Question 1

Which of the following best describes the main difference between autocrines, paracrines, and hormones?

Accepted Answer

Hormones are secreted into the extracellular fluid and act at distant sites, while autocrines and paracrines act locally.

Question 2

Amino acid-based hormones typically exert their effects through which of the following mechanisms?

Accepted Answer

Activation of second messenger systems such as cAMP or PIP$_2$-calcium

Question 3

Which of the following is a correct sequence of events for the cAMP second messenger system?

Accepted Answer

Hormone binds receptor $\rightarrow$ G protein activated $\rightarrow$ Adenylate cyclase activated $\rightarrow$ cAMP produced $\rightarrow$ Protein kinases activated

Question 4

Which hormone is produced by the parafollicular (C) cells of the thyroid gland and what is its primary function?

Accepted Answer

Calcitonin; lowers blood calcium levels by inhibiting osteoclast activity

Question 5

A patient is experiencing excessive thirst, frequent urination, and high blood glucose levels. Which hormone is most likely deficient or not functioning properly?

Accepted Answer

Insulin

Question 6

Which of the following best explains why steroid hormones have longer-lasting effects compared to most amino acid-based hormones?

Accepted Answer

Steroid hormones alter gene transcription, leading to new protein synthesis.

Question 7

Which of the following is an example of a hormone regulated by a positive feedback mechanism?

Accepted Answer

Oxytocin during uterine contractions in labor

Question 8

A patient has a tumor in the anterior pituitary that causes excessive secretion of ACTH. Which of the following is a likely consequence?

Accepted Answer

Increased secretion of cortisol from the adrenal cortex

Question 9

Which of the following best describes the role of aldosterone in the body?

Accepted Answer

Promotes sodium reabsorption and potassium excretion by the kidneys

Question 10

Which hormone is primarily responsible for stimulating the production of red blood cells in response to hypoxia?

Accepted Answer

Erythropoietin

Question 11

Amino acid-based hormones such as epinephrine and ADH use which second messenger system to exert their effects?

Accepted Answer

cAMP or PIP$_2$-calcium second messenger systems

Question 12

Which of the following is NOT a function of thyroid hormone (TH)?

Accepted Answer

Promoting calcium uptake into bone

Question 13

Which hormone is released in response to low blood calcium levels, and what is its effect?

Accepted Answer

Parathyroid hormone (PTH); increases blood calcium by stimulating osteoclasts

Question 14

Which of the following best describes the effect of insulin on body cells?

Accepted Answer

Enhances transport of glucose into cells and promotes glycogen synthesis

Question 15

Which hormone is responsible for the 'fight or flight' response, and what are two of its major effects?

Accepted Answer

Epinephrine; increases heart rate and blood glucose levels

Question 16

A patient with a history of chronic stress is found to have elevated blood glucose, suppressed immune function, and muscle wasting. Which hormone is most likely elevated?

Accepted Answer

Cortisol

Question 17

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

Accepted Answer

Glucagon and epinephrine both raise blood glucose

Question 18

Which hormone is released from the posterior pituitary and helps the body avoid dehydration by reducing urine output?

Accepted Answer

Antidiuretic hormone (ADH)

Question 19

Which of the following best explains why Type I diabetes mellitus requires insulin therapy, while Type II may not?

Accepted Answer

Type I is caused by autoimmune destruction of beta cells, resulting in no insulin production; Type II is due to insulin resistance.

Question 20

Which hormone is produced by the pineal gland and what is its primary function?

Accepted Answer

Melatonin; regulates sleep-wake cycles

The Endocrine System: Hormones and Mechanisms of Action

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