Nokea
The hormone involved in rhythmic activities, such as day/night and seasonal changes, is .
- A. calcitonin
- B. melatonin
- C. estrogen
- D. cyclin
Correct Answer: B
Rationale: The correct answer is B: melatonin. Melatonin is the hormone involved in regulating rhythmic activities like day/night and seasonal changes through its influence on the body's circadian rhythm. Calcitonin is a hormone that regulates calcium levels in the blood; estrogen is a female sex hormone; and cyclin is a protein involved in cell cycle regulation. Melatonin's role in regulating sleep-wake cycles and responding to changes in light exposure makes it the most appropriate choice for a hormone involved in rhythmic activities.
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The secretion of parathyroid hormone is a good example of __________.
- A. pituitary gland stimuli
- B. humoral stimuli
- C. neural stimuli
- D. hormonal stimuli
Correct Answer: B
Rationale: The correct answer is B: humoral stimuli. Parathyroid hormone secretion is regulated by the concentration of calcium in the blood, which is an example of humoral stimuli. When blood calcium levels decrease, parathyroid hormone is released to increase calcium levels. Pituitary gland stimuli (A), neural stimuli (C), and hormonal stimuli (D) are not directly involved in the regulation of parathyroid hormone secretion.
This cone-shaped gland is located in the head and is called the “biological clock.â€
- A. Posterior pituitary
- B. Hypothalamus
- C. Pineal
- D. Thymus
Correct Answer: C
Rationale: The correct answer is C: Pineal gland. The pineal gland is located in the brain and is often referred to as the "biological clock" due to its role in regulating the sleep-wake cycle through the secretion of melatonin. The posterior pituitary (choice A) is responsible for releasing hormones produced by the hypothalamus, not related to the circadian rhythm. The hypothalamus (choice B) is involved in regulating various physiological processes but is not directly associated with the circadian rhythm. The thymus (choice D) plays a role in the immune system, not in regulating the biological clock. Thus, the pineal gland is the correct answer as it specifically controls the circadian rhythm.
Thyroid hormone exerts its influence by ________.
- A. entering some cells and binding to intracellular receptors within the nuclei
- B. exerting only a minor effect on body metabolism
- C. causing a reduction in the number of blood vessel adrenergic receptors, and therefore decreasing blood pressure
- D. acting to decrease basal metabolic rate
Correct Answer: A
Rationale: The correct answer is A because thyroid hormone is a lipid-soluble hormone that can diffuse across the cell membrane and bind to intracellular receptors within the nuclei. This binding activates gene transcription, leading to various metabolic effects. Choice B is incorrect because thyroid hormone actually has a significant impact on body metabolism. Choice C is incorrect as thyroid hormone does not directly affect blood vessel adrenergic receptors or blood pressure. Choice D is incorrect as thyroid hormone actually acts to increase basal metabolic rate, not decrease it.
The neurohypophysis:
- A. is the anterior pituitary gland.
- B. secretes ACTH, TSH, and the gonadotropins.
- C. secretes the releasing hormones.
- D. is the posterior pituitary gland.
Correct Answer: D
Rationale: Step-by-step rationale:
1. The neurohypophysis is the posterior pituitary gland.
2. It stores and releases hormones produced by the hypothalamus.
3. These hormones include oxytocin and vasopressin.
4. These hormones regulate water balance, blood pressure, and uterine contractions.
5. Choice D is correct as it accurately describes the neurohypophysis.
Summary:
A: Incorrect - Anterior pituitary gland is not the neurohypophysis.
B: Incorrect - These hormones are secreted by the anterior pituitary gland.
C: Incorrect - Releasing hormones are produced by the hypothalamus, not the neurohypophysis.
The hypersecretion of growth hormone leads to:
- A. Cretinism
- B. Myxoedema
- C. Acromegaly
- D. Graves disease
Correct Answer: C
Rationale: The correct answer is C: Acromegaly. Hypersecretion of growth hormone in adults leads to acromegaly, characterized by enlarged hands, feet, and facial features. This occurs due to excess GH after epiphyseal plate closure.
A: Cretinism is caused by congenital hypothyroidism, not GH hypersecretion.
B: Myxoedema is a severe form of hypothyroidism, not related to GH.
D: Graves disease is an autoimmune disorder causing hyperthyroidism, not GH hypersecretion.