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Ex Phys > Bergdahl - Chapter 15 and 16 > Flashcards

Bergdahl - Chapter 15 and 16 Flashcards

1
Q

what is the weight of the heart ?

A

300 g for male

250 g for female

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2
Q

what is the main purpose of the heart ?

A

provides the drive for blood flow

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3
Q

what is the volume the heart pumps for each beat ?

A

70 mL/ beat

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4
Q

what is the heart muscle called ? how does it look ?

A

myocardium

its fibers interconnect in latticework fashion to allow the heart to function as a unit (intercalated disc)

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5
Q

what is the main purpose of the right side of the heart

A

receive blood returning from throughout the body

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6
Q

what is the main purpose of the left side of the heart

A

receive oxygenated blood from the lungs

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7
Q

what are the two atrioventricular vales ?

A
  • tricuspid : from right atrium to right ventricle
  • bicuspid (mitral): from left atrium to left ventricle

ONE WAY

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8
Q

what are the semilunar valves ?

A

located in arterial wall just outside the heart, prevent blood from flowing back into the heart between contractions

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9
Q

what is the role of atrial chambers ?

A

they work as primer pumps to receive and store blood during ventricular contraction

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10
Q

describe the gas exchange between arteries and surrounding tissues

A

THERE IS NONE

because of the thickness of the arteries

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11
Q

what do the walls of arterioles contain ? what do they do?

A

smooth muscle cells that constrict or relax to regulate blood flow to the periphery

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12
Q

what creates pressure within the entire arterial system ?

A

the storage of a portion of the blood in the aorta.

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13
Q

what is the formula for BP ?

A

BP= CO x TPR

basically the effect of arterial blood flow / minute and the resistance to that flow

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14
Q

what is systolic blood pressure ? what does it indicate ?

A

estimate of the work of the heart and force that blood exerts against the arterial walls during ventricular systole

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15
Q

what is diastolic blood pressure ? what does it indicate ?

A

the relaxation phase of the cardiac cycle, indicates peripheral resistance or the ease that blood flows from the arterioles into the capillaries

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16
Q

what are the values for normotensive ?

A

SBP

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17
Q

what are the values for prehypertension ?

A

SBP 120-139 mmHg OR DBP 80-89 mmHg

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18
Q

what are the values for stage 1 and 2 hypertension ?

A

stage 1:
SBP > 140 mmHg OR DBP >90 mmHg

stage 2:
SBP > 160 mmHg OR DBP > 100 mmHg

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19
Q

how is cardiac output related to MAP and TPR ? what are the implications of this

A

CO = MAP
______
TPR

resistance decreases dramatically during strenous physical activity. MAP increases (SBP increases considerably), and CO therefore increases

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20
Q

what is mean arterial pressure ? how much is it ? how do you calculate it ?

A

average force exerted by blood against the arterial walls during a cardiac cycle
90 mmHg at rest

MAP = DBP + 1/3 (SBP-DBP)

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21
Q

capillaries hold what percentage of blood volume ?

A

6%

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22
Q

what is the role of the precapillary sphincter ? (and what is it?)

A

it’s a ring of smooth muscle that encircles the vessel and controls capillary diameter
controls blood flow to meet metabolic requirements

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23
Q

what are the two factors that trigger the relaxation of precapillary sphincters ?

A

1) driving force of increased local blood pressure and intrinsic neural control (P1-P2)
2) local metabolites produced in exercise (R)

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24
Q

what is the formula for regulation of blood flow ?

A

flow = (P1-P2) / R

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25
Q

what is the difference between venous and mixed-venous blood ?

A

venous (a-v)
mixed (a- v) avec barre

mixed comes from all of the veins in the body that go into RA and that enters right atrium

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26
Q

what ensures that blood only flow in one direction towards the heart in venous return ?

A

valves within the vains

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27
Q

minor changes where will readily compress the veins ?

A

small muscular contractions or minor pressure changes in the thoracic cavity will readily compress the veins

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28
Q

what would happen without venous valves ?

A

blood would stagnate in veins of the extremities and people would faint because of reduced venous return and cerebral blood flow

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29
Q

what are varicose veins ? where are they usually found ?

A

conditions in which the valves within vein fail to maintain one-way blood flow and blood gathers in them so they become distended and painful

usually in surface veins of lower extremities

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30
Q

what are exercise recommendations for varicose veins ?

A

no static, straining-type exercises that accompany resistance training

regular exercise does not prevent varicose veins but can minimize complications because repeated muscle action can propel blood toward the heart

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31
Q

why is straining exercise so bad for people with heart and vascular disease ?

A

the muscle and ventilatory pumps provide little venous return. this compresses the peripheral arterial vessels supplying the active muscles. there is an acute cardiovascular strain due to the increase in SNS, CO, and MAP

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32
Q

what populations is hypertension more prevalent in

A
  • black
  • men
  • older people
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33
Q

what exercise will make them have the highest BP ?

A

leg press with heavy load.

lying down will increase EDV so more blood will return to heart

34
Q

what happens to the cardiovascular system during rhythmic steady rate muscular activity (jogging, swimming) ? (TPR, BP)

A

vasodilation in active muscles
reduces TPR to enhance blood flow
increase SBP

as activity continues, SBP will decrease due to continued vasodilation and reduction of resistance to blood flow

DBP remains unchanged

35
Q

what happens to SBP, DBP, TPR in graded exercise tests?

A

TPR is reduced to enhance blood flow

SBP: rapid rise and then increase linearly with exercise intensity. can go up to 200 mmHg or higher, probably due to large CO in some athletes

DBP: remains stable or decreases slightly at the higher exercise levels

36
Q

how does blood pressure in upper body exercise compare to blood pressure in lower body

A

exercise with the arms produces higher SBP and DBP than leg exercise performed at a given VO2 max

this is because the smaller arm muscle mass and vasculature offer greater resistance to blood flow than the larger leg mass and blood supply

therefore individuals with cardiovascular problems should exercise large muscle groups in contrast to exercise that engages a limited muscle mass.

37
Q

how does blood pressure look in recovery ?

A

temporarily falls below pre-exercise levels due to a peripheral vasodilation
hypotensive response that can last up to 12 hours

38
Q

what is the blood supply of the heart ?

A

the coronary circulation

39
Q

what are the vessels in the coronary circulation ?

A

right and left coronary arteries (most go into left artery- LA- LV- RV)

for return: blood goes through anterior cardiac veins and leaves through coronary sinus and RV

40
Q

what is the normal blood flow to myocardium at rest ?

A

200-250 mL/ min

41
Q

at rest, how much of the oxygen does the myocardium extract from the blood in the coronary vessels ?

A

70-80%

42
Q

what is the sole mechanism to increase myocardial oxygen supply ?

A

a proportionate increase in coronary blood flow in exercise

43
Q

why would coronary blood flow increase in exercise ? (2 reasons)

A

1) elevated myocardial metabolism dilates the coronary vessels
2) increased aortic pressure during exercise which forces a greater volume of blood into the coronary circulation

44
Q

does the myocardium depend on oxygen supply ? can it function without ?

A

it needs an adequate oxygen supply since it has limited anerobic capacity.

45
Q

how does tissue hypoxia stimulate myocardial blood flow ?

A

is a potent stimulus and can produce chest pains, or angina

46
Q

how can we effectively evaluate the adequacy of myocardial blood flow ?

A

in exercise

47
Q

where is the greatest mitochondrial concentration of all tissues found ?

A

the myocardium

48
Q

what provides energy for myocardial functioning ?

A

glucose, fatty acids, lactate

49
Q

at rest, where does most of the energy come from to the myocardium ?

A

FFA breakdown

50
Q

following a meal, where does the myocardium get most of its energy ?

A

glucose

51
Q

during intense exercise, where does the myocardium get most of its energy ?

A

oxidizing lactate

52
Q

what is the inherent rhythmicity of cardiac muscle ?

A

100 bpm

53
Q

what is the time delay between SA and AV node ? what for ?

A

0.10 seconds

this allows atria to contract and propel blood into the ventricles below

54
Q

what is the transmission path of the cardiac impulse like ?

A

SA- Atria- AV- Purkinje- Ventricles

55
Q

what does the ECG represent ?

A

a composite record of the heart’s electrical events during a cardiac cycle

56
Q

how does the heart function as two separate pumps ?

A

one pump receives blood from the body and pumps it into the lungs
the other pump receives oxygenated blood and pumps it throughout the systemic circulation

57
Q

what is the intrinsic regulation of the heart rate ?

A

the SA node

58
Q

what is the extrinsic regulation of the heart rate ?

A

input from the brain- SNS and PNS

59
Q

what exactly does extrinsic control do in terms of changing HR ?

A

nerves directly supply the myocardium and chemical messengers. accelerate the heart in anticipation before exercise begins, and rapidly adjust to the intensity of physical effort

60
Q

where is the cardiovascular control center found ? where does the input come from ? what does the output do ?

A

in the ventrolateral medulla
brain and peripheral NS constantly bombards it
in response, the center regulates heart output and blood’s preferential distribution to all the body’s tissues

61
Q

can the inherent rhythm of the myocardium be overriden ? by what ?

A

YES

by extrinsic neural influences that come from SNS and PNS

62
Q

how are SNS and PNS fibers distributed in heart

A

SNS and PNS in atria of heart

SNS in ventricles

63
Q

what happens if you stimulate cardioaccelerator nerves ?

A

release of catecholamines (NE, E)

64
Q

what does sympathetic stimulation do to blood vessels ?

A

vasoconstriction, except in coronary arteries

65
Q

what is the chronotropic effect of catecholamines ?

A

accelerate SA node depolarization, meaning the heart beats faster (tachychardia)

66
Q

what is the inotropic effect of catecholamines ?

A

increase myocardial contractility

67
Q

what molecule do parasympathetic axons release ?

A

ach

68
Q

what does ach do to the heart ?

A

it retards the rate of sinus discharge and slows the HR (bradychardia)

69
Q

stimulation of what nerves result in bradychardia ?

A

the 2 vagus nerves that originate in the medulla’s cardioinhibitory center

70
Q

is PNS excitatory or inhibitory ?

A

both

71
Q

what effect does vagal stimulation have on myocardial contractility ?

A

none.

72
Q

at the start of and during low/moderate intensity effort, HR increases through what mechanism ?

A

inhibition of parasympathetic fibers.

73
Q

in strenuous exercise, HR increases through what mechanism ?

A

additional PS inhibition and direct activation of sympathetic fibers

74
Q

what continually modulates medullary activity ?

A

impulses originating in the brain’s higher somatomotor central command center

75
Q

what provides the greatest control over the heart rate during exercise ?

A

central command

76
Q

when is central command operating >

A

during exercise but also in the anticipatory period

77
Q

what does neural input from central command coordinate ?

A

the rapid adjustment of the heart and blood vessels to maximize tissue perfusion and to maintain central BP

78
Q

cardiovascular center receives peripheral input from where?

A

blood vessels
joints
muscles

79
Q

what do peripheral receptors do to monitor the heart ?

A

modify PS or SNS outflow to bring about appropriate cardiovascular and respiratory responses to various states of physical activity

80
Q

what are the three mechanisms that peripherally continuously assess the nature and intensity of exercise and the mass of muscle activated ?

A

1) reflex neural input from mechanical deformation of type III afferents within active muscles
2) chemical stimulation of type IV afferents within active muscles (more rapid feedback)
3) feed-forward outflow from motor areas of central command

81
Q

what are the different peripheral receptors that provide feedback to CNS to regulate blood flow and BP ? what do they do ?

A
  • pressure-sensitive baroreceptors
  • cardiopulmonary mechanoreceptors assess mechanical activity in LV, RA, and large veins

negative feedback controllers to

  • inhibit sympathetic outflow from cardiovascular center
  • blunt inordinate rise in arterial BP

Ex Phys (13 decks)

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