Lecture 5 Flashcards

1
Q

Resting Heart Rate (Healthy Adult)?

A

70 bpm

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2
Q

Resting Heart Rate (Athlete)?

A

50 bpm

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3
Q

Resting Heart Rate (Newborn)?

A

135 bpm

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4
Q

Heart Rate Range?

A

20-250 bpm

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5
Q

ECG?

A

Measure when it contracts and relaxes and it has 12 leads

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6
Q

Factors affecting current flow?

A

1) Number of Cell-Cell Gap Junctions
2) Cell Diameter
3) Cell Alignment

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7
Q

Gap Junctions are made out of?

A

Connexons

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8
Q

Phase 0?

A

“Depolarization Phase”
-Activation of “fast” voltage-gated Na and Ca channels
(Inward Na flux and Ca flux)

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9
Q

Phase 1?

A

“Early Depolarization Phase”
-Activation of a “transient outward” voltage-gated K channels
(outward K flux) Inaction of Na channels

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10
Q

Phase 2?

A

“Plateau Phase” (because not repolarizing or depolarizing)
-Activation of voltage-gated Ca channels, Activation of “delayed rectifier” K channels (Inward Ca flux and outward K flux counteract each other)

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11
Q

Phase 3?

A

“Final Depolarization Phase”
-Inactivation of voltage-gated Ca current, Activation of delayed rectifier K channels, And inward rectifier K channels
(outward K flux)

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12
Q

Phase 4?

A

“Diastolic “Resting” Potential”
-Activated inward rectifier K channels
(outward K flux)

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13
Q

Different ion channels?

A

Na+, Ca2+, and K+

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14
Q

Depolarizing?

A

Inward Na+ and Ca2+ currents

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15
Q

Depolarizing/Hyper?

A

Outward K+ currents

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16
Q

Effective Refractory Period?

A

(ERP) Cell cannot fire another action potential

17
Q

Relative Refractory Period?

A

(RRP) Cell can fire another action potential, but amplitude is reduced

18
Q

ERP and RRP are caused by?

A

Inactivation state of voltage-gated Na and/or Ca channels

19
Q

Automaticity?

A

Initiates Heart Beat

20
Q

Rhythmicity?

A

Regular Pacemaking Activity

21
Q

Dominant Pacemaker?

A

SA Node (with SA Node dysfunction, AV Node can become dominant pacemaker)

22
Q

Resting Heart Rate is Reduced by?

A

Basal Parasympathetic Tone

23
Q

Exercise reduces?

A

Parasympathetic tone increase Sympathetic tone

24
Q

Duration of the Cardiac AP is significantly longer than the?

A

Neuronal AP

25
Cardiac AP being longer results in?
An extended refractory period that provides sufficient time for Heart chambers to fill with blood before depolarizing AP wave comes along
26
Pacemaker cells?
-Slower rising phase in Phase 0 -No early repolarization Phase 1 -No plateau phase Phase 2 -Presence of a slowly depolarizing "pacemaker" potential during Phase 4 -Phase 4 ("resting potential") is more depolarized in pacemaker cells
26
Pacemaker cells?
-Slower rising phase in Phase 0 -No early repolarization Phase 1 -No plateau phase Phase 2 -Presence of a slowly depolarizing "pacemaker" potential during Phase 4 -Phase 4 ("resting potential") is more depolarized in pacemaker cells
27
"Funny" Channel is responsible for?
Automaticity (all pacemaker cells express the "funny" channel)
28
("Slow" Pacemaker AP) Phase 0?
-No Na+ inward -Calcium current -Voltage-dependent Ca channel (slower because Ca2+ slower than Na+)
29
("Slow" Pacemaker AP) Phase 3?
-Potassium current -Voltage-dependent K channel -Ca+ closed
30
("Slow" Pacemaker AP) Phase 4?
-Involves Na+ channel -"Funny" pacemaker current -Cyclic-nucleotide gated Na channel -Necessary for automaticity (because activated by hyperpolarization, increased Na+ slow depolarization of Phase 4)
31
SA Node Cell?
Membrane potential for triggering all-or-nothing AP
32
Altering automaticity and firing frequency (HR)?
1) Change slope of Phase 4 (increased time of depolarization) 2) Hyperpolarization during Phase 4 (increased time to depolarize) 3) A change in threshold for firing
33
Parasympathetic?
Rest and Digest
34
Sympathetic?
Fight or Flight
35
Heart is innervated by?
-Both parasympathetic and sympathetic nerves (mainly myocardial regions)
36
Innervation of nodal regions are?
Predominantly, but not exclusively, parasympathetic