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KINE 4010 B > November 20, 2023 > Flashcards

November 20, 2023 Flashcards

1
Q

Questions at beginning of lecture:

  • Use words to describe in detail the consequences of degranulation
  • Draw a graph of FEV1 performance after exercise at 40% and 75% of VO2max
  • Explain the causes of eccentric and concentric hypertrophy, and describe cellular and heart morphology
  • Why can’t cardiac muscle contract tetanically
  • If HR is 100bpm and systole is 250msec long, how long is diastole (answer: 350msec)
A

If HR is 100bpm and systole is 250msec long, how long is diastole? 350 msec

Take 60 seconds and divide by BPM (will get milliseconds)

Then subtract systolic time to find diastolic time

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2
Q

which action potential is longer, Skeletal muscle AP or Ventricular muscle AP

A

action potential in ventricular muscle is longer because calcium channels open and calcium comes in to make the cell positive for a longer period of time (only in cardiac muscle not skeletal muscle)

page 136

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3
Q

why can’t your heart muscle contract tetanically like skeletal muscle

A

The refractory period is as long as the contraction itself so another contraction can’t occur right after

You don’t want heart muscle to contract tetanically like skeletal muscle (can’t summate force in cardiac muscle, only in twitches)

page 136

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4
Q

what element leaves the cell to bring Action potential back down to resting potential

A

Potassium leaves and cell is brought down to resting potential

page 136

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5
Q

what element enters the cell and cause action potential/membrane potential to become positive

A

Sodium comes in and causes cell to become positive

page 136

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6
Q

does Intraventricular pressure drop or rise as ventricles contract

A

Intraventricular pressure rises as ventricles contract

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7
Q

does Intraventricular pressure fall or rise as ventricles relax

A

Intraventricular pressure falls as ventricles relax

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8
Q

what does S1 heart sound represent?

A

left AV valve closure as pressure develops in ventricle

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9
Q

what does S2 heart sound represent?

A

aortic valve closure when pressure in aorta is greater than pressure in ventricle (80mmHg)

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10
Q

The difference between S1 and S2 is taken as the the time of ___________

A

systole

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11
Q

does diastolic filling take more or less time during exercise

A

In exercise, diastolic filling takes less time

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12
Q

An adaptation to a lower HR has 2 benefits for the heart and 1 benefit for the rest of the body:

A

More diastolic time = better cardiac muscle perfusion through coronary vessels (heart itself has better supply of blood flow)

Less ATP demand of cardiac muscle (higher supply:demand ratio for the heart)

More diastolic time = more time to fill the ventricle with blood for distribution to the rest of the body (more blood in there to distribute)

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13
Q

At very high heart rates is diastole or systole mainly reduced?

A

At very high heart rates, diastole is mainly reduced, however systole can also be reduced

page 138 (graph on bottom)

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14
Q

what is the function of action potential at the sinoatrial (SA) node

A

serves as the natural pacemaker of the heart, goes through several phases

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15
Q

Do SA node cells have a stable resting membrane potential?

A

SA node cells DO NOT have a stable resting membrane potential.

Instead, they exhibit a slow depolarization during diastole (resting phase) called the pacemaker potential.

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16
Q

What is pacemaker potential?

A

slow depolarization is due to a gradual influx of sodium ions (Na⁺) through funny channels

brings the membrane potential to the threshold for firing an action potential.

17
Q

explain the key phases of the action potential at the SA node:

A

Pacemaker Potential:
slow depolarization and a gradual influx of sodium ions (Na⁺) through funny channels

Depolarization:
Once the pacemaker potential reaches the threshold, it triggers the opening of voltage-gated calcium channels

The influx of calcium ions (Ca²⁺) causes a rapid depolarization of the cell membrane, leading to the action potential.

Repolarization:
mainly mediated by the efflux of potassium ions through various potassium channels.

Calcium Reuptake and Membrane Potential Stabilization:
calcium channels close

potassium efflux continues

membrane potential stabilizes, and the cell is ready to initiate the next pacemaker potential.

18
Q

sympathetic tone:

A

Increase in heart rate

19
Q

parasympathetic tone:

A

Slowing of heart through vagus nerve

20
Q

Chronotropic effects:

A

timing effect (either increases or decreases the heart rate)

21
Q

Positive chronotropic agents:

A

epinephrine and norepinephrine

22
Q

Negative chronotropic agent:

A

acetylcholine

23
Q

Ionotropic effects:

A

force effects (increased vs. decreased force of the heart)

24
Q

Ionotropic agents

A

epinephrine and norepinephrine

25
Q

Tachycardia:

A

increase in sympathetic tone (Increase in heart rate)

norepinephrine increases the rate of sodium into the cell, bringing cell to threshold, and AP to completion sooner; therefore increasing HR

26
Q

Bradycardia:

A

increase in parasympathetic tone (Slowing of heart)

further hyperpolarized

release of acetylcholine –>reduce the rate of sodium entry

longer to get to threshold and delays onset of AP

Acetylcholine also increases the amount of potassium exiting the cell

page 139

27
Q

how do Vagal tone and sympathetic tone work together to increase heart rate during exercise

A

At rest:
Vagal tone is usually high (slowing HR)
Sympathetic tone is usually low(slowing HR)

During exercise:
Vagal tone is usually low (increasing HR)
Sympathetic tone is usually high(increasing HR)

28
Q

what is the result of SA node cells responding less to Epi and NE with age

A

reduces your max HR

which is why formula “220 - age” works figure out max HR

29
Q

What Controls HR During Exercise?

A

Central command:
1.Alpha motor neurons are recruited for movement to begin (Voluntary)
2.Activation of CV area of brainstem (Involuntary)

30
Q

what are the mechanisms involved in controlling HR During Exercise?

Hint: talk about sympathetic and parasympathetic tone

A
  • parasympathetic drive DECREASES (Vagal tone reduces) = HR to increase (at low exercise intensity)
  • Sympathetic tone INCREASES = HR to further increase at higher intensities
    also allows for increase in contractility (force of
    contraction since these sympathetic neurons
    innervate ventricular muscle cells)
31
Q

how does atropine INCREASE HR

A

Ach can be blocked with atropine, a cholinergic drug: causes HR to increase

32
Q

how does propranolol DECREASE HR

A

The receptor for NE is a beta1 adrenergic receptor, blocked by propranolol: causes HR to decrease

KINE 4010 B (32 decks)

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