Anatomy and Physiology MCQs

Steroid hormones activate a G-protein and exert their effect via “second messengers”, but the action of amino acid-based hormones results directly on binding to their receptor.

Steroid hormones are lipid soluble so can enter the cell to bind to receptors located inside the cell. Amino acid-based hormones are not lipid soluble so their receptors are located outside the cell on the plasma membrane.

Author: rikazzz Comment

Renal System

What effect is achieved by having an arteriole that supplies blood and another that drains blood from the glomerulus?

Oxygen-rich blood can be supplied to the nephron after blood leaves the glomerulus.

The blood pressure within the glomerulus can be manipulated.

Reabsorption of water and nutrients from the filtrate is facilitated.

The concentration gradient within the kidney’s medulla can be maintained.

Arterioles have smooth muscle in their wall which allows them to constrict and dilate, hence adjusting the flow through them and consequently the blood pressure within them.

Author: rikazzz Comment

Cardiovascular System

If the composition of air is 20% oxygen with an atmospheric pressure of 700 mmHg, what would the partial pressure of oxygen be?

14 mmHg

20 mmHg

140 mmHg

700 mmHg

10% of 700 mmHg is 70, so 20% is 140 mmHg.

Author: rikazzz Comment

Chemistry for Physiology

A certain pure substance, A, when heated is changed into two quite different pure substances, C and D. Which of the following statements must be true?

A is a compound.

C and D are not elements.

A, C and D are all compounds.

C and D are elements.

Only this choice must be true. The others are just possible.

Author: rikazzz Comment

Chemistry for Physiology

What term is applied to an intravenous solution that would cause a net movement of water out of red blood cells?

Hypertonic

Supertonic

Hypotonic

None of these

“Hyper-” refers to greater (tonicity) than inside a RBC. Hence water would move from the less concentrated solution (within the RBC) to the exterior.

Author: rikazzz Comment

Ionising Radiation

Given that a radiopharmaceutical containing the radionuclide technetium 99 m ( ⁹⁹₄₃Tc ) has an activity of 4 MBq immediately prior to injection into a patient, about 12 h later the patient is measured to have an activity of about 1 MBq. How long is the half-life of technetium 99 m?

6 h

12 h

24 h

48 h

After one half-life, half of the radioactive atoms have decayed, so only half remain. One MBq which is one quarter of 4 MBq (= ½ × ½) remains after 12 h, so two half-lives have elapsed in the 12 h period. 12/2 = 6 h.

Author: rikazzz Comment