Cardiovascular Flashcards
what is the sequence of events through the hear in one beat
1) SA node
2) Atria
3) AV node
4) AV bundle (of His)
5) Purkinje fibers
6) Ventricles
there is a time delay of __s from atria to ventricle
about 0.1second
___ transmits signal __X faster then normal ventricular fibers
purkinje fibres
6X
where are most of the parasympathetic nerve endings concentrated in the heart
atria
including the SA and AV nodes
the ____ fibres supply the SA and AV nodes and the muscle of the atria and ventricles
sympathetic nerve fibers
the contents of the vascular system could wrap around the world ___X
4
what are the three most basic roles of the cardiovascular system? provide an example for each
1) to transport nutrients to tissues (oxygen, glucose, lipids, amino acids)
2) to remove metabolic by-products from tissue (CO2, H+)
3) to transport hormones so they can exert their effects on target tissues
what are three limitations of the maximal rate of blood flow to metabolically active tissue
1) the heart has a limit with respect to the maximal amount of blood that it can pump each min (max CO)
2) there is a limited amount of total blood volume within the circulatory system that must perfuse a lot of different tissues
3) there is a limited density of capillaries in each different type of tissue, which directly limits the perfusion of that tissue
what is the cardiovascular system
a series of pipes (arteries, capillaries, veins) that enable the heart to pump blood through the different tissues of the body
what are the cardiovascular system components
a pump
a high pressure distribution circuit
exchange vessels
a low pressure collection circuit
the right side of the heart receives oxygen____ blood
receives oxygen poor
where does the right side of the heart get its blood
gets poor oxygenated blood from the body and pumps it to the lungs
where does the blood come from the body into the right side of the heart
superior and inferior vena cava
after flowing through the inferior and superior vena cava where does the blood go
into the right atria
from the right atria the blood goes through ___ valve into __
tricuspid valve
right ventricle
from the right ventricle the blood goes through ___ valve into the ____
pulmonary valve
pulmonary arteries to the lungs
the left side of the heart receives ____ blood
oxygenated blood
where does the left side of the heart get its blood
the lungs
where does the oxygenated blood come from
the pulmonary veins
where does the oxygenated blood go from the pulmonary veins
into the left atria
from the left atria the blood goes through __ valve into __
mitral valve
left ventricle
from the left ventricle the blood goes through ___ valve into the ___
aortic valve
aorta to the body
___ regulate the flow of blood through the chambers of the heart
valves
what influences the opening/closing of the valves
the pressure the heart creates when it contracts
the opening and closing of valves regulate ____ through the chambers of the heart
blood flow
the left ventricle starts to fill with blood when the ____ valve opens
mitral (bicuspid) (left side of heart)
it takes a lot of pressure to open the ____ valve
aortic
exercise is a good example of how simultaneous changes in factors influence the ___ ____ and ____
1) the pressure volume loop
2) affect ventricular pressures
3) affect volumes
during whole body exercise increased ____ to the heart generally causes a small increase in _____ volume
venous return
end-diastolic volume
_____ nerve system activates the heart and increases ventricular inotropy which ____ end systolic volume
sympathetic
decreases
increased venous return and the activation of the sympathetic nervous system to increase ventricular inotropy and decrease end-SYSTOLIC volume leads to___
a small increase in end-DIASTOLIC volume
and
a large reduction (decrease) in end- SYSTOLIC volume
the increase in end-DIASTOLIC volume and the decrease in end-SYSTOLIC volume leads to ___
an INCREASE in stroke volume and ejection fraction
why does the increase in atrial pressure that usually increases end-systolic volume and decrease stroke volume NOT occur
because the large increase in inotropy is the dominate factor affecting end systolic volume and stroke volume
what does the right coronary artery supply blood to
the right atrium right ventricle
the bottom portion of the left ventricle
back of the septum
what does the coronary veins do
take oxygen poor blood that has already been used by muscles of the heart and return it to the right atrium
what does the left anterior descending artery supply blood to
the front and bottom of the left ventricle
front of the septum
what does the circumflex artery supply blood to
the left atrium and the side and back of the left ventricle
what does the left coronary artery do
divides into two branches
the circumflex artery and the left anterior descending artery
the heart feeds itself through
coronary circulation
what does the great cardiac vein do
returns deoxygenated blood from the anterior surfaces of the LEFT ventricle
what does the anterior cardiac veins do
group of parallel coronary veins that course over the anterior surface of the right ventricle, draining it and entering directly into the right atrium
what is the coronary sinus
the coronary sinus is a collection of veins joined together to form a large vessel that collects blood from the heart muscle (myocardium).
what does the coronary sinus deliver
less-oxygenated blood to the right atrium as do the superior and inferior vena cava
myocardium has a very high content of ____ and capillaries density
mitochondria
the heart muscle tissue (myocardium) is ____ muscle
striated
the arterial system is the ____ pressure distribution circuit
HIGH
what does the arterial system compose of
arteries
arterioles
conduit artery
designed to transport blood to areas of the body
feed artery
vascular resistance vessels designed to regulate flow to specific areas of the body
feed arteries account for ____% of TPR
50%
terminal arteriole
the last control point for regulating blood flow into capillaries. therefore to perfuse a microvascular unit the terminal arteriole MUST be DIALATED
what is the microvascular unit
all of the capillaries arising from a common terminal arteriole
do all three energy systems happen in all types of situations
YES
_____ are considered to be the primary location where oxygen transfer occurs in muscles
capillaries
there is no VSM in capillaries rather there is only an endothelial layer that promotes __
diffusion by limiting the distance that oxygen must diffuse
a tubes resistance is inversely proportional to the ___ power of its radius
4th power
smooth muscle fibres in arterioles control ____
blood flow to capillary beds
osmotic pressure within capillaries ___
draws fluid back
____ forces fluid from capillary
blood pressure
the precapillary sphincter is
a ring of smooth muscle that controls capillary diameter
at rest ___ per min in muscle tissue
5 ml/100g
veins are the ___ pressure collection and return circuit
LOW
valves are important for
venous return
one way flow and important for the milking action produced by skeletal-muscle pump
low pressure of the venous system is potentially problematic for ___ called ____
blood return
venous pooling
___ plays a role in venous pooling
force of gravity
an issue when standing at attention in an upright posture when skeletal muscle contraction is limited can lead to
pooling of blood, reduced return, decreased end diastolic volume which leads to decreased stroke volume and decreased Q which leads to fainting
venous return (low pressure of the venous system) is countered by
1) skeletal muscle pump
2) respiratory pump
3) venoconstriction
explain skeletal muscle pump and venous return
muscular contractions assist with venous return
explain respiratory pump and venous return
changes in pressure gradients
explain venoconstriction and venous return
constriction or narrowing of small veins/venules draining muscles ( controversial)
what component has the most influence on blood pressure
arterioles
_____ are the last control point for regulating blood flow into capillaries
terminal arterioles
to perfuse a MVU the ____ must be ____
terminal arteriole
dilated
explain the left ventricle blood pressure
swings between a low pressure of 0mmHg during diastole to a high pressure of 120mmHg during systole
in the left ventricle when is the pressure the lowest
during diastole
in the left ventricle when is the pressure the highest
during systole
arterial blood pressure fluctuates between a peak systolic pressure of ___ and a low diastolic pressure of ___
120mmHg
80mmHg
do the large arteries have the same or different magnitude throughout
the same
why does the pressure drop precipitously and the systolic to diastolic swings in pressure are converted to nonpulsatile pressure when blood flows through the arterioles
because of the arterioles high resistance
the pressure continues to decline but at a slower rate as blood flows through the ___
capillaries and venous system (venules and veins)
local blood flow is directly regulated by ___
blood pressure and local vascular resistance
what is ohms law
increase blood flow= the change in pressure/resistance
what is the change of pressure in ohms law
volume pushing against arteriole wall
what is the resistance in ohms law
resistance within the vessel is proportional to the size of the arteriole
systemically total peripheral resistance is increased during ___ however local metabolic factors in active tissues promote regional vasodilation therby ____
exercise
enhancing local blood flow
what directly influences local blood flow
vessel radius
a vessel with a greater radius will have greater blood flow or worse
better!
a vessel with greater radius will have more or less resistance then a smaller radius vessel
smaller resistance
the diameter of resistance vessels (feed arteries and arterioles) is controlled by __
vascular smooth muscle
____ nerve fibres surround feed arteries, primary arterioles and terminal arterioles
sympathetic
the systemic increase in total peripheral occurs in response to ____
SNS signalling via norepinephrine and epinephrine induced vascocontriction throughout most of the tissues in the body
why do the arterioles in the brain not vasoconstrict
do not have alpha1 receptors and will not vasocontrict due to catecholamines
one of the most fundamental principals of circulatory function is the ability of
each tissue to control its own local blood flow in proportion to its metabolic demand
does cardiac output increase during exercise
yes
the percentage of cardiac output going to the skeletal muscle and heart rises thereby delivering
extra o2 and nutrients needed to support these muscles stepped-up rate of ATP consumption
why does a percentage of the cardiac output increase in the skin
as a way to eliminate from the body surface the extra heat generated by the exercising muscles
what is the only tissue that the magnitude of blood flow remains unchanged as the distribution of cardiac output is readjusted during exercised
the brain
systolic blood pressure is
the work of the heart and force that blood exerts against the arteriole walls during ventricular systole
systolic blood pressure is the CLOSING of the ____
aortic valve
diastolic blood pressure is
an indication of peripheral resistance or ease that blood flows from the arterioles into the capillaries
diastolic blood pressure is the OPENING of the ___
aortic valve
mean arteriole pressure is
the average pressure in a persons arteries during one cardiac cycle
what is considered a better indicator of perfusion to vital organs; systolic blood pressure or mean arteriole pressure
mean arteriole pressure
pulse pressure is
the difference between systolic blood pressure and diastolic blood pressure
MAP=
diastolic BP + [0.333*(pulse pressure)]
pulse pressure =
systolic BP-diastolic BP
does the heart remains in diastole or systole longer
diastole by 2/3 longer (which is why there is a 0.333 in MAP equation)
what is normal blood pressure
systolic = 120 diastolic = 80
what is prehypertension blood pressure
systolic = 120-139 diastolic = 80-89
what is stage 1 hypertension blood pressure
systolic = 140-159 diastolic = 90-99
what is stage 2 hypertension blood pressure
systolic = 160 diastolic = 100
hypertension leads to
atherosclerosis heart disease congestive heart failure kidney disease myocardial infarction stroke
what is treatment of hypertension
medication
medication
- beta blockers (reduce contractility and slow HR)
- alpha & Ca blockers (dilate blood vessels)
- diuretics (increase renal excretion)
what is treatment of hypertension
lifestyle changes
exercise weight loss stress management cessation of smoking reduce alcohol intake reduce sodium intake ensure adequate potassium calcium and magnesium intake
it is the balance of local substances that regulates
arteriole diameter and thereby the local tissue perfusion
what are the major factors affecting arteriolar radius
local metabolic changes in o2 and other metabolites
sympathetic activity
the sympathetic activity affecting arteriolar radius is ___ control
extrinsic
the local metabolic changes in o2 and other metabolites affecting arteriolar radius is ____ control
local or intrinsic control
what are extrinsic control mechanisms
epinephrine and norepinephrine
angiotensin 2
vasopressin
what are local control mechanisms
histamine release
heat, cold application
myogenic responses to stretch
response to sheer stress
what is the difference between thrombus and plaque
thrombus= complete blockage
what is the percutaneous transluminal coronary angioplasty
double-lumen dilation catheter
what is the revascularization option
coronary artery bypass graft surgery
- mammary artery
- saphenous vein
the myocardium relies almost exclusively on energy produced through ____ metabolism
aerobic (oxygen)
the heart will use ____ fuel source it receives in the blood to fuel aerobic metabolism
whatever!
typically at rest ____ are the primary source of fuel
fatty acids (60-65%) glucose (30%)
after a meal the heart may ____ its use of ____ or fatty acids based on their availability
increase
glucose
as exercise intensity increases the myocardium becomes more reliant on ___ because ___ becomes more available in the blood as it is released from working muscles
lactate
blood glucose fatty acids and lactate enter the myocardium and are then used in ____ metabolism by entering the ___ in the mitochondria
aerobic
TCA (Krebs cycle)
where does the krebs cycle take place
mitochondria
myocardial workload is estimated by the
rate pressure product
what is the rate pressure product equation
SBP X HR
rate pressure product is a common method used to estimate
myocardial workload (or myocardial oxygen utilization)
what does the RPP measure
myocardial O2 consumption and coronary blood flow in healthy individuals
RPP is correlated with the onset of ____ in patients with coronary heart disease
angina
exercise training lowers ___ and ___ at a specific work rate,
HR and SBP
why does exercise training lower HR and SBP at a specific work rate
because the body adapts to exercise over time and better uses aerobic metabolism which thereby reduces the oxygen needed to conduct the required work rate
what is cardiac output =
HR x SV
increasing exercise intensity causes HR and SV to _____ and there for increase _____
increase
cardiac output
increasing exercise intensity increases heart rate. how does this happen
parasympathetic signalling decreases
sympathetic signalling increases
the decrease in parasympathetic happens because the decrease in the ________ nerve stimulation
vagal
the increase in sympathetic signalling happens because of the increase in _____and ____
norepinephrine
epinephrine
why does stroke volume increase in response to increasing exercise intensity
increase in filling due to venous return
increase in contractility (frank starling)
why does blood pressure increase in response to increasing exercise intensity
the increase in cardiac output
the increase in systemic total peripheral resistance
intrinsic regulation of the heart
sinoatrial node
without modulation of the SA node will depolarize 100 times per minute
extrinsic regulation of the heart
neural output and chemical messengers in the blood both influence the extrinsic regulation of the heart rate and the circulatory system
SA node is where in the heart
situated in the posterior wall of the right atrium, the SA node is an intrinsic pacemaker
the SA node depolarizes and repolarizes to provide
constant stimulus to the heart
AV node and (bundle of his) is located where
situated close to the tri-cuspid valve
what does the AV node do
transmits the depolarization to the purkinje fibers through both ventricles
where are the purkinje fibers and what do they do
specialized conducting fibers that transmit the electrical depolarization through the left and right ventricles
it takes a small amount of time for the depolarization to move from the SA node to both ventricles because the _____
purkinje fibers
how long is the delay in the left atria take after the SA node
0.03-0.09 seconds
how long is the delay in the left ventricle after the SA node
0.16-0.22 seconds
how long is the delay in the right ventricle after the SA node
0.17-0.19 seconds
the cardiac rhythm is a complex series of electrical signals that are regulated by the
cardiac conduction system
what is the sequence of the cardiac conduction system
sinoatrial node atrioventricular node atrioventricular bundle of his left and right bundle branches bundle branches
what are the points of the (ECG) electrocardiogram
P wave
QRS complex
T wave
refractory period
what is the P wave
represents the depolarization of the atria
how long does the p wave last
0.15 seconds
what does the P wave signal
atrial contraction
what is the QRS complex
follows the P wave and signals electrical changes from ventricular depolarization and ventricles contraction
what is the T wave
represents ventricular REPOLARIZATION and occurs during ventricular diastole (relaxation)
during the T wave can another contraction occur? if not how long till it can contract again
no other contractions can occur
for 0.20-0.30 seconds
what is the refractory period
allows the ventricles time to refill
what does the wave form of the ECG does not represent
the intrinsic pacemaker activity of a single heart cell
what is the ECG
the sum of the electrical activity of all cell types in the heart
atrial depolarization is recognized by the ____ on the ECG
p wave
what is the P-R interval
the electrical transmission from atria to ventricles
ventricular depolarization is recognized by the ___ on the ECG
QRS complex
what does the R wave indicate
the initial positive deflection
what does the Q wave indicate
the negative deflection before the R wave
what does the S wave indicate
the negative deflection following the R wave
what is the ST segment
ventricular repolarization
what is the Q-T interval
ventricular depolarization
and repolarization
what is the stress test on the ECG
arrhythmia
S-T segment
what does a depressed S-T segment represent on the ECG
pre ventricular contraction
ECG can be used to identify changes in the electrical rhythm of the heart to identify ___
the general area of the heart that is causing the pathological change in electrical rhythm
what is a arrhythmias
changes in the normal rate or rhythm of heartbeat
causes of arrhythmias
SA node dysfunction
usually associated with hypothyroidism, advanced liver disease, hypothermia, acute hypertension, and typhoid fever
defects in impulse conduction
types of arrhythmias
sinus bradycardia sinus tachycardia conduction defects (heart blocks) atrial and ventricular premature complexes flutter fibrillation
signs and symptoms of arrhythmias
fatigue from cardiac output, dizziness, fainting (bradycardia)
irregular heart rate (flutters and fibrillations)
medical surgical treatment of arrhythmias
implantation of a pacemaker
antiarrhythmic drugs
defibrillators
how does heart rate pressure and ECG all fit together
if you align the events recorded for ECG, left ventricular pressure and left ventricular volume it is easier to see how these different parameters measure different properties of the same event
what factors affect heart rate
the autonomic nervous system (PNS + SNS) controls heart rate by modulating the intrinsic pacemaker activity of the heart
what influences extrinsic regulation
neural input and chemical messengers in the blood that influence the extrinsic regulation of the heart rate and circulatory system
what is the extrinsic neural input regulation
sympathetic and parasympathetic
what are the sympathetic receptors
alpha adrenergic and beta adrenergic
what are the sympathetic catecholomines
epinephrine and norepinephrine
what are the neural chronotropic effects
increase heart rate by accelerating how easy it is to depolarize the SA node
what are the neural inotropic effect
increase how strongly the heart contracts to increase stroke volume
also promotes increased vasoconstriction throughout the circulatory system to increase total peripheral resistance
parasympathetic input occurs from the
vagus nerve
what are the parasympathetic catecholomines
acetylcholine
what does acetylcholine do to the heart rate
decreases heart rate by making it more difficult to depolarize the SA node
what are chemical messengers
factors in the blood influence regulate cardiovascular function
the intrinsic pacemaker activity of the heart is usually controlled by the
depolarization of SA node pacemaker cells
how does the autonomic nervous system influence heart rate
by modulating how quickly the different ions move across the cell membrane- which results in a change in heart rate
what is the overall membrane potential the sum of
the movement of different ions across the cell membrane during each heart beat
sympathetic signalling increases how quickly pacemaker cells _____
depolarize to increase heart rate
parasympatheric signalling slows how quickly pacemaker cells depolarize to
reduce heart rate
the cardiovascular control center rapidly regulates the functional parameters of the circulatory system by incorporating ____ input from the ______ and feedback from the ____
feedforward
central command
periphery
where is the cardiovascular center
the ventrolateral medulla
signals from the ____ central center continually modulate the activity of the cardiovascular control center
somatomotor
what is a feed forward mechanism that rapidly adjusts the regulation of heart rate and blood vessels to optimize tissue perfusion and blood pressure
input from the central command
the central command influences the ____ regulation of the cardiovascular system
neural
how is the preexercise anticipatory response activated
activation of the central command from motor cortex and higher area of the brain increase in sympathetic outflow and reciprocal inhibitions of parasympathetic activity
how is the pre exercise anticipatory responded to
acceleration of heart rate; increased myocardial contractility; vasodilation in skeletal and heart muscle; vasoconstriction in other areas especially skin gut spleen, liver and kidneys; increase in arterial blood pressure
what is the feedback from the periphery
the cardiovascular center receives reflex sensory feedback from the periphery through a variety of sensors in blood vessels, joints and muscles
what are baroreceptors
sense the blood pressure (stretch) and relay the information to the brain so that a proper blood pressure can be maintained
baroreceptors are a type of what sensory neuron
mechanoreceptors
where are arterial baroreceptors located
in the aortic arch and in the carotid arteries
what do the arterial baroreceptors do
reflex acts to influence sympathetic nerve signalling when blood pressure needs to be regulated
operating points for the arterial baroreceptors reset during exercise to accommodate
central blood pressure to sufficiently perfuse metabolically active tissue
where are cardiopulmonary baroreceptors located
in the left ventricle, right atrium, and large veins
what do the cardiopulmonary baroreceptors do
monitor changes in pressure in the heart chambers and pulmonary vasculature
what is carotid artery palpitation
external pressure against the carotid artery sometimes slows heart rate due to the addition of pressure to the carotid baroreceptor
why might the carotid artery palpitation give an inaccurate reading in comparison to the radial artery
the external pressure against the artery sometimes causes the heart rate to slow down so after exercise if someone checks their carotid artery pulse they might get a lower then accurate HR
what are the three skeletal muscle ergoreceptors
mechanoreceptors
chemoreceptors
metaboreflex
what are mechanoreceptors
sense the physical state of muscle (determine if it is contracting)
what are chemoreceptors
sense metabolites that are created during contractions
what are metaboreflex
turned on when metabolites accumulate in the interstitial space of muscle during contractions
what do all three ergorecpeptors influence
parasympathetic and sympathetic signalling
what do all three ergoreceptors feedback to the cardiovascular control center is mediated by group of
iii and iv afferents
what does the exercise pressor reflex refer to
these neural regulatory mechanisms that sense muscle activity and use that information to provide feedback to better match sympathetic and parasympathetic signalling with the required level of cardiovascular control
what is the activator of the neural regulation of the cardiovascular system during exercise
parasympathetic withdrawal at onset and during low intensity exercise
sympathetic stimulation
reflex feedback from peripheral mechanical and chemical receptors ect..
what is the response of neural regulation of the cardiovascular system during exercise
further dilation of muscle vasculature
constriction of vasculature in inactive tissues to maintain adequate perfusion pressure throughout arterial system
vasoconstriction, muscle pump ect…
what is Poiseuille’s law
flow= Blood pressure gradient x vessel radius^4/vessel length x fluid viscosity
a small change in blood vessel radius has a very large impact on
flow
what factors stimulate a vasodilation of arterioles to increase blood flow
metabolite accumulation or the lack of oxygen in muscle
hormonal factors such as catecholomines
shear stress flow causing things to rub against the endothelial wall
the exchange system is in the
capillary bed
at rest how many capillaries are open
1 out of every 30
during exercise the pre-capillary sphincters open in response to what
local metabolite accumulation
what does the open sphincters and the local metabolite accumulation lead to
increased tissue blood flow (perfusion)
delivers a large volume of oxygenated blood with minimal changes in cardiovascular regulation
increases the surface area for exchange of gases, nutrients and waste
what are the roles of nitric oxide
vasodilation occurs when nitric oxide penetrates smooth muscle cells
where does nitric oxide come from
ycern elial cells within blood vessels release nitric oxide gas- its either released by autonomic neurons or from drugs like Viagra or ntrg
how does sheer stress stimulate the release of nitric oxide from the cells
the red blood cells bumping into the epithelial cells cause the cell to deform which triggers the release of nitric oxide
normally nitric oxide is able to promote vasodilation when will this not occur
in many disease states causes nitric oxide to be reduced due to an accumulation of oxidative stress which impairs vasodilation
what are some example pathological conditions that reduce nitric oxide
hypercholesterolemia
atherosclerosis
peripheral artery disease
coronary artery disease
what is nitric oxide bioavailability
the total amount of nitric oxide that is biologically active and is the difference between the total production of nitric oxide minus the total amount of nitric oxide destroyed by other processes
the excess O2 combines with NO (nitric oxide) to create___ what is it
ONOO
damages cellular proteins
exercise training and some other medical treatments enhance endothelial function by promoting what
an increase in nitric oxide bioavailability
exercise increases eNOS (endothelial nitric oxide synthase) protein expression that leads to
enhanced NO bioavailability (increased vasodilation)
exercise may reduce the amount of ____ made by NADP(H) oxidase
reactive oxygen
exercise enhances ____ protein expression which reduces oxidative stress
SOD
superoxide dismutase
why does HR not very much in a heart transplant patient
because the neurons don’t connect like they use to
there is no more neural innervation
how is heart rate regulated in a heart transplant patient
hormonal feedback from circulating catecholamines
patients who receive a heart transplant tend to have higher VO2max post surgery why
because the healthy heart tends to have higher stroke volume then the original diseased heart so the transplant heart tends to increase stroke volume in a linear way throughout exercise
a typical VO2max for patients who require a heart transplant is 10-15l O2/kg/min after transplantation the VO2max tends to increase by roughly
50-60%
what is cardiac output
can be thought of as the flow of blood from the heart or as the amount of blood pumped out of the heart during a 1 min period
what does Q represent
flow or cardiac output
what is the cardiac output equation
cardiac output = HR x SV
what are three other methods also typically used to determine cardiac output
direct fick
indicator dilution
CO2 rebreathing
(none of these methods use heart rate or stroke volume to determine Cardiac Output)
what is the principle of the Fick Equation
if you know the average difference between oxygen content of arterial and venous blood and how much oxygen was utilized by that working muscle
what is the only thing not known in the fick equation
how much blood was delivered to the working muscle to supply that amount of oxygen
what is the direct fick equation
Q= [VO2/a-v O2 difference]x100
what is the indicator dilution method
determining flow through a tube. the volume per min flowing in the tube equals the quantity of indicator injected divided by the average dye concentration at the sample site multiplied by the time between the appearance and disappearance of the dye
what is the indicator dilution method equation
Q= [quantity of dye injected/(average concentration of the dye in the blood for duration of curve x duration of curve)]
what is CO2 rebreathing
the use of a rapid CO2 gas analyzer to measure mixed venous and arterial CO2 levels
breath by breath analysis
non-invasive (bloodless)
however this test is only useful when the person is doing steady state exercise
what is the CO2 rebreathing equation
Q= [VCO2/v-a CO2 didderence]x100
cardiac output will provide blood flow in proportion to the bodys
metabolic demands
with increase in metabolic demand cardiac output _______
increases linearly with oxygen uptake
women typically have cardiac output and stroke volume that are about ____% lower then men
25
what is cardiac output for sedentary individual
25Lmin-1
what is cardiac output for the well trained individual
30-35Lmin-1
what is the cardiac output for the world class athletes
35-40Lmin-1
cardiac output increases directly with _____ until when
exercise intensity
until the delivery of oxygen matches the metabolic demands of the metabolically active tissue
what is the average persons stroke volume at rest
80mLbeat-1
what does the average persons stroke volume reach during intense physical activity
130mLbeat-1
in elite athletes what is the resting stroke volume
averages 110mLbeat-1
what can elite athletes (cross country skiers) increase their stroke volume to at peak exercise
200mLbeat-1
what factors have positive effects controlling cardiac output (Q) at rest and during exercise
parasympathetic (negative effect)
sympathetic
venous return
end diastolic volume
heart rate
stroke volume
what does the cardiac output reflect
the functional capacity of the cardiovascular system
what is cardiac output at rest for males
5L
average HR of 70beats.min and
average SVof 71.4mL
what is cardiac output at rest for women
4L
average HR of 70beats.min
and
average SV of 50-60mL
what do heart rates in healthy endurance athletes generally average at rest
50beats.min
what is the average resting stroke volume in healthy endurance individuals
100mL
what are some of the factors that explain why endurance athletes have a large stroke volume and low heart rate
increased vagal tone and decreased sympathetic drive both of which slow the heart
increased blood volume myocardial contractility and compliance of the left ventricle all of which augment the hearts stroke volume
cardiac output increases rapidly during the transition from rest to steady rate exercise and then rises gradually until it plateaus when
blood flow meets the exercise metabolic requirements
the endurance athlete achieves a large maximal cardiac output solely through a
large stroke volume
enhancing stroke volume by….
diastolic filling versus systolic emptying
what are the mechanisms that increase the hearts stroke volume during exercise
1) enhanced cardiac filling in diastole followed by a more forceful systolic contraction
2) greater systolic emptying- normal ventricular filling with a subsequent forceful ejection and emptying during systole
3) training adaptations that expand blood volume and reduce resistance to blood flow in peripheral tissues
the stroke volume is affected by changes in ___,_____ and ____
preload
afterload
inotropy (contractility)
in normal hearts the SV is not strongly influenced by afterload. Is this the same for failing hearts
no, the SV is highly sensitive to afterload changes
what is the stroke volume equation
SV= end diastolic volume - end systolic volume
ie) volume when filled with blood - volume after contraction
what factors affect the end diastolic volume (volume when filled with blood)
size of the heart
filling pressure
compliance of the LV (left ventricle)
what factors affect the end systolic volume (volume after contraction)
afterload
LV contractile force
exercise does what to the stroke volume
increase frank starling mechanism (contraction strength)
increase venous return (PRELOAD) and filling pressure
- end diastolic volume
decrease in afterload due to vasodilation (mean arterial pressure!)
enhanced diastolic filling leads to
stronger contractions
any factor that increases venous return or slows the heart produces greater ______ during the cardiac cycles diastolic phase
preload
an increase in end diastolic volume stretches ___ fibers and initiates a powerful ___
myocardial
ejection stroke during contraction
this ejects normal SV plus additional blood that entered the ventricles in diastole
the frank starling law of the heart states that the
force of contraction of the cardiac muscle remain s proportional to its initial resting length
exercise training further improves what that contributes to the larger stroke volumes observed in athletes
ca2+ sensitivity of the contractile proteins
the increase of the left ventricle during diastole = what
increase stretch and increase calcium sensitivity of the myocardium = increase force of contraction
the heart create pressure as it contracts that pressure leads to
influence the open/closing of valves which regulate blood flow through the chambers of the heart
the left ventricle starts to fill with blood when the ___ valve opens
mitral (tricuspid)
pre load is what
end diastolic volume
increase preload leads to
increased SV and ejection fraction
MORE BLOOD IN VENTRICLE BEFORE CONTRACTION
starlings law in simple terms
ventricle more stretched, more forceful, and more blood ejected
after load (aortic pressure) opens at the same or different pressure then pre load
same
greater systolic ejection occurs despite
increased resistance to blood flow in the arterial circuit from exercise induced elevation of systolic blood pressure
enhanced systolic ejection occurs because
The ventricles always contain a functional residual blood volume
catecholamine release in exercise enhanced ______ to augment stroke power and facilitate systolic emptying
myocardial contractile force
the end systolic pressure volume relationship describes what
the maximal pressure that can be developed by the ventricle at any given LV volume
the increase in contractility =
ventricle contracts more forcefully
it changes neither preload nor afterload
increase SV and EJ
DECREASE end systolic volume
training adaptations that expand blood volume and reduce resistance to blood flow in peripheral tissues which is
redistribution of blood to working tissues
neural and hormonal (sympathetic and parasympathetic)
long term adaptation in blood volume
- endurance trained larger plasma volume and more RBCs
what is cardiovascular drift
describes the gradual time dependent downward drift in several cardiovascular responses, most notably stroke volume with concomitant heart rate increase, during prolonged steady rate exercise
what does cardiovascular drift affect
decrease in volume return during prolonged exercise at submaximal effort
progressive decrease in SV
progressive increase in HR
therefore Q maintained over time
submaximal exercise for more then 15 mins decreases plasma volume which ______
decreases stroke volume
was does a decrease in tissue O2 cause for the vessels
a potent vasodilator stimulus
what causes local dilation
increase blood flow temperature CO2 K NO Mg acidity and adenosine
at rest the myocardium uses about ____% of the oxygen in the blood flowing through the coronary circulation
75%
during exercise how much does coronary circulation increase
four-fivefold increase
cerebral blood flow increases during exercise by about ____% compared with resting flow
25-30%
arterial blood carries ____mL of oxygen per liter
200
if resting cardiac output each min equals 5L potentially how much mL of oxygen will become available to the body
1000mL
the resting oxygen consumption typically averages 250-300mLmin allowing ___mL of oxygen to return to the heart unused
750mL
the extra oxygen circulating above the resting requirement represents what
oxygen in reserve
a low maximal oxygen consumption corresponds with what
a low maximum cardiac output
a 5-6L increase in blood flow accompanies each 1Lincrease in oxygen consumption above resting value; this relationship remains essentially
unchanged regardless of exercise mode
exercise O2 consumption increases by what 2 mechanisms
increased cardiac output
greater usage of O2 by metabolically active tissue (greater a-v O2 difference)
VO2 = Q x a-v O2 difference which means
cardiorespiratory fitness = O2 transport x O2 use
red blood cells in the circulation sense local tissue ___ through their degree of deoxygenation
hypoxia
a-v O2 difference between rest and exercise
rest
- 20mL of O2 in each dL of arterial blood (200 ml of O2 per L)
- at rest only 5mL of O2 is extracted per dL
exercise
- 20mL of O2 in each dL of arterial blood
- during maximal exercise only 16 to 18 mL of O2 is extracted per dL
O2 difference during exercise increases in arterial O2 capacity due to
increase in capillary hydrostatic pressure
osmotic pressure that draws fluid from plasma into tissue spaces
arms vs legs vo2
arms seems to have a higher oxygen consumption
cardiovascular adaptations include
increase ejection
increase contractility
increased blood volume
do athletes have bigger hearts
yes (left ventricular mass)
