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PT 6282: Cardiopulmonary Physiology & Rehabilitation > Cardiac Muscle > Flashcards

Cardiac Muscle Flashcards

1
Q

What are the two types of myocardium cells?

A
  1. Automaticity Cells

2. Contractile Cells

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2
Q

Automaticity cells, which set the pace of the heart, include what?

A
  1. Pacemaker (SA Node)
  2. AV Node
  3. AV bundle of His
  4. Purkinje fibers
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3
Q

Contractile cells, which generate force in the heart, include what?

A
  1. Actin and Myosin
  2. Other contractile proteins
  3. Sarcoplasmic reticulum
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4
Q

Which 4 myocardial cells lack actin and myosin?

Hint: automaticity cells do not have actin/myosin

A
  1. SA node
  2. AV node
  3. Bundle of His
  4. Purkinje fibers

(Hint: automaticity cells do not have actin/myosin)

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5
Q

The 3 major types of cardiac muscle are ____ (contractile), _____ (contractile) and _____ (non-contractile or nodal)

A
  1. atrial
  2. ventricular
  3. excitatory and conductive muscle fibers
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6
Q

What are the 2 similarities of contractile tissue to skeletal muscle?

A
  1. Striated

2. Myofibrils which contain actin and myosin

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7
Q

What are the 3 main differences of contractile tissue to skeletal muscle?

A
  1. Lattice network
  2. Intercalated discs to form “communicating” gap junctions
  3. Syncytium
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8
Q

What is the syncytium?

A

interconnected heart cells; when one becomes excited, the AP spreads to all cells throughout the latticework interconnections

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9
Q

What are the 2 types of syncytium?

A
  1. Atrial

2. Ventricular

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10
Q

The 2 syncytiums are separated by ___ tissue that surround the ___ valvular openings

A

fibrous; AV

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11
Q

Cardiac action potentials last ____x longer in cardiac muscle vs. skeletal muscle because it is _____ms long (much slower than skeletal 2-5ms)

A

15x; 200-300ms

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12
Q

What are the phases of action potentials? (in order)

A

4 = resting membrane potential (-90mv)\

0 = opening of fast V-gated Na+ channels (-70mV)
= opening of slow V-gated Ca2+ channels (-40mV)

1 = closing of V-gated Na+ channels
= opening of V-gated fast K+ channels

2 = slow Ca2+ channels are OPEN (-40mV)
= decreased K+ permeability

3 = Ca2+ channels close
= K+ channels remain open

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13
Q

At what phase of the AP do the V-gated Na+ channels close and the V-gated fast K+ channels open?

A

1

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14
Q

At what phase of AP do the Ca2+ channels close and the K+ channels remain open?

A

3

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15
Q

At what phase of AP is the membrane at resting potential?

A

4

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16
Q

At what phase of AP are the slow Ca2+ channels open and there is decreased K+ permeability?

A

2

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17
Q

What happens at phase 1 of the AP?

A

1 = closing of V-gated Na+ channels

= opening of V-gated fast K+ channels

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18
Q

What happens at phase 2 of the AP?

A

2 = slow Ca2+ channels are OPEN (-40mV)

= decreased K+ permeability

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19
Q

What happens at phase 3 of the AP?

A

3 = Ca2+ channels close

= K+ channels remain open

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20
Q

What happens at phase 4 of the AP?

A

4 = resting membrane potential (-90mv)

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21
Q

At what phase(s) is the membrane potential at -40mV?

A

0 (opening of slow V-gated Ca2+ channels) and 3

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22
Q

At what phase is the membrane potential at -90mV?

A

4

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23
Q

At what phase is the membrane potential at -70mV?

A

0 (specifically the opening of fast V-gated Na+ channels)

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24
Q

At what phase is the membrane potential at +20mV?

A

1

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25
Q

At what phase is the membrane potential at +10mV?

A

2

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26
Q

Excitation-Contraction Coupling is a mechanism by which the action potential causes the _____ of the muscle to ____

A

myofibrils; contract

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27
Q

The AP spreads to the interior of the cardiac muscle fiber along the membranes of what?

A

t-tubules

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28
Q

T-tubules AP act on membranes of the longitudinal ______ tubules to cause release of ___ ions into the sarcoplasm from the SR

A

sarcoplasmic; ca2+

29
Q

Ions diffuse into the myofibril to catalyze reactions for binding of ___ and ___ to produce muscle ___

A

actin; myosin; contraction

30
Q

What is less developed in the cardiac muscle in comparison to skeletal muscle and does not store enough calcium to provide a full contraction?

A

sarcoplasmic reticulum

31
Q

Strength of the cardiac muscle contraction is dependent on the extracellular ____ concentration

A

calcium

32
Q

AP of pacemaker cells include phases ___, ___ and ___

A 
4 = membrane potential (-60mV)
0 = calcium channels open at AP threshold
3 = calcium channels close, potassium channels open
33
Q

At what phase of the pacemaker AP do the calcium channels open?

A

0

34
Q

At what phase of the pacemaker AP do the calcium channels close?

A

3

35
Q

At what phase of the pacemaker AP do the potassium channels open?

A

3

36
Q

At what phase of the pacemaker AP is the resting membrane potential -60mV?

A

4

37
Q

In order for passive filling to occur in the heart, blood collects until ____ drops and ____ open

A

pressure; valves

38
Q

The atria is considered the ____ pump for the ____

A

primer; ventricles

39
Q

80% of blood flows directly through the ____ and into the ___ even before the atria contract (passive process)

A

atria; ventricles

40
Q

Passive filling increasing the ventricular pumping effectiveness by ___%

A

20%

41
Q

Right atrial pressure is ___ than left atrial pressure

A

less

right = 4-6mmHg
left = 7-8mmHg
42
Q

Left ventricular pressure rises above __ mmHg and right ventricular pressure rises above ___ mmHg

A

80; 8

43
Q

When the R/L ventricular pressures rise, the semilunar valves ___ and blood pours into where?

A

open; the aorta and pulmonary arteries

44
Q

The first heart sound is the closure of what?

A

AV valves

45
Q

The second heart sound is the rapid closure of what?

A

semilunar valves

46
Q

In the volume-pressure diagram, phase I is the period of ____, phase II is the ____ contraction, phase III is the period of ____ and phase IV is the period of ____ relaxation

A

filling
isovolumetric contraction
ejection
isovolumetric relaxation

47
Q

The systolic pressure curve shows that _______ filaments of cardiac muscle fibers are pulled far apart and strength of the cardiac fiber contraction becomes what?

A

actin-myosin; less than optimal

48
Q

The diastolic pressure curve shows that ___ tissue in the heart will stretch no more and the ____ becomes filled nearly to its limit

A

fibrous; pericardium

49
Q

Preload is the ____ pressure the the ____ has become filled

A

end-diastolic; ventricle

50
Q

Afterload is the pressure in the ____ leading from the ____

A

aorta; ventricle

51
Q

Increase in ____ will increase stroke volume, while increase in ____ will decrease stroke volume

A

preload; afterload

52
Q

At rest, cardiac output (CO) is ___L/min. During exercise however, CO is ____x this amount

A

4-6L/min; 4-7x

53
Q

There is an intrinsic cardiac regulation of pumping in response to changes in ______ of the blood flowing into the heart from the _____

A

volume; veins

54
Q

Stretch of the ____ wall directly increases the ____ by 10-20%

A

atrial; heart rate

55
Q

As atrial pressure for each side of the heart INCREASES, the ____ work output for that side also increases until it reaches the limit of the ____ pumping ability

A

stroke; ventricle’s

56
Q

The ____ fill in response to higher atrial pressures

A

ventricles

57
Q

Each ventricular volume and strength of the cardiac muscle contraction _____, causing the heart to pump ____ quantities of blood into the arteries

A

increase; increased

58
Q

Sympathetic activation stimulation increases the ____ and increases the force of ____

A

heart rate; contraction

59
Q

Sympathetic activation inhibition ___ heart rate and ___ force of contraction

A

decreases; decreases

60
Q

Parasympathetic activation causes the heart rate to ____ and the force of contraction to ____

A

decrease; decrease

61
Q

Hyperkalemia is an ___ of K+ (potassium) in the blood, muscle ____, _____, ______, arrhythmias, nausea, and can even lead to cardiac ____ and death.

A 
increase
fatigue
weakness
paralysis
arrest
62
Q

Hypokalemia is a ___ of K+ (potassium) in the blood, muscle _____, weakness, ____, paralysis, abnormal _____, low ____, and even ____ failure

A 
decrease
twitches
cramps
heart rhythms 
blood pressure
respiratory
63
Q

High amounts of K+ ion concentration cause the heart rate to _____

A

slow

64
Q

High amounts of K+ ion concentration in large enough quantities can block the conduction of _____ from the atria to the ventricles through the ____ bundle

A

cardiac impulse

AV

65
Q

Hypercalcemia is the increased amount of ____ in the blood which can cause ____ contractions

A

calcium; spastic

66
Q

Hypocalcemia is the decreased amount of _____ in the blood and can cause ____ weakness

A

calcium; cardiac

67
Q

When the body drops to 60-70F, what happens?

A

hypothermia

68
Q

The alterations of which two ions will effect the cardiac pump?

A

potassium and calcium

PT 6282: Cardiopulmonary Physiology & Rehabilitation (14 decks)

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