Muscle Blood Flow Flashcards
what controls skeletal muscle blood flow
local regulation - its more powerful than sympathetic stimulation
sympathetic nerves release NE at what receptors to cause vasoconstriction
alpha
only place there are beta 2 receptors on blood vessels is:
skeletal muscles
what does EPI do to skeletal muscle
vasodilation or lesser effect of NE
EPI does cause vasodilation in
skeletal muscles
at onset of exercise, signals are transmitted to:
Skeletal muscles to cause contraction and to
VMC to increase sympathetic discharge.
you have increased sympathetic discharge before exercise because
your VMC will start to increase the sympathetic discharge
VMC increase in sympathetic discharge is important before exercise b/c
you’ve created pressure head to push the blood through tissues
increase in smpathetic discharge causes
heart stimulation
arterioles of peripheral circulation contracted except for exercixing muscles, brain, and coronary ciruclation
veins constricted to increase venous return
arterioles of peripheral circulation will contract in response to sympathetic discharge, except:
muscles
brain
coronary circulation
if veins dont decrease their compliance, what happens during exercise
CO cannot increase enough to meet needs of body
how much pressure changes depends on
what type of exercise you do
type of pressure change regarding diastolic and systolic has to do with
type of exercise
exercise under tense condition using only a few muscles does what to arterial pressure
large increase in arterial pressure - non-working muscles are constricted
bench press or curls, what happens
blodo vessels to legs are constricted, blood vessels of exercising muscles dilated
whole body exercises, like dancing, what happens to blood pressure compared to say, doing curls
BP will not go up as much b/c all the muscles are vasodilated
what happens to BP in whole body exercise
systolic higher
diastolic lower
b/c all the vessels are open
the more muscles you’re using what happens to rpessure
more muscles you use, the smaller the increase in pressure
flow = ?
change in pressure/resistance
Q =
DeltaP/R
if venous return doesn’t increase during exercise, what is the highest cardiac output you can achieve
see graphical analysis pg 7
during exercise w/ sympathetic stimulation, what do you see happen to splanchnic, renal, and skin blood vessels during exercise
they constrict
what happens to brain and coronary blood vessels during exercise
not much change
what happens to non exercising muscle vessels during exercise
constriction, but not as much as in splanchnic, renal, and skin
why do exercising muscles dilate when there is sympathetic stimluation throughout the whole body?
they release their local dilators, which overcome the effect of sympathetic stimulation
skeletal muscles - sympathetic muscles do what to them
constrict
if exercising muscles are working, what will happen
local dilators will overcome the sympathetic stimulation
the only muscles dilated in exercise are
the ones that are working
the more muscles you have working the less
constriction you have of blood vessels
what does venous return have to do when you have more exercising muscles
has to increase
skeletal muscles have what receptors
alpha and beta
skeletal muscles have alpha and beta receptors, so what is effect of sympathetic stimulation
almost negilible b/c they will counteract each other
right and left coronary arteries exit
at root of aorta
above valve of aorta
coronary arteries come off of
look at coronary arteries on pg 9
pg 9
noneo fthe heart gets blood from
blood in the chamber
there is oxygenated blood in left chamber, will it go to heart
no
where does heart get oxygenated blood
the coronary system
when your heart beats faster it needs
more blood
blood flow through the heart is
phasic
during systole, blood flow in heart
decreases
during diastole, blood flow in heart
increases
when heart is contracting,why does blood flow decrease
it is contracting so pressure is high
right side of heart will not see the kind of phasic change on left side of heart, why
because left side of heart is under mich higher pressure
what is major driving force of blood flow through heart
pressure during diastole
anything that decreases diastolic blood pressure will do what to coronary blood flow
decrease coronary blood flow
what condition might decrease coronary blood flow
aortic regurgitation
anything that decreases diastole
there is still some coronary blood flow through systole, but if you have aortic stenosis, what happens to coronary blood flow
might go to zero b/c the pressure would be higher ( i think?)
when heart contracts it contracts from ____ to ___
inside out
endocardial areas in heart have to have
extra vessels to bring blood back to heart
control of coronary blood flow is almost the same as
skeletal muscle
what is driving force for coronary blood flow
local metabolism
adenosine at level of heart is
most important vasodilator - increases blood flow to heart
does nervous control to heart affect blood vessels themselves
no
why does nervous system change bloodf low to heart
b/c they increase metabolism - they have indirect effect
what kind of effect does nervous system have on blood flow to heart
indirect
most common cause of death in western culture
ischemic heart disease
ischemia means
decrease in blood flow
acute coronary occlusion can lead to
MI
if areas of heart are ischemic or hypoxic, the resting membrane potential of cells or way AP
it changes
anythign that changes electircal activity of local area of heart can lead to things like
V fib
heart that is hypertrophying, and pt has ischemic heart disease, what is happening
making muscle bigger and decreasing blood flow to it which weakens heart
number one cause of ixchemic heart disease is
Atherosclerosis
Atherosclerosis what is it
lots of cholesterol deposit, get foam cells b/c of macrophages, causes fibrous plaque that gets calcified, ad it can grow and either protrude into vessel lumen and block blood flow or
in Atherosclerosis what is ultimate thign that happens
vesel narrows
when pt has Atherosclerosis what happens if body wants to vasodilate
not going to happen, it is rigid
Atherosclerosis plaque can cause local blood clot called
thrombus
thrombus does what
occludes artery
if thrombus breaks off it can cause
coronary embolus
in individuals with blockage or coronary artery thrombus or embolus, the degree of what will determine damage
extent of collateral circulation
the more collateral circulation you have, then what happens with MI
there will be less damage the more collateral circulation you have
Myocardial infarction is:
area of muscle that has zero or so little flow it cannot sustain function
where do MI usually happen
subendocardial region
what happens in subendocardial infarction
High oxygen consumption
Decrease blood flow due to muscle compression
you can decrease blood flow to areas of heart and the cells will remain alive, why?
pg 19
what are 4 causes of death after acute coronary occlusion
- Decreased cardiac output
- Damming of blood in the pulmonary blood vessels and then death resulting from pulmonary edema
- Fibrillation of the heart
- Rupture of the heart
what is systolic stretch
if ventricular area of heart is dmaged, it can’t contract, so when left ventricle contracts, it is pushed out int he systolic stretch area, b/c that area can’t contract
what does systolic stretch do to blood ejection
decreases, b/c it is going to the systolic stretch area
cardiac shock, what is it
Cardiogenic shock is a condition in which your heart suddenly can’t pump enough blood to meet your body’s needs. The condition is most often caused by a severe heart attack.
when does cardiac shock usually occur
> 40% LV infarction
strong sympathetic stimulation can cause
fribrillation
rupture of infarcted area
over time heart gets replaced with fribrous tissue and can rupture
dead heart cells are not
replaced by new heart cells
heart cells do not
proliferate
stages of recovery from acute myocardial infarction
replacement of dead muscle by scar tissue
hypertrophy of undamaged areas
why is rest important after MI
don’t want to increase workload on heart
even though you may have good collateral circulationin heart, most times the collateral circulation can’t dilate
don’t want coronary steal syndrome
if you increase workload on heart, what happens
blood gets diverted away from collaterol circulation and you get coronary steal syndrome
what is coronary steal syndrome
blood is stolen from one area of heart to another
over time what happens after MI
reduced cardiac reserve
what does reduced cardiac reserve mean
the cardiac output curve is decreased, because of the damaged tissue
a person after MI, what happens to cardiac output at rest and exercise
at rest their CO might be fine, but say ,in exercise, their CO can’t be increased enough
cardiac shock is likely to cause
death
function of heart after MI, it depends on
how much damage was caused
what will you see on ventricular function curve after MI
rightward shifts
compared to normal heart, what happens to CO in a heart after MI
there will always be decrease
what is angina pectoris
cardiac pain
when coronary blood flow can’t keep up with heart activity you can feel
pain
heart pain is caled
angina
heart pain is due to release of
acidic substances - lactic acid, histamin, kinins (like bradykinin)
why do you feel heart pain due to acidic substances
the acidic substances build up and go to pain receptors and cause pain
treatment for angina
vasodilator drugs
nitroglycerin and other nitrate drugs release
NO
NO stands for
nitric oxide
nitroglycerin is a
vasodilator
ACE inihbitors are
vasodilators
AII receptor blockers are
vasodilators
calcium channel blockers are
vasodilators
beta blockers are
vasodilators
ranolazine, how does it work
Inhibits inward sodium current in heart muscle
Decreases wall tension and oxygen requirements
Inhibits IKr and causes slight QT prolongation
do the vasodilator drugs for angina cure the pain?
no - they are just symptomatic
how do you fix coronary occlusion? what are the 2surgical treatments for coronary artery disease
CABG
angioplasty
what does CABG stand for
coronary artery bypass graft
how does sCABG work
take vein and make it into artery
how does angioplasty work
string in catheter with balloon and stent and inflate the balloon into open up the artery and put stent into artery to keep it open and then remove the balloon and leave the stent in
