All are characteristics of smooth muscle, except?

Correct Answer: b

Rationale: The correct answer is B because smooth muscle does not utilize troponin to help initiate muscle contraction. Instead, smooth muscle contraction is regulated by calcium-calmodulin complex. A: True - Smooth muscle usually forms 2 layers at right angles to each other. C: True - Smooth muscle contains no striations. D: False - Action potentials in smooth muscle travel slowly via gap junctions, not tight junctions.

Correct Answer: A

Rationale: Testosterone is best described as virilizing because it is the primary male sex hormone responsible for the development of male characteristics such as facial hair, deep voice, and muscle mass. It plays a key role in virilization. The other choices, lactogenic, adenohypophyseal, and pancreatic, are incorrect because testosterone is not primarily associated with lactation, the anterior pituitary gland, or the pancreas.

Correct Answer: D

Rationale: The correct answer is D: It increases plasma levels of calcium. Parathyroid hormone (PTH) acts to increase calcium levels in the blood by stimulating the release of calcium from bones, enhancing calcium absorption in the intestines, and reducing calcium excretion in the kidneys. This process helps maintain proper calcium levels in the blood. Choices A, B, and C are incorrect because PTH does not cause the excretion of calcium in the urine (A), stimulate osteoblastic activity to form bone (B), or stimulate the thyroid gland to secrete calcitonin (C).

Correct Answer: C

Rationale: Excess secretion of epinephrine activates the fight-or-flight response, leading to the release of stored glucose into the bloodstream, elevating blood glucose levels. This helps provide immediate energy for the body to respond to stress. Epinephrine does not relieve anxiety (Choice A), as it is a stress hormone. It does not stimulate glycogen synthesis (Choice B) but rather breaks down glycogen to release glucose. Epinephrine increases heart rate and blood pressure (opposite of Choice D) to support increased energy needs during stress. Thus, the correct answer is C.

Correct Answer: A

Rationale: The correct answer is A: Lowers blood glucose levels. Insulin is a hormone produced by the pancreas that helps regulate blood glucose levels by promoting the uptake of glucose into cells for energy storage. This process reduces the concentration of glucose in the bloodstream. Choices B, C, and D are incorrect because insulin does not stimulate cells to make glucose (B), deficiency does not cause diabetes insipidus (C), and it does not directly affect blood volume (D).