Anatomy and Physiology MCQs

Glaucoma is an eye disease which affects vision. It is caused by:

Blockage of the flow of aqueous humour through the canal of Schlemm and loss of intraocular pressure in the vitreous humour

Detachment of the retina and subsequent loss of vision in this part of the eye

Cataracts that form in the eye’s lens which prevent light from reaching the retina

Increased intraocular pressure which collapses the blood capillaries that perfuse the retina so part of it dies

Glaucoma results from higher than healthy intraocular pressure in the eyeball.

Author: rikazzz Comment

Ionising Radiation

Why is a radionuclide with a short half-life and which emits low-energy gamma radiation preferred for in vivo diagnosis? Because they:

Have a low activity

Are highly penetrating

Emit their radiation in a short time span

Are very damaging to cancerous tissue

Having a short half-life means that a lot of radiation is emitted in a short time period. If the radiation was emitted over a long time, the patient would be required to lie motionless for that long time while the image (the scintigram) was produced.

Author: rikazzz Comment

Gastrointestinal System

What converts pepsinogen to pepsin in the stomach?

Hydrochloric acid

Gastrin

Intrinsic factor

Pepsinase

HCl cleaves off 44 amino acids from pepsinogen to form pepsin.

Author: rikazzz Comment

Organisation of the Body

To what movement is the term “extension” applied?

Extension is where the angle between two long bones is decreased by muscle action.

Extension is an action performed to stretch (extend) a muscle.

Extension is where the angle between two long bones is increased by muscle action.

Extension occurs when an antagonistic muscle is allowed to contract.

To extend a body part is to increase the angle between the moving bone and the stationary bone. For example, when the fingers of a clenched fist are allowed to straighten, the angle between the proximal phalanges and the metacarpals increases.

Author: rikazzz Comment

Nervous System

Which best describes a nerve?

Dendrites, cell bodies, axons, Schwann cells

Dendrites, cell bodies, axon hillock, axon terminals, vesicles

Dendrites, cell bodies, axon hillock, axon terminals, Schwann cells, neurotransmitters

Axons, blood vessels, connective tissue, Schwann cells

A nerve is a bundle of axons of individual neurons. Hence it does not contain nerve cell bodies. A nerve does include the Schwann cells around axons, BV and CT.

Author: rikazzz Comment

Cardiovascular System

The millimetre of mercury (mmHg) is one of the non-SI units used in the measurement of pressure. It is used because:

Mercury is much denser than water so a much shorter tube can be used than if cm H₂O was the unit.

One of the factors that determine pressure is the length of the object supplying the force.

A manometer that utilises mercury does not require an electrical power supply.

Historically the first measurement of air pressure was made using a glass tube containing mercury.

The best answer is the historical use of liquid mercury (hydrogyrum) to measure pressure. The reason that Hg was used is as stated in choice A.

Author: rikazzz Comment

Measurement, Errors, Data and Unit Conversion

A clinical thermometer is used to measure someone’s body temperature to be 101oF (Fahrenheit). When this temperature is converted to degrees Celsius using the conversion formula, T(°C) = (T(°F) – 32) × 5/9, what is the correct value?

−6.5

38.3

82

124

Centigrade temperature values above zero are always smaller than Fahrenheit values. T(°C) = (T(°F) – 32) × 5/9 = (101–32) × 5/9 = 69 × /9 = 345/9 = 38.3 °C.

Author: rikazzz Comment

Respiratory System

When is the respiratory centre of the brain stimulated to increase ventilation?

Plasma CO₂ concentration increases.

Plasma pH increases.

Plasma O₂ concentration decreases.

Plasma HCO₃− decreases.

Concentration of carbon dioxide in plasma stimulates ventilation. The presence of more carbon dioxide would tend to decrease pH where it not for the buffers in blood.

Author: rikazzz Comment

Cardiovascular System

When listening to the “lub-dup” sound of the heart with a stethoscope, what is the cause of the “dup” sound?

The blood flowing through the open semilunar valves

The blood flowing through the open atrioventricular valves

The turbulent blood flow through closing atrioventricular valves

The turbulent blood flow through closing semilunar valves

Turbulent blood flow generates audible sound that can be heard with a stethoscope placed on the skin above the heart. Such turbulent flow is produced when blood flow out of the heart is impeded by the cusps of the semilunar valves as they close.

Author: rikazzz Comment

Endocrine System

The hypothalamus produces “releasing hormones”. What do these releasing hormones do?

They direct the posterior pituitary to release hormones.

They direct the anterior pituitary to release hormones.

They direct the gonads to release hormones.

They act as “second messengers” when hormones bind to their receptor site.

The anterior pituitary produces hormones that stimulate other endocrine organs, but the ant pit does not release hormones until directed to the hypothalamus.

Author: rikazzz Comment