Lecture 9

Question 1

What does the P wave indicate on the ECG?

Answer 1

Atria depolarising

Question 2

What phase begins during the P wave?

Answer 2

Atrial systole

Question 3

describe the action isovolumetric contraction phase?

Answer 3

Atria will repolarise and ventricles depolarise

Question 4

The isovolumetric contraction phase is associated with which ECG phase?

Answer 4

QRS wave

Question 5

Which valves shut during the QRS wave?

Answer 5

AV valves

Question 6

What causes the Lubb sound?

Answer 6

The shutting of the AV valves?

Question 7

What causes the large QRS spike in the ECG?

Answer 7

Atrial repolarisation and venturicular depolarisation

Question 8

What causes blood to flow out of the ventricle?

Answer 8

The semilunar valves open when the pressure in the ventricles is greater than the pressure in the aorta

Question 9

Ventricular ejection phase pressure rises because?

Answer 9

The blood volume drops but the pressure rises because the ventricles are squeezing blood

Question 10

What causes the semilunar valves to close?

Answer 10

Pressure in ventricles fall

Question 11

What causes the second heart sound?

Answer 11

The semilunar valves close, Dupp

Question 12

What phase of the cardiac cycle causes the T wave?

Answer 12

Isovolumetric ventricular relaxation

Question 13

Where does depolarisation start?

Answer 13

Sinoatrial node (SAN)

Question 14

What is the sinoatrial node?

Answer 14

A couple thousand very small cells. The SAN acts as a pacemaker and tells the heart when to beat

Question 15

How does the signal spread to neighbouring conduction cells?

Answer 15

Gap junctions

Question 16

How does the impulse spread between both types of cardiac cells?

Answer 16

Intercalated disks and gap junctions

Question 17

What do intercalated disks connect?

Answer 17

Most cells of the heart

Question 18

What are gap junctions?

Answer 18

Pores with low resistance to ionic current. Allowing current flow between adjacent cells

Question 19

Gap junctions can spread the impulse to?

Answer 19

Along the conduction pathway
between electrical and contractile cells
between contractile cells

Question 20

For the heart to beat millions of cardiac cells have to behave as?

Answer 20

One function synctium

Question 21

The conduction pathway begins at?

Answer 21

The sinoatrial node

Question 22

From the sinoatrial node the conduction pathway splits into?

Answer 22

The left and right atrium causing depolarisation of the atrium
and the internal bundle to the Atrioventricular node

Question 23

The atrioventricular node sends an impulse through the AV bundle which branches into?

Answer 23

The right and left ventricle causing contraction using purkinje fibres in the lateral walls

Question 24

Why is the SAN known as the pace maker?

Answer 24

because it tells the heart when to beat

Question 25

What is the function of the atrioventricular node?

Answer 25

To collect the electrical signal from the internodal bundle and put a pause on it before sending it along.

Question 26

Why does the atrioventricular node put a pause on the signal ?

Answer 26

The delay is essential as it means the atria have enough time to contract and fill the ventricles

Question 27

What is quiescence?

Answer 27

When the heart is fully relaxed and not depolarising or depolarising

Question 28

What is the first part of the excitation and conduction pathway?

Answer 28

Excitation spreads from the SA node

Question 29

What is the order of the conduction pathway?

Answer 29

``` excitation from the SA node Atria full depolarise and contract Atria repolarise and AV node sends excitation to ventricles Ventricles depolarise and contract Ventricles repolarise and relax ```

Question 30

What is the P wave?

Answer 30

atrial repolarisation

Question 31

What is the QRS wave?

Answer 31

Ventricular depolarisation and atrial repolarisation

Question 32

What is the T wave?

Answer 32

ventricular repolarisation

Question 33

What does depolarisation cause?

Answer 33

Contraction

Question 34

What does repolarisation cause

Answer 34

Relaxation

Question 35

A large spike in pressure indicates which phase of the cardiac cycle?

Answer 35

Isovolumetric contraction phase