Nokea
Upper segment > lower segment of body is found in all (in dwarfism) except:
- A. Pituitary dwarf
- B. Cretinism
- C. Achondroplasia
- D. Juvenile myxedema
Correct Answer: D
Rationale: In dwarfism conditions, the upper body segment being greater than the lower body segment is a characteristic feature seen in Achondroplasia. This condition results in a disproportionately short stature with short limbs but a trunk of normal length.
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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.
Thyroid-stimulating hormone (TSH):
- A. is a glycoprotein hormone.
- B. is synthesized in the follicular cells of the thyroid gland.
- C. has gonadotropic activity.
- D. stimulates the activity of parafollicular thyroid cells.
Correct Answer: A
Rationale: Thyroid-stimulating hormone (TSH) is a glycoprotein hormone that is produced and secreted by the anterior pituitary gland. It acts on the thyroid gland to stimulate the production and release of thyroid hormones, T3 (triiodothyronine) and T4 (thyroxine). TSH plays a crucial role in regulating the function of the thyroid gland and maintaining overall thyroid hormone levels in the body.
Oxytocin:
- A. is bound to neurophysin in plasma.
- B. inhibits production of milk.
- C. inhibits myometrial contraction.
- D. inhibits sperm swimming on the gonad.
Correct Answer: A
Rationale: Oxytocin is a hormone produced by the hypothalamus and released by the pituitary gland. In the bloodstream, oxytocin is mostly bound to a carrier protein called neurophysin. This binding helps to protect oxytocin from being degraded too quickly in the bloodstream, thus allowing it to exert its effects on target tissues such as the uterus and mammary glands. Oxytocin plays important roles in stimulating uterine contractions during labor, facilitating milk letdown during breastfeeding, and promoting social bonding and emotional connections.
Hormones are:
- A. biologically inert by themselves.
- B. used as an energy source
- C. incorporated as a structural moiety into another molecule
- D. always stored in secretory granules
Correct Answer: C
Rationale: Hormones are chemical messengers that are produced by various glands in the body and released into the bloodstream to signal and regulate the activity of specific target cells. Unlike energy sources that can be metabolized for energy production (like carbohydrates and fats), hormones are not typically used as an energy source themselves (Choice B). Hormones are typically not biologically inert by themselves (Choice A), as they have specific functions in regulating various physiological processes in the body. While some hormones may be stored in secretory granules before release, not all hormones are stored in this manner (Choice D). Additionally, hormones are not always released by exocytosis (Choice E), as some hormones can also be released through other mechanisms such as diffusion. The correct choice, therefore, is C: hormones are incorporated as a structural moiety into another molecule, as they bind to specific receptors on target cells to elicit a cellular response and regulate physiological functions.
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.