Lecture 18 Flashcards
the percentage of cardiac output going to various organs/regions is not equal and can ______ minute to minute depending on conditions.
change
the percentages of blood flow distribution are the percentage of _____ which is flowing to each organ
CO (carbon monoxide)
at rest, the CO is ___ L/min
5
when exercising, CO is ____ L/min
25
active tissue can require up to _____times increase in blood flow
20
cardiac output only increases ~___times, therefore changes in microcirculation must take place to increase blood flow to the active tissue even more
6
if blood flow exceed the need of the tissue, regulatory mechanisms will _______ blood flow
decrease
______ muscle in small arteries and arterioles can be stimulated to contract or relax via nervous signals, hormonal stimuli, stretch, and changes in chemical environment (doesn’t require an action potential to stimulate contraction like skeletal muscle does)
smooth
SNS or PNS? innervated blood vessels
SNS
SNS or PNS? does not innervate the majority of blood vessels but does regulate dilation of some blood vessels in specific areas of the body, such as genitals
PNS
generalized vasoconstriciton and venoconstriction due to stimulation of the _______ receptors
Alpha-1 adrenergic
the coronary and cerebral circulations have poor ____ vasoconstrictor innervation so are spares the vasoconstrictor effect
SNS
what are the primary controllers of coronary and cerebral blood flow since it isn’t the SNS?
local metabolism and release of vasodilator substaces
in few vascular beds, activation of the SNS can cause vasodilation via activation of ____ receptors
Beta-2
Activation of SNS (in vascular beds) leads to stimuation to __________ release from the adrenal glands
epinephrine
the epinephrine in turn binds to ______ receptors in few vascular beds causing vasodilation
Beta-2
what regulates the blood flow of various tissues?
SNS, local chemical factors, and angiogenesis
factors that are released from metabolically active or hypoxic tissues include:
adenosine, CO2, H+, K+, and lactate
factors that are released from metabolically active or hypoxic tissues cause _______ of smooth muscle and _________ of small arteries and arterioles
relaxation; vasodilation
endothelial cells release _______ in response to sheer stress from blood flow
nitric oxide (NO)
where is nitric oxide produced from?
eNOS
nitric oxide diffuses into smooth muscle in local area and causes smooth muscle __________ or _________
relaxation; vasodilation
causes vasoconstriction
endothelin
causes arteriole dilation and capillary permeability
bradykinin, prostaglandins, and histamine
increase or decrease in number of blood vessels can occur
angiogenesis
in response to chronic ischemia, tissues release ________ factors (VEGF, FGF, etc)
angiogenic
oxygen demand _____ in working muscles (exercise)
increases
blood flow to tissues ________ during exercise
increases
________ consumption of tissues increase during exercise
oxygen (VO2)
by what mechanism is blood flow increased to exercising muscles?
when you exercise, you activate the SNS which causes vasoconstriction (decreased blood flow) except to the heart and brain, contracting muscle starts releasing metabolites and act on smooth muscle to vasodilate, which increases blood flow
by what mechanism is blood flow increased to the heart?
when the SNS is activated, it causes vasconstriction, and the heart starts beating really fast and starts released metabolites and causes vasodilation, just like in skeletal muscle
why does SBP increase while exercising?
due to an increase in CO
who does DPB decrease while exercising?
due to vasodilation in skeletal muscle vasculature
what effect does exercise have on TPR?
decrease it
by what mechanism did HR increase while exercising?
due to an increase in the SNS an decrease in the PNS
by what mechanism did SV increase while exercising?
increase in the activation of SNS and decrease in PNS will increase strength of contraction. SNS will also increase venous contraction/venous return which will increase EDV. Strength of contraction, increase respiratory pump, and increase in venous pump also increase SV
why does SV plateau?
it has to do with the limited filling of the ventricle. the higher the HR, the less time for filling and relaxation. if there is less time for filling, then there is less blood and it will affect EDV and therfore, will affect SV
what is the primary determinant of EDV?
TPR
what is the primary determinant of ESV?
CO (cardiac output)
