Blood Vessels Flashcards
anatomical: what type of fibers for blood vessels? how do they travel?
post ganglionic C-fibers. travel from ganglia along complex routes, often via somatic nerves
anatomy of blood vessel innervation: where? general structure?
autonomic fibers as perivascular axons found in every organ of body. nerve bundles (1-100 axons) branch + merge in adventitia to form meshwork
anatomy: how many varicosities? each varicosity contains? spacing of varicosities?
10^4 to 2X10^6 varicosities per mm3 of tissue; regularly spaced along axon. each varicosity: 0 - 1000 vesicles (with NA)
anatomy: also have ___ fibers, and their vesicles have?
sensory fibers: substance P and CGRP (involved in axon reflex, inflammation, etc)
anatomy: where are vesicles found close to?
many vesicles found in close apposition to muscle cells, others deep within nerve bundle, collagen or near fibroblasts or endothelial cells
anatomy: small granular vesicles characteristic of NA nerve endings contain? (2)
NA + ATP
anat: larg granular vesicles contain?
one or more peptides + other transmitters
structural organization of autonomic junctions vs. NMJ?
somatic NMJ: clearly defined structural organization. but extent of organization at autonomic junctions debated
effector connection vs. NMJ?
unlike skeletal NMJJ, are electrically connected via gap junctions
variation in effector properties : 6?
myogenic activity, hormonal sensitivity, stretch sensitivity, cell cell coupling, NO/endothelin, prostacyclin released from endothelium, accumulation of metabolites in exercising muscle produces vasodilation
electrophysiology: failure? not due to?
high rate of release failure at each varicosity (unlike NMJ, super reliable where one AP = contraction). low prob. of release NOT due to transmission failure
each varicosity releases how many vesicles? what % fibers release?
each varicosity releases 0 - 10 vesicles. 1-2% of fibers release NA/ATP when stimulation occurs
if you stimulate sympathetic nerves to vascular smooth muscle: 3 phases of electrical response?
ATP/P2X fast EJPs. a-adrenergic slow depolarization. NPY/Y1 depolarization.
if you stimulate symp nerve to vascular smooth muscle: what’s associated with contraction?
a-adrenergic and NPY components associated with contraction (so fast ATP EJPs don’t evoke contractions)
low freq. APs in sympathetic nerve: effect and mediated by?
each nerve AP = one brief vasocontraction, mediated by alpha adrenergic effect of NA
high freq APs in sympathetic nerve: effect? mediated by?
sustained contraction; preferential release of NPY
low freq. stimulation preferentially releases? which acts on? effect?
NA: acts on presynpatic alpha 2 adrenoreceptors. limit duration of NA release, reduces release of NPY.
NPY Y2 autoreceptors effect on NA?
also reduce NA release. so NPY on post synpatic Y1 = vasoconstriction. Y2 feedback = presynpatic inhibition of NA
if high freq of APs persists: what happens to NPY? vasoconstrictor response?
NPY depleted. vaconstrictor response maintained by NA, because its release is no longer restricted by NPY effects on Y2 autoreceptors
concl: peptides do what for NA output? does that idea fit?
may alter NA output so that it is appropriate for a particular target. fits w/ idea that functionality of ANS is coded by peptides
