Cellular responses to hormones that initiate second-messenger systems include ________.

Correct Answer: A

Rationale: The correct answer is A because cellular responses to hormones initiating second-messenger systems can activate various pathways. Different hormones can utilize different second messengers such as cAMP, cGMP, IP3, and DAG. This diversity allows for a wide range of responses in target cells. Choice B is incorrect because cyclic AMP phosphodiesterase degrades cAMP, not forms an active second messenger. Choice C is incorrect as it describes the mechanism of a specific protein kinase, which is not a characteristic of second-messenger systems. Choice D is incorrect since hormone binding to intracellular receptors typically leads to gene transcription regulation, not direct activation of second-messenger systems.

Correct Answer: C

Rationale: The correct answer is C: Pancreas. The pancreas is an endocrine gland located in the abdominal cavity near the small intestine. It secretes hormones like insulin and glucagon that regulate blood sugar levels. The adrenal gland (A) is located on top of the kidneys, the hypothalamus (B) is in the brain, and the thyroid gland (D) is located in the neck. These glands are not near the small intestine, making them incorrect choices.

Correct Answer: C

Rationale: The correct answer is C: growth hormone does not promote glucose metabolism. Growth hormone primarily promotes protein synthesis in bones, cartilage, and muscles (B), stimulates the rate of amino acid entrance into the cell (A), and promotes fat metabolism (D). Glucose metabolism is mainly regulated by insulin, not growth hormone.

Correct Answer: A

Rationale: The correct answer is A: sympathetic. Epinephrine and norepinephrine are neurotransmitters released by the sympathetic nervous system. They activate the fight-or-flight response, increasing heart rate, dilating airways, and redirecting blood flow to muscles. The sympathetic nervous system prepares the body for action in response to stress or danger. Choices B, C, and D are incorrect because parasympathetic regulates rest and digest functions, somatic controls voluntary movements, and central refers to the brain and spinal cord, not a division of the autonomic nervous system like sympathetic.

Correct Answer: D

Rationale: Sure! The correct answer is D because type I diabetes (IDDM) is characterized by the body's inability to produce insulin, leading to high blood sugar levels. Insulin injections are necessary to replace the missing insulin. A is incorrect because type I diabetes is not associated with obesity. B is incorrect because type II diabetes is actually the most common form. C is incorrect because in type I diabetes, the body's cells do not produce insulin, rather than not responding to it.