Cardiac Physiology

Question 1

Cardiac cycle is composed of…

Answer 1

• Systole and diastole of both atria

- Systole and diastole of both ventricles

Question 2

Autorhythmic fibres form the…

Answer 2

Conduction system

Question 3

4 components of the conductions system

Answer 3

• SA node
• AV node
• Left/right bundle branches
• Purkinje fibres

Question 4

Phases of an action potential

Answer 4

• Rapid depolarisation
• Long plateau
• Repolarisation

Question 5

Atrial depolarisation is represented on an ECG by the…

Answer 5

P wave

Question 6

QRS complex represents…

Answer 6

Ventricular depolarisation

Question 7

T wave represents

Answer 7

Ventricular repolarisation

Question 8

3 phases of cardiac cycle

Answer 8

• Atrial systole
• Ventricular systole
• Relaxation period

Question 9

3 phases of cardiac cycle

Answer 9

• Atrial systole
• Ventricular systole
• Relaxation period

Question 10

S1 is caused by…

Answer 10

Blood turbulence from the closing of the AV valves

Question 11

S2 is caused by…

Answer 11

Blood turbulence from the closing of the semilunar valves

Question 12

Cardiac output is…

Answer 12

The amount of blood ejected per minute by the left ventricle into the aorta

Question 13

Formula for cardiac output

Answer 13

CO = Stroke volume x Heart rate

Question 14

3 factors that influence stroke volume

Answer 14

• Preload
• Contractility
• Afterload

Question 15

Frank-Starling law of the heart

Answer 15

A greater preload increases the force of contraction of cardiac muscle fibres until their stretching becomes excessive

Question 16

Nervous control of the CV system originates in…

Answer 16

The CV centre in the medulla oblongata

Question 17

4 factors that influence heart rate

Answer 17

• Sympathetic nervous system (increases HR)
• Parasympathetic nervous system (decreases HR)
• Hormones
• Ions