Lecture 5: Heart anatomy

Question 1

Function of Atrioventricular (AV) valves:

Answer 1

• Prevent blood returning to atria during ventricular contraction.
• Right side - tricuspid valve.
• Left side - bicuspid (mitral) valve.

Question 2

Function of Semilunar valves:

Answer 2

• Prevent blood returning to ventricles during filling (diastole).
• Pushed open as blood flows out of heart, - Close as blood starts to backflow
• Right side - Pulmonary (semilunar) valve, 3 cusps.
• Left side - Aortic (semilunar) valve, 3 cusps.

Question 3

Features of Myocardium:

Answer 3

• both smooth & skeletal muscleaswell as cardiac muscle specific specialisations.
  short branched striated cells
• one or two central oval nucleas
• Cytoplasmic organelles packed at the poles of nucleus.
• Intercalated discs

Question 4

What percentage of the cell does mitochondria take up in cardiac muscle

Answer 4

Approx 20%

Question 5

Three structures of intercalated discs:

Answer 5

• Adhesion belts (linking actin to actin) ~Vertical portion.
• Desmosomes (linking cytokeratin with cytokeratin).
• Gap junction (electrochemical communication) ~ Horizontal portion.

Question 6

What is the function of papillary muscle?

Answer 6

Pretension the chordae tendineae prevents hard shutting or prolapsing of the AV valves when pressure rises during ventricular contraction.

Question 7

What is the function of the chordae tendineae?

Answer 7

to maintain the position and tension of the atrioventricular valves (tricuspid and bicuspid valves)