Nokea
Which one of the following statements describes the underlying pathology of Grave's disease?
- A. An autoimmune disease directed against thyroid stimulating hormone (TSH) receptors. The autoantibodies stimulate the TSH receptors causing increased T3 and T4 production.
- B. Inflammation of the thyroid gland due to lymphocytic infiltration causes the stored thyroid hormones to be released into the circulation leading to hyperthyroidism.
- C. Consumption of ground beef which has been contaminated with thyroid tissue. The thyroid tissue contains metabolically active thyroid hormones which causes hyperthyroidism.
- D. A benign tumour of the thyroid gland which produces excessive amounts of thyroid hormones.
Correct Answer: A
Rationale: Graves' disease is an autoimmune disorder where autoantibodies, known as thyroid-stimulating immunoglobulins (TSIs) or thyroid-stimulating antibodies (TSAs), bind to and stimulate the thyroid-stimulating hormone (TSH) receptors on thyroid follicular cells. This leads to increased production and secretion of thyroid hormones T3 (triiodothyronine) and T4 (thyroxine), causing hyperthyroidism. The autoantibodies essentially mimic the action of TSH, resulting in excess thyroid hormone release and manifestation of hyperthyroid symptoms. This underlying pathology of Graves' disease is distinct from other causes of hyperthyroidism, making choice A the correct statement.
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Oxytocin:
- A. is not produced in males.
- B. inhibits lactation.
- C. stimulates smooth muscle contraction.
- D. is produced primarily in the SON in the hypothalamus.
Correct Answer: C
Rationale: Oxytocin is a hormone that is produced in both males and females. In females, oxytocin plays a crucial role in various physiological processes, notably during labor and childbirth. Oxytocin acts on the smooth muscles of the uterus, causing them to contract during labor (parturition) and helps in the ejection of milk during breastfeeding. This hormone is primarily synthesized in the paraventricular nucleus (PVN) and the supraoptic nucleus (SON) of the hypothalamus and stored in the posterior pituitary gland before being released into the bloodstream. Overall, oxytocin's main function is to stimulate smooth muscle contraction in the uterus and the mammary glands.
ADH is secreted by the
- A. Hypothalamus
- B. Posterior lobe of the pituitary
- C. Intermediate Lobe of the pituitary
- D. Anterior lobe of the pituitary
Correct Answer: B
Rationale: ADH (antidiuretic hormone), also known as vasopressin, is secreted by the posterior lobe of the pituitary gland. ADH plays a key role in regulating water balance in the body by controlling the reabsorption of water in the kidneys. When the body senses a decrease in blood volume or an increase in blood osmolarity, ADH is released to signal the kidneys to conserve water, leading to concentrated urine production and water retention in the body.
Commonest cause of 'ambiguous genitalia' in newborn is:
- A. Congenital adrenal hyperplasia
- B. True hermaphroditism
- C. Testicular ferminisation syndrome
- D. Pseudo-hermaphroditism
Correct Answer: A
Rationale: Congenital adrenal hyperplasia (CAH) is the most common cause of ambiguous genitalia in newborns. This condition is due to a deficiency of enzymes in the adrenal gland that are necessary for the production of cortisol. As a result, the body produces excess androgens (masculinizing hormones), leading to abnormal genital development in females. The external genitalia may appear ambiguous, with features of both male and female genitalia. This condition can be detected through newborn screening and confirmed through further hormonal and genetic testing. Treatment involves hormone replacement therapy to normalize hormone levels and surgery may be required to reconstruct the genitalia.
A person with acromegaly usually has:
- A. prognathism and large fleshy lips.
- B. hypoglycemia.
- C. a growth hormone deficiency.
- D. protruding eye balls.
Correct Answer: A
Rationale: Acromegaly is a hormonal disorder that results from the overproduction of growth hormone (GH) in adulthood. One of the key physical characteristics associated with acromegaly is the enlargement of facial features. People with acromegaly often develop prognathism, which is a condition where the lower jaw protrudes forward, leading to a prominent lower face. Additionally, they may have large fleshy lips due to the soft tissue swelling that occurs as a result of excess GH. Other common signs of acromegaly include enlarged hands and feet, thickened skin, and joint pain.
All are features of diabetic ketoacidosis except:
- A. Hyperthermia
- B. Drowsiness
- C. Dehydration
- D. Air hunger
Correct Answer: A
Rationale: Hyperthermia is not a typical feature of diabetic ketoacidosis (DKA). DKA is typically characterized by high blood sugar levels, ketone accumulation, metabolic acidosis, dehydration, drowsiness, and, in severe cases, unconsciousness. Common symptoms include drowsiness, dehydration, and air hunger (deep and rapid breathing). However, hyperthermia, which refers to an elevated body temperature, is not a characteristic typically associated with DKA. It is important to monitor and manage DKA promptly as it is a serious complication of diabetes that requires immediate medical attention.