oral practice questions Flashcards
composition of peripheral blood
blood: specialised CT where cells suspended in extracellular fluid=PLASMA. 5L in adult. Has formed ELEMENTS circulating in plasma= leukocyte, erythrocyte and platelet
when leaves circulatory system plasma protein react and form clot, forming SERUM: blood plasma w NO clotting factors (no fibrinogen) but has other growth factors/proteins.
centrifugation of blood: 45% HEMATOCRIT (erythrocytes); BUFFY COAT 1% (leukocytes+platelets) and 55% PLASMA
blood functions:
1) transportation vehicle (O2,CO2 metabolites +hormones)
- O2 transported by haemoglobin in rbc
- abundant in arterioles
- CO2 by hydrogen carbonate +hemoglobin
2) osmotic balance (regulate organ function) +3) heat distribution
Plasma: aq sol 7.4pH. its an indication mean composition of ec fluid in tissues
- 92% water
- proteins= 7%
albumin most abundant 58%, in liver maintain osmotic p
globulin 37%
lagma: plasma cells produce
alpha+beta: liver- FIBRONECTIN, TRANSFERIN, PROTHROMBRIN and LIPOPROTEINS
fibrinogen 4% largest, liver helps w clotting; polymerised as insoluble
complement proteins 1% helps w inflammation and destroying microorganisms
other solutes: electrolytes, waste, nutrients, resp gases
plasma cells are b lymphocyte-derived
antibody-producing cells
large, ovoid cells w spherical nucleus (w compact peripheral region w HETEROCHROMATIN+ alter w light areas EUCHROMATIN=clockface
BASOPHILIC cytoplasm (rich RER)
GA+centriole(pale when stained)
lifespan 10 days+abundant in infected cells
erythrocytes, structure+ function
structure:
- biconcave (large SA:V) ;
- flexible (allow passage of materials through irr turns)
- larger blood vessels rbc adhere to each other in loose stacks= ROULEAUX
- cell membrane (plasmalemma)- 40%lipids, 10% carbs, 50% protein: integral proteins (BAND-3-PROTEIN+GLYCOPHORIN A- has antigenic sites for ABO blood typing; also inner surface proteins: SPECTRIN which binds lattice to actin F+ ANKYRIN binds lattice to integral proteins)
function: stabilize membrane, maintain cell shape + provide cell elasticity required for passage through the capillary
- no organelles, densely packed w haemoglobin (TETRAMERIC O2 -each binds to four O2)
- Hb+O2-> oxyhemaglobin
- Hb+CO2-> carboaminohemaglobin
both reversible
- Hb+CO-> irreversible decrease cell capacity to transport O2
erythropoiesis:
- promyeloblast: 20h in stage
20um, first morphological distinguishable stage, EUCHROMATIN, spherical nucleus, cytoplasm basophilic, 1 week to mature to rbc, mitotic division possible
erythropoietin (highly GLYCOSYLATED protein in liver + kidney, has receptor JANUS KINASE 2- helps to stimulate differentiation of proerythroblast by affecting signalling pathway of erythropoietin, circulates in blood for 5h and main goal is DNA transcription);
- basophilic myeloblast: 20h
10-16um, spherical nuclei+ NO NUCLEOLUS, COARSE chromatin, basophilic cyto(ribosome), mitotic division - polychromatophilic myelobast: 25h
10-12um, spherical but chromatin is WHEEL LIKE condensed in coarse granules, HEAMOGLOBIN forms, stains both basophilic+eisinophilic, cytoplasm basophilic, last stage for mitotic division - orthochromatophilic myeloblast: 30h
8-10um, OESINOPHILIC cyto due to haemoglobin, nucleus DENSELY PACKED and becomes EXTRACTED
reticulocyte 1-2d
immature stage, physiologically 0.5-1.5% of cells, biconVEX shape non-nuclear, eosinophilic cyto, stains w BRILLIANT CRESYL BLUE due to remaining polyribosomes
rbc: lifespan 120 days
biconcave, 7.5um and 2.6um thickness
W: 4- 5.2x 10^12/L
M: 4.5- 6x10^12/L
red blood cell distribution width 11.5-15.4% (measures variation of shape+volume)
pathological forms: microcytosis, macro, aniso, poikilocytosis (sickle cell, sphero, acantho)
Leukocytes, classification, structure and function, leukogram
leukocytes make up your granulocytes+ agranulocytes. F: to defense+ conc in CT. All have azurophilic granules+ nucleated
granulocytes: have 2 granules, POLYMORPHIC nuclei, low lifespan and few mitochondria low energy needs so depends on glycolysis (glucose->pyruvate= ATP+NADH) agranulocyte: no specific granules, spherical nucleus w no lobes. Azurophilic granule= STAINS AZURE A.
Granulopoeisis
- myeloblast: 10-14 days to mature
15-20um, first morphological stage, euchromatin, big round nucleus w 3-5 NUCLEI, basophilic cyto, mitotic division possible. Key cytokines: stem cell factor+ interleukins (monocyte+macrophage, endothelial, CD4+ T-cell)
promyelocyte:
22-25um, spherical nucleus w coarse chromatin, GRANULES start to form (2), BASOPHILIC cyto, mitotic division
neutrophilic myelocyte: 1 week to mature
15-20um, spherical w COARSE chromatin, NO NUCLEOLI, cyto is slightly EOSINOPHILIC (from specific granules), last stage of mitotic division
neutrophilic metamyelocyte
10um, weak eosinophilic cyto, HORSESHOE-shaped nucleus, chromatin CONDENSED
neutrophilic band: immature; mean life in blood 8-12h, CT for 1-2d
10um, nucleus elongated but NOT yet POLYMORPHIC (having many lobes), weak eisonophilic cyto
neutrophil 1-4CT, 6-8h in blood
10-12um, most abundant 54-67% in blood, 3-5 lobes connected by thin nuclear extension (thin strands of chromatin), weak eosinophilic cyto, solder for immunity, usually inactive when circulating blood but during diapedesis activated+ becomes ameboid
eosinophils 1-2 weeks
12-15um, large eosinophilic granules(flattened crystalloid core+e- dense), BILOBED, abundant in interstitial lining+ sites of chronic inflammation in lung patient w asthma+ remove antibody+antigen complex from interstitial fluid by phagocytosis
basophils
12-15um, not as numerous, less densely packed, NO LOBES/ 2 IRREG lobes, strong BASOPHILIC GRANULES due to histamine, supplement function of MAST cells= have receptors for IgE and secrete granular components in response to antigen. also METACHROMATIC
monopoiesis:
- common cytokines cells w granulocyte GM colony forming unit
- monoblast: precursor cell like myeloblast
- promonocyte:
basophilic cyto w fine azurophilic granules (high rer+golgi=BASOPHILIC), large INDENDED nucleus+ nucleoli, DIVIDE 2X during differentiation
- monocyte: lifespan months
enter bloodstream for 8h, go to CT-> macrophage
structure:
12-15um, largest cell in blood, chromatin less condensed, precursor of macrophage, microglia and osteoclasts, horseshoe, stains lighter than large lympho, with light basophilic cyto
lymphopoiesis: projenitor cells originate in red bone marrow= lymphocyte colony forming cell
lymphoblasts:
prolymphocyte: immature lymphocyte, also DIFFERENTIATE X2-3
small cell w large nucleus and coarse chromatin synthesize cell surface proteins that into B (make antibody)/T lymphocytes (release cytokines/ recognize+kill infected cells)
BCR b cell receptor
TCR
CD antigens - to identify
structure:
9-18um, few/none granules, MOST NUMEROUS granulocyte, T+B lymphocyte +NK (kill infected cells)
large lymphocyte: INDENDED nucleus, cyto basophilic, few azurophilic granules (organelles)
small: basophilic rim+spherical nucleus w highly CONDENSED chromatin 6-8um
Leukogram:
*Neutrophils 60-70%
*Lymphocytes 20-40%
*Monocytes 2-10%
*Eosinophils 2-5%
*Basophils 0-1%
Platelets- structure, function and differentiation
structure: 10 days lifespan
2-4um, biconVEX (like reticulocyte), small, NON-NUCLEATED+ MEMBRANE-BOUND in endothelial tissue
150,000-400,000/ uL
originate from end of cytoplasmic proc of megakaryocytes,
F: promote CLOTTING+ REPAIR in endothelial,
DISCOID shape: peripheral HYALUMERE (light stained) and central GRANULOMERE (dark); Has MARGINAL BUNDLE: MICROTUB+MICROFIL to maintain shape
blood coagulation:
-GLYCOCALYX in plasmalemma involved in adhesion+activating during coagulation
- primary agg: platelet PLUG forms by glycocalyx adhere to cell wall
- 2 agg: enlargement of plug by releasing glycoproteins +ADP-> agrr more
- blood coagulation: release of FIBRINOGEN, VON WILLEBAND factor form 3D network of trapped fibres (rbc+platelets)= clot
- clot retraction: CONTRACT blood clot (use myosin+actin) for bulge to flatten
- clot removal: new endothelia formed, clot removed by PLASMIN (proteolytic enzyme)
granules(other deck)
thrombopoiesis: myeloid st, progenitor and then megakaryoblast:
25-30um, non-lobbed +nucleoli + KIDNEY-shaped nucleus, basophilic +homogenous cyto, sensitive to thrombopoietin (liver+kidney).
- Promegakaryocyte: forms azurophilic granules+specific, ENDOMITOSIS occurs (repeated rounds of DNA replication w out cytokinesis = polyploidy up to 64n)
- megakaryocyte
50-150um, multilobed, multiple centriole, golgi+rer+mito. many plasma membrane invagination= DEMARCATION MEMBRANE ( represent reservoir that facilitate the elongation of protoplatelets)
platelet formation: protoplatelets (long branching process of megakaryocyte, penetrates the sinusoidal endothelium and exposed to circulating blood) have actin F+loose mixed microtubules form loop =tear shaped enlargement and pinches off cytoplasm=platelet
Hematopoiesis, periods, stem cells, growth factors, structure of the bone marrow
hematopoiesis development : 3 phases
- MESOBLASTIC 3 week-3 month
forms BLOOD ISLAND in YOLK SAC (outside of embro, too small) and in mesenchyme of CONNECTING STALK +CHORION
- HEPATIC/hepatolineal phase 2-8th fetal month
form major blood-forming organ:liver+ progenitor cells come to proliferate. HEMATOPOETIC CENTRES appear and limited to erythrocytes formation (some leukocytes)
- bone marrow/MEDULLARY phase 4th month-birth
red bone marrow becomes major hematopoietic organ: and in lymphatic tissue
Hematopoiesis: all blood cells derive from pluripotent(assymetric division + self renewal-> multipotent (myoloid+lymphoid stem cell)-> forms erythrocytes, megakaryocyte, granulocyte+ monocyte
growth factors (colony stimulating factors): erythropoietin, thrombopoietin, interleukin, colony stimulating factors=stemcell factors)
Bone marrow
in MEDULLARY CANAL OF LONG BONE+ small cavity of CANCELLOUS bone.
- stroma: composed of RETICULAR CT(loose arrangement of reticular fibres) +hematopoietic CORDS/islands+SINUSOIDAL capillaries (found in hematopoietic organs: larger than normal capillaries, wider gaps than endothelial, basal lamina DISCONTINOUS or absent, more permeable=rapid nutrient exchange)
- stroma cells: meshwork of fibroblasts
- matrix: collagen type I, proteoglycans, fibronectin, laminin and GAGs
- site of phagocytosis of old erythrocytes+ iron storing due to hemaglobin break down
- all bone marrow is red but changes to yellow as matures
Preparation, staining and evaluation of the blood smear
slide preparation
disinfect the 3/4 fingertip, puncture into ball of fingertip w sterile lancet. Wipe first drop and second drop place on near end of glass slide. Spread using another slide and place cover slip on top at 45 degrees + spread by capillary forces.
staining
Fixate w May Grunwald sol 3m
(eosinate of methylene blue in methanol)
stain w diluted May grunwald sol 1-2m
(add same amount od distilled water)
pour off mixture
stain w Giemsa Romanowsky solution 15m
(eosinate of methylene azure, blue +violet)
washing
w distilled water
air dry
results:
RBC pink/red
nuclei blue/purple
neutrophilic granule salmon pink
basophilic blue/violet
eisinophilic brick red
azurophilic granules purple/red
cyto of lymphocyte sky blue
monocyte pale blue/greyish
CT general structure, function and classification
CT provides matrix SUPPORT and PHYSICALLY CONNECT tissues+cells together in organs
- interstitial fluid provides metabolic support for cells as meeting for diffusion of nutrients + waste
origin:mesenchyme abundance in ECM, two types of cells:
resident- fibroblast+cystes, myofibroblasts, adipocytes, mesenchymal, reticular, and pigment cells
wandering (migrate to CT for maturation)- macrophage (histocyte), leukocytes, plasma, mast cells (heparinocyte)
main function: support, structure,defense, storage and nutrition
types of CT
connective tissue proper
CT w special properties:adipose, reticular+ elastic and embryonic: mesenchymal and jelly like CT, BLOOD
supporting CT
cementum
bone
CARTILAGE
dentin
cells of CT:
1) fibroblast- branched +irr basophlic cyto (rer,golgi,mito), active: nucleus large ovoid euchromatic w prominent nucleolus
inactive: smaller+spindle shaped heterochromatin=darker
- main function synthesize ECM components, secrete collagen, elastin, reticular fibres.
2) myofibroblasts: have contractile proteins alpha smooth muscle actin (contract wound to bring closer together)-causes fibrosis excessive accumulation of matrix components
3) heparinocytes- 7-20um +irr shaped, developed from progenitor cells, basophilic granules (STAIN ALCIAN BLUE+ PAS+), nucleus obstructed by secretory granules (e- dense heterogeneous), METACHROMATIC (change colour of basic dye blue to purple/red due to high acidic radicals of GAGs therefore poorly presented)
- numerous near small blood vessels (skin or mesentery called pre-perivascular mast cell; mucosal mast cell along lining of git+resp tract.
- main function- allergic reaction: IgE ginds to mast cells and releases materials of secretory granules (like basophils)
6 cells in granules:
heparines- sulphated GAG act as coagulant
histamine- increase vascular permeability, and increase muscle contraction
phospholipid- precursor for conversion of leukotrines (signaling mol of leukocytes)+ prostaglandins (both signaling mol for inflammation)
cytokines- polypeptide direct activity of rbc+leokocytes
neutrophilic + eisinophilic chemotactic factors- aggregate + attract other leukocytes
serine protease- activates mediator of inflammation
4) pigment cells
neuroectodermal, dark brown granules, startum basale, melanocytes (melanin for pigment+protect UV)
5) adipocytes: Large fat cell, store lipis, cushion+insulate, less common heat production; types: uniocular+multiocular
6) plasma+ leukocytes
CT fibers:
1) collagen-
- most abundant fibre, eosinophilic glycoprotein, differ in size but avg 300nm long, 1.5nm thick.
- formed by three alpha chains= triple helix
- type I: accounts for 90% of collagen, in loose, dense CT+ bone
- type II: hyaline and elastic cart
- type III: forms reticular fibers. in loose, smooth muscle+ ENDONEURIUM (around myelin sheath)
- type IV: basal lamina of epithelial cells
2) reticular: type III collagen fibril rich on sugar: GLYCOSYLATED SILVER IMPREGNANTION+ PAS+. argyrophilic- affinity to silver
- produced by fibroblasts in reticular lamina of basement membrane.
- F: Surrounds adipocytes, smooth m +nerve cells, small blood vessels; characterize stroma of hematopoietic tissue+lymphoid organs (except thymus); rich in microvasculature of liver+endocrine glands; serve as supportive stroma for perenchymal secretory cells (support, facilitate adhesion, maintain structure by forming scaffold+ regeneration by facilitating migration of cells+organizing)
3) elastic: outer fibrillin+ inner elastin core. has fenestrated sheets=lamellae
- non coding AA (desmosine+ isodesmosine).
- AA (lysine, glycine +proline)
- to maintain rubber-like property: lysine oxidised on 2 diff elastin= condense as desmosine ring and covalently cross-link between polypeptide
- ALDEHYDEFUCHSIN(magenta) , ORCEIN (red-brown) AND RESORCINFUCHSIN (blue-black)
Extracellular matrix of CT– structure and function
Gylcoaminoglycans- mucopolysaccharides, long polymers of disaccharide unit
1) uronic acid (idunonic acid+ glucoronic)
2) hexosamine
(galactoseamine+glucosamine)
3) hylauronic acid - glucosamine + glucoronic
proteoglycans-
sulphated GAGs (4): chondroitin, heparan, keratan, dermatan sulphate - hydrophilic, contribute to viscosity, bind to proteins synthesized in GA
non sulphate: (5)
1) aggrecan- hydrate cartilage ECM
2) perlecan- main protein in basal lamina
3) syndecan- cell-ECM linkage
4) decorin- binds fibrils to collagen type 1
5) versican- bind cell-cell/cell-ECM; fibroblasts, smooth muscle+chondrocytes
multiadhesive glycoproteins
1) laminin- binding site for integrin+collagen IV+proteoglycans; anchor to basal lamina
2) osteopontin- bind to osteoblasts
3) tenascin- cell -ECM attachment
4) fibronecin- made by fibroblasts: binding site for integrins + collagen IV
Connective tissue proper – characteristics and classification
1) CT proper
loose CT- irregular fibrillar component that is loosely arranged fibres flexible but not very resistant to stress, abundant matrix w wandering cells, type I, elastin+reticular fibres , well vascularized
- function: supports epithelial tissue, provide environment for exchange of compounds, involved in immune reactions
- in lamina propria of mucosa, interstitial fluid of glands and stratum papillae dermis(papillary layer of dermis)
dense CT- fewer cells+ground substance, poorly vascularized, type I
-->reg- fibers oriented in one direction, fibroblasts arranged in parallel orientation to collagen fibres - tendon, lig, aponeurosis
--> irr- oriented in many directions - function: less flexible but more resistance due to dense collagen - periosteum, perichondrium, stratum reticulare dermis (reticular layer of dermis), and sclera
in tendons: tendinocytes
- densely, closely packed bundles of collagen separated by little ground substance
- fibrocytes have elongated nuclei that lie parallel to fibres;
- cytoplasm has portion of collagen bundles. cyto stains same as fibres:yellow lig of vertebral column has abundant parallel elastic fibres
- poor vascularization (repair low)
- some tendons: dense irr CT has synovial cells secrete hylauron
structure:
inner peritendinum: dense reg CT
outer epitendinum: dense irr CT
2) Adipose CT
white adipose tissue
- 50-150um spherical when isolated; polyhedral when closely packed
- uniocular: one large droplet of triglyceride; surrounded by rim of cytoplasm w nuclei; has mitoch, cistern in rer, golgi and polyrib
- surrounded by thin submembranous layer (collagen IV) has pinocytotic vesicles .
- found: neurovascular bundle and subcutaneous tissue around kidneys
- f: store energy, cushion of vital organs + insulation, secrete organs
brown adipose tissue
- polygonal; subdivided by partitions of CT into lobules- makes more pronounced and delineated
- multiocular: smaller w many lipid droplets; abundant in mitochondria (why brown) scattered around lipid droplet of fat cell+ in capillaries
- f: heat production+ thermogenin in mitochondrial membrane (produce heat by non shivering using uncoupling proteins)
beige adipose tissue
- similar to brown morphologically; in insulated cells dissipated in white adipose tissue
3) embryonic CT STAIN: H&E
mesenchymal: small stellate shaped cell, interconnected by gap j, forms 3D network. ECM has sparse collagen+reticular fibres
- developed in lymphatic+ circulatory tissue+ musculoskeletal (bone, cartilage)
Mucous: found in umbilical cord, Warton’s Jelly- dispersed fibrocyte-like cellular portion between ECM. High abundance of ground substance (fibroblasts, collagen+reticular fibres)
4) bone talk about in other question unless asked
Cartilage - structure and function, description of the individual types
cartilage is supporting CT, mesenchymal in origin. Made from dense CT; avascular (low metabolic activity+low regeneration) and aneural and nutrition supplied by diffusion from perichondrium (double layer dense irr CT (type I collagen fibrils) inner layer: contains chondroprogenitor cells and outer layer is fibrous layer)=EOSINOPHILIC
matrix: sparse fibrillar component
sulfated GAGs (keratan+chondroitin+ hylauronic acid), proteoglycans and multiadhesive glycoproteins: chondronectin binds to GAGs, integrin and collagen to help w adherence of chondrocytes to ECM
basophilic: STAIN ALCIAN BLUE, NUCLEAR RED H&E
cells:
- chondroblasts (help w development of cartilage, is in perichondrium and proliferate due to somatotrophin released (GH)
- chondrocyte (help w maturation +maintain structure by secreting metalloproteinase to degrade cartilage )
hyaline cartilage: type II collagen fibers. most common, and it’s the skeletal model for endochondrial oss.
territorial: basophilic (less fibrils-collagen)
inter-territorial: eosinophilic (more fibrils)
- chondrocytes on surface more elongated and deeper are oval; form isogenic lineages (cluster)
- resp system +nose+larynx , coastal cartilage, growth plate (epiphysial plate for growth of long bones); articular surface of bone don’t have perichondrium has synovium (secrete synovial fluid for nutrition- no perichondrium)
elastic cartilage: type II collagen. Similar to hyaline but has branching elastic fibres (elastin+fibrillin)= fibrillar component more abundant. more flexible. Has perichondrium
- chondrocyte= alone/isogenic groups
ALDEHYDOFUCHSIN, RESORCINBUCHSIN (black) ORCEIN
- auricle, eustachian tube, epiglottis, and small cartilage of larynx
fibrocartilage: mix of hyaline+dense reg CT= type I+II , not visible perichonderium. less vascularized bc has dense bundles of type I collagen fibers that alternate w cartilage matrix. EOSINOPHILIC (low GAGs)
- chondrocyte= alone/linear groups
interstitial growth= diff from preexisting chondroblast
apposition is from new chondroblast
damage= perichondrium produce scar of dense CT to form new cartilage (low repair bc bad vascularization)
- f: provide tensile strength+ bear weight+ resist compression
- in intervertebral disc+ menisci at knee+ pubic symphysis
AZAN/MASON TRICHROME
Endochondral and intramembranous ossification
intramembranous
- 8th week makes: mandible, maxilla, skull, clavicle, growth of short bone, thickening of long bones(appositional), parts of occipital+temporal, frontal+ parietal
- mesenchymal blastema is first ossification centre: cells differentiate (mesenchyme-progenitor cells-osteoblast) around network of developing capillaries. From surface osteoblast face away from capillaries to secrete osteoid (bc polarized)
- osteocyte form bone spicules (thin sheet like layer of bone tissue that grow+fuse- important for structure, support+ increase SA of bone)
- calcification of matrix = trabecular network of woven bone
- osteocyte enclosed within lacunae and still continued matrix secreted= more layers form compact bone enclosed around cancellous bone (w marrow+large blood vessels) + fusion of neighbouring oss centres occur
- in cranial flat bones bone formation> bone reabsorption= two layers internal layer (diploe maintain its spongy nature) +external (fontanelle)- happens when no ossification of CT forming periosteum+endosteum
endochondral -long bones, vertebra, ribs
- hyaline as model forms around diaphysis w bone collar (osteoblast from perichondrium)- to impede diffusion of nutrients to promote degeneration
- chondrocyte produce alkaline phosphatase cause swelling/hypertrophy (lacunae enlarge +compress matrix into narrow trabeculae=calcifies)
- due to degeneration of bone collar chondrocytes undergo apoptosis creating porous structure made of calcified cartilage remnants covered by osteoblast layer
- osteogenic buds (complex structure have capillaries, mesenchymal, osteoprogenitor) forms where bone will be developed
- blood vessels pierce through bone collar and bring osteoprogenitor cells to porous central region. Osteoblasts adhere to remnants and make woven bone
- calcified cartilage (more basophilic) than new bone (more eosinophilic)
process= primary oss centre in diaphysis
secondary oss centre at epiphysis
- during expansion+remodelling of 1+2 oss centre produces more cavities filled of bone marrow + trabecullar of cancellous bone
- two parts remain where bone doesn’t replace cartilage: articular cartilage (within joints, persist through life) +epiphysial (growth of length-interstitial, disappear as adult)
Epiphyseal cartilage zones/growth plate
*Zone of reserved cartilage exhibits no active ECM production.
*Zone of proliferating cartilage actively produces collagen type II.
*Zone of hypertrophy contains greatly enlarged (hypertrophic) cartilage cells.
*Zone of calcified cartilage is where cartilage calcifies (duh) and chondrocytes apoptose
*Zone of resorption blood vessels+ osteoblasts invade the old cartilage leaving only longitudinal spicules behind+produce marrow cavities
Microscopical structure of the bone tissue
bone supporting CT, main constituent of skeletal tissue, protects vital organs, acts as reservoir for Ca+PO4 ions, lever for body mov= mechanical+metabolic functions
Layers: dense CT, blood vessels, collagen fibres and fibroblasts
periosteum
inner cellular. Osteoprogenitor cells. responsible for appositional bone growth+repair
outer - fibrous layer, dense irr CT+perforating sharpy’s fibres (bundles of periosteum collagen fibres w purpose to bind periosteum to bone by penetrating matrix)
endosteum- lines marrow cavity, and surface of trabeculae of compact bone. same as periosteum but thinner
cells
1) osteoblasts: mesenchymal active form cuboidal/columnar cells with high basophilic cyto; inactive-flattened and less basophilic. Majority inactive form on surface between endosteum+periosteum.
- secrete osteoid-layer of matrix components between osteoblast+preexisting bone surface and now in contact w preexisting bone matrix: euchromatin, nuclei, abundant GER +GA
- osteoid essential for apposition growth completed by deposition of calcium salts into newly formed matrix.
comm w gap j. stimulated by parathyroid hormone (bone remodeling)
osteocyte- flat almond-shaped, diff array of genes than blast; less GER, smaller GA and more condensed nucleus. enclosed within lacunae, w blood supply that runs through canaliculi (250-300nm). Organized in isogenic groups/lines. Also comm gap j. produce sclerostin+cytokines= bone remod
- help w Ca hemostasis+ sensors detect mechanical stress
osteoclasts: not mesenchymal in origin, hematopoietic (comes from projenitor cells in bone marrow). Large motile cells 50-100um, multinucleated, lie within reabsorption cavities. Active ones are at surface against matrix, has irregular projection= ruffled border surrounded by AF;
- formation: two polypeptide osteoblasts secrete: MCSF macrophage colony stimulating factor + rankl receptor-activated of nuclear factor kb ligands
bone remodelling: osteoclasts secrete lysosomal enzymes (collagensa+cathepsin k) cause protein pumps to secrete H, increase acidity. Dissolved crystals+digest matrix. Endocytosis occurs, infoldings of PM going to ECM.
- osteopetrosis condition: overly dense w abnormal growth, very brittle fracture easily. No ruffled border so reabsorption is low
bone matrix 50% each
organic
- collagen type I
- proteoglycans (sulphate keratan, chondroitin+hyaluran)
multi adhesive glycoproteins
- osteonectin-bind crystals to collagen fibrils
- sialoproteins (sialoproteins I,II, osteopoitin) non- collagemous mineralization
- non-specific vit K: osteocalcin (bind Ca) + protein S (moves apoptotic cells)
inorganic
- hydroxyapatite crystals (amorphous, noncrystalline)- has layer of water to facilitate exchange of ions between mineral + body fluid
- ions bicarbonate, citrate, Mg,Na,K
calcification
1)vit k dependent osteocalcin +glycoproteins bind to Ca
2) osteoblasts secrete matrix vesicles w alkaline phosphatase (increase PO4 conc)
3) make hydroxyapatite crystals which grow rapidly in + around mateix
form calcified materials embedded in collagen and proteoglycans
description of the individual types of bones
types of bones
long bone-
-bulbus ends- epiphysis (are rounded bulbus structures at end of each side of bone. covered by layer of articular cartilage. bulbus ends important for the stability and support of joint.
epiphysis composed of spongy bones convered by thin layer of compact bone
- diaphysis- compact bone w thin layer of spongy bone (around central merrow cavity)
short bone- cores of spongy bone surround by compact
flat bone form calvaria (2 layers of compact called plates separated b thicker layer of spongy bone diploe
trabeculae (cancellous)- at epiphysis of bones, contain red bone marrow. Weaker= easier to fracture. thin therefore allow diffusion of vessels to bone marrow- important for stem cell+blood cell production
compact bone
- packed osteons- bone matrix, 3-7um of lamellae parallel oriented conc around haversion canal. space between lamellae=lacunae which where osteocytes reside. have dendritic process allowing for communication between osteocyte for diff of nutrients, waste and senses mechanical stress of bones.
- cement line outer boundary of osteon collagen rich
- volkmann canal comm merrow cavity w periosteum
- lamellae interconnected by canaliculi. organization:
- interstitial lamillae- between osteon remnants after remodeling. irr shaped
- Circumferential between/ around bone. external: beneath periosteum and Volkman canal or inner: around merrow cavity covered by endosteum
Woven bone/fibrillar
random dispersion of type I, primary bone newly formed (immature) replaced w lamellar when matured
not replaced for sutures of calvaria
lower mineral content but high osteocyte (rapidly grow but weaker)
lamellar bone
has lamellae (organized in conc around central canal)
multiple layer of matrix
lamellae appear as alternating dark and bright bands- due to diff orientations +layers of fibres = strong
bright- birefringence of collagen fibres
bone remodeling (children have 200x turnover excellent capacity for repair due to osteoprog cells)
osteoclasts remove old bone, replace it
- osteoclast in tunnel-like cavities w diameter = size of new bone
tunnel invaded by osteoprog cells and sprouts loops of capillaries. diff to blasts which on the walls secrete osteoid in cyclical manner = conc lamellae around bone w trapped osteocytes
metabolic role of bone
controlled by Ca2+ 9-10mg/dL
Ca from hydroxyapatite crystals or interstitial fluid
parathyroid hormone: release Ca2+ stimulate osteoblasts (secrete factors that make osteoclasts) which then reabsorb matrix (indirect affect)
calcitonin- decrease Ca2+ tell psteoclasts to slow down reabsorption+ bone turnover
specialised cell surface
found in polarized epithelium. in most cuboida/columnar cells.
apical domain- tall cuboidal epithelial cells face lumen F: absorb +move substances
cilia- 5-10um, 0,2diameter (longer than microvilli twice wide)
- one cilia=primary cilia non-motile.
- has receptor +signal transduction complexes: light, odour, mov, flow of fluid
- abundant in columnar+cuboidal at apical
- lung, resp tract+ ear
- motile in epithelial cells w organized microtubular core. basal bodies (similar to centriole-cylindrical w 9 microtubules in triplets. make up cilia + control axoneme assemble) + axoneme (9 doublets surround 2 central microtubules, peripheral joined by NEXIN and joined to central sheath by RADIAL SPOKES. responsible for motility bc of protein motors dynein+kinase).
sterocilia 5-10um, long motile microvilli. in hair cells, men (reproductive system) : epithelium of ductus deferens+epidydimus.
- no VILLIN at tip of sterocili (unlike microvilli)
microvilli 1um and 0.5um diameter
- intestinal microvilli has glycocalyx has enzyme for digestion of macromol.
- bundles of actin f capped+crosslinked to eachother+PM via actin-binding proteins (MYOSIN, FIMBRIN, FASCIN).
- intestinal microvilli has actin F anchored to villin extend processes to apical cytoskeleton interacting w/ terminal web (provide support+rigidity)
- (intestinal fluid has striated border and PCT has brish border)
lateral domain tight junction (occludens) forms tight relationships w neighbouring cells- most apical, forms band encircles each cell. transmembrane proteins act sealing strands to form barrier on apical end (CLAUDINS+OCCLUDIN).
- F: control transport of mol by redirecting to go through cell=trasncellular rather than paracellular. force to go through intracellular cleft
- few in PCT- very permeable to water
- prevents membrane protein at one apical end to move= two domains basolateral and apical
- diffusion of outer memb= pentalaminar sheets help reg permeability
Desmosome- disc-shaped.
- F: attach IF to cell. contain large member of cadherin fam DESMOGLEIN+DESMOCOLLIN- insert to dense attachment plaque of anchoring proteins= DESMOPLANKIN+PLAKOGLOBIN.
- non-epithelial cells, intermediate f attach to desmosome via VIEMENTIN+DESMIN. most common cable-like filament is CYTOKERRATIN.
- in most stratified squamous spithelia keratinized to protect against water loss.
zona adheres (anchoring junctions)- lateral surface of neighbouring cells under zona occludens in epithelial tissue. In intercalated disc of cardiac. Actin F anchored to attached plaque (site of cell membrane that attaches junction). Actin bind to E-CADHERIN (transmembrane glycoprotein) through linking protein (ALPHA ACTININ, VINCULIN+ CATENIN) - depend on Ca2+
Communicating junctions- aggregated transmembrane protein complex in circular patches of PM.
- protein CONNEXIN forms hexametric complexes= CONNEXONS (hydrophilic core 1.5nm; 1000x or more between cells move in coordinated manner- cardiac cells.
- injury, channel close to prevent spread)
basal domain
binds to basal lamina via hemidesmosome or focal contacts. Striation, caused by attachment of epithelium due to hemi+focal striation looks like linear arrangement of cytoskeletal elemental+adhesion complexes (also bc if mitochondria). have invagination of cell membrane that enlarge the area of basal cell surface= enhance power of enzymes located there. vertically position mitochondria inside the invagination. typical in ions transporting cells (proximal+distal renal tubules, cells of striated ducts in salivary glands.)
1) Hemidesmone- proteins of IF anchored to intercellular plaque bound to INTEGRIN (receptor to laminin+fibronectin in basal lamina)
2) focal contacts- actin F anchored to them via adaptor proteins+ INTEGRIN.
- Infolding of basement membrane (has ion-transporting epithelia)
basal labyrinth-cell membrane invagination (enlarge SA) abundant in mito (contain pumps, source of energy for ion transporting cells)
Basement membrane
basal lamina
lucida- 20-100um, e- dense, under epithelia, extracellular portion of integrin has LAMININ+FIBRONECTIN receptors
densa: e- dense, adj to CT composed of collagen IV fibrils+ENTACTIN+ proteoglycans + LAMININ)
- attach to CT through collagen IV+FIBRILILN
- laminin+ collagen form network help together by ENTACTIN, NIDOGEN +PERLECAN
Reticular lamina: layer of reticular fibres under basal domain. Not produced by epithelia (belong to CT). more diffusible in fibrous layer, stains PAS+ and eosinophilic due to collagen III (bind to basal lmaina through IV)
- F: support structure, polarity for epithelial cells, and helps organization of proteins affect endocytosis and signal trasnduction. proteins of lamina help w filter conc of mitotic growth factors. forming scaffold for epithelial repair
epithelia
4 types of cells, CT, muscle, nervous and epithelia.
closely aggregated polyhedral cells & no ECM, avascular, basement mem only in planar epithelium
- F: Lines all organs + glandular tissue. Cover inner+outer surface of bodies (skin+mucous membrane)
- exception of synovial membrane (synovium) has synoviocytes- non-epithelial. line inner surface of joint capsule, tendon sheath+synovial bursa
- lamina propria is CT underlies epithelial lining of digestive, resp + runiary tract (endoderm).
F: protect, secrete, absorb, transport, respiration and reception
formed: 3 germ layers.
Ectoderm- epithelium and skin appendages (nails+ hair follicle)
mesoderm- epithelium of serous membrane= mesothelium. Makes up peritoneum, pleural and pericardial cavities. cells line inner surface of blood+lymphatic vessels
endoderm line epithelium of resp+GIT
according to structure classification
3 types:
trabecular epithelium (plate/cords made from cuboidal cells) in liver +mainly exocrine cell exception thyroid glands
reticular epithelium(cells w process form 3D network; secrete +produce thymic hormones, support lymphocytes and signal their proliferation+maturation . thymus+organ of enamel+ epithelium of crypts in tonsils
planar epithelium-sits on one side of basement membrane. cover cavities+ducts+exocrine glands
simple epithelium
- squamous w flat cell+nuclei: diffusion. alveoli in lung+ glomeruli+ mesothelium (pleural, peritoneum).
- cuboidal- round nuclei in middle of cell. secretion. thyroid glands+collecting duct of kidney
- columnar- tall cells w elongated nuclei. secret+absoption. intestine+gallbladder+ endometrium
stratified epithelium- common arrangement have cuboidal cells on basement membrane. polyhedral cells are intermediate cells for differentiation of cells (start on basal layer and goes up diff, eventually faltten=epithelial cell)
- squamous: barrier+protection. keratinized:cells on top no nuclei visible-protect against water loss. epidermis
non keratinized: lines wet cavities (mouth+vagina+ esophagus)
- cuboidal: duct of sweat+mammary glands
- columnar: conjunctiva (hydrates eye by secret mucin?) +spars spongiosa(urethra)
transitional epithelium - one layer cells at diff heights
urothelium-mixed epithelium. protect against hypertonic+cytotoxic effects of urine. urinary passages
pseudostratified columnar ciliated- goblet cells produce mucous. respiratory passages
classification to function
covering: protect by selective barrier. simple squamous columnar (fallopian tube)+cuboidal, stratified squamous, urothelial +pseudostratified (trachea).
respiratory: F:gas exchange, type I pneumocytes- simple squamous bc diffusion. type II cuboidal cells produce surfactant. F: moisten+ during exhalation the P greater in lungs and surface decrease surface tension in alveoli preventing collapse.
absorptive: apical surface, microvilli assoc w brush border;high ATP +high SA ratio. intestinal erythrocyte+PCT
sensory:
- according to stimulus: photoreceptors (rods+cones); chemoreceptors (olfactory cells +lingual taste buds) and mechanoreceptor
- to structure: Primary: modified neurons w axon present. in retinal rods+cones+nasal olfactory cells. Secondary- no axon w modified epithelial. in inner ear hair cells+ lingual taste buds.
myoepithelial: surrounds smooth m of secretory glands- mammary, salvary+swear. contractial apparatus actin+myosin f aid to facilitate secretion. Musculus dilator papillae
Germinal: develop gamete-haploid. Males: seminiferous tbules has sertoli cells produce spermatozoa. Females:ovarian surface (waldeyer) simple squamous and cuboidal cells.
Transportation
along surface of epithelium by motile cilia: small intestine. across epithelial tissue to CT: ion transportation in epithelial duct of kidney.
secretory
planar+trabecular epithelium. both secretory glands (endo+exo) units supported by stroma of CT. in larger glands layer of CT also surround duct forming separate lobules (w secretory units ) enclosed w capsule (capsulated)
Endocrine- secrete hormones absorbed +trasnported to blood. single cells or groups+no duct (obliterated connection w surface epithelium)
Exocrine: secretion enter duct, cavity/body surface. unicellular (goblet cells) muticellular (glands w duct: connection preserved w epithelium)
- has serous cells: large enzyme= ALPHA AMYLASE non glycosylated stain PAS - and EOSINOPHILIC but cyto BASOPHILIC has well filled rer+GA w secretory granules. round nucleus, euchromatin. apical domain has tight+ adherent junction- accinar in shape.
acini of pancreas + parotid/salivary glands. epner glands in tongue conc in circumvallate papillae
(parotid- serous acini drain to intercalated duct then form large striated duct. lined w columnar epithelium)
- mucous cells: goblet cells; low columnar cells, nuclei flat +condensed+tubular in shape, granules mucigenous stains poorly w eosin (mucins) hydrate to make mucus- glycosylated proteins stain PAS + and ALCIAN BLUE (basophilic bc mucin is GAG). Mucin is hydrophilic so stains poorly w eosin (washes away) but enough oligosaccharide remain so stain pas.
minor glands (distributed throughout oral+submucosa+has plasma cells), weber glands (salivary- open at lingual tonsil. serous but has mucous membrane). palatine glands. glands are developed from covering epithelia in featus by cell proliferation onto CT
- serous mucous: on some salivary glands (serous acinar+ mucous tubules capped by groups of serous cells ) product watery mucous +digestive enzyme
Paracrine: secrete material reach target cell through diffusion by extra cellular space. subjacent to CT.
mechanism of exocrine secretion
merocrine- secretory procuduct released into vesicles of apical surface of cell. fise w PM+ excrudes contents by exocytosis serous+mucous cell. Eccrine sweat gland+salivary and mammary glands.
eccrine glands: simple tubular coiled, myoepithelium+stratified duct (2 layers unfolding of basolateral membrane along elongated mitochondria). cuboidal epithelial on surface
apocrine: secretory product accumulated on apical cell ends, excruded to release w a but of cytoplasm and portion of PM. how droplets of lipids released in mammary glands+aromatic glands of skins=axilla
holocrine: not apoptosis, secretory product accumulate within maturing cell. cause rupture of cells releasing product+cell debris onto lumen. sabecous glands
sabecous glands
branched acinar, ducts, hair follicles in surface of vermilion zone (stratified squamous becoming thinner lose epithelium at junction and become non keratinized, highly innervated and vascularised area, has melanocytes)+ areola
appocrine sweat glands
in axila+perineal region
coiled tubular merocrine glands
2 layers of stratified duct w cuboidal cells
myoepithelium
composed pheromones
classification of secretory epithelium. acinar l=w serous tubuli l>w mucous cells.
- duct structure: simple (not branched-large intestine) /compound (branched w short duct-salivary glands)
- shape of glands:
acinar (salivary+urethra); branched acinar (cardia of stomach)
coiled tubular(eccrine sweat glands); tubular (mucous glands of colon) branched tubular (pylorus of stomach)
compound tubular, elongated (duodenum-submucosal Brunner glands); acinar compound, sac like (pancreas); tubuloacinar (salivary glands-merocrine secetory mechanism)
