Week 3 electrical properties of the heart Flashcards by Shane Hudson | Brainscape

Q

Find the sinoatrial (SA) Node

A

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Q

Find the internodal pathways

A

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Q

Find the Atrioventricular (AV) node

A

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Q

Find the AV Bundle

A

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Q

Find the bundle branches

A

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Q

Find the purkinje fibres

A

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Q

Find the Action potential

A

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Q

Find the pacemaker potential

A

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Q

What is the action potential?

A

the activation of the cell

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Q

What is the pacemaker potential?

A

slower rise in membrane potential towards threshold

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Q

Find where the rise of K+ occurs

A

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Q

Find where the rise of Ca2+ occurs

A

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Q

Find the rise in Na+

A

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Q

What is the funny channel?

A

It is a voltage-gated Na+ channel that activates with repolarization.

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Q

What normally initiates the action potential in the SA node cell?

A

.

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Q

Is there another way that an action potential can be initiated?

A

.

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Q

What causes the action potential to stop?

A

.

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Q

What causes the voltage-gated Ca2+channel to close?

A

.

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Q

Where are the four sites the pacemaker cells are located?

A

SA Node,
AV Node,
AV Bundle
Purkinje fibres

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Q

Which is the fastest discharge rate for a node? AV Node or SA node?

A

SA

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Q

The rate of discharge of SA node cells (and therefore heart rate) is regulated by what nerves

A

autonomic nerves

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Q

The inherent rate of AP discharge in a SA node cell is once every

A

0.8 seconds

Q

Which of these lines are sympathetic stimulation or circulating adrenaline?

A

Q

Which of these are parasympathetic?

A

Q

Find the slower depolarization

A

Q

Find rapid depolarization

A

Q

Find Less depolarization

A

Q

What is the average resting heart rate of an adult?

A

75 bpm

Q

The speed at which pacemaker cells in the SA node depolarize determines what?

A

he rate at which the heart contracts (typical about every 0.8 s).

Q

HR is modulated by

A

neural and hormonal input.

Q

A “beta blocker” is a drug that bocks the ß1receptor in the body. What effect would it have on heart rate?

A

.

Q

Atropine blocks the muscarinic receptor. What effect would it have on HR?

A

.

Q

Ivabradine is a drug that blocks the funny channel. Would it have an effect onHR? If so, what would it do?

A

.

Q

Describe the difference between a SA Node (pacemaker) and a contractile cell

A

Q

What is happening at step one?

A

Q

What is happening at Step 2?

A

Q

What is happening in step 3

A

Q

Where do Ca2+ions enter the SA node cell?

A

.

Q

Where do K+ions leave the contractile cell?

A

.

Q

Where do Na+ions enter a cell (either cell type)

A

.

Q

Where do K+ions enter a cell (either cell type)

A

.

Q

A single cardiac cycle is made up of what 2 sets of contractions & relaxations

A

The atria contract (& then relax)
The ventricles contract (& then relax)

Q

The conducting system of the heart consists of what?

A

Pacemaker Cells and Conducting Cells

Q

Cardiac muscle cells are “joined together” – i.e.they are physically connected to their adjacent “neighbours” how?

A

via intercalated discs.

Q

What would happen if the AV node was damaged (such as an infarction in this area)?

A

.

Q

Would the ventricles cease to work (& so the subject would die)?

A

.

Q

What does the P wave represent?

A

.

Q

What does the QRS complex represent?

A

.

Q

What does the T wave represent?

A

.

Q

When does repolarisationof the atria occur?

A

.

Q

What is the most common rhythm disorder?

A

Atrial Fibrillation

Q

What is the main problem with Atrial Fibrillation?

A

t increases the risk of blood clot formation in atria and therefore increases the risk of stroke

Q

How do you work out the Mean Arterial pressure?

A

Find out the diastolic pressure, add a third of the Pulse pressure.

Pulse pressure is systolic pressure minus diastolic pressure,

Divide the PP by 3 to get a third.

DBP + 1/3PP
MAP = 80 (120-80)/3=93.33