Question 1

Thyroid hormone (a small iodinated amine) enters target cells in a manner similar to ________.

Accepted Answer

Thyroid hormone is a lipid-soluble hormone, and it can diffuse easily through the plasma membrane of target cells. This is also true for steroid hormones, which are also lipid-soluble and diffuse through the membrane to bind to intracellular receptors.

Question 2

One of the least complicated of the endocrine control systems directly responds to changing blood levels of ions and nutrients. Which of the following describes this mechanism?

Accepted Answer

This mechanism is called humoral stimulation, which involves the secretion of hormones in response to changing blood levels of ions and nutrients. The hormones act on target cells to regulate the ion or nutrient levels and restore homeostasis. Examples include the regulation of blood glucose levels by insulin and glucagon.

Question 3

Cellular responses to hormones that initiate second-messenger systems include ________.

Accepted Answer

When hormones initiate second-messenger systems, they can activate multiple different second-messenger systems, such as cyclic AMP, inositol triphosphate, and calcium signaling pathways. The specific second-messenger system activated depends on the type of hormone and the target cell.

Question 4

In circumstances where the body requires prolonged or increased levels of a hormone, the DNA of target cells will specify the synthesis of more receptors on the surface of the cells of the target organ. This is known as ________.

Accepted Answer

The process described in the statement is known as up-regulation. Up-regulation leads to an increased number of hormone receptors on the target cells, allowing the body to respond more effectively to the hormone and maintain homeostasis. Choices A, B, and D do not accurately describe this process.

Question 5

Which organ is responsible for synthesizing ANP?

Accepted Answer

Atrial natriuretic peptide (ANP) is synthesized and secreted by the heart, specifically the atrial myocardium.

Question 6

ACTH ________.

Accepted Answer

ACTH (adrenocorticotropic hormone) is secreted by the anterior pituitary and its secretion is regulated by the hypothalamic regulatory hormone, corticotropin-releasing hormone (CRH). It stimulates the adrenal cortex to secrete glucocorticoids, which are involved in metabolism, immune function, and stress responses. It does not cause the release of hormones from the adrenal medulla, which is regulated by the sympathetic nervous system. Therefore, the best choice is B.

Question 7

Aldosterone ________.

Accepted Answer

Aldosterone functions to increase sodium reabsorption in the kidneys, which in turn leads to water retention and an increase in blood volume and blood pressure. It does not come from the neurohypophysis, increase potassium concentration in the blood, or greatly influenced by ACTH.

Question 8

The most important mineralcorticoid regulator of electrolyte concentrations in extracellular fluids is ________.

Accepted Answer

Aldosterone is the most important mineralocorticoid regulator of electrolyte concentrations in extracellular fluids, especially sodium and potassium. Insulin, glucagon, and cortisol are not directly involved in regulating electrolyte balances.

Question 9

Mineralocorticoid is to aldosterone as glucocorticoid is to ________.

Accepted Answer

Mineralocorticoids, such as aldosterone, regulate electrolyte balance and blood pressure. Glucocorticoids, such as cortisol, regulate metabolism and immune system function. Testosterone and estrogen are both sex hormones and are not related to mineralocorticoids or glucocorticoids. Epinephrine is a hormone involved in the fight or flight response and is not related to either mineralocorticoids or glucocorticoids.

Question 10

Leptin is secreted by ________.

Accepted Answer

Leptin is mainly secreted by adipocytes, which are specialized cells that store fat in the body. Leptin acts as a hormone and plays a key role in regulating appetite and metabolism, as well as other physiological processes such as reproduction and immunity.

Question 11

Eicosanoids do not include ________.

Accepted Answer

Eicosanoids include paracrines, leukotrienes, and prostaglandins, but not hydrocortisones which are a type of steroid hormone.

Question 12

Which of the following is not a parathyroid gland mechanism to maintain adequate levels of blood calcium?

Accepted Answer

The parathyroid gland does not inhibit calcitonin synthesis, it actually works in opposition to calcitonin to regulate blood calcium levels. The other three mechanisms listed (activation of osteoclasts, increase calcium ion reabsorption by the kidneys, and increase in intestinal absorption of calcium ions) are all ways in which the parathyroid gland maintains adequate levels of blood calcium.

Question 13

The single most important regulator of calcium levels in the blood is ________.

Accepted Answer

Parathyroid hormone is the single most important regulator of calcium levels in the blood. When calcium levels in the blood decrease, the parathyroid glands release parathyroid hormone, which increases calcium levels by stimulating the release of calcium from bone, increasing calcium absorption in the kidneys, and increasing calcium absorption in the intestines.

Question 14

Regulating hormones from the hypothalamus ________.

Accepted Answer

Hormones from the hypothalamus first enter into the hypophyseal portal system, a network of blood vessels that connects the hypothalamus to the anterior pituitary gland. This allows for efficient transport and regulation of hormones to the pituitary gland.

Question 15

When it becomes necessary to enlist the fight-or-flight response, a hormone that is released during the alarm phase of the general adaptation syndrome is ________.

Accepted Answer

The hormone released during the alarm phase of the general adaptation syndrome, which triggers the fight-or-flight response, is epinephrine (also known as adrenaline). Estrogen, angiotensinogen, and renin are not directly involved in the fight-or-flight response.

Question 16

The major targets of growth hormone are ________.

Accepted Answer

Growth hormone primarily targets bones and skeletal muscles, promoting growth and development. While it can have secondary effects on other tissues and organs, such as the liver and adrenal glands, these are not its main targets. The blood vessels are not typically considered targets of growth hormone.

Question 17

Which of the following is not a steroid-based hormone?

Accepted Answer

Epinephrine is a hormone derived from the amino acid tyrosine, not from steroid precursors like the other options listed (estrogen, aldosterone, and cortisone).

Question 18

Thyroxine is a peptide hormone, but its mechanism is different from other peptide hormones. Which of the following statements is True concerning this difference?

Accepted Answer

Unlike other peptide hormones, thyroxine does not require a second messenger to effect a response. Instead, it enters the target cell and binds to specific receptors in the nucleus, where it directly alters gene transcription and protein synthesis. This is a characteristic of steroid hormones, which thyroxine closely resembles in its mechanism of action.

Question 19

Which organ does not produce hormones?

Accepted Answer

The spleen does not produce hormones; it is primarily involved in filtering blood and managing immune responses. The heart, kidney, and skin all have roles in hormone production.

Question 20

A man has been told that he is not synthesizing enough follicle-stimulating hormone (FSH), and for this reason he may be unable to father a child. Choose the correct statement to explain this problem.

Accepted Answer

FSH is a hormone made in the adenohypophysis that stimulates the production of sperm in the testes. Therefore, if a man is not synthesizing enough FSH, he may have a decreased sperm count and difficulty fathering a child. Choice A is incorrect because FSH stimulates follicle growth in females, not estrogen secretion. Choice B is incorrect because hormones produced by the adenohypophysis, such as FSH, can have significant effects on fertility. Choice D is incorrect because progesterone does not inhibit the synthesis of FSH.

Quiz 15: The Endocrine System