Question
What is a function of the pancreas?
A. To control the rate of metabolism by releasing thyroxine when metabolic rate is low
B. To release glucagon when blood glucose levels are low
C. To release insulin when blood glucose levels are low
D. To secrete an endopeptidase which lowers the blood glucose levels
▶️Answer/Explanation
Answer: B. To release glucagon when blood glucose levels are low
Explanation:
The pancreas plays a key role in regulating blood glucose levels by releasing hormones:
- When blood glucose is low, the pancreas releases glucagon. Glucagon signals the liver to break down glycogen into glucose and release it into the blood, raising blood glucose levels.
- When blood glucose is high, the pancreas releases insulin to help cells absorb glucose and lower blood glucose levels.
Option Evaluation:
A. Incorrect — Thyroxine is released by the thyroid gland, not the pancreas.
B. Correct — The pancreas releases glucagon when blood glucose is low.
C. Incorrect — Insulin is released when blood glucose is high, not low.
D. Incorrect — Endopeptidases break down proteins, not involved in lowering blood glucose.
Question
What distinguishes capillaries from other blood vessels?
A. They have valves which allow blood flow in one direction only.
B. They have a thin layer of muscle to help pump blood to the veins.
C. They have thin, permeable walls to allow exchange of materials between tissue and blood.
D. They have a thin layer of elastic fibre to resist changes in blood pressure.
▶️Answer/Explanation
Answer: C. They have thin, permeable walls to allow exchange of materials between tissue and blood.
Explanation:
Capillaries are the smallest blood vessels and are specially adapted for the exchange of substances between the blood and the surrounding tissues. Their walls are just one cell thick, making them very thin and permeable. This thinness allows oxygen, nutrients, and waste products to easily pass through by diffusion.
Option Evaluation:
A. Incorrect — Valves are found in veins to prevent backflow, not in capillaries.
B. Incorrect — Capillaries do not have muscle layers; arteries have muscle layers to control blood flow.
C. Correct — Thin, permeable walls are the key feature allowing exchange in capillaries.
D. Incorrect — Elastic fibers are prominent in arteries, helping them resist pressure changes, not capillaries.
Question
The diagram shows how heart sounds are aligned with the changes in blood pressure in the cardiac cycle.
What can be deduced about the cause of the heart sounds?
A. The 1st heart sound is caused by the closing of the atrio-ventricular valves
B. The 2nd heart sound is caused by the opening of the atrio-ventricular valves
C. The 1st heart sound is caused by the closing of the semi-lunar valves
D. The 2nd heart sound is caused by the closing of the atrio-ventricular valves.
▶️Answer/Explanation
Answer: A. The 1st heart sound is caused by the closing of the atrio-ventricular valves
Explanation:
The heart sounds (S₁ and S₂) are associated with valve closures during the cardiac cycle:
1st Heart Sound (S₁) – “Lub”
- Occurs at the start of ventricular systole
- Cause: Closure of the atrioventricular (AV) valves (tricuspid and mitral valves)
- Seen just after the ventricular pressure sharply rises, indicating ventricular contraction
- Prevents backflow into the atria
2nd Heart Sound (S₂) – “Dub”
- Occurs at the end of ventricular systole
- Cause: Closure of the semilunar valves (aortic and pulmonary valves)
- Happens when ventricular pressure drops below aortic pressure, leading to semilunar valve closure
Evaluation of Incorrect Options:
B. The 2nd heart sound is caused by opening of AV valves
Incorrect — valve openings are silent; the 2nd sound marks closure of semilunar valves
C. The 1st heart sound is caused by semilunar valve closure
Incorrect — these close at the end of systole, causing the 2nd sound
D. The 2nd heart sound is caused by the AV valve closure
Incorrect — AV valves close at the start of systole (1st sound)
Question
What is a function of luteinizing hormone (LH) in the female menstrual cycle?
A. To promote secondary sexual characteristics
B. To inhibit progesterone secretion
C. To stimulate the follicle to release estrogen
D. To trigger ovulation
▶️Answer/Explanation
Answer: D. To trigger ovulation
Explanation:
Luteinizing hormone (LH) plays a crucial role in the female menstrual cycle. Its main function is to cause the mature follicle in the ovary to release an egg — a process called ovulation. This LH surge happens roughly in the middle of the cycle.
Option Evaluation:
A. Incorrect — Secondary sexual characteristics are promoted mainly by estrogen and progesterone, not LH.
B. Incorrect — LH does not inhibit progesterone secretion; progesterone is secreted after ovulation by the corpus luteum.
C. Incorrect — Estrogen is mainly produced by the follicle itself; LH surge occurs after estrogen levels peak.
D. Correct — LH triggers ovulation, releasing the egg from the follicle.
Question
On the graph, which curve represents the change in FSH levels during the menstrual cycle?
▶️Answer/Explanation
Answer: D.
Explanation:
The graph shows hormonal changes during the menstrual cycle (typically 28 days). Let’s identify which curve corresponds to FSH (Follicle Stimulating Hormone):
FSH Overview:
- Secreted by the anterior pituitary
- Stimulates follicle development in the ovary
- Peaks just before ovulation (around day 14)
- Slight secondary rise may occur in the luteal phase
Interpretation of Curves:
Let’s analyze each label:
A.
- Sharp peak at day 14
- Then rapid drop
- This is LH (Luteinizing Hormone) – triggers ovulation
B.
- Rises after ovulation and peaks during the luteal phase
- This is Progesterone, secreted by the corpus luteum
C.
- Rises gradually before ovulation
- Then dips and rises again
- This is Estrogen (Oestrogen), produced by growing follicles and later corpus luteum
D.
- Low baseline with a modest peak just before day 14
- Small bump later in the cycle
- Matches FSH pattern