ECFMG Medical Knowledge & Clinical Science — Questions and Answers

Question 1: What is the primary function of hemoglobin in the human body?

Transporting carbon dioxide to the lungs.
Carrying oxygen to tissues (Correct answer)
Regulating blood pressure.
Fighting infections.

Correct answer: Carrying oxygen to tissues

Hemoglobin is a protein found in red blood cells that contains iron. Its primary function is to bind with oxygen in the lungs and transport it efficiently through the bloodstream to various tissues and organs throughout the body. This oxygen is vital for cellular respiration and energy production, making hemoglobin essential for life.

Question 2: Which organ is primarily responsible for insulin production?

Liver.
Kidneys.
Pancreas (Correct answer)
Thyroid gland.

Correct answer: Pancreas

The pancreas is a glandular organ located behind the stomach that plays a crucial role in both digestion and hormone production. Specifically, the beta cells within the islets of Langerhans in the pancreas are responsible for producing insulin. Insulin is a hormone essential for regulating blood glucose levels by facilitating glucose uptake into cells.

Question 3: What type of joint is the knee classified as?

Ball and socket joint.
Hinge joint (Correct answer)
Pivot joint.
Saddle joint.

Correct answer: Hinge joint

The knee joint is classified as a hinge joint, which primarily allows for movement in one plane, similar to a door hinge. This type of joint facilitates flexion (bending) and extension (straightening) of the leg. While it does allow for some limited rotation when flexed, its main function is uniaxial movement.

Question 4: Which vitamin deficiency causes scurvy?

Vitamin A.
Vitamin C (Correct answer)
Vitamin D.
Vitamin B12.

Correct answer: Vitamin C

Scurvy is a disease caused by a severe deficiency of Vitamin C, also known as ascorbic acid. Vitamin C is essential for the synthesis of collagen, a crucial protein for connective tissues, wound healing, and maintaining healthy blood vessels, bones, and teeth. Without sufficient Vitamin C, these bodily functions are impaired, leading to characteristic symptoms.

Question 5: What is the normal range for adult human body temperature?

35.0°C to 36.0°C.
36.5°C to 37.5°C (Correct answer)
37.5°C to 39.0°C.
34.0°C to 35.5°C.

Correct answer: 36.5°C to 37.5°C

The normal range for adult human body temperature is generally considered to be between 36.5°C and 37.5°C (or 97.7°F to 99.5°F). While 37.0°C (98.6°F) is often cited as the average, individual temperatures can fluctuate slightly throughout the day and vary based on factors like activity level. Maintaining this narrow range is crucial for optimal physiological function.

Question 6: Which blood type is considered the universal donor?

Type A positive.
Type AB positive.
Type O negative (Correct answer)
Type B negative.

Correct answer: Type O negative

Type O negative blood is considered the universal donor because its red blood cells lack A, B, and Rh antigens. This means it can be safely transfused to patients of any blood type without triggering an immune response, making it critically important in emergency situations when a patient's blood type is unknown. However, O negative individuals can only receive O negative blood.

Question 7: What is the main neurotransmitter involved in muscle contraction?

Dopamine.
Serotonin.
Acetylcholine (Correct answer)
GABA.

Correct answer: Acetylcholine

Acetylcholine is the primary neurotransmitter responsible for muscle contraction in the somatic nervous system. When an action potential reaches the neuromuscular junction, acetylcholine is released and binds to receptors on the muscle fiber, initiating a cascade of events that leads to muscle contraction. It also plays a crucial role in the autonomic nervous system and brain function.

Question 8: Which condition is characterized by the destruction of myelin sheaths in the central nervous system?

Parkinson’s disease.
Alzheimer’s disease.
Multiple sclerosis (Correct answer)
Amyotrophic lateral sclerosis.

Correct answer: Multiple sclerosis

Multiple sclerosis (MS) is a chronic, autoimmune disease that affects the brain and spinal cord, which constitute the central nervous system. In MS, the immune system mistakenly attacks and damages the myelin sheath, the protective covering around nerve fibers. This demyelination disrupts the transmission of nerve impulses, leading to a wide range of neurological symptoms.

Question 9: Which electrolyte imbalance is commonly seen in patients with Addison’s disease?

Hypernatremia and hypokalemia.
Hyponatremia and hyperkalemia (Correct answer)
Hypercalcemia.
Hypomagnesemia.

Correct answer: Hyponatremia and hyperkalemia

Addison's disease is characterized by adrenal insufficiency, meaning the adrenal glands produce insufficient amounts of cortisol and often aldosterone. Aldosterone's primary role is to regulate sodium and potassium balance. A deficiency in aldosterone leads to increased sodium excretion (hyponatremia) and decreased potassium excretion (hyperkalemia) by the kidneys, which are hallmark electrolyte imbalances of the condition.

ECFMG Medical Knowledge & Clinical Science

What is the primary function of hemoglobin in the human body?