Question 1

Which of the following best describes the initial step in the synthesis of peptide hormones?

Accepted Answer

Peptide hormones are synthesized as preprohormones on ribosomes and processed to prohormones in the endoplasmic reticulum (ER).

Question 2

A patient with a mutation that prevents the insertion of aquaporin-2 (AQP2) into the apical membrane of collecting duct cells would most likely present with which clinical finding?

Accepted Answer

Large volumes of dilute urine due to impaired water reabsorption (diabetes insipidus).

Question 3

Which of the following statements about hormone-receptor interactions is correct?

Accepted Answer

The hormone-receptor interaction is saturable, meaning there is a maximum number of receptors that can be occupied.

Question 4

Which hormone signaling pathway involves the activation of phospholipase C (PLC), leading to the production of inositol trisphosphate (IP$$_3) $$and diacylglycerol (DAG)?

Accepted Answer

The IP$$_3$$ pathway, which increases intracellular Ca$$^{2+}$$ and activates protein kinase C (PKC).

Question 5

Steroid hormones exert their effects primarily by:

Accepted Answer

Binding to nuclear receptors and regulating gene transcription.

Question 6

A researcher is studying a hormone that binds to a cell-surface receptor, activates adenylate cyclase, and increases intracellular cAMP. Which hormone is most likely being studied?

Accepted Answer

Glucagon

Question 7

Which of the following best explains why peptide hormones generally have rapid effects compared to steroid hormones?

Accepted Answer

Peptide hormones act via cell-surface receptors and second messenger pathways, while steroid hormones alter gene expression.

Question 8

A patient presents with hyponatremia, low serum osmolarity, and concentrated urine. Which of the following is the most likely underlying mechanism?

Accepted Answer

Excessive vasopressin (ADH) release leading to syndrome of inappropriate antidiuretic hormone secretion (SIADH).

Question 9

Which of the following is a correct sequence of events in the cAMP signaling pathway?

Accepted Answer

Ligand binds GPCR $$\rightarrow G$_\alpha$$ activates adenylyl cyclase $$\rightarrow$$ cAMP produced $$\rightarrow$$ PKA activated

Question 10

Which of the following best describes the mechanism by which vasopressin increases water reabsorption in the kidney?

Accepted Answer

Vasopressin binds to V$$_2$$ receptors, activating adenylate cyclase, increasing cAMP, which activates PKA and leads to insertion of aquaporin-2 channels into the apical membrane.

Question 11

Which of the following is a key feature of hormone receptors that allows for transient endocrine responses?

Accepted Answer

The hormone-receptor interaction is reversible, allowing hormones to dissociate from their receptors.

Question 12

Which of the following hormones is synthesized from cholesterol?

Accepted Answer

Cortisol

Question 13

A mutation in the gene encoding the G$$_\alpha$$ subunit of a G-protein-coupled receptor (GPCR) would most directly affect which of the following processes?

Accepted Answer

Activation of adenylate cyclase and production of cAMP

Question 14

Which of the following best explains why steroid hormone responses are generally slower than peptide hormone responses?

Accepted Answer

Steroid hormones alter gene expression, requiring transcription and translation of new proteins.

Question 15

Which of the following is a correct pairing of hormone and its receptor type?

Accepted Answer

Insulin – Tyrosine kinase receptor

Question 16

A patient with a pituitary tumor is found to have excessive release of vasopressin. Which of the following laboratory findings would you expect?

Accepted Answer

Low serum sodium and high urine osmolality

Question 17

Which of the following best describes the role of the hypothalamus in endocrine regulation?

Accepted Answer

It integrates information from the brain, environment, and peripheral organs to maintain homeostasis via neuroendocrine signaling.

Question 18

Which of the following is a direct effect of oxytocin binding to its receptor in the uterus during childbirth?

Accepted Answer

Increased intracellular Ca$$^{2+}$$ leading to smooth muscle contraction

Question 19

Which of the following best describes the difference between V$$_1$$ and V$$_2$$ vasopressin receptors?

Accepted Answer

V$$_1$$ receptors mediate vasoconstriction via increased Ca$$^{2+}$$, while V$$_2$$ receptors mediate water reabsorption via increased cAMP.

Molecular Basis of Hormone Action: Synthesis, Receptors, and Signal Transduction

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