Cardiac cycle

Question 1

What are the 3 basic components of the circulatory system?

Answer 1

Heart

pump that provides pressure gradient needed for blood to flow

Blood vessels

passageways through which blood is distrubuted to different parts of the body

Blood

transport medium for delivery of gases, nutrients + hormones

Question 2

A pulse in the internal jugular vein reflects _____

What does each letter represent on the diagram

Answer 2

Right atrial pressure changes

a = rise in pressure associated with atrial systole

v = rise in pressure as atrium fills during ventricular systole

c = pressure wave during isovolumetric ventricular contraction causing bulging of the AV tricuspid valve

Question 3

2 heart sounds - lub + dup

They reflect the closing/opening of valves

Which valves associate with each sound?

Answer 3

1st = lub - AV (mitral) valve closure

2nd = dup - aortic/pulmonary valve closure

Question 4

Describe the pressure profiles in the left atrium, left ventricle and the aorta in a single cardiac cycle in a healthy adult and given a relevant diagram be able to:

Label the pressure axis

Label the time base (assuming heart rate = 60 beats per min)

Indicate the points where the cardiac valves open and close

Draw the profile of the volume changes in the left ventricle

Indicate the positions of the 1st and 2nd heart sounds and explain their origins

Answer 4

Question 5

Excessive noise causes turbulence - leading to abnormal sounds

This can be due to high flow + flow in different directions

What are the 2 causes for these abnormal heart sounds?

Answer 5

Stenosis (narrowing)

• creates steep pressure gradient - high flow across the valve
• murmur when valve opens
• e.g. aortic stenosis

Leaky/incompetent/insufficient valve

• means flow in different directions
• Murmur when valve should be closed
• e.g. aortic regurgitation