translucent blue-white to naked eye, but light pink in microscope. Cells in lacunae, found in nose, articular surfaces (no perichondrium), respiratory system and fetal skeleton

Front 48

elastic cartilage

Back 48

a variation on hyaline that has criss-crossing elastic fibers in the matrix (sometimes pink sometimes darker), found in external ear and epiglottis

Front 49

fibrocartilage

Back 49

variation on hyaline that has extensive type 1 collagen added, no perichondrium because it blends to surrounding connective tissues, found in intervertebral disks, pubic symphysis and some tendon insertions.

Front 50

bone

Back 50

rigid matrix of type 1 collagen and GAGs and hydroxyapatite crystals forming a very hard tissue. 50% of matrix is organic (osteoid) and 50% is inorganic (collagen)

Front 51

osteocyte

Back 51

only cell in bone, cells in lacunae with canaliculi which allow for intercellular touching

Front 52

osteon/Haversian system

Back 52

concentric lamellae, cementing lines, Haversian canal (nerve and blood vessel), osteocyte lacunae, interstitial lamellae, circumferential lamellae (inner-endosteal and outer-periosteal)

Front 53

osteoclast

Back 53

a special bone macrophage, constantly erodes bone for the purposes of remodeling. Large and often multinucleated

Front 54

osteoblast

Back 54

reside in marrow wall (as the endosteum) and in the canals (Haversian and Volkmann's) as well as on the "osteogenic" aspect of the periosteum (as opposed to the fibrous aspect).

Front 55

periosteum

Back 55

similar to perichondrium: "fibrous aspect" is dense regular/irregular CT, has insertion points known as Sharpey's fibers. "Osteogeneic aspect" of quasi-bone with cells turning into osteoblast and laying down periosteal bone

Front 56

compact bone

Back 56

solid, carries the load, most common

Front 57

spongy bone

Back 57

distributes the load, common in marrow cavities and of the epiphyses of long bones

Front 58

lamellar bone

Back 58

layered, most common

Front 59

woven bone

Back 59

disorganized and usually replaced during development

Front 60

endochondrol bone

Back 60

forms hyaline cartilage

Front 61

intramembranous bone

Back 61

forms directly from mesenchyme, seen with flat bones, eg cranial bones

Front 62

epiphyseal plate

Back 62

represents a transistion zone, and is a microcosm of the entire conversion process from hyaline cartilage to bone, there are 5 zones of change

Front 63

resting zone

Back 63

(zone of reserve cartilage) normal, resting hyaline cartilage, no perichondrium on the articular surface, but some on the sides that blends to periosteum of the diaphysis. Completely lost once a second marrow cavity forms

Front 64

proliferative zone

Back 64

rapid cell division and growth of the cartilage, chondrocytes stack up in rows

Front 65

hypertrophic zone

Back 65

swelling of the cartilage: chondrocytes lacuna swell and coalesce

Front 66

calcification zone

Back 66

mineralization of the cartilage, matrix accumulates calcium salts and turns purple (with H&E), chondrocytes begin to die and matrix decays

Front 67

ossification zone

Back 67

conversion of calcified cartilage to bone, dying cartilage allows marrow fluid to flush in with new osteoblasts, osteoblasts land on old struts of calcified cartilage and reorganize the matrix, bone laid down as red osteoid (with H&E)

Front 68

blood

Back 68

sometimes considered a 5th basic tissue type, a fluid CT found in vascular tubes, matrix known as "plasma" (55% of volume), formed elements (45%)

Front 69

erythrocyte

Back 69

RBC vast majority, anucleated, no organelles, bi-concave (first emerge as reticulocyte), 8 um in diameter and bi-concave, 4-5 mission per mm^3, a very durable cell (last 120 days), 2 million made/destroyed per second, relative percent termed hematocrit, many die in the spleen

Front 70

leukocyte

Back 70

WBC defender cells, cells that do most of their job extra-vascularly (diapedesis the process of escape), 10-15 um and with a nucleus, 5,000-9,000 thousand per mm^3, come in 5 types from 2 groups: granulocytes (G) vs. agranulocytes (A)

Front 71

neutrophil

Back 71

(G) neutral staining granules, multilobed nucleus, 50-70% of WBC's, general defender cells

Front 72

eosinophil

Back 72

(G) red staining granules of varying types, bilobed nucleus (most), 2-4% of WBC, destroyers of antigen-antibody complexes

Front 73

basophil

Back 73

(G) purple staining granules, 0.5% of WBCs, turn into mast cells outside the blood stream

Front 74

lymphocyte

Back 74

(A) small cell (10 um) with round nucleus, light blue cytoplasm, 20-30% of WBCs, a few subtypes: B & T (with additional subtypes)

Front 75

monocyte

Back 75

large cell (15 um) with irregular nucleus (usually described as a horse-shoe or globular), 1-5% of WBCs, turn into macrophages outside blood stream

Front 76

platelet (thrombocyte)

Back 76

small fragments of a marrow cell called a megakaryocyte (2-4 um), 200,000-400,000/mm^3, involved in preventing blood loss: form platelet plugs, release chemicals that promote clotting and vasocronstriction

Front 77

skeletal muscle

Back 77

a striated muscle, under nervous control; voluntary control, majority of body muscle, long slender cells (myofibers) with striations running perpendicular to the long axis of the cell

Front 78

red skeletal muscle

Back 78

slow-twitch, with many mitochondria and stored lipid

Front 79

white skeletal muscle

Back 79

fast-twitch, with few mitochondria and little stored lipid

Front 80

sarcomere

Back 80

smallest unit of contraction, formed by organization of myofilaments, consists of actin and myosin forming bands (striations): A-band, I-band, Z-lines

Front 81

cardiac muscle

Back 81

striated muscle of the heart, under nervous or hormonal control, but has auto-rhythmicity, involuntary. Short, stubby cells that sometimes branch, connected by intercalated disks for anchoring and points of low electrical resistance, has endomysium rich with capillaries and nerves

Front 82

smooth muscle

Back 82

non-striated muscle of many body hollow organs, under nervous or hormonal control with some auto-rhythmicity; involuntary control, short spindle shaped cells, muscle of vascular tubes, GI tract, airways, uterus, mixed with very little endomysium but cells can synthesis some elastin

Front 83

neuron

Back 83

an electrically excitable cell that comes in a variety of shapes (multipolar most common); polarity is a function of recieving/sending APs; each has a cell body and one or more processes

Front 84

perikaryon

Back 84

cell body of neuron

Front 85

Nissl substance/bodies

Back 85

clumps of rER revealed by perikaryon

Front 86

synapse

Back 86

connection to another neuron, determines neuron polarity; an extremely small secretory point of communication

Front 87

axon/efferent neuronal process

Back 87

transmitting process

Front 88

efferent

Back 88

outgoing

Front 89

afferent

Back 89

incoming

Front 90

dendrite

Back 90

receiving process

Front 91

axo-dendritic

Back 91

axon to dendrite (classic model)

Front 92

axo-somatic

Back 92

axon to cell body (common in CNS)

Front 93

axo-axonic

Back 93

axon to axon (less common)

Front 94

myoneural

Back 94

at the neuromuscular junction (of the PNS)

Front 95

glial cells

Back 95

those found in the CNS; mostly perform functions that neurons can't do due to specialization or functions that enhance neuronal function

Front 96

astrocyte

Back 96

primary supporting cell; star-like, 2 subtypes: fibrous and protoplasmic (most); end-feet that touch blood vessels and synaptic clefts (found in gray and white CNS); function in: neuron migration in the embryo, physical support of CNS order, metabolic exchange between neurons and capillaries, assist in removal of extracellular neurotransmitter

Front 97

microcyte

Back 97

smallest and relatively uncommon; a special kind of CNS macrophage; function in: scavenge damaged CNS cells, fibers or other materials

Front 98

oligodendrocyte

Back 98

common, small star-shaped cell, found in both gray and white matter but substantial in white matter; function in: myelination of CNS processes, a kind of fatty insulation

Front 99

ependymal cells

Back 99

kind of cuboidal epithelium; line the brain ventricles and spinal cord canal; some have cilia; function in: participate in CSF production

Front 100

Schwann cell

Back 100

myelin-producing cell in PNS, seen all through nerves; thousands line up to form a protective coating that greatly speeds up the propagation of the AP; responsible for protecting/covering un-myelinated nerves as well

Front 101

myelination

Back 101

consists of 30-50 wrappings of the plasma membrane of a Schwann cell

Front 102

node of Ranvier

Back 102

where Schwann cells abut each other along the neuronal process

Front 103

neurolemma

Back 103

layer formed by myelin wrappings, usually partially washed away in preparations

Front 104

CNS

Back 104

brain and spinal cord, where the vast majority of neurons are found

Front 105

PNS

Back 105

consisting of everything outside CNS, mostly nerves

Front 106

nucleus

Back 106

group of cell bodies in CNS

Front 107

ganglion

Back 107

group of cell bodies in the PNS

Front 108

tract

Back 108

group of processes in CNS

Front 109

nerve

Back 109

group of processes in PNS, and is not a neuron

Front 110

ganglia

Back 110

nodular masses of cell bodies with some supporting cells encapsulated by mostly dense irregular CT

Front 111

sensory ganglia

Back 111

contain afferent pseudounipolar neurons, eg dorsal root ganglion

Front 112

autonomic ganglia

Back 112

contain efferent post synaptic multipolar neurons, eg sympathetic chain ganglion or myenteric plexus

Front 113

nerve

Back 113

afferent or efferent collections of processes, usually wrapped with CT (providing support and access for blood vessels

Front 114

endoneurium

Back 114

holds axons together, myelinated or not; scant and made of loose CT

Front 115

perineurium

Back 115

binds endoneurium with axons forming a primary bundle (or fascicle); desner CT

Front 116

secondary bundle

Back 116

primary bundles bound together by a perineurium; interspaces commonly contain blood vessel, even small nerves

Front 117

epineurium

Back 117

organization continues outward to form tertiary bundle

Front 118

gray matter

Back 118

primarily cell bodies, local processes, neuroglia (with their processes) and small blood vessels; on inside of spinal cord forming an H-pattern. bilateral dorsal and ventral horns, ventral motor neurons, gray commissure and central canal

Front 119

neuropil

Back 119

gray matter forms a texture of dendrites, axons, and glial processes

Front 120

white matter

Back 120

primarily myelinated fibers (and no cell neuronal cell bodies). On outside of spinal cord forming an oval/round shape; ascending and descending tracts, appears like x-section of nerve, bilateral dorsal and ventral roots

Front 121

meninges

Back 121

membranes covering spinal cord and brain

Front 122

pia mater

Back 122

innermost, delicate ("tender mother") layer

Front 123

arachnoid mater

Back 123

fluid-filled layer with blood vessels and entangled CT

Front 124

dura mater

Back 124

outermost, tough layer of dense CT

Front 125

cerebrum

Back 125

divided into 2 hemispheres and has surface of deep folds that increase surface area (gyri and sulci); gray matter is outermost (opposite of spinal cord), though there are patches in deep; white matter is innermost, running to and from cortical areas

Front 126

pyramidal cell

Back 126

primary neuron in gray matter of cerebrum

Front 127

cerebellum

Back 127

with a cortex that is elaborately convoluted; gray matter is outermost

Front 128

molecular layer

Back 128

outer layer of small neurons in cerebellum

Front 129

Purkinje cells

Back 129

huge neurons making up the middle thin layer of cerebellum

Front 130

granular layer

Back 130

inner layer of cerebellum, many small neurons