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Cardiopulmonology Final > (1) Cardiac Action Potential & Conduction System (Rogers) > Flashcards

(1) Cardiac Action Potential & Conduction System (Rogers) Flashcards

1
Q
A

E. **Increased Na+ Conductance

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2
Q

Describe how an action potential starts:

A
  • Increase in permeability of membrane Na+
  • Voltage-gated Na+ channels open rapidly
  • Shortly following, channels close automatically
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3
Q
A

C. K+ Permeability

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4
Q
A

A. Opening of K+ gates

-> At repolarization, voltage gated K+ channnels are open, membrane permeability to Na+ decreases, and permeability to K+ continues to rise

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5
Q

Describe how the SA node functions

A
  • Have pacemaker that causes spontanous action potential
  • AP spreads througout atria, and cause atria to contract
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6
Q

What is the order of the cardiac conduction system from start to finish?

A

SA Node

AV Node

Bundle of His

R/L Bundle branch

Purkinje fibers

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7
Q

Which ventricle epicardium receives the electrical impulse first?

A

Right Ventricle Epicardium

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8
Q

T/F

The Epicardium of ventricles receives action potential prior to Endocardium

A

FALSE!!!

Electrical impulses travel from innermost to exterior

Endocardium of ventricles receives action potential prior to epicardium

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9
Q

Why is fiber size important?

A

Larger fibers have faster AP transmission/greater velocity

Purkkinje (and atrial pathways) > atrial and ventricular muscle > AV node

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10
Q

What does the delay in the AV allow physiologically to happen?

A

Allows atria to empty into ventricles before ventricles contract

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11
Q

Draw out the cardiac action potentials:

(A) Ventricle

(B) Atrium

(C) Sinoatrial Node

A
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12
Q

What is the resting membrane potential of ventricles and atria?

A

-90mV

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13
Q

What are distinguishing characteristics of sinuatrial node cardiac AP?

A
  • Phase 4 has a slope upward
  • Resting membrane potential = -65mV
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14
Q

Key Cardiac Ion Channels for Membrane Potential

State the Gate Family, Equilibrium potential, What causes activation, Action, Phase and Special features

A
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15
Q

What are K(d) potassium channels?

A

Voltage gated K+ channels

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16
Q

Describe the important aspects of:

Phase 4; SA node Action Potential

A
  • Pacemaker
  • In the SA NODE, resting membrane potential gradually depolarizes until it reaches threshold
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17
Q

What is phase 4 of the action potential in SA node caused by?

A

“Funny” Voltage gated Na+ (f) channels

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18
Q

What is phase 0 of the SA node due to?

A

Opening of slow Ca2+ channels

and

Closing of Special K+ (b) channels

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19
Q

Why is there no phase 1/2 in SA node?

A

Very few traditional voltage gated Na+ channels

20
Q

What is phase 3 of SA node action potential due to?

A

Closing of Ca2+ gates

and

Opening of Special K+ (b) gates

*a reversal of phase 0

21
Q

What is the primary difference b/w the SA node action potential and the AV node?

A

AV node is similar to SA node BUT!!!!

With a slower depolarization during phase 4

22
Q

What does the graph for an action potential in fast tissue fibers look like?

A

*Ignore the arrows

23
Q

What is phase 4 in an action potential in fast tissue/fibers?

What is it sustained by?

A

Resting potential

High K+ (c) conductance

24
Q

What is phase 0 in an action potential in fast tissues/fibers?

Caused by?

A

Rapid upstroke

Voltage-gated Na+ channels (m) opening

25
Q

What is phase 1 in the action potential in fast tissues/fibers?

A

Small repolarization

Voltage gated Na+(m) channels closing

Some K+ (a) channels opening

26
Q

What is phase 2 in an action potential withing fast tissues/fibers?

Caused by?

A

Plateau phase

Slow opening of voltage gated Ca2+ channels

Closing of voltage gated K+ (b) channels

27
Q

When does a contraction of a muscle occur in relation to an action potential being generated?

A

Prolonged contraction

28
Q

What is phase 3 within the fast tissues/fibers?

Caused by?

A

Complete repolarization

Slow voltaged-gated Ca2+ channels closing

and

K+ (b) channels opening

29
Q

What is conduction velocity related to?

A

The steepness of phase 0

The more steep phase 0 is, the faster the conduction velocity will be

30
Q

Define the following General Refractory Period

Absolute Refractory Period (ARP)

A

No depolarization

31
Q

Define the following General Refractory Period

Relative Refractory Period (RRP)

A

AP can be generated but will have an abnormal conduction

32
Q

Define the following General Refractory Period

Supranormal period (SNP)

A

Cell is more excitable than normal

33
Q

T/F

Conduction of an action potential is weaker if stimulated during RRP

A

TRUE!

34
Q

Define:

Chronotropic

A

Effect changes rate of depolarization of SA node

and therefore, Heart Rate

Positive=faster

Negative=slower

35
Q

Define:

Dromotropic

A

Effect is speed of conduction

36
Q

Define:

Inotropic

A

Effect changes the strength of muscular contraction

37
Q

Define:

Lusitropic

A

Effect changes the rate of muscular relaxation

38
Q

Parasympathetic stimulus is carried by the ______ nerve

A

Vagus

39
Q

Neurotransmitter for parasympathetic system?

A

Acetylcholine

40
Q

Receptor for parasympathetic system?

A

Muscarinic (M2/M3)

41
Q

How do negative chronotropic effects manifest themselves?

A

Slowed opening of Na+(f) channels during phase 4

Hyperpolarization by increasing the outward K+ current via K+-Ach channel

42
Q

How to negative dromotropic effects manifest themselves?

A

Reduced Ca2+ inward current

Increased outward K+ current via K+-Ach

43
Q

Describe the graphic differences between a sympathetic stimulation and parasympathetic stimulation

A
44
Q

What is atropine?

A

Muscarininc receptor antagonist

45
Q

What is propranolol?

A

Beta adrenergic antagonist

46
Q
A

A. **Increased inward Na+ current during phase 4

47
Q
A

Cardiopulmonology Final (21 decks)

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