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199 Cards in this Set
- Front
- Back
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If a cell is actively transcribing large amounts of its genome then what would it look like?
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It would have a lightly staining nucleus
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If a cell is not actively transcribing large amounts of its genome then what would it look like?
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it would have a dark staining nucleus
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What would a dead or dying cell's nucleus look like?
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It may shrink and become intensely heterochromatic
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Interphase
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normal nucleus, DNA duplicated in pregious S phase (2N--> 4N), copies of chromosomes (chromatids) are attached at centromere, two pairs of centrioles are present
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Prophase
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chromosomes condense, coil, and are visible as dark threads, each pair of centrioles separate and migrate to each pole, microtubules of mitotic spindle continue to form
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when does prophase end?
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with the disappearance of the nuclear membrane and nucleolus
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Metaphase
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mitotic spindle attaches to the chromosomes at the kinetechore, chromosomes line up at the equator of the cell, chromosomes are most condensed, chromosomes are karyotyped at this stage
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Anaphase
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sister chromatids split apart at the centromere forming two separate chromosmes, chromosomes are pulled towards opposite poles
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Telophase
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Chromosomes begin to uncoil until no longer visible. Nuclear membrane and nucleolus reform
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Cytokinesis
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cleavage of the cytoplasm into 2 separate cells occurs by constriction of the cell at the equator by the contractile ring composed of actin/myosin filaments
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what are centrioles composed of?
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microtubules
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G2 phase?
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synthesis of mitotic apparatus
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G1 phase
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protein + RNA synthesis. grow and perform specialized functions
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what phase are most cells in?
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G1 or G0
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S phase
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synthesis of DNA and proteins associated with chromatin
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Axoneme
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Cilia/flagella. 9 sets of doublet microtubules + a central doublet (9+2) extending through the shaft
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basal bodies
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similar in structure to a centriole (9 triplets), but at the base of each cilium
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Having lots of mitochondria makes the cell what color?
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pink
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What organelle makes the cytoplasm basophilic?
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The endoplasmic reticulum (or ribosomes). (makes cell blue)
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Ribosomes
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contain RNA, are manufactured in nuceolus, assemble A.A. into proteins (along with mRNA). Those associated with RER produce secretory, lysomal and integral proteins. Free ribosomes produce proteins for their cell's cytoplasm such as thick filaments
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Secretory vesicles (granules)
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membrane bound "bags" containing products destined for release from the cell by exocytosis
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5 steps of synthesis and secretion of proteins?
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1) mRNA goes to the RER 2) Assembly of A.A. on the ribosomes of the RER into proteins 3) Transfer vessicles leave RER and fuse with the Golgi apparatus 4)Wrapped secretory vessicles leave golgi. 5) Secretory vesicles fuse with the cell membrane, releasing the products into the extracellular space
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What do plasma cells secrete?
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immoglobulins
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What do serous cells secrete?
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digestive enzymes
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Lysosomes
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membrane bound bags of hydrolytic enzymes. The acid hydrolases must be segrgated by a membrane or they will destroy the cell. They are synthesized in the RER and packaged in the Golgi apparatus
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Primary lysosomes
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newly formed, virgin lysosomes
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secondary lysosomes
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vesicles formed after fusion of the primary lysosome with the membrane bound materials to be destroyed
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residual bodies
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left over material after destruction, can slowly dissolve, be exocytosed, or remain inside the cell (lipfuscin granules)
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Mitochondria
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Large motile organelles composed of 2 unit membrane, with the inner membrane highly folded into shelves (cristae). Mitochondria are self replicating, having their own DNA and membrane bound enzymes. They produce ATP. The more ATP the more inner folds.
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What organelle is most responsible for the acidophilic (pink staining) cytoplasm
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mitochondira
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Heterophagy
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breakdown of materials brought into the cell by phagocytosis. They are brought into the cell, segregated within a membrane, fused with a primary lysosome, and destroyed.
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Autophagy
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Breakdown of materials normally found within the cell. Old mitochondria, cytoskeleton, RER etc. are segregated within a membrane, fused with a primary lysosome, and destroyed.
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Apoptosis
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programmed cell death, normal physiological process
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Necrosis
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refers to death caused by deleterious stimuli (ischemia mechanical injury, toxins)
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Euchromatic nucleus
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transcriptionally active and metabolically active
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Heterchromatic nucleus
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transciptionally inactive and metabolically inactive
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centriole
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composed of 9 sets of triplet microtubules in bundles, 2 per cell, acts as a microtubule organization center for the assembly of the mitotic spindle
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What is the DNA content of cells during metaphase?
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4N
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Barr body
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Inactivated X chromosome in the female. Usually appears as a small dark mass of heterochromatin on the edge of the nucleus
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Microfilaments
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tiny rods made of actin, found in all cells called thin filaments in muscle
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What are 3 specializations containing microfilaments?
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microvilli, terminal web, contractile ring
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microvilli
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small fingerlike projections in epithelial cells
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terminal web
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network of filaments in come epithelial cells
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contractile ring
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responsible for cytoplasmic constriction at end of mitosis
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Myosin filaments
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also called thick filaments, present in all cells but best developed in muscle where it is involved in contraction
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intermediate filaments
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a heterogenous class of filaments especially important in cell support and shape. They are present in adhering type of cell junctions
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TIght junction Zonula occludens
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Area of fusion between adjacent cell membranes, completely encricles cell. Blocks passage of molecules btwn cells and is basis of blood brain barrier
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Intermediate junction--Zona adherens
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Dense area with actin filaments, completely encircles cell. Anchors actin filaments to cell membrane and stabilizes cytoskeleton
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Desmosomes--Macula adherens
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Intermediate filaments inserted into electron sense plaques, strong spot attachment. Strong cell to cell attachment and keeps neighboring cells from pulling apart
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Hemidesomes
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half a desmosome. Attaches cell to basal lamina
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Gap junctions--communicating nexus junction
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forms channels/bridges between cells, spot communicating junction. Permits movement of small molecules between cells and metabolic and electric coupling of cells.
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Terminal bar
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a junctional complex linking neighboring epithelial cells
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Function of cilia?
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Motile projections used for movement of material. In respiratory system they transport mucus in female reproductive system they transport ovum.
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What is the flagella of sperm?
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The flagella of sperm is a modified cilium
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Function of microvilli?
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increases surface area, usually for absorption
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Alternate terms for microvilli?
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Striated border (small intesitines), brush border (kidney nephron) and sterocilia (male reproductive system, extremely long microvilli)
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Simple squamous epithelium
Function and location? |
scale-like, flat thin cells
Function- ion and gaseous exchange, diffusion, filtration common location-blood and lymph vessels, lung alveoli, endothelium of blood vessels, mesothelium, serosa |
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Simple cuboidal epithelium
Function and location? |
May have microvilli or cillia
Function-secretion and/or absorption Common locations-kidney tubules, gland and bile ducts |
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simple columnar epithelium
Function and location? |
May have microvilli or cillia
Function-secretion and/or absorption Common locations-stomach intestines, gall bladder, female reproductive system (uterus, uterine tube) |
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Pseudostratified epithelium
Function and location? |
appears multilayered but all cells are attached to basal lamina. May contain microvilli or cillia
Function-secretion and/or absorption Common locations-respiratory system (trachea, bronchus) Male reproductive system (epididymus, ductus deferens) |
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Stratified squamous epithelium Non Keratinized
Function and location? |
Surface cells and nuclei are flat
Function-protection from abrasion, irritation Common locations: lining mucosa of oral cavity, vagina, anal canal, espophagus, cornea |
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Stratified squamous epithelium keratinized
Function and location? |
Surface cells are flat and lack nuclei (anucleated). Cells are dead and filled with ketatin
Function-potection from abrasion, irritation common locations: epidermis (skin), masticatory mucosa |
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Transitional epithelium
Function and location? |
Surface cells are rounded but can become flatter
Function-protection from urine, can distend common locations: urinary system (bladder ureter, urethra) |
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Stratified columnar or cuboidal epithelium
Function and location? |
surface cells are columnar or cuboidal
Function: protection common locations: areas of change from one epithelium to another. (e.g. where the lining of a gland duct changed from simple columnar to stratified squamous epithelium) |
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what structures in large amounts would result in more acidophilic cytoplasms?
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Mitochondria, Secretory vesicles that stain with eosin (may appear grainy) and lysosomal vesicles that stain with eosin (esoinophils)
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Which structures in large amounts would result in a basophilic cytoplasm
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Ribsomes (cell makes lots of in-house proteins/secretory vesicles) and secretory vesicles that stain with hematoxylin
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What materials would result in an empty or clear cytoplasm?
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Lipids (in doplets--adipose cells--or in membranous organelles--SER, golgi)
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Neutrophil
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Most numerous WBC, 3-6 lobes, Auzurophilic granules (primary) are largely lysosomal, contain myeloperoxidase, lysozyme and acid phosphatase. Specific granules (secondary) are commonest, primarily antibacterial, lactoferin, alkaline phosphatase.
Phagocytotic killing of bacteria, increased numbers in acute inflammation. Contains the barr body. |
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Eosinophil
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bilobed nucleus. acidophilic grains in its cytoplasm. Function is phagocytosis of antigen/antibody complexes. Major basic protein and arginine are responsible for the eosinophilic staining. High count = parasite infection. Presence of this cell in circulating blood is considered pathological. Also seen in chronic inflammations, asthma, and hay fever counteracts basophils
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Basophil
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rarest WBC, bilobed nucleus function is IgE mediated reactions, anaphylaxis, and hypersensitivity and allergies. Granules contain histamine, platelet activating factor (PAF) and heparin.
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Monocyte
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Largest WBC, indented U shaped nucleus, basophilic cytoplasm. Function is to enter into CT and differentiate into macrophages, actively phagocytic cells--hisiocytes, osteoclasts, Kupffer cells of the liver, dust cells of lung.
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Lymphocyte
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commonest agranulocyte, nucleus is round, large, and intensely heterochromatic and surrounded by a thin basophillic rim. Function is the major cells of immune system (T cells and B cells)
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Characteristics of metamyelocytes?
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nucleus: Kidney shaped
cytoplasm: specific granules still visible |
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Characteristics of myelocytes?
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nucleus: rounded to oval, may be eccentric
cytoplasm: specific granules |
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Characteristics of Band granuloctyes?
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nucleus: horseshoe or U shaped
cytoplasm: band neutrophil and band eosinophil only. rare |
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Myeloblast
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very large blast cell non-differentiated
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What do megakaryocytes form?
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platelets.
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Sites of blood formation?
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Embryonic sites: yolk sac, liver, bone marrow, thymus, spleen and lymph nodes
After birth: bone marrow (lymphocytes also in lymphoid organs) |
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Proerythroblast
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nucleus: large and round, nucleoli visible (pale staining)
cytoplasm: mildly basophilic due to polyribisomes, large cell |
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Basophilic erythroblast
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nucleus: round, beginnig to get splochy due to heterochromatin
cytoplasm: intensely basophilic due to many polyribosomes (peacock blue) |
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polychromatic erythroblast
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nucleus: checkerboard of hetochromatin
cytoplasm: mixed color (icky gray), polychromatic (many colors). |
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Orthochromatic normoblast
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nucleus: small dense, full of heterochromatin.
cytoplasm: eosinophilic, approached the color of mature RBC full of hemoglobin |
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Where do monocytes develop from?
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stem cell in bone marrow
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What do B-immunoblasts generate?
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plasma cells
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When stimulated by an antigen what do B-lymphocytes turn into?
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B-immunoblasts
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Reticulocyte
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nucleus: absent
cytoplasm: stained with cresyl blue stain a residual reticulum of polyribsomes. In %1 of blood |
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Mature erythrocyte
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nucleus: absent
cytoplasm: eosinophilic due to hemoglobin all other organelles have extruded |
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reticular lamina?
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Secreted by fibroblasts in the connective tissue. Primarily contains type III collagen fibrils (reticular fibers), continuous with the extracellular matrix of connective tissue
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basal lamina
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secreted by epithelial cells. Has type IV collagen fibrils, large sticky molecules that bind cell membrane, and large molecules that filter material by charge or size.
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What does the term basement membrane mean?
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used to describe the sheet when it is thick enough to be visible in the light microscope
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Atrophy
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decrease in cell size and organelles
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Hypertrophy
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increase in cell size and organelles (and function)
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Hyperplasia
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increase in cell number, cells must be capable of cell division
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Smooth endoplasmic reticulum
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contains the enzymes for the synthesis of lipids (including membrane phospholipids) and cholesterol-derived compounds. Its well developed in cells that secrete lipids, lipoproteins or STEROID HORMONES In liver is involved in removal of toxins. Is generally acidophilic.
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Functions of golgi apparatus?
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chemical modifications of proteins, packaging and distribution of secretory proteins to form secretory vesicles and hydrolytic enzymes to form lysosomes, distribution and recycling depot for the various kinds of membranes in the cell
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lipofuscin
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yellowish-brown pigment composed of residual bodies that accumulate with age
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melanin
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brownish-black pigment, present in membrane bound vesicles called melanosomes
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Serum
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a blood protein solution minus fibrinogen and factors of clotting
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Platelets
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small cytoplasmic fragments of megakaryocytes. Platelets lack nucleus and have two regions: peripheral hyalomere and central granulomere
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Hyalomere
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outer light staining zone, contains primarily cytoskeletal elements (e.x microtubules)
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Granulomere
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inner dark staining zone, filled with dense bodies
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Leukocytes
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white blood cells have a nucleus and are capable of amoeboid movement. They use the blood stream for transport to their usual site of action: CT
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Blastocyst
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forms when fluid seeps between cells. Embryo implants in the uterus
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Primitive streak
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appears in the disc. polarity of the embryo is established
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Neural tube/neural crest
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is formed when ectoderm folds inward
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What does the endoderm turn into?
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Epithelium of: GI tract (liver, pancreas, urinary bladder)
Respiratory system (trachea, bronchi, lungs) Pharynx, thyroid gland, tympanic cavity, pharynogotymapanic tube, tonsils, parathyroid gland |
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What does the mesoderm turn into?
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supports tissues of body-bone, cartilage, connective tissue, muscle
blood cells, lymph cells, cardiovascular system, lymphatic system, adrenal cortex, urogenital system, serous membranes |
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what does the surface ectoderm turn into?
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epidermis and derivatives (nails, glands, hair), mammary gland, enamel of teeth, internal ear, corneal epitheliu, lens
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what does the neuroectoderm turn into?
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neural tube (central nervous system, retina, pineal gland, posterior pituitary gland)
neural crest (ganglia, schwann and satellite cells, Adrenal medula/chromaffin cells, melanocytes) |
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Exocrine cells
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cells specialized to secrete onto an epithelial surface (free or apical surface)
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endocrine cells
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Cells specialized to secrete product (hormone) into connective tissue where it enters blood supply. Endocrine glands do not have ducts
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Merocrine (Eccrine)
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secretory vesicles discharge with little or no loss of apical cytoplasm. Most exocrine cells secrete in this mode
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Apocrine
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secretory vesicles discharge with loss of come apical cytoplasm. Present in mammary and in specialized sweat glands
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Holocrine
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secretory vesicles discharge when the whole cell explodes or disintegrates. Present in sebaceous glands
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Serous cells
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secrete watery, protein rich secretion. In the GI system the secretory granules (zymogen granules) contain digestive enzymes. Rough ER, euchromatic round nucleus, basophilic cytoplasm wiht secretory granules, light nucleus visible nucleolus
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Mucous cells
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secrete slimy, viscous, lubricating mucus (glycoprotein). Mucous dissolved away with normal tissue preparation, leaving an "empty" cell. Common--can be single (goblet), epithelial sheets (stomach lining) or glands (sublingual gland).
Mucin, Golgi, heterochromatic nucleus, light or empty cytoplasm, dark nucleus flattened at base of cell. |
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Metaplasia
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replacement of one fully differentiated cell type for another. This adaptive reaction to injury is reversible if the stimulus is removed
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Dysplasia
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is disordered development of the tissue. Abnormal maturation of the tissue, exhibited by alterations in size, shape, and organization of the cells. Typically there is an increase in mitotic figures. Although displasia is considered a reversible process, it can lead to cancer
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How are benign or malignant tumors classified?
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1) degree of fidelity to precursor cells, ranging from differentiated to cells so primitive (anaplastic) that the cell can not be identified
2) rate of growth 3)Ability to invade and metastasize to distant sites |
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Benign tumors
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localized growths that do not penetrate adjacent tissue borders of metastasize (spread) to distant sites. They contain differentiated cells similar to their parents.
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Five benign tumors?
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epitheliomas (surface epithelia), fibromas (connective tissue) ,osteomas (bone), adenomas (glands), chrondromas (cartilage)
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Malignant tumors
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cancer. Neoplasms that have the ability to invade nearby tissues and metastasize to distant sites. Malignant tumors display many signs of dedifferentation (anaplasia) and abnormality
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Carcinomas
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epithelial tumors
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Adenocarcinomas
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cancers that arise from glandular epithelial cells
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Sarcomas
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cancers from mesenchyme derived tissues (bone, cartilage, connective tissue, muscle)
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Teratomas
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derived from embryonic tissue
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Carcinoma in situ
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If carcinoma does not penetrate the basement membrane
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Three types of fIbers in all connnective tissue?
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collagen fibers (type I)
Reticular fibers (type III collagen) Elastic fibers |
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Fixed cells in connective tissue?
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Fibroblast cels
adipose cells |
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Wandering cells in CT?
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Macrophages
plasma cells mast cells visting white blood cells-lymphocytes, neutrophils, eosinophils |
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How is CT classified?
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according to predominant fiber type and organization
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Where is adult CT derived from?
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embryonic mesenchyme
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What are the derived tissues from malignant tumors called?
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sarcomas
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What is ground substance composed of?
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This is the amorphous gelatinous material occupying the space between cells and fibers. Composed of tissue fluid with water, electrolytes, glycosaminoglycans (especially hyalutonic acid)
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What is the function of ground substance?
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Allows diffusion of oxygen, nutrients, waste products, and hormones between cells and capillaries. Increased fluid in the ground substance results in tissue swelling or edema
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Collagen fibers (type I)
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Most common form. The fibrils polymerize into large buncles. In the LM they appear as wavy acidophilic bundles of fibers. Collagen fibers are extremely strong but flexible.
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Reticular fibers (type III)
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Only visible in a special stain. From a network that supports cells, capllaries, nerves and muscle cells. Also stroma for hemopoietic tissues and lymphatic tissues. Major sources include fibroblasts adipocytes smooth muscle, endothelial cells, schwann cells, reticular cells
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Elastic fibers
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thin brancing fibers composed of elastin. They are present as individual fibers or as discontinuous sheets. Elastic fibers are visualized with special stains (unless large amounts are present) They return tissues to their original state after stretch and distension
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Major sources of type I collagen?
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Fibrobasts, osteoblasts, chondroctyes, chondroblasts, odontoblasts, also smooth muscle cells
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Type II collagen?
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Resistance to pressure, fibrils in EM. Contains hyaline cartilage and elastic cartilage. Chrondroblasts and chrondocytes are the major sources.
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Type IV collagen?
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Organized into a meshwork provides support, attachment to the underlying connective tissue and flitration barriers. Basal lamina is the major distribution. The major sources are the epithelial cells, endothelial cells, Adipose cells, schwann cells, all 3 types of muscle cells lens fibers (capsule)
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Fibroblasts
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Long, thin, heterochromatic nucleus, cytoplasm not visible. They secrete and maintain the components of EM including all fibers and ground substance. More active fibroblasts have a plumper more basophilic cytoplasm (RER) with a more euchromatic nucleus
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Myofibroblasts
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Are contractile cells that appear in wounds. They display properties of both fibroblasts and smooth cells. They are active in wound contraction,
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Adipose cells
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The unilocular (white) adipocyte is a large cell with a giant lipid droplet. Store neutral fat, Multilocular (brown) fat is present in the fetus and newborn where it is used as an energy source providing heat to newborns
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Where are macrophages derived from?
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monocytes
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Cell that presents antigens to lymphocytes?
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macrophage
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Foreign body giant cells
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formed when marcophages fuse together to form a large cell with up to 100 nuclei. They are capable of walling off relatively large masses of foreign material like splinters
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Plasma cells
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small, basophilic cytoplasm (RER) and eccentric nucleus. Soccer-ball heterochromatin pattern.
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Mast cells
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Secrete HEPARIN, HISTAMINE and LEUKOTRINES. Large motile cell is often amoebiod in shape. Cytoplasm filled with secretory metachromatic, granules. They usually stain blue, purple or pinkish. They also have eosinophili chemotactic factor and neutrophil chemotactic factor. They can also cause immediate hypersensity reactions, allergy and anaphylaxis due to leakage
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What do plasma cells secrete?
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They secrete circulating antibodies (immunoglobins)
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Mesenchyme
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loose CT of the embryo that fills the embryo. Contains star shaped cells, abundant ground substances and very few fibers
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How are mesenchymal cells pluripotential cells/ what do they differentiate into?
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connective tissue (fibroblasts, adipoctyes)
cartilage (chrondroblasts--> chondrocytes) Bone (osteoprogenitor cells --> osteoblasts --> osteocytes) also blood cells, endothelial cells, pericyted and muscle cells |
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Loose CT
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contains only a few poorly organized fibers and abundant ground substance. Highly vascularized. Is commonly found underneath the surface epithelium of hollow organs
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Dense irregular connective tissue
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irregular organization, fibroblast are the main cell type present, can resist stress. The dermis and the connective tissue capsules around organ are examples of dense irregular connective tissue
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Dense regular connective tissue
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fibers are arranged in parallel bundles extending in the direction of tension. The fibroblasts are also arranged in the same parallel orientation. Dense regular C.T. is present in tendons and ligaments
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Adipose tissue
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white unilocular fat, fatipose. Specialized loose connective tissue in which adipose cells are the predominant cell. It is highly vascular
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Elastic connective tissue
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dense regular tissue, primary type of fiber is elastic. The elastic fibers are organized into large parallel bundles. Present in vocal cords and in tissue connecting adjacent vertabrae (ligamenta flava) Important component of arteris
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Reticular connective tissue
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CT framework or stroma of the lymphatic (lymph node, sleen) and hemopoitic tissue (bone marrow, spleen, liver). The fibers are secreted by reticular cells (probably modified fibroblasts)
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General characteristics of cartilage
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1) supports tubular organs to keep them open (trachea, bronchus)
2) forms a semi-felible union between dones (ribs and sternum) 3) forms a gliding surface at the articular surfaces of bone (joints) 4)Serves as a precursor for many bones in development (endochondral ossification) and after injury |
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What are the small holes that cartilage cells are trapped in called?
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lacunae
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How does cartilage get oxygen and nutrients?
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Cartilage is avascular so it receives oxygen and nutrients that diffuse from blood vessels in the surrounding
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three types of cartilage in the matrix?
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Hyalin, elastic and fibrocartilage
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Cartilage's appositional growth
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By differentiation of chondroblasts from fibroblasts in the perichondrium. Chrondroblasts secrete matrix, becoming trapped in the matrix (now called chondrocytes). Adds matrix outside
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Cartilage's intersitial growth
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-By division of chondrocytes in lacunae
-addition of matrix from within -results in isogenous groups -common in development when matrix is soft |
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Degeneration of cartilage
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condrocytes hypertrophy, the matrix calcifies (precipitation of mineral salts) and the chondrocyte dies. Important ot endochondral bone development
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Regeneration of cartilage
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damaged adult cartilage regenerates with difficulty primarily from the perichondium. If the damage is too extensive, the cartilage is replaced by a connective tissue scar
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Articular cartilage
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smooth friction free layer of hyaline cartilage at the end of bones in synovial joints. Does not have a perichondrium and has poor ability to repair. Gets nutrients from synovial fluid
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Osteoarthritis
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most common degenerative joint disease, characterized by progessive degeneration and erosion of acticular cartilage. Eventually the cartialge is lost and the bone becomes exposed
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Rheumatoid arthritis
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chronic systemic autoimmune, inflammatory disorder that affects many tissues and organs. It especually attacks joints, destroying the cartilage and replacing it with a vascular connective tissue
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Elastic cartilage
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Present in areas needing more flexibilty--external ear, external auditory canal, eustachian tubes, epiglottis and areas of the laryngeal. Has elastic fibers (makes it different from hyaline cartilage)
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Fibrocartilage
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present where extra strength is need (pubic symphysis, joint capsules, ligaments and attachments of hyaline cartilage. Always associated with dense regular CT. Fibrocarilage does not have a perichondrium
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What does fibrocartilage contain?
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1) a matrix reinforced with parallel bundles of strong type I collagen fibers aligned in the direction of mechanical stress. Has acidophilic collagen fibers
2) Chondrocytes lined up in rows between the collagen fibers |
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What does the extracellular matrix of bone contain?
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type I collagen fibers, ground substance and minerals
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organic phase of bone?
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1) type I collagen fibers (%90) responsible for acidophilic matrix in decalcified H&R preps
2)Ground substance-proteoglygans, GAGs, glycoporteins (osteonectin, osteocalcin, sailoprotein) |
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inorganic phase of bone?
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mineral salts in the form of hydroxyapatite (calcium phosphate crystals)
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characteristic of bone?
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1)calcified-acts as support and as a reservoir for minerals
2)highly vascularized 3)constantly being remodeled (matrix produced or destroyed) |
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Osteoprogenitor cell?
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osteogenic stem cell
-can replicate -differentiate into osteoblasts and then osteoctyes -present in the periosteum and endosteum |
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osteoblasts
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primary producer of bone matrix
-basophilic cell with round euchromatic nucleus -lined up in one cell thick rows -secretes organic components of bone matrix (prebone, osteoid) and matrix vesicles that inhibit mineralization -becomes trapped in matrix then called osteoctye -cannot replicate |
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osteocyte
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Trapped in lacunae in the bone matrix
-long thin cell processes extend into tiny channels called canaliculi -communicate with other osteocytes by gap junctions -maintain bone matrix (some synthetic and resorptive ability) -osteocytes can NOT replicate |
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osteoclast
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bone reasorbing cell
-acidophilic cytoplasm lying in a shallow depression on the bone surface (Howship's lacunae) -phagocytic cell derived from monocytes in blood -contains many lysosomes, cell membrane highly folded into a ruffled border -secretes acid, collagenase and other lytic enzymes, that break down bone matrix (bone reabsorption), releasing calcium and phosphate into the blood |
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Haversian system (osteons)
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4 to 20 lamallae (layers) of matrix and osteocytes surrounding central haversian canal. All interconnected osteocytes receive nutrients from the blood vessel in the center. They run longitudinally and are lined with endosteum
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Volkmann's canals
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transverse canals that bring blood vessels to and from the periosteum, Haversian canals, and the marrow cavity. They are also lined by endosteum
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Interstitial lamellae
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remnants of partially resorbed osteons
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Intramembranous ossification
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bone (osteoblasts) develop directly from mesenchyme. Flat bones on face and skull, mandile, maxilla (membrane bones)
mesenchyme--> bone |
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Endochondral ossification
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A temporary cartilage model is first formed from mesenchyme. The continously growing catilage model is progressively replaced by bone tissue through a long process. Most of the bones in the body.
mesenchyme--> cartilage model--> bone |
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What type of bone is formed first?
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immature spongy woven (primary) bone (not organized in lamallae (layers)
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What does bone remodeling replace the immature woven bone with?
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Mature secondary lamellar bone
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What is the main criterion for classification of cartilage?
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type of fibers in the matrix
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Stages of the developing embyro?
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1)Zygote formed 2)Cell division 3)Blastocyst forms 4)Two layered embryonic disc 5)primitive streak 6) Changes to tubular shape 7) Neural tube and neural crest are formed
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simple gland
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single duct
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compound gland
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more than one duct, many branches
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Red marrow
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active hemopoiesis in ribs, sternum, vertebrae and pelivs
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Components of Red marrow?
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stroms, hemopoietic cords, sinusoids
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Stroma
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reticular cells and fibers, sparse adipose tissue
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Hemopoietic cords
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developing blood cells
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Sinusoids
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discontinuous irregular capillaries with large lumen, newly formed cells enter circulation by squeezing between endothelial cells of sinusoids
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Yellow marrow
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inacitve, mostly adipose cells
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Hematocytoblasts
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pluripotent large stem cells with euchromatic nucleus and distinct nucleoli
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What do Hematocytoblasts give rise to?
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1) Myeloid series cells (in bone marrow) RBCs, megakaryocytes--> platelets granulocytes, monocytes--> macrophages
2) Lymphoid series cells (in thymus/lymphoid tissues) lymphocytes--> plasma cells |
