Cardiac Physiology

Question 1

The wall of the left ventricle is thicker than the wall of the right ventricle because:

Answer 1

The left ventricle must pump the same amount of blood into the high-resistance, high pressure systemic system (as does the right ventricle into the low-resistance, low pressure pulmonary system)

Question 2

The aortic valve:

Answer 2

Prevents back flow of blood into the left ventricle during ventricular diastole

Question 3

The right half of the heart pumps blood through the _________ circuit and the left half pumps blood through the _______ circuit

A) Systolic/diastolic
B) Coronary/pulmonary
C) Systemic/pulmonary
D) Pulmonary/systemic
E) Systemic/coronary

Answer 3

D) Pulmonary/Systemic

Question 4

4. Which component of the cardiac conduction system distributes electrical signals through the papillary muscles directly?

Answer 4

Our kindie Fibres

Question 5

The function of the atrioventricular node is to:

Answer 5

Prevent the atria and ventricles from contracting simultaneously

Question 6

The QRS complex represents:

Answer 6

Depolarisation of the ventricles

Question 7

7. Which is the normal sequence of the spread of cardiac excitation?
8. AV node
9. SA node
10. Atria
11. Purkinjie fibres
12. Bundle of HIS
13. Ventricular myocardium

Answer 7

2, 3, 1, 5, 4, 6

Question 8

The electrocardiograph is most useful in determining which component of cardiac output?

Answer 8

Heart rate

Question 9

If the stroke volume is 80ml and the heart rate is 70 beats per minute, the cardiac output is:

Answer 9

5600 ml/min

Question 10

Cardiac output:

Two answers

Answer 10

• Is the volume of blood pumped by each ventricle per minute
• Equals heart rate X stroke volume

Question 11

The __________ nerves to the heart alter cardiac output by increasing heart rate and increasing contractility.

A) Motor
B) Sensory
C) Sympathetic
D) Parasympathetic

Answer 11

C) Sympathetic

Question 12

The parasympathetic nervous system has little effect on ________ activity.

A) Atrial
B) AV node
C) Heart rate 
D) SA node 
E) Ventricular

Answer 12

E) Ventricular

Question 13

Blood flow through the coronary circulation occurs:

Answer 13

Mainly during diastole

Question 14

The heart valves open and close due to:

Answer 14

A pressure difference on two sides of the valve

Question 15

Twelve ECG patterns are recorded from a sheep over ten seconds. If this pattern continues, the rate of the heart beat in the sheep is  \_\_\_\_\_\_\_\_\_\_\_\_\_ beats per minute.

A) 60
B) 72
C) 90
D) 108
e)	120

Answer 15

B) 72

Question 16

The refractory period of a cardiac muscle:

Two Answers

Answer 16

• Lasts almost as long as the contraction period

- Is much longer than the refractory period in skeletal muscle