Exam2 - Circulatory System Flashcards
contents of circulatory system
heart, blood vessels, lymphatic system
blood vessel layers
tunica intima, tunica media, tunica adventitia
vasa vasorum
smaller vessels branching off large vessels through adventitia and outer part of media
which vessels have more vasa vasorum?
veins
nervi vascularis
lymphatics and nerves in adventitia of large vessels
tunica intima composition
endothelium + underlying subendothelial CT - including internal elastic lamina in larger vessels
tunica media composition
mostly smooth muscle cells and external elastic lamina when present
tunica adventitia composition
fibroelastic CT
fibroelastic CT
dense irregular CT w/ small amounts of elastic fibers
artery classifications
large = elastic; medium = muscular; small = arterioles
elastic arteries
conducting arteries that conduct blood to muscular arteries
examples of elastic arteries
aorta, pulmonary, brachiocephalic, common carotid, subclavian, common iliac arteries
elastic artery internal elastic lamina
present but incomplete
elastic artery subendothelial layer composition
loose CT w/ collagen, elastic fibers, fibroblasts
elastic artery media
thick w/ 40-70 concentric elastic sheets
elastic artery adventitia
thin w/ elastic and collagen fibers
elastic artery external elastic lamina
no distinct layer
muscular arteries
distributing arteries that deliver blood to organs
size of muscular arteries
0.5 mm - 1 cm
innervation of muscular arteries
postganglionic sympathetic nerves
muscular artery intima
thinner than in elastic arteries
muscular artery internal elastic lamina
yes -well developed
muscular artery subendothelial CT
lacks smooth muscle cells
muscular artery media
up to 40 circular layers of smooth muscle interspersed w/ elastic fibers
muscular artery external elastic lamina
yes - thick
muscular artery adventitia
may be as thick as the media, contains collagen and elastic fibers
size of arterioles
diameter less than 0.5 mm
arteriole subendothelial CT
very sparse
arteriole internal elastic lamina
may or may not be present - consists of a network of fibers not always seen w/ LM
arteriole media
1-3 layers of smooth muscle cells w/ occasional elastic fibers
arteriole adventitia
layer of loose CT w/ longitudinally arranged collagenous and elastic fibers
size of capillaries
7-10 um diameter
capillaries
consist of a single layer of endothelial cells surrounded by thin sheath of reticular and collagenous fibers and some pericytes
three types of capillaries
continuous, fenestrated, discontinuous
pericytes
mesenchymal-like stem cells that differentiate into fibroblasts or smooth muscle cells during wound healing
location of pericytes
primarily on post-capillary side of circulation
continuous capillaries
somatic capillaries that have continuous endothelium and basal lamina
vesicles in continuous capillaries?
numerous pinocytotic vesicles for transcytosis
location of continuous capillaries
muscle, CT, CNS, exocrine pancreas, gonads
continuous capillaries in CNS have what type of junctions and why?
tight junctions - contribute to BBB
fenestrated capillaries
visceral capillaries that have attenuated endothelium w/ large 60-80 nm fenestrae closed by thin 4-6 nm diaphragms but a continuous basal lamina
location of fenestrated capillaries
mucosa of GI tract, endocrine glands, renal, kidney (glomerular and peritubular capillaries), choroid plexus, ciliary body
special feature of fenestrated endothelium in glomerular capillaries
no diaphragms
discontinuous capillaries
sinusoidal capillaries that have irregular, tortuous walls and wide gaps b/w cells with an incomplete basal lamina
location of discontinuous capillaries
liver and hemopoietic organs (bone marrow, spleen)
veins function
return blood to heart
size of venules
12 um - 1 mm diameter
venule intima
endothelial cells
venule media
1-2 layers of smooth muscle cells