1. Iron is absorbed predominantly in the

a) Stomach

b) Duodenum

c) Jejunum

d) Ileum

e) Colon

Correct Answer: b) duodenum and c) upper jejunum. Iron enters the stomach from the esophagus. Iron is oxidized to the Fe3+ state no matter its original form when taken in orally. Gastric acidity as well as solubilizing agents such as ascorbate prevent precipitation of the normally insoluble Fe3+ . Intestinal mucosal cells in the duodenum and upper jejunum absorb the iron. The iron is coupled to transferrin in the circulation which delivers it to the cells of the body.

2. Which type of blood is more dark than the other?

a) Venous

b) Capillary

c) Spider veins

d) Arterial

Correct Answer:c) Spider veins. Human blood is red, ranging from bright red when oxygenated to dark red when not. It owes its color to hemoglobin, to which oxygen binds. Deoxygenated blood is darker due to the difference in color between deoxyhemoglobin and oxyhemoglobin. There exists a popular misconception that deoxygenated blood is blue and that blood only becomes red when it comes into contact with oxygen. Blood is never blue, but veins appear blue because light is diffused by skin. Moreover, the blood inside is dark red and exhibits poor light reflection. Blood also changes color due to the amount of oxygen in it.

Telangiectasias / spider veins are small dilated blood vessels near the surface of the skin or mucous membranes. Since spider veins are caused by poor blood flow and circulation it is likely to be most deoxygenated than other.

3. Active transport : Physiology MCQ

a) Takes place in the kidney

b) Takes place in the placenta

c) Takes place in the liver

d) Takes place in the red blood cell

e) Of glucose requires Na+ to move across the cell membrane in the opposite direction

Correct Answer: a,b,d.

4. Radiation : Physiology MCQ

Cells are most susceptible to radiation in which phase?

a) M phase

b) G2 phase

c) G1 phase

d) S phase

Correct Answer: a) M phase. Cells are least sensitive when in the S phase, then the G1 phase, then the G2 phase, and most sensitive in the M phase of the cell cycle. Quickly dividing tumor cells are generally more sensitive than the majority of body cells. Most sensitive cells are those that are undifferentiated, well nourished, dividing quickly and highly active metabolically. Amongst the body cells, the most sensitive are spermatogonia and erythroblasts, epidermal stem cells, gastrointestinal stem cells. The least sensitive are nerve cells and muscle fibers.

5. Wound healing is delayed by deficiency of

a) Vitamin D

b) Zinc

c) Calcium

d) Sulphur-containing amino acids

e) Glucocorticoid hormones

Correct Answer: b and d. Zinc deficiency impair wound healing as a result of altered inflammatory responses. Sulphur-containing amino acids such as methionine and cystine impair wound healing. Also deficiency of Vitamin C also impair wound healing.

6. Electrolyte : Physiology MCQ

Which electrolyte has a role in maintaining intracellular fluids, helping the regulation of pH and establishing resting membrane potential of the cells?

a) Bicarbonates

b) Calcium

c) Chloride

d) Potassium

e) Sodium

Correct Answer: d) Potassium. Hypokalaemia may be caused by inadequate replacement by intravenous therapy, insulin therapy, vomiting and diarrhoea. It is commonly associated with paralytic ileus. Sodium has a key role in fluid balance. It contributes half the osmolarity of the extracellular fluid. Calcium has a main role in excitable cells, neurotransmitter release and blood clotting.

7. Repolarisation : Physiology MCQ

Opening of which channel leads to Repolarisation of muscle

a) Calcium

b) Potassium

c) Sodium

d) Chloride

e) Hodgkin-Huxley sodium channels

Correct Answer: b) Potassium. Action potentials: rapid influx of sodium ions causes the polarity of the plasma membrane to reverse, and the ion channels then rapidly inactivate. As the sodium channels close, sodium ions can no longer enter the neuron, and then they are actively transported back out of the plasma membrane. Potassium channels are then activated, and there is an outward current of potassium ions, returning the electrochemical gradient to the resting state.

8. Partial Pressure of CO2 in atmospheric air

a) 760 mm Hg

b) 159 mm Hg

c) 0.3 mm Hg

d) 600 mm Hg

e) 3 mmHg

Correct Answer: c) 0.3 mm Hg. PCO2 in inspired air is 0.3 mmHg and is 46 mmHg in venous blood. The net direction of diffusion therefore is from the blood to the alveoli resulting in a PCO2 in arterial blood of 40 mmHg.

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