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WEEK 7 Flashcards

1
Q

what is the primary function of the cardiovascular system?

A
  • to deliver blood to the tissues
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2
Q

describe the two pumps found in the heart

A
  1. right heart pumps blood to the lungs (pulmonary circulation)
  2. left heart pumps blood through the systemic circulation (rest of the body)
    * each “heart” is a two chambers pump
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3
Q

what do the arteries of the heart do? Verses veins?

A
  • carry blood away from the heart to the rest of the body
  • veins carry blood back to the heart
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4
Q

what three major arteries branch off the trunk of the arch of the aorta?

A
  • brachiocephalic trunk
  • left common carotid artery
  • left subclavian artery
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5
Q

what does the superior vena cava do? and the inferior vena cava?

A
  • superior vena cava: returns blood from the head and upper extremities, and enters into right atrium
  • inferior vena cava: returns blood from the rest of the body to the right atrium
    they deliver deoxygenated blood from the body to the heart
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6
Q

Fill in:
pulmonary veins deliver _____ blood blood back to the _____ atrium

A

oxygenated ; left

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7
Q

What do inflow valves do? out-flow valves?

A
  • inflow valves push blood from the atria to the ventricle
  • outflow valves push blood from the ventricles to the blood vessels
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8
Q

what are the inflow and outflow valves in the heart?

A

In-flow valves: Tricuspid and Bicuspid (mitral) valves
- tricuspid valve regulates blood from the right atrium to the right ventricle
- bicuspid valve regulates blood from left atrium to the left ventricle by bicuspid valve

out-flow valves: Pulmonary and aortic valves
- pulmonary trunk communicates with right ventricle via pulmonary valve
- left ventricle communicates with ascending aorta via aortic valve

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9
Q

what does the papillary muscle do?

A

-the papillary muscle anchors the valve leaflets (chord tendineae) in place
-the chordae tendineae attach to the papillary muscle

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10
Q

Fill in:
the cardiac conduction system generates _______ electrical impulses and thus initiates its ________ contraction of heart muscle

A

rhythmic; rhythmic

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11
Q

True or false
the cardiac conduction system rapidly conducts electrical impulses throughout the heart in an unorganized way

A

False. the electrical impulses are conducted in an organized way

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12
Q

what does the cardiac conduction system include?

A
  1. sinoatrial node (or SA node); this is the pacemaker for the heart
  2. Atrioventricular node (AV node) ; internal pathways conduct the impulses from the SA to here
  3. The Bundle of His; this exits the AV node. As it travels through the septum of the heart it branches as it heads to the apex of the heart; it splits into the right and left bundle branch
  4. Purkinje fibers
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13
Q

Fill in.

Conduction velocity is ____ _________ throughout the conduction system of the heart

A

not ; uniform

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14
Q

Where does action potential in the heart start?

A

the SA node

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15
Q

What is the rate that SA nodal impulses occur regularly?

A

60-100 impulses per minute

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16
Q

How does activation of the myocardium occur?

A

in a correct sequence with the correct timing and delays.
Action potential beings in the SA node > Atria > AV node (this is where conduction slows and allows the ventricle time to fill)

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17
Q

what is the conduction velocity of the atria? AV node? ventricle?

A

1 m/sec ; 0.01- 0.05 m/sec; 1 m/sec

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18
Q

what component of the conduction system has the slowest conduction velocity?

A

Bundle of His-Purkinje fibers (2-4 m/sec)

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19
Q

How do the SA node action potentials differ from other regions of the heart

A

SA node:
- has a slow depolarization phase (phase 4) b/c of the SLOW opening voltage-gated Na+ channels (funny current)
- SA node action potential is Calcium based rather then potassium based
- SA node gets to threshold slowly b/c of the activation of the Calcium channels is slow (phase 0)
- repolarization phase is due to K+ channels being activated (phase 3)

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20
Q

How do you modify the heart rate in terms of action potential?

A
  • heart rate can be modified by changing how long it takes the depolarization phase to reach threshold
  • if you increase the slope of phase 4, you will get to threshold faster
  • if you decrease the slope of phase 4, you will get to threshold slower
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21
Q

True or False
A. The SA node is normally NOT the pacemaker for the conduction system.
B. All components of the conduction system discharge action potentials spontaneously.

Fill in.
C. All components of the conduction system discharge action potentials spontaneously and at a _____ rate

A

A. False. The SA node is normally the pacemaker for the conduction system

B. True.

C. regular rate

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22
Q

What is the discharge rate for the SA node?

A

70- 80 times per minute

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23
Q

what 4 things impacts SA node function?

A
  1. Increased vagal tone (vagus nerve activity)
  2. cardiovascular disease
  3. infection
  4. drugs (like digitalis, which interrupts the SA nodes ability to pace the heart)
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24
Q

what happens when the SA node function is impacted?

A
  • Another pacemaker will emerge
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25
Q

what are ectopic pacemakers?

A
  • abnormal pacemakers
  • they induce an abnormal electrical pattern and disordered sequence of contraction
  • discharge rate is usually faster than the SA node
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26
Q

Describe Atrial ectopic pacemakers, ectopic pacemakers near the AV node, and ectopic pacemakers in the ventricles

A

Atrial ectopic pacemakers: rate of 60-80 bpm. these are harder to detect because the range is similar, but doesn’t get as high as SA node

ectopic pacemakers near the AV node: rate of 40-60 bpm. slower than SA node

Ventricle ectopic pacemakers: rate of 30-45 bpm

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27
Q

when an ectopic pacemaker is trying to emerge, what happens if there is an obstruction in the AV node?

A

SA node will place a pacemaker in the ventricles

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28
Q

Blockage of transmission through the conduction system will also, do what?

A

block/interrupt the normal transmission of impulses

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29
Q

The heart rate and force of contraction are modulated by the _____

A

ANS

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30
Q

What is the purpose of rapid ANS regulation of the heart

A
  • match blood output to the perfusion demands of the organism
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31
Q

where do the sympathetic postganglionic axons arise from? what do they form? Where do they terminate?

A
  • from autonomic ganglia along the cervical and thoracic cord
  • these axons form the cardiac nerves that innervate the SA and AV nodes
  • terminate throughout the myocardium
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32
Q

what does sympathetic excitation do in the heart?

A
  • increase heart rate (chronotropy)
  • force of contraction (inotropy)
  • conduction velocity (dromotropy)
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33
Q

Parasympathetic axons are carried within which nerve? This nerve innervates what nodes?

A
  • vagus nerve (CN 10)
  • SA and AV
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34
Q

Strong parasympathetic activation causes what?

A

heart rate decrease (- chronotropy)
20-40 bpm

35
Q

How does the Sympathetic nervous system effect the SA node vs. the parasympathetic nervous system?

A

Sympathetic effect on SA node:
- increased rate of depolarization
- increased heart rate
- increased slope in phase 4, time to threshold decreases; SA node discharges A.P faster

Parasympathetic effect on SA node:
- decreased rate of depolarization
- decreased heart rate
- decreases slope in phase 4, time to threshold increases; SA node discharges A.P slower

36
Q

How does the sympathetic nervous system effect the AV node vs. the parasympathetic nervous system?

A

Sympathetic effect on AV node:
- increased conduction rate

Parasympathetic effect on AV node:
- decreased conduction rate

37
Q

How does the sympathetic nervous system effect the atrial muscle vs. the parasympathetic nervous system?

A

sympathetic effect on atrial muscle:
- increased strength of contraction

parasympathetic effect on atrial muscle:
- no significant effect

38
Q

How does the sympathetic nervous system effect the ventricular muscle vs. the parasympathetic nervous system?

A

sympathetic effect on ventricular muscle:
- increased strength of contraction

parasympathetic effect on ventricular muscle:
- no significant effect

39
Q

What is diastole? What is EDV?

A
  • diastole is filling of the ventricles
  • end diastolic volume (EDV) is volume of blood in ventricles at end of diastole
40
Q

What is systole? what is ESV?

A
  • systole is pumping/ contracting of the ventricles
  • ESV is volume of blood in ventricles at end of systole
41
Q

describe the cardiac cycle

A

Inflow phase (late diastole and atrial systole) PHASE 1:
- blood from systemic and pulmonary veins comes to the right and left atrium
- blood is filling in AV valves so arterial pressure is greater than ventricular pressure
- the AV valves (bi and tricuspid) are open but semilunar valves are closed.
- during late diastole both sets of chambers are relaxed and ventricles fill passively with majority of blood.
- during atrial systole atrial contraction forces a small amount of additional blood into ventricles. this is when the SA node fires, producing depolarization of atria. when atria depolarizes it contracts (P-wave) pushing remaining blood into ventricle

Isovolumetric contraction (isovolumic ventricular contraction) PHASE 2:
- blood is in ventricles now
- atrial pressure < ventricular pressure. AV valves closed “Lub” sound (S1)
- both sets of valves are closed, no blood flow, but volume remains the same.
- first phase of ventricular contraction pushes AV valves closed but does not create enough pressure to open semilunar valves.
- arterial pressure > ventricular pressure
- ventricles continue to contract

Ejection phase (ventricular ejection) PHASE 3:
- pressure in ventricles exceeds arterial pressure. ventricular pressure > arterial pressure
- ventricular pressure > atrial pressure.
- the semilunar valves are open, AV valves are closed.
- blood is ejected

Isovolumetric relaxation PHASE 4:
- blood remains after ejection is ESV
- blood is in arteries, arterial pressure > ventricular pressure
- blood that tries to move back into semilunar valves snaps SLV closed. “dub” sound (S2)
- atrial pressure is zero. atrial pressure < ventricular pressure
- both sets of valves are closed.
- as ventricles relax, pressure in ventricles falls.
- ventricles are depolarizing (t-wave)

  • these events take place on both the right and left sides of the heart
42
Q

the systole includes which phases

A

the contracting phases
- phases 2 (isovolumetric contraction) and 3 (ventricular ejection)

43
Q

the diastole includes which phases

A

when the ventricles are relaxing
- phases 4 and 1

44
Q

when does atrial systole occur?

A

phase 1

45
Q

when does atrial diastole occur?

A

phase 2,3, and 4

46
Q

How do you calculate the duration of the cardiac cycle?

A

duration of cardiac cycle= (60 seconds/minute) / (heart rate)

47
Q

if the cardiac cycle is 0.8 seconds, what is the heart rate?

A

75 bpm

(60 secs/min) / (0.8) = 75 bpm

48
Q

to create a pressure-volume loop, pressure is plotted as the ______ variable and volume is the _______ variable?

A

dependent ; independent

49
Q

what are the metrics for cardiac function?

A
  • Stroke volume (SV)
  • cardiac output (CO)
  • Left ventricular ejection fraction (LVEF)
50
Q

What is stroke volume? (SV)

A
  • the volume of blood pumped out of the left ventricle of the heart during each systolic cardiac contraction
  • the average stroke volume for an adult 70 kg male is 70ml
    SV = EDV - ESV
51
Q

what is cardiac output? (CO)

A
  • the volume of blood the heart pumps through the systemic circulation per minute
  • measured as liters/min
  • calculate CO by multiplying SV by HR (heart rate)
52
Q

what is left ventricular ejection fraction (LVEF)

A
  • a measurement for assessing cardiac dysfunction
  • LVEF is computed by dividing SV by EDV
  • in healthy adults LVEF should be greater than 0.55
53
Q

what are the four determinants of CO?

A

Extrinsic factors:
1. heart rate
2. preload- the degree of myocardial distension prior to shortening. this depends on blood volume being returned to the heart.
3. afterload- the resistance the ventricles must overcome in order to eject blood. largely dependent on arterial blood pressure and vascular tone.

Intrinsic factor:
4. contractility

54
Q

What is cardiac output dependent on?

A

heart rate (directly)
Stroke volume (SV)

55
Q

what does SV depend on?

A

contractility
Preload
Afterload

56
Q

what is modulating sympathetic tone?

A

modulates the inotropic (force of contraction) and chronotropic (heart rate) effect of the sympathetic division of the ANS and influence SV and CO

57
Q

True or False.
cardiac output depends on venous return

A

True

58
Q

What is the frank-starling mechanism of the heart

A
  • the ability of the heart to adjust its output, which is measured as stroke volume, to blood returned to the heart (EDV)
  • an intrinsic property of the myocardium
  • as EDV increases, stroke volume increases
59
Q

what shifts the frank-staring curves up and to the left?

A

increased contractility, which is caused by increased sympathetic nerve innervation

60
Q

Why does cardiac output at a high heart rate (200 bpm) decrease ?

A

At a high heart rate, or rapid HR, the ventricles do not have enough time to fill properly leading to a decrease in Cardiac output

61
Q
  1. Heart rate determines the _______ _______ time. therefore ________ _______ time determines ____ _____ volume. ________ then determines _______ _______.
  2. As a result ________ determines Cardiac output
A
  1. diastolic filling time; Diastolic filling; end diastolic volume ; EDV; Stroke volume (SV)
  2. SV
62
Q

what do the ventricular function curves do? what are they based on

A

-they express the ability of ventricles to pump blood
- they are based on the Frank-Starling relationship

63
Q

Fill in.
As atrial pressure increases, stroke work output ________ until it _____

A

increases ; plateaus

meaning if you have a higher atrial pressure you’ll have a higher stroke work output

64
Q

Fill in.
As right atrial pressure increases, ventricular output ______

A

increases

65
Q

when you reduce contractility you reduce ______

A

EDV, SV and thus output

66
Q

right atrial pressure is related to _________ , _________ , and __________

A

venous return; end-diastolic volume ; end-diastolic fiber length

67
Q

Fill in.

Cardiac output is increased with increased _______ ___. This specifically includes increased ________ and increased ________

A

Sympathetic tone; heart rate ; contractility

68
Q

cardiac output is reduced by increased _________ _____

A

parasympathetic (vagal) tone

  • increased vagus nerve activity slows the heart
69
Q

True or false.
Strong parasympathetic activation can stop the heart.

A

True. There will be a brief/temporary stop in the heart, but sympathetic pathways will restart it

70
Q

True or False.
A reduction in contractility does not cause a reduction in cardiac output

A

False.

Reducing contractility does reduce cardiac output

71
Q

Why is right atrial pressure a point of measure for cardiac output in regards to ventricular function

A

Right atrial pressure is point of measure for cardiac output in regards to ventricular output because that is where blood from the superior and inferior vena cava goes too.

72
Q

what are considered adrenergic agonists? what do they do in regards to the heart? what type of receptors do they act on?

A
  • catecholamines: epinephrine, norepinephrine
  • they increase force of contraction, thus increase HR contractility, and SV. This increases CO
  • they act on B1 adrenoreceptors, cAMP, L-type channels
73
Q

Fill in. What is the effect of these drugs and conditions?

  1. Adrenergic agonists cause _______
  2. Cardiac Glycosides cause ________
  3. High extracellular Calcium concentration causes _________ and why?
  4. Calcium channel blockers causes _________ and why?
  5. Low extracellular calcium causes __________ and why?
  6. High extracellular sodium causes __________ and why?
A
  1. positive inotropic effect
  2. Positive inotropic effect
  3. positive inotropic effect; the driving force is increased so intracellular calcium will increase causing an increase in contraction
  4. Negative inotropic effect; decrease intracellular calcium by inhibiting L-type calcium channels, thus decreasing contractions
  5. Negative inotropic effect ; decreases driving force so calcium levels inside decreases, reducing contractions
  6. Negative inotropic effect; this increases the driving force Na+ causing more Calcium to be pumped out through the Na-Ca exchanger, thus lowing intracellular calcium and contractions
74
Q

what are examples of calcium channel blockers?

A
  • verapamil, diltiazem, nifedipine they all inhibit L-type calcium channels
75
Q

what are cardiac glycosides? what do they do?

A
  • example of cardiac glycosides are digitalis
  • they inhibit the Na-K pump on the plasma membrane, thus reducing the sodium gradient needed for the Na-Ca exchanger
  • intracellular calcium increases, longer activation of TnC, longer time for cross-bridge cycles to occur and, thus contraction increases.
76
Q

Fill in.

Increasing blood volume will ________ venous return. This will increase ________, which will increase _______. Therefore, cardiac output will _________. Overall _______ _______ will increase

A

increase ; EDV ; SV ; increase ; blood pressure

77
Q

Fill in.
The depolarization of cardiac muscle is due to the rapid ______ of voltage gated _____ channels

A

opening ; sodium

78
Q

The plateau in the action potential of cardiac muscle is due to the _______ of voltage-gated ______ channels and the closing of some _______ channels

A

opening ; calcium ; potassium

79
Q

phase 3 or ________ is due to the ________ of voltage gated ________ channels and __________ of _________ channels

A

repolarization; opening ; potassium ; closing ; calcium

80
Q

what is different about the left and right side of a wiggers diagram

A
  • the right side of the heart operates at lower pressure, but the same thing is happening on both sides
81
Q

When you increase contractility, you increase ______ which increases stroke volume

A

EDV

82
Q

what are considered adrenergic agonists? what do they do in regards to the heart? what type of receptors do they act on?

A
  • catecholamines: epinephrine, norepinephrine
  • they increase force of contraction, thus increase HR contractility, and SV. This increases CO
  • they act on B1 adrenoreceptors, cAMP, L-type channels
83
Q

what are cardiac glycosides? what do they do?

A
  • example of cardiac glycosides are digitalis
  • they inhibit the Na-K pump on the plasma membrane, thus reducing the sodium gradient needed for the Na-Ca exchanger
  • intracellular calcium increases, longer activation of TnC, longer time for cross-bridge cycles to occur and, thus contraction increases.
84
Q

atrial pressure is ______ related to blood returned to the heart which is related to ______ return

A

directly; venous

advanced human physiology (13 decks)

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