Nokea
Commonest enzymatic defect for development of congenital adrenal hyperplasia is:
- A. C-21 hydroxylase deficiency
- B. 3b dehydrogenase deficiency
- C. C-11 hydroxylase deficiency
- D. C-17 hydroxylase deficiency
Correct Answer: A
Rationale: C-21 hydroxylase deficiency is the most common enzymatic defect leading to the development of congenital adrenal hyperplasia (CAH). This enzyme is necessary for the synthesis of cortisol and aldosterone in the adrenal glands. When there is a deficiency in C-21 hydroxylase, the pathway is shifted towards the production of androgens instead of cortisol and aldosterone, leading to excess androgen production. This results in the characteristic features of CAH, such as ambiguous genitalia in females and virilization in both males and females. Other enzyme deficiencies listed in the choices can also lead to different types of CAH but are less common compared to C-21 hydroxylase deficiency.
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The receptors for non-steroid peptide hormones are found on the ______.
- A. plasma membrane
- B. nuclear envelope
- C. mitochondria
- D. lysosomes
Correct Answer: A
Rationale: The receptors for non-steroid peptide hormones are typically found on the plasma membrane of target cells. These hormones are large or polar molecules that cannot easily diffuse through the cell membrane. Instead, they bind to specific receptors on the cell surface, initiating signaling pathways that eventually lead to changes within the cell. Once the peptide hormone binds to its receptor on the plasma membrane, secondary messenger systems are activated to relay the signal into the cell and initiate the appropriate cellular response. This distinct mechanism of action highlights the importance of the plasma membrane as the location of receptors for non-steroid peptide hormones.
Which of the following are common symptoms of hyperthyroidism?
- A. Tremor
- B. Weight gain
- C. Heat intolerance
- D. Diarrhoea
Correct Answer: A
Rationale: Tremor (A): Tremors or shaky hands are common symptoms of hyperthyroidism. This is due to the increased metabolic rate caused by excess thyroid hormone in the body.
Regarding syndrome of inappropriate antidiuretic hormone (SIADH), which is true?
- A. Hyponatremia is dilutional
- B. Urine is relatively hypertonic to plasma
- C. ADH-mediated water reabsorption does not occur
- D. Renal function is jeopardized
Correct Answer: A
Rationale: In the syndrome of inappropriate antidiuretic hormone (SIADH), there is excessive secretion of antidiuretic hormone (ADH) leading to increased water reabsorption in the kidney tubules. This results in dilutional hyponatremia because the amount of water reabsorbed is greater than the electrolytes, such as sodium, leading to a relative decrease in their concentration in the blood. As a result, hyponatremia occurs in SIADH, contributing to symptoms such as nausea, confusion, and seizures due to the imbalance in electrolytes.
Charcot joint in diabetes mellitus commonly affects:
- A. Hip
- B. Shoulder
- C. Knee
- D. Foot
Correct Answer: D
Rationale: Charcot joint, also known as neuropathic arthropathy, is a serious complication of diabetes mellitus that affects the joints. It commonly affects the foot, especially the midfoot and hindfoot. The condition is characterized by joint deformities, fractures, and dislocations due to nerve damage and loss of sensation in the foot. The repetitive stress on the foot from walking or weight-bearing activities can lead to progressive joint destruction and deformity. It is important for individuals with diabetes to monitor their foot health closely and seek prompt medical attention if they notice any changes or deformities in their feet.
Parathyroid hormone:
- A. increases deposition of calcium in bones.
- B. causes development of goitre.
- C. is the molecule formed when T4 and T3 are degraded.
- D. is secreted in increased amounts when blood calcium level is below normal.
Correct Answer: D
Rationale: Parathyroid hormone (PTH) is a hormone produced by the parathyroid glands in response to low blood calcium levels. Its main function is to raise calcium levels in the blood by acting on the bones, kidneys, and intestines. PTH stimulates the release of calcium from the bones, enhances the absorption of calcium by the intestines, and promotes the reabsorption of calcium by the kidneys. Therefore, it is secreted in increased amounts when blood calcium levels are below normal in order to maintain overall calcium balance in the body.