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A and P II > 18.4-18.6 Cardiac Muscle > Flashcards

18.4-18.6 Cardiac Muscle Flashcards

1
Q

Striated, short, branched, fat, and interconnected
Cardiac muscle cells

A

Cardiomyocytes

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2
Q

Contain numerous large mitochondria, which resist fatigue
One central nucleus
Rest of volume composed of sarcomeres

A

Cardiac muscle cells

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3
Q

Wider, but less numerous in cardiac muscle cells

A

T tubules

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4
Q

Simpler in cardiac muscle rather than in skeletal muscle

A

Sarcoplasmic reticulum

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5
Q

Connecting junctions between cardiac cells

A

Intercalated discs

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6
Q

Allow ions to pass from cell to cell
Electrically couple adjacent cells
Allows heart to be a functional syncytium

A

Gap junctions

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7
Q

Holds cell together
Prevents cells from separating
Velcrow like

A

Desmosomes

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8
Q
  1. Muscle contraction is preceded by depolarizing action potential
  2. Depolarization wave travels down T tubules
  3. Excitation-contraction coupling occurs
A

Similarities between skeletal and cardiac muscles

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9
Q

Cardiac muscle type; Responsible for contraction
Bulk of heart and are responsible for pumping action

A

Contractile cells

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10
Q

Cardiac muscle type; Autorhythmic cells
Non Contractile cells that spontaneously depolarize and initiate depolarization of entire heart
No nervous system support (self-excitable)

A

Pacemaker cells

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11
Q

Network of pacemaker cells; Initiate and distribute impulses to coordinate depolarization and contraction of heart
Electrical events precede mechanical events
5 parts

A

Intrinsic cardiac conduction system

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12
Q

“Pacemaker” of the heart

A

Sinoatrial node (SA node)

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13
Q

Rhythm of the SA node and determines heart rate

A

Sinus rhythm

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14
Q

Device that can detect electrical currents generated by the heart

A

Electrocardiograph

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15
Q

A graphic recording of electrical activity of the heart

A

EKG

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16
Q

Depolarization of SA node and atria
First wave

A

P wave

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17
Q

Ventricular depolarization and atrial repolarization

A

QRS Complex

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18
Q

Ventricular repolarization

A

T wave

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19
Q

Beginning of atrial excitation to beginning of ventricular excitation

A

P-R interval

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20
Q

Entire ventricular myocardium depolarized
Flat line on EKG

A

S-T segment

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21
Q

Beginning of ventricular depolarization through ventricular repolarization

A

Q-T interval

22
Q

Depolarization and repolarization

A

Electrical events

23
Q

Contraction of heart

24
Q

Relaxation of heart

25
Q

Cardiomyocytes in an area contract as a unit

A

Functional syncytium

26
Q

Does cardiac muscle use extracellular Ca2+?

27
Q

True or false. Tetanic (sustained) contractions cannot occur in cardiac muscles

28
Q

True or false. Cardiac muscle relies more on oxygen than skeletal muscle?

A

True - More mitochondria

29
Q

Unstable resting membrane potential in cardiac muscle cells
Never a flat line; upward trend from trough to threshold
Na+ open, K+ close

A

Pacemaker potential

30
Q

Pacemaker potential
Depolarization
Repolarization

A

Cardiac AP

31
Q

Action potential begins when pacemaker potential reaches threhold; Ca2+ influx through channels

A

Depolarization

32
Q

Ca2+ channels inactivating and K+ channels opening
K+ efflux, brining membrane potential back to original voltage

A

Repolarization

33
Q

Where impulses pause in conduction system
Part 2

34
Q

Connects atria to ventricles

35
Q

Irregular heart rhythms

A

Arrhythmias
(Murmurs)

36
Q

Rapid, irregular heart beat
Heart useless for pumping blood

A

Fibrillation

37
Q

Defective AV node
AP “blocked”

A

Heart block

38
Q

Increase rate and force of heartbeat
“Accelerator”
Fight or flight

A

Sympathetic nervous system

39
Q

Slows heart rate down

A

Parasympathetic nervous system

40
Q

Depolarization due to Na+ influx through fast voltage-gated Na+ channels

A

Depolarization of contractile muscle cells

41
Q

Due to Ca2+ influx through slow Ca2+ channels
Keeps cell depolarized because K+ channels are closed

A

Plateau phase of contractile muscle cells

42
Q

Due to Ca2+ inactivating

A

Repolarization of contractile muscle cells

43
Q

True or false. Are action potentials and contraction longer in cardiac muscle?

44
Q

Longer contraction ensures efficient blood ______

45
Q

First stage of cardiac cycle; 80% of blood passively flows from atria through open AV valves into ventricles
AV = open
SL = closed
Fills ventricles with blood

A

Ventricular filling

46
Q

Second stage of cardiac cycle; Atria relax and ventricles contract; Rising ventricular pressure causes closing of AV valves
Blood flows into pulmonary trunk and aorta
AV = closed
SL = open

A

Ventricular systole

47
Q

Following T wave; Ventricles relax and atria fill with blood
AV = open
SL = closed

A

Early diastole
(Isovolumetric relaxation)

48
Q

Volume of blood in each ventricle at end of each ventricular diastole

A

End diastolic volume (EDV)

49
Q

Volume of blood remaining in each ventricle after systole

A

End systolic volume (ESV)

50
Q

cardiac cycle page

A and P II (15 decks)

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