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112 Cards in this Set
- Front
- Back
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what are the three concentric layers that comprise vessel walls?
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Tunica intima
Tunica media Tunica adventitia |
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where is the tunica intima?
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bordering the lumen
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what is the tunica intima composed of?
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endothelial cells
basal lamina subendothelial layer of loose connective tissue |
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how are endothelial cells of the tunica intima generally connected?
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tight junctions to prevent diffusion between cells
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how do substances get transported across tunica intima?
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pinocytosis (non-specific)
transcytosis (receptor-mediated) |
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how is the long axis of endothelial cells oriented in the tunica intima?
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parallel to the direction of blood flow
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what are the rod-like granules inside arterial endothelial cells which facilitate the binding of platelets to injured endothelium?
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Weibel-Palade granules
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what do Weibel-Palade granules contain?
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coagulating factor VIII
aka von Willebrand's factor |
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what are the general secretory and metabolic functions of endothelial cells?
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synthesis of prostacyclin (PGI2)
breakdown of lipoproteins to yield TAGs and cholesterol deactivation of bioactive compounds |
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what are the functions of prostacyclin?
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inhibits platelet aggregation
induces vasodilation |
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what bioactive components do endothelial cells generally deactivate?
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serotonin
thrombin |
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where is the tunica media?
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the middle layer of blood vessels
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what does the tunica media mainly consist of?
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circumferentially arranged smooth muscle or elastic fibers
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where is the tunica adventitia?
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the outermost layer of blood vessels
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what does the tunica adventitia mainly consist of?
how are they oriented? |
fibroblasts
collagen fibers elastic fibers oriented longitudinally |
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what is the purpose of tunica adventitia?
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to anchor vessel in surrounding tissue
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what is in the tunica adventitia of large vessels (vena cava, aorta, etc), but not small vessels?
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vasa vasorum
small blood vessels to provide vasculature for vessel itself |
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what structure separates the tunica intima and tunica media in all arteries?
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internal elastic lamina
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what is the internal elastic lamina?
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a fenestrated lamina of elastin
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what structure is present in large arteries to demarcate the border between tunica media and tunica adventitia?
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external elastic lamina
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what are the three types of arteries?
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elastic (aorta)
muscular (femoral and radial) arterioles |
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what is the function of elastic arteries?
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to maintain constant pressure in arterial system
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which layer is the thickest in elastic arteries?
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tunica media
(composed of concentric, fenestrated elastic lamellae and smooth muscle) |
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how does the tunica intima relate to other arteries?
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subendothelial layer is relatively thick with smooth muscle cells, elastic and collagen fibers
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how does the tunica adventitia relate to other arteries?
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relatively thin
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why are internal and external elastic laminae not apparent in elastic arteries?
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abundant elastin in tunica media
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what is the main function of muscular arteries?
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maintain blood pressure and distribute blood to limbs and organs
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how does the tunica media appear on a muscular artery?
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well-developed with concentric layers of smooth muscle
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how does the tunica adventitia appear on a muscular artery?
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thin, and composed mainly of collagen fibers
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how does the internal elastic lamina appear on a muscular artery?
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prominent and dark
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what is the main function of arterioles?
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control blood flow to capillary beds
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where are arterioles found?
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in connective tissue
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how many layers of muscle are in the tunica media of arterioles?
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small - 1-2 layers
large - up to 6 layers |
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what do arterioles often lack?
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subendothelial layer and internal elastic lamina
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what is the name for a terminal branch of an arteriole?
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metarteriole
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what is the slight thickening of the smooth muscle layer of arterioles just before dumping into a capillary?
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precapillary sphincter
can shut off flow to a capillary bed |
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how do elastic arteries respond during systole and diastole to maintain blood pressure?
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systole - stretch as they receive blood
diastole - passive elastic recoil pushes blood into next arteries |
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what is the main factor in maintaining mean arterial pressure?
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smooth muscle tonus of small arteries and arterioles
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what effect does vasodilation have on muscle tonus? vasoconstriction?
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vasodilation -> decreased tonus
vasoconstriction -> increased tonus |
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what is the main function of capillaries?
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site of exchange of gases, nutrients and metabolites between blood and tissues
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what do capillaries consist of?
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single layer of endothelial cells
basal lamina |
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what are the three types of capillaries?
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continuous capillaries
fenestrated capillaries sinusoids |
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what type of endothelial lining do continuous capillaries have?
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smooth
nonporous lots of tight junctions surrounded by continuous basal lamina |
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where are continuous capillaries found?
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muscle
brain peripheral nerve exocrine glands |
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what mechanisms are used to transport nutrients?
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pinocytosis
transcytosis |
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what are pericytes?
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unspecialized cells which may divide and differentiate during wound healing
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where are pericytes found?
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enclosed in basal lamina of some continuous capillaries
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what type of endothelial lining do fenestrated capillaries have?
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endothelial cells have pores called fenestrae
surrounded by contiuous basal lamina |
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what are the two types of pores in fenestrated capillaries?
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unobstructed (60-70nm wide)
pores covered by thin diaphragm (<5.5nm particles allowed through) |
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where are fenestrated capillaries found?
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kidney glomeruli
intestinal mucosa pancreas endocrine glands (where rapid materials exchange is necessary) |
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how do sinusoids compare to other types of capillaries?
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wider lumens
irregular shaped (not simple tubular) more abundant fenestrations discontinuous, partial, or absent basal lamina |
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where are sinusoids found?
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lymphoid organs (spleen, lymph nodes)
liver adrenal cortex |
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where might macrophages be in sinusoids?
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embedded within the endothelium (e.g. Kupffer's cells in liver sinusoids)
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what is the name for a direct connection between an arteriole and a venule?
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arteriovenous shunts or anastomoses
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what is the purpose of an AV shunt?
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bypass capillary beds
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what is the function of AV shunts in the dermis?
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thermoregulation
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what is the carotid sinus?
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baroreceptor to sense changes in blood pressure
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where is the carotid sinus located?
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within the wall of the internal carotid artery
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where are the sensory nerve endings for the carotid sinus?
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in tunica adventitia (thin tunica media)
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what is the carotid body?
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chemoreceptor to sense changes in blood pH and O2/CO2 concentrations
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where is the carotid body located?
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at the bifurcation of the common carotid artery
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what is the role of type I cells in the carotid body? of type II cells?
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Type I resemble secretory cells in adrenal medulla
Type II are supporting cells |
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where is about 70% of total blood volume contained?
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veins
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what are the valves of veins formed from? what do they consist of?
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extensions of the tunica intima
core of fibroelastic tissue covered by endothelium |
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how do veins generally compare to arteries?
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thinner walls
larger, more irregular lumen |
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what is in the thick, well developed tunica adventitia of large veins to keep them from over-distending?
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collagen and longitudinal bundles of smooth muscle
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what is contained in the tunica media of large veins?
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several circumferential layers of smooth muscle and sparse elastin
(no internal elastic lamina) |
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how does the tunica media of a small vein compare to that of a large vein?
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thinner (less smooth muscle)
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which layer is the thickest in small veins?
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tunica adventitia
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which layer of a small vein may be thrown into folds when the vein is not distended?
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tunica intima
(has elastic fibers but no elastic lamina) |
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what does the wall of a venule look like?
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very thin with 0-2 layers of smooth muscle
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what is most important about postcapillary venules?
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they are the preferential site for emigration of leukocytes
principal site of action of vasoactive agents more permeable membrane than capillaries |
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what is a portal vessel?
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a vein or arteriole which carries blood from one capillary bed to another without first returning to the heart
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where are portal systems found?
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liver
kidney hypothalamus-pituitary |
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what type of portal system is present in the kidneys? the liver?
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arterial portal system
venous portal system |
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which tissues do lymphatics not drain?
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nervous system
bone marrow |
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where do lymphatic capillaries begin?
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begin as blind vessels in loose connective tissue
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what are lymphatic capillaries composed of? (how are they identified?)
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single layer of endothelial cells
discontinuous basal lamina no fenestrae few tight junctions wider lumen than capillaries irregular lumen no RBCs |
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what are the molecules which prevent the collapse of lymphatic capillaries when they are empty?
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anchoring fibrils
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what is the structure of valves in lymphatic vessels similar to?
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valves in small veins
(have larger lumens and thinner walls) |
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what are the two large trunks formed by all lymphatic vessels?
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thoracic duct
right lymphatic duct |
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what are lymphatic ducts similar to?
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large veins
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what do lymphatic ducts contain in their tunica media?
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longitudinal and circular layers of smooth muscle
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what is contained within the poorly developed tunica adventitia of lymphatic ducts?
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vasa vasorum and nerves
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where do the lymphatic ducts return lymph to blood supply?
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junctions of internal jugular and subclavian veins
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where does the formation and recovery of interstitial fluid mainly occur?
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in capillary beds
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what causes fluid to flow out of capillary bed?
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hydrostatic pressure in arterial system forces fluid out of capillary system, creating interstitial fluid
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what causes fluid to be drawn into capillary bed?
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osmotic pressure (caused by albumin in blood) draws fluid into capillaries
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what are the 4 causes of edema?
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increased venous hydrostatic pressure
obstruction of lymphatic drainage increased capillary permeability reduction of osmotic pressure |
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what could cause increased venous hydrostatic pressure?
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pregnant uterus pressing on common iliac veins
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what could cause obstruction of lymphatic drainage?
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removal of axillary nodes
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what could cause increased capillary permeability?
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histamine release from mast cells
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what could cause reduction of osmotic pressure?
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decreased plasma proteins as in cirrhosis and nephrotic syndrome
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what are the three layers of the heart, and what do they correspond to?
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endocardium - tunica intima
myocardium - tunica media epicardium - tunica adventitia |
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what does the endocardium consist of?
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endothelium with basal lamina
subendothelial connective tissue with elastic fibers and some smooth muscle cells subendocardial layer of loose connective tissue with small blood vessels, nerves and impulse-conducting system of heart |
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what does the myocardium consist of?
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cardiac muscle fibers
fibrous skeleton of dense fibrous connective tissue |
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what does the fibrous skeleton of the myocardium do?
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provides scaffolding onto which cardiac muscle fibers insert
supports valves forms membranous portion of interventricular septum |
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what is another name for the Epicardium?
what layer does it correspond to? |
visceral pericardium
tunica adventitia |
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what does the epicardium consist of?
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one layer of mesothelial cells
thin basal lamina connective tissue (including adipocytes) |
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where are the blood vessels and nerves that supply the heart contained?
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in the epicardium
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what are cardiac valves composed of?
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dense connective tissue core surrounded by endocardium
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how are purkinje fibers connected?
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via gap junctions
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what organelles do purkinje fibers have few of?
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myofibrils
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what organelles are abundant in purkinje fibers?
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mitochondria
glycogen vesicles |
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how well developed are the T tubules in purkinje fibers?
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purkinje fibers have no T tubules
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how often is a transvascular endomyocardial biopsy performed?
why might it be performed? |
quite rarely is it performed
to determine presence of rare disorders of heart muscle (myocarditis, sarcoidosis, hemachromatosis, amyloidosis, and heart transplant rejection) |
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where are gap junctions concentrated in cardiac muscle?
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in and around intercalated disks
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what protein in ventricular myocyte gap junctions can be used to tag and immunofluoresce gap junctions?
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connexin43
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what disorder is associated with reduced levels of connexin43?
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congestive heart failure
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what is the gap junction protein associated with congestive heart failure?
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connexin43
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what occurs in congestive heart failure?
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fewer gap junctions,
so conduction is slow and inhomogeneous, so likelihood of ventricular arrhythmias increases |
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what type of therapy is used to partially reverse connexin43 down-regulation?
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beta-blocker therapy
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