Integration of Cardiac Function Flashcards

1
Q

what receptors are used for sympathetic and parasympathetic effects upon the heart and what are their second messengers?

A

SNS- beta1 adrenergic receptors (increase cAMP)

PNS- M 2 muscarinic receptors (decrease cAMP)

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2
Q

what are the two intrinsic mechanisms or regulating cardiac output?

A

starlings law- increased volume=increased contractility

membrane potentials and therefore ionic concentrations

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3
Q

what are the extrinsic mechanisms of regulation of cardiac output?

A

neuronal and hormonal signaling

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4
Q

why is the cardiac output the same into the aorta and into the pulmonary artery?

A

because the two circuits are in series

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5
Q

graphically what is the difference between cardiac output and oxygen consumption?

A

linear

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6
Q

what eight factors increase cardiac output?

A

fever, exercise, anxiety, body weight, pregnancy, hyperthyroidism, chronic anemia and hypoxia

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7
Q

what five factors decrease cardiac output?

A

sleep, aging, severe anoxia, acute hemorrhage and heart disease

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8
Q

what is histotoxic hypoxia?

A

tissue poisoning that causes the tissues to be less able to use oxygen

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9
Q

why does cardiac output have varying responses to hypoxia and severe anoxia?

A

because severe anoxial causes oxygen deprivation in the heart and decreases cardiac output

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10
Q

what is the effect of hypertension on cardiac output?

A

it is unaltered

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11
Q

what are the only two ways to produce a different steady state match of CO?

A

changing the cardiac function curve or the vascular function curve

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12
Q

during exercise what happens to the body’s vasculature and what is the overall effect?

A

there is arteriolar and venous vasoconstriction. the overall effect is functionally increasing venous return by the venous constriction

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13
Q

how does muscle contraction promote venous return?

A

by pumping venous blood past valves towards the heart

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14
Q

why is there an overall decrease in peripheral resistance to blood flow during exercise?

A

because local hypoxia, hypercapnea and acidemia promote vasodilation and prevent MAP from increasing too much

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15
Q

what happens to the mean systemic filling pressure during an increase and a decrease in sympathetic stimulation?

A

increase- increase in MSFP and decrease with a decrease in sympathetic stimulation

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16
Q

what happens to cardiac output and venous return during exercise? does a difference in central venous pressure cause this?

A

both increase, however here is not an increase in CVP

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17
Q

what does depolarization and repolarization look like on an EKG?

A

depolarization is a bump on the graph in the positive y axis while repolarization is a bump in the negative region of the graph

18
Q

what does the P wave of the electrocardiogram correspond to?

A

atrial depolarization

19
Q

what does the QRS complex correspond to in the EKG?

A

ventricular depolarization

20
Q

what does the T wave in the EKG correspond to?

A

ventricular repolarization

21
Q

why is the T wave of the EKG inverted?

A

because the ventricles repolarize from the epicardium towards the endocardium (opposite of depolarization)

22
Q

why can’t atrial repolarization be seen in EKG?

A

because it is obscured by ventricular depolarization

23
Q

what depolarizations occur during the PR interval?

A

the SA node, atria, AV node, the His bundle, the bundle branches and the purkinji fibers

24
Q

why do the depolarization of the AV node, AV bundle, bundle branches and Purkinje fibers not appear on the EKG?

A

because they do not generate voltages large enough to be detected

25
Q

what does the ST segment correspond to in the action potential of the ventricular myocardium?

A

the plateau phase

26
Q

what is produced by the upstroke of all of the ventricular action potentials?

A

the QRS complex

27
Q

what segments are contained in ventricular diastole?

A

the TP segment and the PR interval

28
Q

when does most ventricular filling occur? how does this correspond to atrial contraction?

A

ventricular filling occurs mostly in early diastole and atrial contraction occurs at the end of ventricular diastole

29
Q

what does atrial contraction contribute to preload?

A

produces only a small rise in ventricular volume and pressure (both sides of the heart)

30
Q

when does atrial diastole occur and what happens to the atrial pressure during this time?

A

it occurs during ventricular diastole and the atrial pressure increases

31
Q

why is there a fall in ventricular pressure even after the mitral and tricuspid valves open?

A

because the forward momentum of blood into the ventricle expands them and drops the pressure simultaneously

32
Q

how does blood flow into the aorta continue during systole even though there are times when aortic pressure is greater than ventricular pressure?

A

because the forward momentum continues the flow even though there is a deceleration of flow until it stops and closes the aortic valve

33
Q

what is the relationship of the P wave and atrial contraction?

A

the P wave precedes atrial contraction

34
Q

what happens to flow at the dichrotic notch?

A

the decrease of the pressure gradient causes the reversal of flow

35
Q

what does the R wave coincide with?

A

the onset of ventricular contraction

36
Q

how many sounds are produced by the heart? which ones can be heard with a stethoscope?

A

4

closure of the AV valves and closure of the semilunar valves

37
Q

when does the T wave occur with respect to blood flow?

A

during the second half of the ejection phase

38
Q

what six factors affect stroke volume?

A

atrial filling pressure, ventricular filling time, ventricular compliance, heart rate (increase causes a decrease in diastole time), preload and afterload

39
Q

what is the timing of the right and left atria? the ventricles?

A

the right atrium contracts prior to the left atrium

the left ventricle contracts prior to the right

40
Q

how does the amount of time that the pulmonary valve is open compare to the aortic valve?

A

the aortic valve is open for less time even though the left ventricle contracts earlier because there is an increased time of isovolumetric contraction because aortic pressure is higher

41
Q

what two sounds are not normally heard in adults?

A

ventricular diastolic filling and atrial contraction