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Animal Physiology > Conduction > Flashcards

Conduction Flashcards

1
Q

Which circuit does the right side of the heart go to?

A

Pulmonary

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2
Q

What is the pressure in the pulmonary circuit?

A

Low

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3
Q

What is the relative resistance in the pulmonary circuit?

A

Low

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4
Q

Why doesn’t the right side of the heart need to contract as strong as the left side?

A

Not going as far

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5
Q

What circuit does the left side of the heart go to?

A

Systemic

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6
Q

What is the pressure in the systemic circuit?

A

High

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7
Q

What is the relative resistance in the systemic circuit?

A

High

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8
Q

What controls the heart rate?

A

Pacemakers

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9
Q

What are the two types of pacemakers?

A

Neurogenic and myogenic

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10
Q

What is a neurogenic pacemaker? What animals use it?

A

Heart rate is controlled by the brain and contractions are initiated by neurons. Used by invertebrates

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11
Q

What is a myogenic pacemaker? What animals use it?

A

Contractions are initiated by cardiac myocytes. Used by vertebrates

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12
Q

What are pacemakers?

A

Cells that produce spontaneous, rhythmic depolarizations that initiate contractions

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13
Q

How do cardiac myocytes spread a depolarization from one cell to another?

A

Gap junctions

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14
Q

Which pacemaker cells will determine the heart rate?

A

The one with the fastest intrinsic rhythm

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15
Q

How do neurogenic pacemakers work?

A

Pacemaker neurons are contained in cardiac ganglion. A sequential firing of neurons from anterior to posterior initiates a series of contractions. The heart rate is controlled by the brain

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16
Q

What are the 4 nodes in vertebrate hearts? What order do they fire in?

A

SA node
AV node
Bundle of His
Purkinje fibres

17
Q

How is the signal spread between nodes in a vertebrate heart?

A

Gap junctions

18
Q

Which node initiates the contractions?

A

SA node

19
Q

What happens when the SA node fires?

A

The signal moves from the right atrium to the left atrium and they both contract at the same time. At the same time, the signal follows an internodal pathway at a slight delay to the AV node

20
Q

Where is the SA node located?

A

Right atrium

21
Q

Why is the AV node delay so important?

A

Allows contraction of the atria for the ventricles to fill completely before the ventricles contract

22
Q

What happens once the AV node fires?

A

Signal goes down the left and right branches of the Bundle of His and then the Purkinje fibres spread the signal through the ventricle walls and cause the contraction of the ventricles

23
Q

What is the entire process of conduction in vertebrate hearts called, including the delay between the SA and AV nodes?

A

Functional sysncytium

24
Q

What determines the heart rate in a myogenic heart?

A

The fastest node, normally the SA node

25
Q

What would happen to heart rate if the SA node was damaged?

A

Rate is determined by the AV node instead, which is slower so the heart rate is slower too

26
Q

What would happen if the AV node was damaged?

A

Rate will still be driven by the SA node, but there will be a much longer delay between the initial signal and ventricle contraction

27
Q

What is ectopic focus?

A

The Purkinje fibres fire much faster than the SA node, so the heart rate is driven by that instead

28
Q

What is conduction?

A

Spread of an electrical signal through nerves or muscles via the movement of ions

29
Q

What is depolarization?

A

Reversal of charge across the cell membrane caused by rapid ion movement

30
Q

What is the ion balance in myocytes?

A

Low calcium, low sodium, and high potassium inside the cells

31
Q

What are the sodium channels in myocytes called? How are they gated?

A

Funny channels, voltage gated

32
Q

How does sodium permeability change in a myocyte throughout an action potential?

A

Low permeability during repolarization and right after a depolarization. Sodium channels open to cause the depolarization and close at the highest membrane potential

33
Q

How does potassium permeability change in a myocyte throughout an action potential?

A

High permeability right after a depolarization and lowers during the plateau phase and increases again during repolarization

34
Q

How does calcium permeability change in a myocyte throughout an action potential?

A

Increases during a depolarization and decreases right after

35
Q

How does acetylcholine affect heart rate?

A

Decreases depolarization rate and heart rate

36
Q

What is the receptor of acetylcholine?

A

Muscarinic receptor

37
Q

What effect does acetylcholine have on pacemaker cells?

A

Increases potassium efflux and decreases calcium influx

38
Q

How does epinephrine and norepinephrine affect heart rate?

A

Increases depolarization rate and increases heart rate

39
Q

What effect does epinephrine and norepinephrine have on pacemaker cells?

A

Opens the voltage gated sodium and calcium channels and allows ion influx into the cell

Animal Physiology (32 decks)

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