Acute exercise response

Question 1

cardiac output

Answer 1

amount of blood pumped by the heart during a 1-minute period
Q= SV x HR

Question 2

cardiac output at rest

Answer 2

values vary depending upon emotional state

at rest regardless of training state
average male = 5L min-1
average female 4L min-1

Question 3

measuring cardiac output

Answer 3

direct fick method
VO2 / a-VO2 diff x 100

Question 4

a person consumes 250ml O2 and the a-VO2 difference is 5ml per 100ml blood. What is Q?

Answer 4

5000ml blood

would be a resting value

Q will increase with increasing demand of the system

Question 5

steady state exercise

Answer 5

when the energy expenditure provided for exercise is balanced with the energy required (plateau reached)

Question 6

exercise intensity

Answer 6

oxygen uptake (L/min), %VO2max, %HR max (%220-age)
cardiac output- most important factor for increasing oxygen consumption during exercise

Question 7

Max HR equation revisited

Answer 7

220-age may need to be reconsidered
overestimate in younger than 40 yrs
underestimate in over 40 yr olds

suggest : HRmax= 206.9- (.67 x age)

both are still estimates !

Question 8

heart rate
anticipatory response

Answer 8

pre exercise HR is often greater than resting HR
-release of norepinephrine (catecholamine) sympathetic nervous system

-decreases in vagal tone (refers to parasympathetic system, means a withdrawl in the parasympathetic system) = (increase HR)

parasympathetic withdrawal

Question 9

heart rate
at onset of exercise

Answer 9

HR increases rapidly in proportion to exercise intensity
-plateaus/hits steady if exercise intensity is stable

Question 10

steady state HR

Answer 10

optimal heart rate for meeting circulatory demands at a specific work rate

-indicates heart efficiency
-fitness level
- lower HR at a given submit indicates better fitness, heart is not having to work as hard to do the same amount of work

Question 11

what is the equation for Q

Answer 11

HR x SV

Question 12

true or false
the resting heart rate (RHR) of an average person is 60-80 bpm

Answer 12

true

Question 13

true or false
the resting SV of an average person is 60-80ml

Answer 13

true

Question 14

true or false
Q at rest is 6-8 L/min

Answer 14

false

Question 15

if Q is relatively no different between trained and untrained at rest, but trained individuals have a lower RHR, what does that say about SV of trained individuals?

Answer 15

trained individuals have a more stronger and more efficient heart
-it ejects more blood (higher SV)
heart doesn’t have to beat as often

Question 16

stroke volume influenced by (3 primary factors)

Answer 16

-preload (filling, getting stretch)
-force of contraction (influenced by stretch, sympathetic nervous system)
-afterload (resistance to ventricular emptying)

Question 17

preload (definition)

Answer 17

end diastolic pressure

Question 18

stroke volume increases with exercise

Answer 18

increase in LVEDV (causes increase in preload) exercise helps venous return back to the heart
-stretches myocardial fibers

frank Starling mechanism (relationship between contractile force and resting length of myocardial fibers)

increased contractility via sympathetic nervous system

Question 19

stroke volume
increase contractile force = increase ejection fraction

Answer 19

-some good always remains in the left ventricle after systole (residual volume) but a greater fraction will be ejected during exercise vs. rest

Question 20

SV almost doubles from rest to maximal exercise
60ml at rest, increases to approx 100-120ml and then plateaus
why would it plateau

Answer 20

the heart can only hold so much
the left ventricle can only stretch so much

Question 21

untrained characteristics of Q

Answer 21

HR 70bpm
SV 71.4 ml
average female 25% lower due to smaller size

Question 22

endurance athletes
characteristics of Q
and
mechanisms

Answer 22

HR = 50 bpm
SV = 100 ml
mechanisms
-increased vial tone w/decreased sympathetic drive
-increased blood volume
-increased myocardial contractility and compliance of left ventricle

Question 23

cardiac output during exercise

Answer 23

-Q increases rapidly during transition from rest to exercise
-Qat max exercise increases up to 4 times

Question 24

cardiac output and MAP

Answer 24

Q increases during the initial stage of exercise as the result of an increase in HR and SV

Q increases to match the need for increases oxygen supply in working muscles

increased q results in an increased SBP
DBP does not change

Question 25

blood pH and exercise blood pH decreases with exercise of moderate to high intensity (________)

Answer 25

becomes more acidic resting arterial blood pH 7.0= neutral -body will always try to maintain neutral pH as exercise progresses pH continues to drop due to build up of H+ and lactic acid

Question 26

exercise = loss of blood plasma

Answer 26

first due to fluid shifts then due to sweating increase hematocrit blood plasma is 90% water

Question 27

things that affect TPR

Answer 27

viscosity, diameter, length

Question 28

three things that affect SV

Answer 28

preload afterload contractility

Question 29

CV responses to sub maximal exercise

Answer 29

-Q increase and levels out as steady states (metabolic requirements of exercise are met) -HR increase until a steady state is reached (sympathetic nervous system act) -SV increase (follows Q), DBP no change, MAP increase slightly (MAP follows SBP, but more, determined by DBP) -RPP increases until steady state -TPR decrease why because Q is rising significantly

Question 30

A-V O2 difference at rest =6 ml of O2

Answer 30

-20ml of O2 per 100ml of blood in arteries -14ml of O2 per 100 ml of blood remaining in veins increases progressively with exercise - more oxygen is needed so more is extracted 2-4 ml of O2 per 100 ml blood remains in veins during exercise

Question 31

factors affecting the a-VO2 differences

Answer 31

-redistribution of flow to active tissues during exercise -increased capillary density due to training, increases surface area and O2 extraction -increased number and size of mitochondria -increased oxidative enzymes -vascualr and metabolic improvements

Question 32

at max (this much oxygen is taken in)

Answer 32

6:1 ratio Q: VO2

Question 33

blood pH -arterial blood pH at rest ranges from 6.9-7.5 -as exercise intensity increases above 50% of VO2max pH starts to decrease decrease is gradual at first results from increase reliance on anaerobic metabolism and increased _______-

Answer 33

lactic acid (exercise intensity)

Question 34

changes in plasma volume

Answer 34

during moderate exercise, plasma volume decreases, but decrease is greatest in the first 5 minutes of exercise

Question 35

fluid shifts rather than fluid loss in the main reason (for changes in plasma volume)

Answer 35

vascular compartments (vessel) to interstitial space -with prolonged exercise, blood volume is reduced by loss of water through sweating

Question 36

cardiovascular drift

Answer 36

with prolonged steady state exercise, blood volume decreases due to fluid shift and redistribution of blood to periphery for cooling-decreasing venous return -decreases stroke volume (due to decreased venous return) -increases heart rate *Stroke volume goes down causing heart rate to go up

Question 37

cardiovascular drift is characterized by

Answer 37

an increase in HR without an increase in exercise intensity

Question 38

cardiovascular drift results from

Answer 38

dehydration reduction in SV HR drifts upward to maintain the same Q -HR must compensate for decreasing SV to maintain cardiac output Q= HR x SV

Question 39

upper body exercise -lower stroke volume and higher heart rate than lower body exercise (greater physiological strain) -_________ sympathetic input ( increased Hr) -______ venous return -recruitment of more _______ to stabilize

Answer 39

increased lower torso muscles

Question 40

SBP DBP TPR and RPP are higher in _________ exercise

Answer 40

upper bosy -BP change due in part by sympathetic stimulation -static nature of upper body exercises VO2 max is 20-30% lower in upper-body exercise -smaller muscle mass of upper body