Interior of Heart and Posterior Mediastinum - SDL

Question 1

What is the function of the foetal foramen ovale?

Answer 1

To allow oxygenated blood from the placenta by pass the lungs during foetal development - closes at birth

Question 2

What is the function of the moderator band?

Answer 2

Allows purkinje fibres to pass to the papillary muscle associated with the heart valves.

Question 3

What is the function of the chordae tendinae?

Answer 3

To prevent the valve everting in to the respective atria during ventricular systole.

Question 4

What would be the effect on the right atrium of incomplete closure of the tricuspid valve? How might this manifest itself clinically?

Answer 4

Regurgitation of blood into the right atrium leading to a backlog of blood in the venous system as not as much blood can enter via the SVC, IVC and CS. Oedema will be present and neck veins will swell. Heart murmur could be detected.

Question 5

Describe difference in:

1. Shape
2. Thickness of wall
3. AV valves

between left and right ventricles

Answer 5

1. In cross section the left ventricle is circular; the right is eliptical
2. The left is thicker than the right
3. Tricuspid guard the right atrioventricular orifice – three cusps; the bicuspid valve guards the left AV orifice – two cusps.

Question 6

In which direction would blood tend to flow through a ventricular septal defect? How does such a defect arise?

Answer 6

From the area of high pressure to low pressure, so left to right. Failure for septums between chambers to appropriately close (embryology)

Question 7

What would be the consequences of incompetence of the left atrioventricular valve?

Answer 7

Regurgitation of blood into left atrium, reduced cardia output.

Question 8

What is the function of the ductus arteriosus during development?

Answer 8

To shunt blood from the pulmonary trunk to the aorta and therefore bypass the lungs

Question 9

In which direction would blood flow through a ductus arteriosus which remained patent postnatally? What would be the consequences of this abnormality?

Answer 9

Aorta into pulmonary trunk, reduced cardiac output and reduced deoxygenated blood going to lungs.

Question 10

What is the function of the thoracic duct?

Answer 10

Drain lymph from the entire body except for the upper right quadrant of the body. Drains into the venous system at the formation of the left brachiocephalic vein.

Question 11

Where does the thoracic duct terminate?

Answer 11

Formation of the left brachiocephalic vein.