Cardiovascular physiology

Question 1

Layers of the heart

Answer 1

• pericardium (sac around the heart)
• epicardium (outer surface)
• myocardium (heart muscle)
• endocardium (inner lining)

Question 2

Properties of a cardiac muscle

Answer 2

•rhythmicity
• excitability
• contractility
• conductivity

Question 3

Cardiac Action Potential

Answer 3

0 = Na+ (in)
1 = K+Cl (out)
2 = Ca2 (in)
K+ (out)
3 = K+ (out)
4 = resting potential

Question 4

Cardiac output - Stroke volume

Answer 4

Volume of blood pumped by each ventricle in one contraction. Approx. 70ml

Question 5

What is Cardiac Output (CO)

Answer 5

Amount of blood pumped by the heart in one minute.
CO = (heart rate [HR] x stroke volume [SV])

Question 6

Blood pressure during cardiac output

Answer 6

BP = (cardiac output [CO] x Total peripheral resistance [TPR])

Question 7

Which heart chambers does blood flow into on its return from the rest of the body?

Answer 7

Right atrium, into Right Ventricles

Question 8

Name the heart valves between:

Right atria and Right Ventricle

Right Ventricle and Pulmonary artery

Left Atria and Left Ventricle

Left Ventricle and Aorta

Answer 8

Tricuspid

Pulmonary (Semilunar)

Mitral

Aortic (Semilunar)

Question 9

What is the anatomical landmark for auscultation of the aortic valve

Answer 9

Right sternal border, second intercostal space

Question 10

What is the relative voltage of the cardiac cell membrane at rest?

Answer 10

-90mV

Question 11

What changes the action potential of cardiac cells?

Answer 11

Movement of positively charged ions into the cell until it increases to -40mV

Question 12

Describe the path of electrical impulses through the heart?

Answer 12

Starts at the sinoatrial node, through the atria, to the atrioventricular node, down the left and right bundle branches, to the perkinje fibres

Question 13

ECG:

What electrical action does the P wave relate to?

Answer 13

Atrial Depolarisation

Question 14

ECG:

What does the QRS complex relate to?

Answer 14

Ventricular depolarisation

Question 15

ECG:

What does the T Wave represent?

Answer 15

Ventricular Repolarisation

Question 16

ECG:

What is a PR interval, and what is the normal range?

Answer 16

The gap between the start of the P wave and the start of the QRS complex, usually between 120 - 200ms

Question 17

Heart sounds are often described as “Lub-Dub”, what causes the “Lub” sound?

Answer 17

Closing of the Atrioventricular valves during isometric contraction of the ventricles

Question 18

What simple and fast response does the body do to compensate for falling blood pressure?

Answer 18

Raise heart rate

Question 19

What is preload

Answer 19

Blood volume in the ventricles before contraction