Week 3 electrical properties of the heart

Question 1

Find the sinoatrial (SA) Node

Answer 1

Question 2

Find the internodal pathways

Answer 2

Question 3

Find the Atrioventricular (AV) node

Answer 3

Question 4

Find the AV Bundle

Answer 4

Question 5

Find the bundle branches

Answer 5

Question 6

Find the purkinje fibres

Answer 6

Question 7

Find the Action potential

Answer 7

Question 8

Find the pacemaker potential

Answer 8

Question 9

What is the action potential?

Answer 9

the activation of the cell

Question 10

What is the pacemaker potential?

Answer 10

slower rise in membrane potential towards threshold

Question 11

Find where the rise of K+ occurs

Answer 11

Question 12

Find where the rise of Ca2+ occurs

Answer 12

Question 13

Find the rise in Na+

Answer 13

Question 14

What is the funny channel?

Answer 14

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

Question 15

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

Answer 15

.

Question 16

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

Answer 16

.

Question 17

What causes the action potential to stop?

Answer 17

.

Question 18

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

Answer 18

.

Question 19

Where are the four sites the pacemaker cells are located?

Answer 19

SA Node,
AV Node,
AV Bundle
Purkinje fibres

Question 20

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

Answer 20

SA

Question 21

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

Answer 21

autonomic nerves

Question 22

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

Answer 22

0.8 seconds

Question 23

Which of these lines are sympathetic stimulation or circulating adrenaline?

Answer 23

Question 24

Which of these are parasympathetic?

Answer 24

Question 25

Find the slower depolarization

Answer 25

Question 26

Find rapid depolarization

Answer 26

Question 27

Find Less depolarization

Answer 27

Question 28

What is the average resting heart rate of an adult?

Answer 28

75 bpm

Question 29

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

Answer 29

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

Question 30

HR is modulated by

Answer 30

neural and hormonal input.

Question 31

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

Answer 31

.

Question 32

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

Answer 32

.

Question 33

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

Answer 33

.

Question 34

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

Answer 34

Question 35

What is happening at step one?

Answer 35

Question 36

What is happening at Step 2?

Answer 36

Question 37

What is happening in step 3

Answer 37

Question 38

Where do Ca2+ions enter the SA node cell?

Answer 38

.

Question 39

Where do K+ions leave the contractile cell?

Answer 39

.

Question 40

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

Answer 40

.

Question 41

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

Answer 41

.

Question 42

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

Answer 42

1. The atria contract (& then relax)
2. The ventricles contract (& then relax)

Question 43

The conducting system of the heart consists of what?

Answer 43

Pacemaker Cells and Conducting Cells

Question 44

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

Answer 44

via intercalated discs.

Question 45

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

Answer 45

.

Question 46

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

Answer 46

.

Question 47

What does the P wave represent?

Answer 47

.

Question 48

What does the QRS complex represent?

Answer 48

.

Question 49

What does the T wave represent?

Answer 49

.

Question 50

When does repolarisationof the atria occur?

Answer 50

.

Question 51

What is the most common rhythm disorder?

Answer 51

Atrial Fibrillation

Question 52

What is the main problem with Atrial Fibrillation?

Answer 52

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

Question 53

How do you work out the Mean Arterial pressure?

Answer 53

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