oxygen delivery and circulator response to exercise Flashcards
coronary arteries consist of two vessels ?
epicardial vessels andsubendocardial vessels
which vessel is outside of the heart
epicardial vessels
which vessels are inside of the heart
subendocardial vessels
if a blockage to the epicardial vessels what happens to subendocaridal arterial plexus?
blood lost
blood flow is greatest during diastole due to
decrease of muscle contraction therefore lack of pressure to close arteries allowing a greater blood flow
cardiac muscle extracts 70 percent of the O2 coming to it at rest. why?
its always working
to increase O2 delivery, blood flow must
increase
systole occurs during which part of the EKG
ST segment
ACh bind too this receptors of the endothelium causing them to release nitric oxide as a vasodilator substance
muscarinic
SNS receptors and effects
- alpha1 (vasoconstriction)
- beta2 (vasodilation
SNS has a direct stimulation - what are the hormones and where do they innervated?
- Ach - release NO, vasodilator
- NE - SNS, vasoconstriction
- Epi - humoral
PSNS indirect stimulation
alteration in metabolic demand - producing more metabolites
MVO2 =
Hr x SBP
vasodilators are released from the cardiac cells in response to
low O2
NO is released from coronary vessels in response to
shear stress
locally derived vasodilators
- adenosine
- ADP & AMP
- K+
-H+ - CO2
- prostaglandins
- NO
what stimulates NO release
shear stress
high shear stress may occur when you have
plaque build up (thrombus)
other NO functions
- decrease in platelet activation and aggregation
- decrease vascular smooth muscle cell proliferation
- decrease adhesion molecule expression
- decrease oxidation of LDL
decrease platelet activation and aggregation results in
decreases thumbs formation int eh material wall
decrease vascular smooth muscle cell proliferation results a
decreases thickening and stiffening of the artery
decrease in adhesion molecule expression results in
DCAM1 - immune cells
decrease of oxidation of LDL results
atherosclerosis
double product =
Heart rate x systolic BP
blood flow oscillates in cardiac and skeletal muscle as a result of muscle contraction? true or false
true
increased O2 demand
-increase blood flow
- increase O2 extraction
increase blood flow results
- increase CO
- redistrubte blood
increase O2 extraction results
- open more capillaries
increase of cardiac output due to
- increase HR
- increase SV
Max HR =
208 - (.7xAge)
increased SV =
- increase, then plateau at 40 to 60% VO2 max
- no plateau in highly trained subjects (better venous return)
the plateau in SV that occurs in the untrained at 40 to 60% of VO2max is due to
decreased in filling time
total of _____ of blood to be circulate dhtorught the entire body at rest
5 to 6 L
why is there a need of redistribution of blood flow during exercise
- increased blood flow to working skeletal muscle
- less blood flow to less active organs
percent of blood flow to SM at rest and during maximal exercise
- at rest 15 to 20%
- max 80 to 85%
maximal cardiaci output
20-30 L/min of blood to be circulated at maximal exercise
the increase in muscle blood flow that occurs during exercise is regulated by several factors that promote
vasodilation
autoregulation is
- blood flow increased to meet metabolic demands of tissue
- due to changes in O2 tension, CO2 tension, nitric oxide, potassium, adenosine, and PH
why have vasoconstriction
to visceral organs and inactive tissues?
- stimulated by SNS vasoconstriction
- decrease blood flow to 20 to 30$ of resting values to SM
the local inhibition of sympathetic induced vasoconstriction that occurs during exercise is called
sympatholysis
produce of No, ATP, prostaglandins is the promotion of dilation which then
increases smooth muscle relaxation in the arterioles
ATP and adenosine are important vasodilators for
they increase muscle blood flow during exercise
what does adrenergic stimulation do?
constricts the arteriole at rest limiting the amount of blood flow to the muscle
true or false: only 50-80% of the pre capillary sphincters are open at rest
true
as intensity increases, motor units increases, what happens to capillaries
more created to match metabolic demand
local factors to cause arterioles/metarterioles to open
- decreased O2
- increased CO2
-H+ - increased NO
- Adenosine
- prostaglandins
humoral control that causes the arterioles/metaarteroles to open
epinephrine
active hypermia
the increase in blood flow secondary to metabolites
overcoming the SNS vasoconstriction with active hyperemia is referred to as
functional sympatholysis
cardiac muscle extracts _____ of the O2 in the blood at rest
70%
skeletal muscle extracts ___% of the O2 in the blood at rest
22%
O2 uptake in skeletal muscle increases as a result of (2)
- an increase in blood flow
- an increase in O2 extraction from the blood
arteriovenous difference is the (a-VO2 diff)
arterial oxgen centent minus the venous O2 content
changes in arteriovenous difference depends on
- myoglobin
- capillarity
- mitochondria
- mitochondria enzymes
to meet the increased oxygen demand of the skeletal muscles during exercise, it is necessary to?
increase muscle blood flow hwoile reducing blood flow to less active organs
the arterioles in skeletal muscle have a high vascular resistance at rest due to
adrenergic sympathetic stimulation
adrenergic sympathetic stimulation causes
arteriole smooth muscle to contact (vasoconstriction)
what is VO2max
maximal oxygen consumption
what is maximal aerobic capacity
the maximal amount of physiological work that an individual can do as measured by oxygen consumption
Fick equation
VO2 = Q x (a-v-)O2 diff
what limits VO2max?
stroke volume
incremental exercise affects HR and CO by
- increases linearly with increasing work rate
- reaches plateau at 100% VO2 max
incremental exercise affects on blood pressure
- mean arterial pressure increases linearly
- systolic BP increases
- diastolic BP remains fairly constant
what happens to BP as CO increases
BP increases
why does diastolic not increase when incremental exercise increases?
due to TPR - vasodilation will cause a lower TPR
elevated HR and BP in emotionally charged environment due to
increases in SNS activity
- can increase pre exercise
- does not increase peak HR or BP during exercise
during an emotional state, which could cause an increase of HR and BP. What is the steps of that happening?
increase of stress stimulates the brain to release NE/E due to its purpose of fight or flight response. these hormones further enhance the sympathetic stimulation of the heart, blood vessels. therefore increase in HR and BP
at the onset of exercise: what happens?
- rapid increase in HR, SV, and cardiac output
- plateau in submaximal (below lactate threshold) exercise)
what happens during recovery after an exercise
- decrease in HR, SV, and cardiac put toward resting levels
- this depends on: duration and intensity of exercise and training state of subject
intermittent exercise recovery heart rate and blood pressure between bouts deepens on
- fitness level
- temperate and humidity
- duration and intensity of exercise
heavy intensity intermittent exercise
near maximal Hr values are possible
During arm and leg exercise, which causes a higher heart and blood pressure?
arm
why does your arm have a higher heart rate and blood pressure?
theres a greater sympathetic outflow to the heart during arm work when compared to leg exercise
the large increase in blood pressure during arm work is due to
vasoconstriction in the active muscle groups
larger muscle groups (leg) that is exercising causes more resistance vessels to dilate. therefore causing?
lower peripheral resistance causing lower blood pressure
at the same oxygen uptake, arm work results in higher HR and BP due to
- due to higher sympathetic stimulation
- due to vasoconstriction of large inactive muscle mass
during a prolonged exercise cardiac output is maintained because of
- a gradual decrease in stroke volume due to dehydration and reduce plasma volume
The increase in heart rate and decrease in stroke volume observed during prolonged exercise is often referred to as
cardiovascular drift
supine vs upright exercise
supine exercise have a much greater venous return and Higher SV and lower HR
the central command refers to
a motor signal developed within the brain -
fine tuned by feedback from
- heart mechanoreceptors
- muscle mecnachorecepotrs
- muscle chemoreceptors
- baroreceptors
muscle chemoreceptors are sensitive to increases in
muscle metabolites (potassium, lactic acid)
- exercise pressor reflex
what is exercise pressor reflex
its a type of peripheral feedback to the cardiovascular control center (medulla oblongata)
muscle mechanoreceptors are sensitive to
force and speed of muscular movement (muscle spindles, GTOs)
baroreceptors are sensitive to
changes in arterial blood pressure
what proposes that the initial signal to “drive” the cardiovascular system at the beginning of exercise comes from higher brain centers.
central command theory