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35 Cards in this Set
- Front
- Back
Tunica intima
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innermost layer of vessels
made of 1.endothelium and basal lamina 2. subendothelial CT (longitudinally oriented) made of fibroblasts and Collagen I 3. internal elastic lamina |
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Tunica Media
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Circular layer of smooth muscle cells, each sm. mm cell surrounded by basement membrane, and mixed with reticular fibers (Coll. III) and proteoglycans
also has: -elastic laminae -external elastic lamina |
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Tunica adventitia
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1. elastic and collagenous CT (longitudinal) w/fibroblasts, collagen I, and elastic fibers
2. Blood vv (vasa vasorum), nerves, lymphatics |
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3 Basic types of arteries
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1. elastic (conducting)- often close to heart where high P (aorta, pulm a.)
2. Muscular (distributing)- downstream of elastic (eg, named aa- hepatic , renal) 3. Arterioles- located w/in organs or tissues |
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Elastic arteries
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Relatively thick intima (20% in aorta)
Media forms bulk of wall (40-70 elastic laminae in aorta) Adventitia is thin prominent vasa vasora and lymphatics structure of them fcns to smooth out pressure diff. between systole and diastole |
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Muscular Arteries
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thin intima w/prominent internal elastic membrane
thick media- mostly smooth muscle, external elastic lam. less evident adventitia is 1/2 to 2/3 of media, w/ vasa, nn, and lymphatics fcns to distribute blood to body |
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Arterioles (<100microm. diam)
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wall thickness~to size of lumen
very thin intima (lg art. may have IEL) Media- 1-5 layers of sm. musc., w/EEL in lg arterioles Adventitia- very thin, mostly collagenous fibers Reduces pressure before blood enters capillaries and also maintains blood pressure of system |
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Artery/vein shape differences
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A: circular w/crinkled IEL
V:deformed w/smooth IEL |
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Artery/vein wall thickness differences
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A: very thick
V: thin for the same diameter |
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Artery/vein media/adventitia differences
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A: media prominent
V: adventitia prominent |
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Norepinephrine
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delivered via sympathetic fibers
causes vasoconstriction via alpha1 receptors on the SMC Outer SMC are innervated, then excitation is spread via gap jcns |
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Epinephrine
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delivered via circulation
causes vasodilation via beta2 receptors on SMC Transmitter is diffused across SMC layer |
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General structure of capillaries
-EC setup -cytoplasm characteristics -between ECs? |
-endothelial tube of 1-3 cells + basal lamina
-thin cytoplasm w/pinocytotic vesicles (eg, caveolae) and microfilaments to allow shape change) -cell junctions |
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cell junctions of capillaries
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-intercellular clefts (15-20 nm) and/or
-tight junctions (fascia or occludens) -gap jcns |
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Continuous capillaries
-characteristics -where are they found -important for what aspect of cerebral circulation? |
-continuous layer of cytoplasm (via tight jcns)
-continuous basement membrane -pinocytotic vesicles for bidirectional exchange -found in muscle, CT, nervous system, exocrine glands -blood-brain barrier (zonula occludens w/few pinocytotic vesicles) --found where macromolecular transport not that important |
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Fenestrated capillaries w/diaphragms
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-cytoplasmic openings called fenestrae (60-80nm) closed off by diaphragm (not a cell membrane)
-continuous basement membrane -allows more rapid movement between blood and tissues -found in viscera, endocrine glands |
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Fenestrated capillaries w/o diaphragms
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thickened basement membrane
only found in renal glomerulus |
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Sinusoids
-characteristics -found where -their function |
-irregularly shaped, very thin walls, large lumen
-discontinuous cytoplasm (fenestrae w/o diaphragms) -basement membrane often discontinuous -allows free exchange of particles and cells (bact, erythrocytes) -found in liver, spleen, bone marrow |
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Pericytes
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pleuripotent mesenchymal stem cells surrounding capillaries and small venules
-enclosed in basement membrane -contractile fcn -can differentiate into SMC, fibroblasts |
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Terminal arterioles
where can they open into? |
sm. arterioles regulating flow into capillary beds
-open into true capillaries w/precap. sphincter -metarterioles- larger than cap., w/sm. muscle, bypasses capp |
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Arteriovenous anastamoses
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direct connections between aa/vv systems w/ flow through vessels larger than capillaries
-important for heat conservation in skin |
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post-capillary venules
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-similar structure to capillaries
-exhibit migration of leukocytes between ECs (diapedesis) this causes: enhanced migration of cells and fluid in inflammation high endothelial venules are found in lymph nodes-- fcn for lymphocyte homing |
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endocardium
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-endothelium + basal lamina
-subendothelial layer of dense CT (fibros, SMCs, elastic fibs) -subendocardium w/looser irregular CT (continuous w/CT around cardiac mm) subendocardium contains branches of impulse-conducting system and blood vv |
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myocardium
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thickest layer
-cardiac m + basal lamina in spiralling sheets; attached to fibrous skeleton of heart (dense CT, tendency toward cartilage formation) -delicate, loose CT (Collagen I & III) w/ blood vv, lymphatics, nn fibers |
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epicardium
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-simple squamous mesothelium (secretes serous fluid) lined w/collagenous CT
-looser subepicardial CT w/blood vv, lymphatics, nn (and some adipose) |
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Differences between atria/ventricles: thickness of endocardium
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atrium > ventricles
(endocardium thickness inversely proportional to myocardium thickness) |
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Atria/vent difference- thickness of myocardium
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LV > RV >> atria
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Atria/vent differences- Atrial natriuretic factor (ANF)
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found atrial myocytes, stored in granules
secreted in response to increased distension converted to active peptide in blood signals kidney to natriuresis and diuresis (loss of NaCl and water) |
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A/V valve structure
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folds of endocardium are reinforced w/core of dense CT and are attached to cardiac skeleton (prevents dilation of A-V outlets)
chordae tendinae- dense CT cords from papillary muscles of ventricles to ventricular surface of each leaflet -parallel bundles of collagen fibers -covered w/endothelium |
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Semilunar valve structure
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similar to A/V valves but thinner and no chordae
thickened at free margin and at nodule where cusps meet |
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SA node location
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right hand wall of SVC and RA
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AV node location
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lower interatrial septum
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AV bundle (of His) location
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in interventricular septum, then branches into right and left bundle branches in subendocardium of respective ventricles (purkinje fibers)
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nodal cell structure
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fine caliber
extensive branching and anastamosing pattern few myofibrils probably connected via gap jcns |
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Purkinje fiber sturcture
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large caliber
myofibrils around periphery large quantities of glycogen gap jcns |