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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
What is **phase 1** in the action potential in **fast tissues/fibers?**
Small repolarization **Voltage gated Na+(m) channels closing** Some **K+ (a) channels opening**
26
What is **phase 2** in an action potential withing **fast tissues/fibers?** Caused by?
Plateau phase Slow opening of **voltage gated Ca2+ channels** Closing of **voltage gated K+ (b) channels**
27
When does a contraction of a muscle occur in relation to an action potential being generated?
Prolonged contraction
28
What is **phase 3** within the **fast tissues/fibers?** Caused by?
Complete repolarization Slow **voltaged-gated Ca2+** channels _closing_ and **K+ (b) channels** _opening_
29
What is conduction velocity related to?
The steepness of phase 0 The more steep phase 0 is, the faster the conduction velocity will be
30
# Define the following **General Refractory Period** _Absolute Refractory Period (ARP)_
No depolarization
31
# Define the following **General Refractory Period** _Relative Refractory Period (RRP)_
AP can be generated but will have an abnormal conduction
32
# Define the following **General Refractory Period** _Supranormal period (SNP)_
Cell is more excitable than normal
33
T/F Conduction of an action potential is **weaker** if stimulated during RRP
TRUE!
34
# Define: ## Footnote **Chronotropic**
Effect changes **rate of depolarization of SA node** and therefore, **Heart Rate** Positive=faster Negative=slower
35
# Define: Dromotropic
Effect is speed of conduction
36
# Define: Inotropic
Effect changes the **strength of muscular contraction**
37
# Define: Lusitropic
Effect changes the **rate of muscular relaxation**
38
Parasympathetic stimulus is carried by the ______ nerve
Vagus
39
Neurotransmitter for **parasympathetic system?**
Acetylcholine
40
Receptor for **parasympathetic system?**
Muscarinic (M2/M3)
41
How do **negative chronotropic effects** manifest themselves?
Slowed opening of **Na+(f) channels during phase 4** Hyperpolarization by increasing the **outward K+ current** via **K+-Ach channel**
42
How to **negative dromotropic effects** manifest themselves?
Reduced Ca2+ inward current Increased outward K+ current via K+-Ach
43
Describe the graphic differences between a sympathetic stimulation and parasympathetic stimulation
44
What is **atropine?**
Muscarininc receptor antagonist
45
What is **propranolol?**
Beta adrenergic antagonist
46
A. \*\*Increased inward Na+ current during phase 4
47

Cardiopulmonology Final (21 decks)

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