Ex Phys Exam 2

End Diastolic Volume

volume of blood in the left ventricle after diastole (fully filled)

EDV value at rest

125 mL

End systolic volume

volume of blood left in the left ventricle after systole (a full contraction, will be less than EDV)

ESV value at rest

42 mL

Stroke volume

volume of blood pumped out of the heart in one beat

SV value at rest

82 mL

length of cardiac cycle at rest

0.8 ms

four primary determinants of cardiac output

prelaod

afterload

heart rate

contractility

preload definition

stretch of the myocardium

factors affecting preload (4)

frank starling

q/blood volume/venous tone

filling time/HR

muscle pump/respiratory pump

frank starling mechanism

more stretch = greater contraction

higher EDV = higher SV

cardiac output equation

Q = HR x SV

Q value at rest

5-6 L/min

afterload

resistance the ventricle must overcome to eject blood

endurance exercise increases volume/pressure load

volume

resistance exercise increases volume/pressure load

pressure

valsalva maneuver

forced expiration against a closed glottis

collapses veins, decreased venous return, decreased SV, decreased BP

phase 1 valsalva

brief rise in arterial pressure due to rise in intrathoracic pressure pressing on aorta

no change in HR

phase 2 valsalva

arterial pressure low due to continued strain and compression of veins; lowers venous return

HR increases due to baroreceptors increasing sympathetic tone

phase 3 valsalva

strain released; brief drop in pressure as venous return restored

phase 4 valsalva

arterial pressure returns to baseline and overshoots

sudden return of blood increases preload and SV

HR slows and pressure returns to normal

contractility definition

strength of contraction independent of preload

contractility is affected by

positive inotropes and negative inotropes

positive inotropes

sympathetic stimulation and catacholamines via calcium influx and CICR

negative inotropes

acidosis, hypoxemia, reduced sympathetic drive

systolic pressure

peak pressure during ejection

diastolic pressure

lowest pressure during ventricular filling

pulse pressure

systolic pr - diastolic pr

mean arterial pressure (MAP)

average driving pressure for blood flow in systemic circulation

Cardiovascular drift

during prolonged exercise, HR rises and SV declines while Q is maintained

At higher intensities, SV plateaus or declines but Q is maintained. Why?

continued rise in HR

Cardiovascular endurance training adaptations

lower HR

improved Ca handling and contractility

increases SV

What percent of blood flow can be redistributed to muscle during exercise?

85%

Poiseuille’s law

small changes in vessel radius produce large changes in resistance/flow

3 solutions to central conflict during exercise

large increase in Q

vasoconstriction in inactive vascular beds

rise in blood pressure set point

baroreceptor location

carotid sinus and aortic arch

myogenic response

autoregulation

responds to changes in vascular pressure and stretch to constrict vessels

local in muscle

sympatholysis

autoregulation

overrides vasoconstriction in response to rising metabolite levels

local in muscle

myogenic response

senses changes in stretch and tell the control center to increase sympathetic tone

4 mechanisms that support venous return during exercise

muscle pump

respiratory pump

sympathetic venoconstriction

increased blood volume

how much can endurance training increase blood volume by

300-500 mL in a few days

cardiovascular triage

protects brain and coronary blood flow during exercise

fick equation

VO2 = Q x A-VO2 diff

resting value for AVO2 diff

5.6 vol%

maximal value for AVO2 diff

16 vol%

why does stroke volume plateau while HR rises?

shortened filling time decreases EDV

structural and functional adaptations from endurance training

increased LV mass

increased LV volume

increased blood volume

increased calcium handling

increased stroke volume

why does systolic pressure rise during exercise?

increase in Q

why does diastolic pressure stay the same or decrease during exercise?

decrease in TPR

minute ventilation

volume of air breathed each minute

alveolar ventilation

volume of air participating in gas exchange

dead space ventilation (ADS)

air in the conducting zone not participating in gas exchange

4 factors that contribute to pulmonary gas exchange

tissue area

diffusion coefficient

difference in partial pressure`

tissue thickness

OH Curve

arterial PO2 can fluctuate without large drops in saturation

at lower PO2, there is a larger unloading of O2 to tissues

Bohr effect

hemoglobin’s affinity for oxygen decreases in response to lower pH and higher levels of CO2

enhances oxygen delivery to tissues

what 3 things affect the oxyhemoglobin dissociation curve?

low pH

2,3 DPG concentration

body temperature

three mechanisms of CO2 transport in the blood

carbonic anhydrase-bicarbonate ions

chloride shift

haldane effect

haldane effect

CO2 unloading in the lungs