Q: Which equation best represents the amplification effect in the cAMP signaling cascade, if one hormone activates $$n G $$proteins, each G protein activates $$m$$ adenylate cyclase enzymes, each adenylate cyclase produces $$p$$ cAMP molecules, and each cAMP activates $$q$$ protein kinases?

$$Total = n \times m \times p \times q$$

Question 1

Which of the following best explains why the endocrine system's responses are generally slower but longer-lasting than those of the nervous system?

Accepted Answer

Hormones are released into the blood and act on distant targets, while nervous signals are transmitted directly to specific cells.

Question 2

A patient presents with excessive thirst and large volumes of dilute urine. Laboratory tests reveal low levels of antidiuretic hormone (ADH). Which condition is most likely?

Accepted Answer

Diabetes insipidus

Question 3

Which of the following hormones is lipid-soluble and acts by directly activating genes within the target cell nucleus?

Accepted Answer

Thyroid hormone

Question 4

Amino acid-based hormones (except thyroxine) are generally unable to cross the plasma membrane. How do they exert their effects on target cells?

Accepted Answer

By binding to plasma membrane receptors and activating second messenger systems

Question 5

Which of the following is an example of humoral stimulus for hormone release?

Accepted Answer

Low blood calcium levels stimulating parathyroid hormone (PTH) secretion

Question 6

Which process describes the phenomenon where one hormone cannot exert its full effect without another hormone being present?

Accepted Answer

Permissiveness

Question 7

A patient with a pituitary tumor is found to have enlarged hands, feet, and facial bones, but normal height. Which hormone is most likely oversecreted, and what is the condition called?

Accepted Answer

Growth hormone; acromegaly

Question 8

Which of the following best describes the cAMP second messenger system?

Accepted Answer

Hormone binds to receptor, activates G protein, which activates adenylate cyclase to convert ATP to cAMP, leading to protein phosphorylation.

Question 9

Which equation best represents the amplification effect in the cAMP signaling cascade, if one hormone activates $$n G $$proteins, each G protein activates $$m$$ adenylate cyclase enzymes, each adenylate cyclase produces $$p$$ cAMP molecules, and each cAMP activates $$q$$ protein kinases?

Accepted Answer

$$Total = n 	imes m 	imes p 	imes q$$

Question 10

Which of the following is NOT a direct effect of growth hormone (GH) on metabolism?

Accepted Answer

Stimulating bone matrix formation via insulin-like growth factors (IGFs)

Question 11

Which hormone is released from the posterior pituitary in response to high blood osmolarity and acts to conserve water in the kidneys?

Accepted Answer

Antidiuretic hormone (ADH)

Question 12

Which of the following best describes the role of the hypothalamic-hypophyseal portal system?

Accepted Answer

It transports releasing and inhibiting hormones from the hypothalamus directly to the anterior pituitary.

Question 13

Which of the following is a tropic hormone produced by the anterior pituitary that stimulates the adrenal cortex?

Accepted Answer

Adrenocorticotropic hormone (ACTH)

Question 14

Which feedback mechanism is most commonly used to regulate hormone levels in the blood?

Accepted Answer

Negative feedback

Question 15

A patient is found to have high levels of prolactin and is experiencing inappropriate lactation and infertility. What is the most likely cause?

Accepted Answer

Anterior pituitary tumor causing hypersecretion of prolactin

Question 16

Which of the following best describes the difference between up-regulation and down-regulation of hormone receptors?

Accepted Answer

Up-regulation increases receptor number in response to low hormone levels; down-regulation decreases receptor number in response to high hormone levels.

Question 17

Which of the following is true regarding the transport of steroid hormones in the blood?

Accepted Answer

They are bound to plasma proteins for transport.

Question 18

Which hormone is released in response to stress and hypoglycemia, and what is its primary target?

Accepted Answer

Adrenocorticotropic hormone (ACTH); adrenal cortex

Question 19

Which of the following best describes the effect of antagonism between hormones?

Accepted Answer

One hormone opposes the action of another hormone.

Endocrine System: Structure, Function, and Hormonal Mechanisms

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