Nokea
The endocrine gland(s) that makes insulin is the:
- A. pancreas
- B. adrenal glands
- C. thyroid gland
- D. pituitary gland
Correct Answer: A
Rationale: The correct answer is A: pancreas. The pancreas is responsible for producing insulin, a hormone that helps regulate blood sugar levels. It is located near the stomach and plays a crucial role in the endocrine system. The other choices (B: adrenal glands, C: thyroid gland, D: pituitary gland) do not produce insulin. Adrenal glands produce hormones like adrenaline and cortisol, thyroid gland produces hormones like thyroxine, and the pituitary gland produces various hormones that regulate other endocrine glands. Therefore, the pancreas is the only gland among the options that produces insulin, making it the correct answer.
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The beta cells of the islets of Langerhans:
- A. are the hormone-secreting cells of the adrenal cortex.
- B. are insulin-secreting pancreatic cells.
- C. secrete releasing hormones.
- D. secrete steroids.
Correct Answer: B
Rationale: The correct answer is B because beta cells of the islets of Langerhans are specialized pancreatic cells that secrete insulin, a hormone crucial for regulating blood sugar levels. Insulin helps cells absorb glucose from the bloodstream, lowering blood sugar levels. Choice A is incorrect because the hormone-secreting cells of the adrenal cortex are called adrenal cortical cells, not beta cells. Choice C is incorrect as releasing hormones are typically secreted by the hypothalamus to stimulate the pituitary gland. Choice D is incorrect because steroids are primarily secreted by the adrenal cortex, not the beta cells of the islets of Langerhans.
Hormones produced by the hypothalamus and secreted by the posterior pituitary include:
- A. ADH and aldosterone
- B. ADH and oxytocin
- C. oxytocin and prolactin
- D. cortisol and aldosterone
Correct Answer: B
Rationale: Step 1: The hormones produced by the hypothalamus and secreted by the posterior pituitary are ADH (vasopressin) and oxytocin.
Step 2: ADH regulates water balance by increasing water reabsorption in the kidneys.
Step 3: Oxytocin is involved in uterine contractions during childbirth and milk ejection during breastfeeding.
Step 4: Therefore, choice B (ADH and oxytocin) is correct.
Summary:
- Choice A (ADH and aldosterone) is incorrect because aldosterone is produced by the adrenal glands, not the posterior pituitary.
- Choice C (oxytocin and prolactin) is incorrect because prolactin is produced by the anterior pituitary.
- Choice D (cortisol and aldosterone) is incorrect because cortisol is produced by the adrenal glands, not the posterior pituitary.
When blood Calcium level is elevated, the body is in a state of hypercalcemia. Which gland is responsible for secreting a hormone to return Ca2+ level to normal and therefore maintain homeostasis?
- A. Hypothalamus
- B. Pituitary
- C. Thyroid
- D. Parathyroid
Correct Answer: c
Rationale: The correct answer is D: Parathyroid. The parathyroid gland secretes parathyroid hormone (PTH) when blood calcium levels are elevated. PTH acts to increase calcium reabsorption in the kidneys, release calcium from bones, and enhance calcium absorption in the intestines, ultimately lowering blood calcium levels back to normal.
A: The hypothalamus plays a role in regulating body temperature, thirst, hunger, and circadian rhythms, but not in calcium homeostasis.
B: The pituitary gland secretes various hormones, but none specifically involved in regulating blood calcium levels.
C: The thyroid gland secretes thyroid hormones that regulate metabolism and growth, not calcium levels.
Which of the following elements is required for the synthesis of thyroid hormone?
- A. copper
- B. iodine
- C. sulfur
- D. zinc
Correct Answer: B
Rationale: The correct answer is B: iodine. Iodine is an essential element required for the synthesis of thyroid hormone. Thyroid hormones such as thyroxine (T4) and triiodothyronine (T3) contain iodine atoms. Without sufficient iodine, the thyroid gland cannot produce these hormones, leading to thyroid disorders like hypothyroidism or goiter. Copper (A), sulfur (C), and zinc (D) are not directly involved in the synthesis of thyroid hormone. Copper is important for enzyme function, sulfur is present in amino acids, and zinc is involved in various cellular processes but not specifically in thyroid hormone synthesis.
The most common second messengers for peptide hormones are ______ and _____.
- A. peptide hormones and calcium.
- B. calcium and glucose.
- C. cAMP and calcium.
- D. cAMP and sodium.
Correct Answer: C
Rationale: The correct answer is C: cAMP and calcium. Peptide hormones bind to their receptors on the cell surface, activating G-proteins which then trigger the production of cAMP as a second messenger. cAMP then further activates protein kinases to initiate various cellular responses. Calcium is also a common second messenger in peptide hormone signaling pathways, regulating processes like muscle contraction and gene expression. Choice A is incorrect because peptide hormones themselves are not second messengers. Choice B is incorrect as glucose is not a common second messenger for peptide hormones. Choice D is incorrect as sodium is not typically involved in peptide hormone signaling pathways.