lecture 11: cardiovasc reg., functional capacity etc Flashcards
beta cells do dilation or constriction
dilation
alpha receptors do constriction or dilation
constriction
true or false;Any increase in energy expenditure requires rapid adjustments in blood flow
true
how does increase in energy expenditure (rapid adjustments in blood flow) impact the entire cardiovascular sysyem
takes blood from unimportant tissues (not needed for activity atm) and redistrubutes it to the needed muscle
During exercise, local arterioles of active muscles dilate or constrict
dilate
During exercise, vessels to tissues that can temporarily compromise their blood supply, constrict or dialte
consict
during exercise what is happes to the vessels of the active adn resting vessels
active muscle vessels dilate which inactive constriction
give an example of inactive muscle constricting to redistribute blood flow
ex: during running, your gut and kidney vessels will constrict and ur sksletel will dilate
what are the 2 factors taht contribute to reduced blood flow to non-active tissues:
Increased sympathetic nervous system outflow
Local chemicals that directly stimulate vasoconstriction or enhance the effects of other vasoconstrictors
true or false: Increased sympathetic nervous system outflow contribute to icnrease blood flow to non active tissues
false, DECREASE BLOOD FLOW
epinephrin released by sympatethic will active what types of receptors
beta and alpha
skeletal muscle blood flow couples to what
metabolic demand (will not waste sending oxygen if not needed)
how does regulation of active myscle flow occur
Regulation occurs from the interaction of neural vasoconstriction activity and locally derived vasoactive substances within the endothelium and red blood cells
at rest, what is happening at the capilary of sksletal muscle
only 1 in 30-40 capilarries remains open
because increase blood supply is not needed at rest
what are the 3 functions of the opening of dormant capilaries in exercises
Increase total muscle blood flow
Deliver a large blood volume with only a minimal increase in blood flow velocity
Increase the effective surface for gas and nutrient exchange between the blood and muscle fibers
true or false: you must increase blood velocity to increase the amounft of blood volume to tisse
false, you can just open dormant capilaries
vasodilation occurs from local factored related to what
related to tissue metabolism that act directly on the smooth muscle bands of small arterioles and precapillary sphincters
what are some local factors that act directly on vasodilation
Decreased tissue oxygen, local increases in blood flow, temperature, carbon dioxide, acidity, adenosine, magnesium and potassium ions, and nitric oxide production by the endothelial cells lining the blood vessels
can the venous side release vasodilatory factors>
yes if there needes to be active msucle
what is the function of nitric oxide
serves as an important signal molecule that dilates blood vessels and decreases vascular resistance
is NO a constrictor or dialtor
Dialator
what are exmaples of things that provoke NO synthesis and release
Stimuli from diverse signal chemicals, sheer stress and vessel stretch from increased blood flow through the vessel lumen
how is NO released
vascular endothelium
where are places that the endothelium produces less NO
In coronary artery disease (atherosclerosis), diabetes and other disruptions of normal cardiovascular function
(less. vasodilation)
what is cardiac output expresses
the amount of blood pumped by the heart during a 1-minute period
what deos CO reflect
functional capacity of the cardiovascular system
what is the formualte for cardiac output
Cardiac output = Heart rate x Stroke volume
what are 3 methods to assess cardiac output
Direct Fick
Indicator dilution
CO2 rebreathing
what does direct fick method express
Expresses the relationships among cardiac output, oxygen consumption, and a-vO2 difference
true or false: direct fick is complex?
true
Requires complex methodology usually performed in a hospital
how can you get CO from direct fick method
Measuring oxygen consumption involves open-circuit spirometry methods
Measuring a-vO2 difference involves a sample of arterial blood and from an anatomic “mixing chamber”, then sampling arterial and mixed-venous blood simultaneously
explain the indicator diluation method
A known quantity of an inert dye whose concentration curve can be measured in blood by light absorption is injected into a large vein
The indicator material remains in the vascular stream and then mixes in the blood as the blood travels to the lungs and returns to the heart before ejection throughout the systemic circuit
A photosensitive device continually assesses arterial blood samples and the area under the dilution–concentration curve reflects the average concentration of indicator material in blood leaving the heart
what two methods use open circuit spirometry
co2 rebreathing method
direct fick
explai nthe co2 rebreathing method
The same open-circuit spirometry method for determining O2 consumption in the typical Fick technique determines CO2 production in the rebreathing method
Using a rapid CO2 gas analyzer and making reasonable assumptions about gas exchange provides valid estimates of mixed-venous and arterial CO2 levels
Requires breath-by-breath CO2 analysis
Does not require blood sampling or medical supervision
One limitation is that exercise must be under steady-rate aerobic metabolism, restricting the method’s use during maximal and in the transition from rest to exercise
true or false: CO2 required blood sample
flase, it does not require sampling or supervision
what is one limitation of c02 rebreathing method
One limitation is that exercise must be under steady-rate aerobic metabolism, restricting the method’s use during maximal and in the transition from rest to exercise
true or false: cardiac output varies considerably during rest
true
what are some influencing factors or cardiac output at rest
Influencing factors include emotional conditions that alter cortical outflow to the cardioaccelerator nerves and nerves that modulate arterial resistance vessels
how can emotional conditions influence CO at rest
they alter corticol outflow to the cardioaccelerator nerves
what is an avergae CO at rest for men
5 L
what is the average CO at rest for women
4L
men or women have a higher cardiac output at rest
MEN
CO is mostly affected by SV or HR
SV
what are heart rates and SV for resting athetles
Heart rates in healthy endurance athletes generally average 50 beats/min at rest while the resting stroke volume averages 100 mL
what are the 2 factors that explain the large stroke vol and low heart rate of endurance trained atheltes
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 heart’s stroke volume (traiininng ventircular muscles to pump more)
true or false: endurance athletes dont need to pump as much to get the same CO
true
how are sarcomeres arranged for endurance traininng
in series (allow for larger SV)
how are sarcomeres arranged for resistnace training
iin parallel (smaller SV)
explain how cardiac output moves during exercise
Cardiac output increases rapidly during the transition from rest to steady-rate exercise and then gradually until it plateaus when blood flow meets the exercise metabolic requirements
when does cardiac output increase rapidly
during the transition from rest to steady state
when does CO plateau
when blood flow meets the exrcise metabilic requirements
know the cardiac output curve
.
The endurance athlete achieves a large maximal cardiac output how
solely through a large stroke volume at submaximal exercise
what are the 3 factors that increase SV during exercisee
1) increased preload
2) decreasd afterload
training adaptations that expand blood vol and ressistnace to blood flow
explain how icnreased preload leads to incrase in SV
Enhanced cardiac filling in diastole
followed by a more forceful systolic
contraction (frank starling)
explain how decraesed afterload/increased contractility increases heart SV
Normal ventricular filling with a
subsequent forceful ejection and
emptying during systole
true or false: training adaptations have no effect on stroke volume
false, Training adaptations that expand
blood volume and reduce resistance
to blood flow in peripheral tissues
what factors produce a greater preload during cardiac diastole phase
Any factor that increases venous return or slows down the heart will produce greater preload
an increase in end disstolic does what to the myocardial fibers
stretches them and initiates a powerful ejection stroke during contraction (ejects normal blood and additional)
what does frank starling law state
Frank-Starling law of the heart states that the force of
contraction of the cardiac muscle remains proportional
to its initial resting length
true or false: greater systolic ejection occurs despite increased resistance to blood flow and why
true beacsuse of exterice induced elevation of systolic bp
if there is an increased BP will there be greater systolic ejection or less
greater = more contractility
what enhances myocardial contractiole force
catacholine relrease in exercise
what is the fucntion of catacholine release in exercise
Catecholamine release in exercise enhances myocardial contractile force to augment stroke power and facilitate systolic emptying
true or false: the ventricles always contain functional residual blood bolume and why
true because it is easier to fill if blood is already in and does not allow the ventricles to collapse
during exercise there is an incrase in pressure in systemic circulation so what does the heart need to do to compensate and how does it do it>
heart must build up a higher diastolic pressure to pump blood against the higher resistance.
iwth more sympathetic innervation and catechline release, the heart will increase pressure and eject more blood despite increase in ressitance
what does cardiovascular drift describe
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
ADD SLIDES ON CARDIOVASCULAR DRIFT
/
at rest, the typical cardiac output generally distributes by what locations
One fifth flowing to muscle tissue
The digestive tract, liver, spleen, brain, and kidneys receive major portions of the remaining blood
=depends on metabolic needs
most of cardiac output divers to where during exercise
to active muscles
most of the blood diversed to what portions of the muscle during exrceise
Most of the blood diverts to oxidative portions of muscle at the expense of those with high glycolytic capacity
for trained individuals, when does blood redistrubute begin
blood redistribution begins in the anticipatory period just prior to exercise
what causes blood to route to active muscles from areas that temporailry tolerate compromised blood flow
hormonal vascular regulation and local metabolic condiations
hormonal vascular regulation and local metabolic conditions cause blood to do what
to route to active muscles away from areas that temporailiy ttolerate compromised blood flow
blood redistribution among specfiic tisses occurs primarily during what
high intensity exercise
true or false: heart and brain tissue can tolerate a compromised blood supply
false
during redistribution, does blood even get redirected away from heart or brain
no , they cannot tolertate reduced blood flow
at rest, the myocardium uses what percentage of oxygen in the blood flowingn through coronary circulation
75%
what does it mean that tthe myocardium uses 75% of the oxygen
no backup, therefore if metabolic needs increase, you must increase blood flow sincne you are already taking up oxygen
durinng exercise, coronary circulation has what icnrease
4-5 fold icnrease
does cerebral blood flow ixnrease or decreaes during exercise
it icnrease (25-30% compared tp rest)
true or false: blood flow to heartt and brain decrease during exercise
false, it cannot tolerate that
what does an increase in max cardiac output produce
produces a proportionate increase in capacity to circulate oxygen and profoundly impacts an individual’s maximal oxygen consumption
what is the VO2 formulat
VO2 = CO x av VO2 diff
A low maximal oxygen consumption corresponds closely with whta
with a low maximum cardiac output
for every 1 L increase in o2 consumption aboce resting value, you get an icnrease or decrase in blood flow
5 to 6 L increase in blood flow
true or false: depending on the exercise mode, that will affect the oxugen consumption to blood flow relationship?
no
what provide distinguishing characteristics for preadolescent and adult endurance athletes
High levels of maximal oxygen consumption and cardiac output
An almost proportionate increase in maximum cardiac output accompanies what
increases in V·O2max with endurance training
how can you reach increase levels of oxygen consumpton
icnrease CO
true or false: Cardiac output and oxygen consumption remain linearly related during graded exercise for boys and girls and men and women
true
true or false and why Teenage and adult females exercise at any level of submaximal oxygen consumption with a 5-10% larger cardiac output than males
true due to a 10% lower hemoglobin concentration
do the higher heart rates in children during submaximal exrcise compensate for a smaller decreased volume
no
since kids have a smaller SV, they compensate with their HR
false cannot therefore they have a smaller cardiac output
since kids have a smaller SV and therefore a decrase CO what expands to meet the oxygen requirements
the a-VO@ difference expands
during rest what is the VO2 difference
5 ml of oxygen per dl of blood perfusing the tissue capilarry bed
during rest, we use alot of oxygen
false, we keep 75% of origial oxygen load bound to hemoglobinn
where is 75% of the bloods origian oxygen load remai nbound to
hemoglobin
why is there 75% of oxygen that remain in circulation at rest
because it keeps it as a back up incase you need to increase oxygen consumption nwithout icnrease CO
During maximum exercise, what does hemoglobin do
releases a considerable quantity of its “reserve” oxygen from blood that perfuses active tissues
What are the two factors tht increse oxygen consumption durinf exedtckse
increased CO
expanded vo2 diff
The progressive expansion of the a-vO2 difference results from what
a reduced venous oxygen content
why dies The capacity of each deciliter of arterial blood to carry oxygen increases during exercise
from an increase in hemoconcentration
hemoconcentrationn results from what
Hemoconcentration results from the progressive movement of fluid from the plasma to the interstitial space with:
- increased in cap hydrostatic pressure as BP arries
- metabolic byproducts of exercise metabilise that osmotically draw flioe into tissue spaces from plasma
what interacts to increase oxugen extraction in active tissue during exrecise
central and peripheral factors
what are the central and peripheral factors icnrease oxygen extractionn inn active tissues during exrceise
A large portion of the cardiac output is diverted to active tissue
Some tissues temporarily decrease their blood supply to make more oxygen available
Exercise training redirects a greater portion of the central circulation to active muscle
An increase in skeletal muscle microcirculation
An increased capillary-to-fiber ratio
An increase in the size and number of mitochondria
Augmenting aerobic enzyme activity
Local vascular and metabolic improvements within muscle enhance its capacity to produce ATP aerobically
explai nthe factors effecting the execsinng aVO2 difference
.
The highest oxygen consumption during arm exercise averages BLANK lower than leg exercise
20 to 30%
IS MAXIMAL oxygen soncumption lower in arm por leg
leg
why is the oxygen consumption for arms lower
Arm exercise produces BLANK for heart rate and pulmonary ventilation
lower maximal values
WHY ARE There differences between arm and leg vo2
relate to the relatively smaller muscle mass activated in arm exercise
there are higher or lower oxygen consumption during arm exercise at all submaximal power outputs
higher
what are te 2 factors that produce additional oxygen cost at higher intensityies of arm execise
Lower mechanical efficiency in upper-body exercise from the additional cost of static muscle actions that do not contribute to external work
Recruitment of additional musculature to stabilize the torso during arm exercise
Any level of submaximal oxygen consumption or power output with upper-body exercise provides greater BLANK than lower-body exercise
physiologic strain than lower-body exercise
submaximal arm exersices produce higher…
Heart rates, pulmonary ventilations, perceptions of effort, and blood pressure
true or false: submaximal arm exrcised are good for cardiovascular patients
no because it increases bp and HR
why is there an elevated heart rate response durinng sibmaximal arm exrcises
Greater feed-forward stimulation from the brain’s central command to the medullary control center
Increased feedback stimulation to the medulla from peripheral receptors in active tissue
true or false: Exercise prescriptions based on running and bicycling do not apply to arm exercise
true
why can you not predict aerobic capacity for arm exercise based on a test that uses the legs and vice versa
becuase low correlations between vo2 max in arm and leg
what amplifies the specficicity concept
The lack of strong association between the two exercise modes amplifies the specificity concept
