Question 1

Which of the following best describes a key difference between the nervous system and the endocrine system?

Accepted Answer

The nervous system acts at specific locations determined by axon pathways, while the endocrine system acts at diffuse locations wherever blood reaches.

Question 2

A patient presents with abnormally high blood calcium levels. Which hormone is most likely under-secreted, and what is its normal mechanism of action?

Accepted Answer

Parathyroid hormone (PTH); it is normally secreted in response to low blood calcium and increases blood calcium levels.

Question 3

Which of the following is NOT a function of the endocrine system?

Accepted Answer

Initiating rapid, short-duration responses to stimuli.

Question 4

Which statement correctly distinguishes between exocrine and endocrine glands?

Accepted Answer

Exocrine glands produce nonhormonal substances and have ducts; endocrine glands produce hormones and lack ducts.

Question 5

Amino acid-based hormones (except thyroid hormone) exert their effects through which mechanism?

Accepted Answer

Binding to plasma membrane receptors and activating G protein second messenger systems.

Question 6

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

Accepted Answer

A hormone binds to a receptor, activating a G protein, which then activates adenylate cyclase to convert ATP to cAMP, which activates protein kinases.

Question 7

Which of the following is an example of a hormone acting via the PIP2-calcium second messenger system?

Accepted Answer

A hormone activates phospholipase C, which splits PIP2 into DAG and IP3; IP3 then causes Ca$^{2+}$ release from intracellular stores.

Question 8

A patient is given a drug that acts as a phosphodiesterase inhibitor. What is the most likely effect on hormone signaling via the cAMP pathway?

Accepted Answer

The drug will prevent cAMP degradation, prolonging and amplifying the hormone response.

Question 9

Which of the following best explains why steroid hormones can have a delayed onset of action compared to peptide hormones?

Accepted Answer

Steroid hormones bind to intracellular receptors and initiate gene transcription, which takes time to produce new proteins.

Question 10

Which scenario is an example of hormonal stimulation of an endocrine gland?

Accepted Answer

The hypothalamus releases TRH, which stimulates the anterior pituitary to release TSH.

Question 11

A patient with a pituitary tumor is experiencing excessive growth of hands, feet, and face as an adult. Which hormone is most likely over-secreted, and what is the condition called?

Accepted Answer

Growth hormone (GH); acromegaly

Question 12

Which of the following is a correct example of hormone antagonism?

Accepted Answer

Insulin and glucagon have opposite effects on blood glucose levels.

Question 13

Which of the following best describes the mechanism of action for antidiuretic hormone (ADH)?

Accepted Answer

ADH stimulates the kidneys to reabsorb more water, reducing urine formation.

Question 14

Which of the following is a direct effect of growth hormone (GH) on metabolism?

Accepted Answer

Increasing blood levels of fatty acids for use as fuel and encouraging protein synthesis.

Question 15

A patient is experiencing inappropriate lactation, lack of menses, and infertility. Which hormone is most likely involved, and what is the likely cause?

Accepted Answer

Prolactin (PRL); hypersecretion due to an anterior pituitary tumor

Question 16

Which of the following best describes the concept of up-regulation in hormone signaling?

Accepted Answer

Target cells form more receptors in response to low hormone levels.

Question 17

Which hormone is released from the posterior pituitary and acts as a strong stimulant of uterine contractions during childbirth?

Accepted Answer

Oxytocin

Question 18

Which of the following best explains why the effects of some hormones persist even after their blood levels have dropped?

Accepted Answer

Some hormones activate gene transcription, leading to protein synthesis that continues after the hormone is gone.

Question 19

Which of the following is a correct example of a hormone acting via direct gene activation?

Accepted Answer

Cortisol diffusing into a target cell, binding to an intracellular receptor, and initiating mRNA synthesis.

Endocrine System: Structure, Function, and Regulation

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