MCQs on Human Endocrine System - Biology MCQs

# Which of the following hormones acts via an intracellular receptor mechanism?
A. Insulin
B. Epinephrine
C. Cortisol
D. Glucagon

# A patient presents with bilateral exophthalmos, heat intolerance, weight loss, and an enlarged thyroid gland. Which condition is most likely?
A. Myxedema
B. Grave's disease
C. Cushing's syndrome
D. Addison's disease

# Which hormone is NOT synthesized by the anterior pituitary gland?
A. Adrenocorticotropic Hormone (ACTH)
B. Growth Hormone (GH)
C. Thyroid-Stimulating Hormone (TSH)
D. Oxytocin

# The primary function of Parathyroid Hormone (PTH) is to:
A. Decrease blood calcium levels
B. Increase blood calcium levels
C. Decrease blood glucose levels
D. Increase blood glucose levels

 

# The Islets of Langerhans are found in which organ?
A. Spleen
B. Pancreas
C. Liver
D. Kidney

# Aldosterone, a mineralocorticoid, primarily acts on the:
A. Distal convoluted tubule and collecting duct
B. Loop of Henle
C. Proximal convoluted tubule
D. Glomerulus

# Which of the following is an example of a positive feedback loop?
A. Release of oxytocin during childbirth
B. Regulation of blood glucose by insulin
C. Regulation of cortisol by ACTH
D. Regulation of thyroxine by TSH

# The hormone responsible for the development and maintenance of female secondary sexual characteristics is:
A. Progesterone
B. Luteinizing Hormone (LH)
C. Estrogen
D. Follicle-Stimulating Hormone (FSH)

A patient presents with bilateral exophthalmos, heat intolerance, weight loss, and an enlarged thyroid gland. Which condition is most likely?

 # A patient presents with bilateral exophthalmos, heat intolerance, weight loss, and an enlarged thyroid gland. Which condition is most likely?

A. Myxedema

B. Grave’s disease

C. Cushing’s syndrome

D. Addison’s disease

The most likely condition is B. Graves’ disease.

Explanation:

• Bilateral exophthalmos (bulging eyes), heat intolerance, weight loss, and enlarged thyroid gland (goiter) are hallmark symptoms of Graves’ disease, an autoimmune disorder causing hyperthyroidism. It results from thyroid-stimulating antibodies that overactivate the thyroid, leading to excess thyroid hormone production.
• Myxedema (A) is associated with hypothyroidism, presenting with symptoms like weight gain, cold intolerance, and fatigue, not matching the patient’s symptoms.
• Cushing’s syndrome (C) involves excess cortisol, leading to weight gain (often central), moon face, and hypertension, but not typically exophthalmos or thyroid enlargement.
• Addison’s disease (D) is adrenal insufficiency, causing weight loss, fatigue, and hypotension, but it lacks exophthalmos or thyroid involvement.

Thus, Graves’ disease best fits the clinical presentation.

Which of the following hormone acts via an intracellular receptor mechanism?

 # Which of the following hormone acts via an intracellular receptor mechanism?

A. Insulin

B. Epinephrine

C. Cortisol

D. Glucagon

The correct answer is C. Cortisol.

Cortisol acts via an intracellular receptor mechanism. It is a steroid hormone that binds to glucocorticoid receptors inside the cell, affecting gene expression.

Explanation:

• Insulin (A) and Glucagon (D) are peptide hormones that bind to cell surface receptors (tyrosine kinase and G-protein-coupled receptors, respectively), triggering extracellular signaling pathways.
• Epinephrine (B) is a catecholamine that also acts through cell surface G-protein-coupled receptors (e.g., adrenergic receptors).
• Cortisol (C), a steroid hormone, crosses the cell membrane and binds to intracellular glucocorticoid receptors, forming a complex that translocates to the nucleus to regulate gene transcription.

Thus, the correct answer is C. Cortisol.