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Physiology Block 6 > Introduction And Electrical Activity Of The Heart > Flashcards

Introduction And Electrical Activity Of The Heart Flashcards

1
Q

How is the heart set up as?

A

2 pump system

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2
Q

What direction does blood flow

A

Unidirectional

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3
Q

Right side of hte heart

A

Pulmonary system

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4
Q

Left side of the heart

A

Systemic system

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5
Q

Where is the biscuit (mitral) valve?

A

Between left atrium and left ventricle

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6
Q

Where is the tricuspid valve

A

Between the right atrium and the right ventricle

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7
Q

Period of contraction, force generation and blood expulsion

A

Systole

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8
Q

Period of relaxation, filling with blood, readying for next systole

A

Diastole

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9
Q

Blood is carried via ________ to capillary beds in organs

A

Arterial system

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10
Q

Blood returns to the heart via ________ system

A

Venous

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11
Q

Blood volume

A

Always constant. Increase in one area causes a loss elsewhere.

Blood shifts from GI tract to the skeletal muscles when you need to run from something

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12
Q

Left A fib wold most greatly affect filling of which other heart chambers?

A

Left ventricle

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13
Q

nodes

A

Highly modified myocytes
No contraction, only APs
Connected to myocytes via gap junctions

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14
Q

How are nodes connected to myocytes

A

Via gap junctions

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15
Q

What are the nodes responsible for?

A

Rhythmic excitation and coordinated contraction of heart muscle

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16
Q

How are nodes controlled?

A

Auto rhythmic but modulated by ANS

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17
Q

What leads to arrhythmia and altered pump functions

A

Dysregulation of nodes

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18
Q

What is the first node to depolarize

A

Sinus node (sinoatrial node)

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19
Q

What is the pacemaker of the heart

A

Sinoatrial node

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20
Q

What does the SA node cause

A

Atrial contraction

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21
Q

What allows the atria to fully contract before ventricles do?

A

The fact that the AV node has a reduced conduction velocity, fewer gap junctions

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22
Q

Which has fewer gap junctions, SA or AV node

A

AV node

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23
Q

Which has slower AP, SA node or AV node?

A

AV node

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24
Q

Where does the AV node carry AP?

A

From atria to ventricles

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25
Q

Where is the SA node (pacemaker)?

A

Right atrium

26
Q

Steps of conduction

A

SA node- Av node - bundle of His - perkinje system - ventricular monocytes

27
Q

What part of node system is super fast (other than SA node)

A

Purkinje system

  • large diameter cells
  • fast AP
  • speeds conduction to ventricular myocytes
28
Q

What allows for maximal blood ejection

A

Coordination of depolarization

29
Q

Flow of depolarization

A

SA nodes-atria depolarizes-septum and inner layer of ventricular muscle depolarizes-ventricles depolarize

30
Q

All of the heart is _____

A

Auto rhythmic

All have different depolarization rates

31
Q

Why is SA node pacemaker?

A

Because it is the fastest

32
Q

Why is the SA node the fastest

A

It fires while the others are still slowly depolarizing

-overdriving suppression

33
Q

Firing rate of SA node

34
Q

Ectopic pacemaker can override SA node if

A

SA node slows
Ectopic is faster
Pathology introduces a conduction block

35
Q

What is the heart innervated by

A

Both the sympathetic and parasympathetic NS

36
Q

What primarily controls the SA/AV nodes?

A

Parasympathetic

37
Q

Heart rate is modulated by

A
  • altering SA node firing rate

- altering conduction through the AV node

38
Q

What Node do we care about the speed?

A

SA node only

39
Q

Anything that effects the heart rate

A

Chronotrope

40
Q

What causes a positive chronotrope?

A

Sympathetic

  • increase HR
  • B1 receptors
  • increase funny channels
  • increase Ca current
41
Q

What causes negative chronotrope

A

Parasympathetic

  • reduce HR
  • M2 receptors
  • decreases funny current
  • decreases Ca current
  • increases K current
42
Q

Something that affects conduction velocity

A

Dromotrope

43
Q

What causes positive dromotrope

A

Sympathetic

  • increases conduction velocity
  • B1 receptors
  • increase Ca current during upstroke
  • shortens ERP
44
Q

What causes negative dromotrope?

A

Parasympathetic

  • slows conduction velocity
  • lengthen AV nodal delay
  • M2 receptors
  • decrease Ca current
  • increase K current
  • lengthens ERP
45
Q

What node is involved with chronotrope

46
Q

What node is involved in dromotropy

47
Q

Measures the electrical activity of the heart over time

A

EKG

X axis big square equals 200 milliseconds

Taxis big square is .5mV

48
Q

Measured changes in voltages on EKG

49
Q

Time periods that include the wave

50
Q

Time periods that do not include the wave

51
Q

What starts the P wave

A

SA node

Atria is small, P wave is small

52
Q

Atrial depolarization on EKG

53
Q

Ventricular depolarization on ekg

A

QRS complex

AV node

54
Q

Ventricular repolarization

55
Q

Purkinje repolarization in EKG

A

U wave

Usually not seen. May indicated hypokalemia and hypercalcemia

56
Q

Time from initiation of atrial depolarization to initiation of ventricular depolarization

A

PR interval

.12-.2 seconds

57
Q

Time from end of atrial depolarization to initiation of ventricular

A

PR segment

58
Q

Total time to depolarize ventricles

A

QRS interval

59
Q

Time from first ventricular depolarization to last repolarization

A

QT interval

How long its refractory is

60
Q

Time from last depolarization to initiation of repolarization

A

ST segment

Can be elevated during myocardial infarction (MI) - STEMI

61
Q

What effect would increasing parasympathetic tone have on the ECG?

A

Increase the PR interval

62
Q

What effect would a sodium channel (Na) blocker have on the ECG?

A

Increase the QT interval

Physiology Block 6 (7 decks)

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