Week 8 Lectorial Questions

In the body, oxygenated and deoxygenated blood generally do not mix.  This is because blood flows in one direction and, the heart is divided into right and left sides.

• Q1. List the pathway that blood flows through the heart. Start from when it enters the right atrium until it leaves the heart from the aorta. Include in your answer, the side of the heart, blood vessels, lungs and the valves. (3 marks)

• Q2. Explain why the left ventricle of the heart has a thicker muscular wall compared to the right ventricle. (50 words or fewer) (1 mark)

• Q3. When our heart beats, distinctive ‘lub/dup’ sounds can be heard.  Describe what these sounds refer to based on the contraction and relaxation of the heart. (75 words or fewer) (2 marks)

Before birth, the majority of blood flow is diverted away from the lungs through a shunt between the right atrium and left atrium, known as the foramen ovale.  When a baby is born, generally their first breath closes the foramen ovale and blood is now directed to the lungs.

• Q4. In some cases, the foramen ovale may not close properly. Explain what impact this may have on the oxygen content of the blood within the systemic circulation. (100 words or fewer) (2 marks)

• Q5. Based on your answer above, describe what impact this may have on a person’s ability to perform strenuous exercise. (100 words or fewer) (2 marks)

Note the following table lists the partial pressures of oxygen and carbon dioxide within the body. Partial pressure is the pressure of a single gas in a mixture of gases.

• Q1. Provide one reason for the difference in the partial pressure of oxygen between the arterial and venous blood. (50 words or fewer) (1 mark)

• Q2. Provide one reason for the difference in the partial pressure of carbon dioxide between the arterial and venous blood. (50 words or fewer) (1 mark)

• Q3. Define the two types of alveoli cells. (50 words or fewer) (1 mark)

• Q4. Explain why the partial pressure of oxygen is the same in the alveoli as the arterial blood. (75 words or fewer) (2 marks)

• Q5. Air flow into and out of the lungs is achieved by the contraction and relaxation, respectively, of muscles in the ribcage. Describe why the lungs move with the ribcage during this process. (75 words or fewer) (2 marks)