Nokea
Steroids:
- A. are secreted by the adrenal medulla.
- B. include the glucocorticoids, mineralocorticoids, and androgens.
- C. stimulate the membranes of the target cells to produce the second chemical messenger, cAMP.
- D. are secreted by the pancreas.
Correct Answer: B
Rationale: The correct answer is B because steroids include glucocorticoids, mineralocorticoids, and androgens, which are hormones secreted by the adrenal cortex. Glucocorticoids regulate metabolism and immune response, mineralocorticoids regulate electrolyte balance, and androgens are male sex hormones.
Choice A is incorrect because steroids are secreted by the adrenal cortex, not the adrenal medulla. Choice C is incorrect because steroids act by entering the target cells and binding to intracellular receptors, not by stimulating second messengers like cAMP. Choice D is incorrect because steroids are not secreted by the pancreas; instead, the pancreas secretes hormones like insulin and glucagon.
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Which gland secretes melatonin and is concerned with our biological rhythms?
- A. Pancreas
- B. Adenohypophysis
- C. Pineal gland
- D. Adrenal gland
Correct Answer: C
Rationale: The correct answer is C: Pineal gland. The pineal gland is responsible for secreting melatonin, a hormone that regulates our biological rhythms such as sleep-wake cycles. This gland is located in the brain and plays a crucial role in maintaining our circadian rhythm. The other choices are incorrect because:
A: The pancreas secretes insulin and glucagon to regulate blood sugar levels, not melatonin.
B: The adenohypophysis, or anterior pituitary gland, secretes various hormones but not melatonin.
D: The adrenal gland produces hormones like cortisol and adrenaline, not melatonin.
Peptide hormones function by binding to receptor proteins within the ________. Once the hormone binds to a receptor, it activates ______.
- A. cell: a second messenger
- B. cell: particular genes
- C. plasma membrane: a second messenger
- D. plasma membrane: particular genes
Correct Answer: C
Rationale: The correct answer is C because peptide hormones typically bind to receptor proteins on the plasma membrane. This is because peptide hormones are not able to pass through the cell membrane due to their size and polarity. Once the hormone binds to the receptor on the plasma membrane, it activates a second messenger system within the cell, leading to various cellular responses.
Choice A is incorrect because peptide hormones do not bind directly to intracellular components like second messengers inside the cell. Choice B is incorrect because peptide hormones do not directly activate particular genes within the cell. Choice D is incorrect because peptide hormones do not bind directly to genes on the plasma membrane.
Glucagon, growth hormone, cortisol, and epinephrine:
- A. are all secreted by the adrenal gland.
- B. expand blood volume.
- C. raise blood glucose levels.
- D. stimulate osteoclastic activity.
Correct Answer: C
Rationale: The correct answer is C: raise blood glucose levels. Glucagon, growth hormone, cortisol, and epinephrine all work together to increase blood glucose levels through various mechanisms. Glucagon stimulates the breakdown of glycogen into glucose, growth hormone promotes gluconeogenesis, cortisol increases blood sugar through gluconeogenesis and inhibiting glucose uptake, and epinephrine triggers glycogen breakdown and inhibits insulin release. Choices A, B, and D are incorrect because not all of these hormones are secreted by the adrenal gland, they do not directly expand blood volume, and they do not stimulate osteoclastic activity, respectively.
Which form of intestinal smooth muscle contraction does NOT occur in normal health?
- A. peristalsis
- B. weak antiperistalsis
- C. peristaltic rushes
- D. tonic contractions
Correct Answer: C
Rationale: The correct answer is C: peristaltic rushes. Peristaltic rushes are abnormal and excessive contractions that can result in diarrhea or bowel urgency. In normal health, peristalsis (A) is the coordinated contraction and relaxation of intestinal smooth muscles that moves contents along the digestive tract. Weak antiperistalsis (B) refers to reverse contractions that are weaker than normal peristalsis. Tonic contractions (D) are sustained contractions that help maintain muscle tone and control flow. Therefore, peristaltic rushes are the only option that does not occur in normal health due to their abnormal and disruptive nature.
Sometimes prolonged excessive exposure to high hormone concentrations causes a phenomenon known as ________.
- A. diabetes mellitus
- B. cellular inhibition
- C. down-regulation
- D. metabolism of protein kinases
Correct Answer: C
Rationale: The correct answer is C: down-regulation. Prolonged exposure to high hormone concentrations can lead to down-regulation, where cells decrease their responsiveness to the hormone by reducing the number of hormone receptors. This is a regulatory mechanism to prevent overstimulation.
A: Diabetes mellitus is a chronic condition characterized by high blood sugar levels, usually caused by insulin deficiency or insulin resistance, not directly related to prolonged exposure to high hormone concentrations.
B: Cellular inhibition is a broad term that may refer to various cellular processes being inhibited, but it is not a specific phenomenon resulting from prolonged exposure to high hormone concentrations.
D: Metabolism of protein kinases is a cellular process involved in signal transduction, but it is not a direct consequence of prolonged exposure to high hormone concentrations.