LESSON 19 - control of blood flow during exercise Flashcards
how do cardiac output and muscle blood flow increase ? (proportional to what)
increase in proportion to metabolic rate
when we increase our cardiac output as a function of exercise intensity what do we also match ?
match it very well with our muscle blood flow
what is hyperemic ?
higher blood flow than normal
what is the formula for Q = ?
Q = HR x SV
how does HR rise ?
linearly
how does SV increase ?
increases initially and then plateaus as HR increases
an increase in HR, CO, SV and VO2 means an increase or decrease in ATP ?
increase in ATP
what is the SA node innervated by ?
the autonomic nervous system
what controls heart rate ?
SA node
what does the SA node inhibit ?
the parasympathetic nervous system
what is vagus ?
slows down HR and runs parallel to carotid arteries to the heart
what is responsible for slowing down heart rate ?
vagus
what is the vagus anatomically …
a nerve (cranial nerve 10)
what is the increase in contractility during exercise ?
inotropy
what is inotropy ?
is the strengthening/weakening function of the cardiac tissue
why is inotropy a good thing ?
helps you push more blood
what is term used to define (increasing contractibility) ?
inotropy
define “inotrope” :
agent that alters the force of muscle contraction
what are the two examples of positive inotropes ?
norepinephrine and epinephrine
what does an increase positive inotrope concentration mean for cardiac muscle tension for a given preload and rate of muscle tension development ?
increase cardiac muscle tension for a given preload and increased rate of muscle tension development
if there is an increase cardiac muscle tension is it better or worse able to go againts resistance ?
better able
what does an increase in inotropy mean for SV ?
increase in SV
during exercise what happens to inotropy ?
increase in inotropy
during exercise when we have an increase in inotropy what do we see ?
- increase firing of sympathetic nerves innervating ventricle
- increase circulating catecholamines
- intensity-dependent
what are the two catecholamines ?
epinephrine and norepinephrine
where do catecholamines come from ?
adrenal glands
what happens to sympathetic input to the heart with higher exercise intensity ?
the higher the exercise intensity, the more sympathetic input to the heart, the more the higher the contraction fo circulating catecholamines and the greater the contractibility will be
does muscle contraction help with increased or decreased venous return ?
increased
why does muscle contraction help with venous return ?
propels blood away from muscle and back to the heart
what does an increase in VR mean for SV ?
increase in SV
what do central effects do ?
allows us to increase our venous return
what does more contractions lead to an increase in ?
increase in VR and increase in SV
what does it mean when theres an increase in SV ?
more blood to heart
why does HR increase ?
because we have an increase in sympathetic nervous system drive to the heart
over time which organs decrease blood circulation to focus more on muscles during increased activity ?
GI tract organs (stomach, liver, etc)
what are the two muscle pump effects ?
central and peripheral
what do peripheral effects do ?
muscle contraction increases arterial flow (mechanical)
what term pumps our blood away faster ?
peripheral effects
at any pressure, flow through blood vessels is regulate by modifications in what ?
local vascular resistance
what are the three types of arterioles (in regards to diameter) ?
- vasoconstriction
- normal arteriole
- vasodilation
define vasoconstriction :
reduce radius and increase resistance
define vasodilation :
increase radius and decrease resistance
between vasoconstriction and vasodilation which is non-active tissue ?
non-active tissue = vasoconstriction
between vasoconstriction and vasodilation which is active tissue ?
vasodilation
how many things are there in regards to the diversion of blood flow ?
5
between the 5 things in regards to the diversion of blood flow; how many are vasoconstriction and how many vasodilation ?
vasoconstriction = 2
vasodilation = 3
describe the three vasodilation factors in regards to the diversion of blood flow :
- vasodilator formation in skeletal muscle
- flo-induced vasodilation
- myogenic vasodilation
describe the two vasoconstriction factors in regards to the diversion of blood flow :
- sympathetic vasoconstriction
- circulating vasoconstrictors
what innervates the smooth muscle in arterioles ?
the sympathetic nervous system
is the baseline sympathetic activity always on ? yes or no ?
yes always on
what is the vasomotor tone ?
the end result of a complex set of interactions that control relaxation and contraction of blood vessels
an increase in sympathetic activity leads to an increased or decreased vasoconstriction ?
increased vasoconstriction
a decrease in sympathetic activity leads to an increased or decreased vasoconstriction ?
decreased vasoconstriction
what is another term for passive vasodilation ?
vasoconstriction
what does an increase (more impulses) of sympathetic activity lead to in regards of NE and neurotransmitters ?
more NE and neurotransmitters to the smooth muscles
where does sympathetic activity come from ?
coming from the CNS
what innervates the adrenal medulla ?
the sympathetic nervous system
TRUE OR FALSE
vasoconstriction doesn’t cause smooth muscle relaxation
TRUE
does an increase in sympathetic activity increase or decrease catecholamine release ?
increases
what are two catecholamines ?
NE and Epi
what does increased circulating epinephrine and norepinephrine lead to ?
- increased vasoconstriction non-active tissues
- increased HR and contractility
- increased glycogenolysis and glycogenesis (liver and muscle)
what does increased vasoconstriction of non-active tissues mean for dilation in muscle ?
it means that areas that need more blood will get it
when we don’t want / need blood what does the body do ?
vasoconstriction
why do we have glycogenolysis near the muscles ?
to keep glucose stores close to where it is needed
describe the pathway of vasoconstriction control :
- hypothalmus
- nerve impulses
- spinal cord
- adrenal medula
- catecholamines (Epi and NE)
what does increase catecholamine release (due to increased sympathetic activity) lead to (in regards to blood vessels ?
vasoconstriction of non-active tissues
what does MSNA stand for ?
muscle sympathetic nerve activity
what does splanchnic mean ?
organs in abdominal cavity
in regards to the formula for resistance what is the most important factor ?
radius
is intrinsic control the constrictor or dilator side ?
dilator side (vasodilator control)
how many types of intrinsic control are there ?
3
name the three types of intrinsic control :
- metabolic
- endothelial
- myogenic
define metabolic intrinsic control :
chemical agents released as consequence of metabolism directly on smooth muscle
define endothelial intrinsic control :
dilator substances produced within endothelium of arterioles in response to various stimuli
what is endothelium ?
the inner lining of arterioles
the following is seen in what type of intrinsic control ?
nitric oxide, prostaglandins, endothelium-derived hyper polarizing factor
endothelial
the following is seen in what type of intrinsic control ?
increased CO2, K, H and lactic acid
metabolic
define shear stress :
when we increase that release of nitric oxide from the endothelial cell & nitric oxide has a basal relaxation/vasodilation effect on the smooth muscle
what does increased flow within endothelial intrinsic control do ?
helps get O2 rich blood to where it is needed
is nitric oxide a vasodilator or vasoconstrictor ?
vasodilator
does nitric oxide work very fast or very slow ?
very fast
does “sheer stress” mean a greater or lower interaction of RBC on the all of the endothelial ?
greater
define myogenic intrinsic control :
pressure changes within the vessels themselves can cause smooth muscle constriction or relaxation
what between the three intrinsic controls increases during exercise because there is an increased pressure on the outside of the vessel wall leading to dilation ?
myogenic
