REGULATION OF BLOOD FLOW Flashcards
the heart pumps the of blood that the body needs is defined as?
cardiac output
cardiac output control by the?
autonomics
tissue control by?
local regulation
which of the tissues require the most blood?
brain and heart because of work load
what is the main cause for increase flow in local regulation?
increase metabolism or increase altitude in response to decrease local O2
what is the vasodilator theory?
increase metabolism in which the cells release chemicals to increase:
hydrogen ion concentration histamine adenosine CO2 potassium this leads to:
relax smooth muscle to decrease resistance to increase flow
what is the most potent vasodilator?
adenosine
what is the intrinsic property of smooth muscle? what type of regulatory mechanism is this?
what is the effect of increase pressure?
when stretched it contracts
non metabolic local regulatory mechanism
increases flow and increase resistance to flow is constant
so if we have multiple neighboring capillary beds vasodilating, how do upstream vessels get the message?
EDRF
endothelial derived releasing factor aka nitric oxide which is a 6 second life span
what does the heart undergo due to increased metabolic demand? population this usually occurs in?
increased vascularity due to angiogenesis which can take days to weeks
children, damaged tissue and cancers
what are the signals that stimulate angiogenesis? and this is because of ____?
vascular endothelial growth factor (VEGF)
fibroblast growth factor (FGF)
angiogenin
increased metabolic demand
what is angiogenesis?
promotes new vessels to sprout off of the existing vessels
what are the important systemic vasoconstrictor humoral agents?
NE/EPI
Angiotensin II (constricts the arterioles and increases TPR to maintain BP)
Vasopressin
endothelin (produced by damaged vessels, limits blood loss at the wound site)
what are the systemic vasodilators? how do these work?
bradykinin
histamine
increase flow and increase capillary porosity, so area becomes flushed and edematous
what are the ions below affect on vascular function?
increase ECF calcium increase ECF magnesium increase ECF potassium increase ECF hydrogen ion increase ECF PCO2
increase ECF calcium - vasoconstriction
rest, vasodilation and also in the brain when there is an increase in ECF PCO2