Question 1

Which of the following best describes the primary function of hormones in the endocrine system?

Accepted Answer

They serve as cell-to-cell communication molecules that regulate physiological processes at very low concentrations.

Question 2

A patient is diagnosed with Grave's disease. Which of the following best explains the underlying mechanism of this condition?

Accepted Answer

An autoimmune antibody activates the TSH receptor, leading to overproduction of thyroid hormone.

Question 3

Which of the following statements about peptide hormones is TRUE?

Accepted Answer

They are stored in vesicles and released by Ca$^{++}$-dependent exocytosis upon receiving a signal.

Question 4

Steroid hormones differ from peptide hormones in that steroid hormones:

Accepted Answer

Are synthesized from cholesterol and can cross the cell membrane to bind cytoplasmic or nuclear receptors.

Question 5

A researcher is studying the effect of two hormones, glucagon and epinephrine, on blood glucose levels. When both are administered together, the increase in blood glucose is greater than the sum of their individual effects. This phenomenon is best described as:

Accepted Answer

Synergism

Question 6

Which of the following is an example of a hormone derived from tyrosine?

Accepted Answer

Epinephrine

Question 7

A patient presents with an enlarged thyroid gland (goiter) but low levels of thyroid hormone. Which of the following is the most likely cause?

Accepted Answer

Iodine deficiency leading to decreased thyroxine synthesis and compensatory gland hypertrophy.

Question 8

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

Accepted Answer

A system of two capillary beds in series that allows hypothalamic hormones to reach the anterior pituitary directly without dilution.

Question 9

Which of the following is a correct sequence for the hypothalamo-pituitary-adrenal (HPA) axis?

Accepted Answer

Hypothalamus → Anterior pituitary → Adrenal gland

Question 10

Which of the following best explains why peptide hormones cannot cross the cell membrane?

Accepted Answer

They are hydrophilic and cannot dissolve in the lipid bilayer of the cell membrane.

Question 11

A patient is given a drug that blocks the action of cAMP in target cells. Which hormone's action would be most directly affected?

Accepted Answer

Most peptide hormones that use cAMP as a second messenger

Question 12

Which of the following is a feature of steroid hormone action?

Accepted Answer

They activate DNA for protein synthesis after entering the target cell.

Question 13

Permissiveness in hormone interactions is best illustrated by which of the following scenarios?

Accepted Answer

Thyroid hormone is required for normal development of reproductive system, even though it does not directly stimulate reproductive tissues.

Question 14

Which of the following best describes negative feedback in endocrine reflex pathways?

Accepted Answer

The physiological response to a hormone inhibits further hormone release.

Question 15

A patient with a pituitary tumor is found to have elevated levels of ACTH (adrenocorticotropic hormone) and cortisol. Which type of endocrine pathology does this represent?

Accepted Answer

Secondary pathology

Question 16

Which of the following is a correct statement about the release of peptide hormones?

Accepted Answer

They are released together with inactive fragments after a Ca$^{++}$-dependent exocytosis signal.

Question 17

Which of the following best explains why steroid hormones generally have a longer half-life than peptide hormones?

Accepted Answer

Steroid hormones are bound to carrier proteins in the blood, protecting them from rapid degradation.

Question 18

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

Accepted Answer

Glucagon increases blood glucose while insulin decreases it.

Question 19

Which of the following best describes the process of signal transduction for peptide hormones?

Accepted Answer

Peptide hormones bind to surface receptors, activating second messenger systems such as cAMP.

Question 20

A patient is found to have low levels of a hormone due to atrophy of the gland that produces it. Which of the following best describes this condition?

Accepted Answer

Hyposecretion

Introduction to the Endocrine System: Structure, Function, and Hormone Classification

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