Spread Of Excitation Through The Heart+ECG

Question 1

Outline the path of blood flow through the heart of oxygenated blood.

Answer 1

1. Pulmonary vein
2. LA
3. AV-valve
4. LV
5. SL-valve
6. Aorta

Question 2

What’s the trace of electrical impulses through the heart?

Answer 2

1. SAN
   2.Delay to allow atria to fully contract
2. AVN
   4.Bundle of His
3. Purkinje Fibres

Question 3

Describe the meaning of the following on an ECG:
-P wave
-QRS complex
-T wave

Answer 3

P=atrial Depolorisation
QRS=ventricular Depolorisation
T=ventricular repolorisation

Question 4

Outline the path taken by blood of deoxygenated blood through the heart.

Answer 4

1. S/I vena cava
2. RA
3. AV-valve
4. RV
5. SL-valve
6. Pulmonary artery

Question 5

What’s the meaning of the P-Q interval on ECGs?

Answer 5

AVN conduction time

Question 6

When does ventricular systole occur?

Answer 6

Q-> end of T wave

Question 7

What is the function of pacemaker cells?

Answer 7

• fire action potentials spontaneously

Question 8

How soon do pacemaker cells Depolarise after action potential is caused?

Answer 8

Immediately

Question 9

What are the cells called that are responsible for the heart contractions?

Answer 9

Cardiac contractile cells

Question 10

What causes arrhythmias?

Answer 10

-abnormal SAN firing