Nokea
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.
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Which gland secretes two hormones, one that elevates blood glucose levels and another that decreases blood glucose levels?
- A. Pancreas
- B. Adenohypophysis
- C. Thyroid
- D. Adrenal cortex
Correct Answer: A
Rationale: The correct answer is A: Pancreas. The pancreas secretes insulin to decrease blood glucose levels and glucagon to elevate blood glucose levels. Insulin helps cells absorb glucose for energy, while glucagon triggers the release of stored glucose into the bloodstream. Adenohypophysis (B) secretes various hormones but not related to blood glucose regulation. Thyroid (C) secretes hormones that regulate metabolism, not directly impacting blood glucose levels. Adrenal cortex (D) secretes hormones like cortisol and aldosterone, which are not primarily involved in blood glucose regulation.
An example of a hormone that under certain circumstances is regulated by positive feedback is:
- A. calcitonin.
- B. histamine.
- C. oxytocin.
- D. melatonin.
Correct Answer: C
Rationale: Rationale:
1. Oxytocin is released during childbirth to stimulate uterine contractions.
2. As contractions increase, oxytocin secretion is further stimulated in a positive feedback loop.
3. This positive feedback mechanism amplifies the contractions until delivery.
4. Calcitonin regulates calcium levels, histamine is involved in allergic responses, and melatonin regulates sleep-wake cycles.
Summary:
- Calcitonin, histamine, and melatonin do not exhibit positive feedback regulation like oxytocin during childbirth.
Which endocrine gland normally produces insulin?
- A. Adrenal
- B. Parathyroid
- C. Pancreas
- D. Liver
Correct Answer: C
Rationale: The correct answer is C: Pancreas. The pancreas is the endocrine gland responsible for producing insulin, which regulates blood sugar levels. It is located behind the stomach and plays a crucial role in maintaining glucose balance in the body. The other choices, A: Adrenal, B: Parathyroid, and D: Liver, do not normally produce insulin. Adrenal glands produce hormones like adrenaline and cortisol, the parathyroid regulates calcium levels, and the liver performs various metabolic functions but does not produce insulin. Therefore, the pancreas is the correct choice for insulin production.
Which term describes the maintenance of a stable internal environment?
- A. negative feedback
- B. positive feedback
- C. homeostasis
- D. metabolism
Correct Answer: C
Rationale: Homeostasis is the maintenance of a stable internal environment to support optimal physiological functioning. It involves mechanisms that regulate variables within a narrow range. Negative feedback is a key mechanism in maintaining homeostasis by counteracting deviations from set points. Positive feedback amplifies changes and is not involved in maintaining stability. Metabolism refers to the chemical processes in the body and is not specifically related to the maintenance of internal stability. Therefore, the correct answer is C (homeostasis) because it directly relates to the concept of maintaining a stable internal environment through regulatory mechanisms.
Underproduction of growth hormone during the growing years produces ______.
- A. myxedema.
- B. gigantism.
- C. pituitary dwarfism.
- D. acromegaly.
Correct Answer: C
Rationale: The correct answer is C: pituitary dwarfism. Growth hormone deficiency during growing years results in pituitary dwarfism due to stunted growth. Myxedema (choice A) is associated with hypothyroidism, not growth hormone deficiency. Gigantism (choice B) occurs due to excessive growth hormone production in childhood. Acromegaly (choice D) is caused by excess growth hormone in adulthood, not during the growing years. Thus, choice C is the most appropriate based on the impact of growth hormone deficiency on growth during childhood.