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35 Cards in this Set

  • Front
  • Back
Tunica intima
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
Tunica Media
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
Tunica adventitia
1. elastic and collagenous CT (longitudinal) w/fibroblasts, collagen I, and elastic fibers

2. Blood vv (vasa vasorum), nerves, lymphatics
3 Basic types of arteries
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
Elastic arteries
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
Muscular Arteries
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
Arterioles (<100microm. diam)
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
Artery/vein shape differences
A: circular w/crinkled IEL
V:deformed w/smooth IEL
Artery/vein wall thickness differences
A: very thick
V: thin for the same diameter
Artery/vein media/adventitia differences
A: media prominent
V: adventitia prominent
delivered via sympathetic fibers
causes vasoconstriction via alpha1 receptors on the SMC

Outer SMC are innervated, then excitation is spread via gap jcns
delivered via circulation
causes vasodilation via beta2 receptors on SMC

Transmitter is diffused across SMC layer
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
cell junctions of capillaries
-intercellular clefts (15-20 nm) and/or
-tight junctions (fascia or occludens)
-gap jcns
Continuous capillaries
-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
Fenestrated capillaries w/diaphragms
-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
Fenestrated capillaries w/o diaphragms
thickened basement membrane
only found in renal glomerulus
-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
pleuripotent mesenchymal stem cells surrounding capillaries and small venules

-enclosed in basement membrane
-contractile fcn
-can differentiate into SMC, fibroblasts
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
Arteriovenous anastamoses
direct connections between aa/vv systems w/ flow through vessels larger than capillaries
-important for heat conservation in skin
post-capillary venules
-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
-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
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
-simple squamous mesothelium (secretes serous fluid) lined w/collagenous CT
-looser subepicardial CT w/blood vv, lymphatics, nn (and some adipose)
Differences between atria/ventricles: thickness of endocardium
atrium > ventricles

(endocardium thickness inversely proportional to myocardium thickness)
Atria/vent difference- thickness of myocardium
LV > RV >> atria
Atria/vent differences- Atrial natriuretic factor (ANF)
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)
A/V valve structure
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
Semilunar valve structure
similar to A/V valves but thinner and no chordae

thickened at free margin and at nodule where cusps meet
SA node location
right hand wall of SVC and RA
AV node location
lower interatrial septum
AV bundle (of His) location
in interventricular septum, then branches into right and left bundle branches in subendocardium of respective ventricles (purkinje fibers)
nodal cell structure
fine caliber
extensive branching and anastamosing pattern
few myofibrils
probably connected via gap jcns
Purkinje fiber sturcture
large caliber
myofibrils around periphery
large quantities of glycogen
gap jcns