Question 1

Regarding the structure and synthesis of hormones,
A)Steroid hormones are synthesized from cholesterol
B)Thyroid hormones are catecholamines
C)The hormones of the adrenal cortex have the same structure as the neurotransmitters of adrenergic neurons
D)Most peptide hormones require binding proteins for transport in the blood
E)Vasopressin is synthesized in the posterior pituitary

Accepted Answer

Steroid hormones, such as testosterone and estrogen, are synthesized from cholesterol.

Answer: E
 Vasopressin, also known as antidiuretic hormone (ADH), is synthesized in the hypothalamus and transported to the posterior pituitary for storage and release.

Question 2

A hormone may be
A)Inactivated by its target cell
B)Activated by its target cell
C)Inactivated by nontarget cells
D)Excreted before it has a chance to act on a target cell
E)All of the choices are correct

Accepted Answer

Hormones can be inactivated by target or nontarget cells, activated by target cells, or excreted before acting on target cells.

Question 3

Which of the following statements is not true of the endocrine system?
A)It is one of two major regulatory systems of the body
B)It is composed of glands that secrete chemical messengers into the blood
C)It is an important regulator of homeostatic mechanisms
D)It influences and is influenced by the nervous system
E)All of the choices are true

Accepted Answer

All of the statements are true.

Question 4

Hormones(,)
A)Are chemical regulators that are conveyed from one organ to another via the bloodstream
B)In some cases, also function as local regulators and/or neurotransmitters
C)In some cases, contain carbohydrates
D)Both are chemical regulators that are conveyed from one organ to another via the bloodstream and, in some cases, also function as local regulators and/or neurotransmitters are correct
E)All of the choices are correct

Accepted Answer

Hormones are chemical regulators that are conveyed from one organ to another via the bloodstream (A). In some cases, they also function as local regulators and/or neurotransmitters (B). Hormones do not contain carbohydrates (C).

Question 5

In the absence of thyroid hormone,epinephrine stimulates release of a small amount of fatty acids from adipose cells.In the presence of thyroid hormone (which has no effect by itself),epinephrine causes a much more substantial release of fatty acids from the cells.The effect of thyroid hormone on epinephrine's actions is called
A)Antagonistic
B)Agonistic
C)Permissive
D)Direct
E)Paracrine

Accepted Answer

The effect of thyroid hormone on epinephrine's actions is permissive, meaning that thyroid hormone does not have a direct effect on the release of fatty acids, but it allows epinephrine to exert its full effect. Therefore, choice C is the best answer.

Question 6

Which of the following statements about hormone activation is true?
A)Prohormones are inactive messengers that must undergo conversion to an active form at their site of production
B)Conversion of T3 to T4 is an example of hormone activation
C)Conversion of testosterone to estradiol is an example of hormone activation
D)Both prohormones are inactive messengers that must undergo conversion to an active form at their site of production and conversion of T3 to T4 is an example of hormone activation are true
E)Both prohormones are inactive messengers that must undergo conversion to an active form at their site of production and conversion of testosterone to estradiol is an example of hormone activation are true

Accepted Answer

Prohormones are indeed inactive and require conversion to become active hormones. Additionally, the conversion of testosterone to estradiol is a form of hormone activation through enzymatic conversion.

Question 7

The liver participates in endocrine regulation by
A)Producing hormones and hormone-binding proteins
B)Clearing hormones from plasma
C)Secreting an inactive form of a hormone that is activated in the plasma
D)Producing hormones and hormone-binding proteins and clearing hormones from plasma
E)Doing all of these things

Accepted Answer

The liver plays a role in endocrine regulation by producing hormones and hormone-binding proteins, clearing hormones from the plasma, and secreting inactive forms of hormones that are activated in the plasma.

Question 8

Peptide hormones are
A)Often derived from larger molecules called prohormones
B)Packaged into secretory vesicles in the endoplasmic reticulum of the cells that synthesize them
C)Secreted in response to a stimulus that causes depletion of cytosolic calcium in the secreting cell
D)Both often derived from larger molecules called prohormones and packaged into secretory vesicles in the endoplasmic reticulum of the cells that synthesize them are correct
E)Both often derived from larger molecules called prohormones and secreted in response to a stimulus that causes depletion of cytosolic calcium in the secreting cell are correct

Accepted Answer

Peptide hormones are often derived from larger precursor molecules called prohormones. They are packaged into secretory vesicles in the Golgi apparatus, not the endoplasmic reticulum, and are typically secreted in response to an increase in cytosolic calcium, not depletion.

Question 9

If a patient were given a drug that inhibited the actions of proteolytic enzymes in the blood plasma only (i.e.,not in cells),which of the following is most likely to result?
A)Conversion of thyroxine to triiodothyronine would be inhibited
B)Conversion of angiotensinogen to angiotensin would be reduced
C)Conversion of testosterone to estradiol would be unaffected
D)Both conversion of thyroxine to triiodothyronine would be inhibited and conversion of angiotensinogen to angiotensin would be reduced would result
E)Both conversion of angiotensinogen to angiotensin would be reduced and conversion of testosterone to estradiol would be unaffected would result

Accepted Answer

The answer of If a patient were given a drug...

Question 10

Rapidly acting chemical regulators generally
A)Bind to receptor proteins in the nucleus of target cells
B)Are polar
C)Activate plasma-membrane-associated receptors
D)Both bind to receptor proteins in the nucleus of target cells and are polar are correct
E)Both are polar and activate plasma-membrane-associated receptors are correct

Accepted Answer

Rapidly acting chemical regulators are typically polar, allowing them to travel easily in the bloodstream, and they activate plasma-membrane-associated receptors because they cannot easily cross the cell membrane to reach intracellular receptors.

Question 11

The main difference between the modes of action of peptide hormones and steroid hormones is that
A)Peptide hormones bind to intracellular receptors whereas steroid hormones bind to receptors on the cell surface
B)Peptide hormones bind to receptors in the nucleus whereas steroid hormones bind to receptors in the cytosol
C)Peptide hormones bind to receptors on the cell surface whereas steroid hormones act as second messengers
D)Peptide hormones bind to receptors on the cell surface whereas steroid hormones bind to intracellular receptors
E)There are no differences; both act by binding to receptors on the cell surface

Accepted Answer

Peptide hormones bind to receptors on the cell surface, whereas steroid hormones bind to intracellular receptors. Peptide hormones are water-soluble, and therefore cannot pass through the cell membrane. They bind to specific receptors on the cell membrane, and activate intracellular signaling pathways through second messengers such as cyclic AMP. Steroid hormones, on the other hand, are lipid-soluble and can pass through the cell membrane. They bind to specific receptors in the cytosol or nucleus of the cell and activate gene expression.

Question 12

Endocrine regulation
A)Refers to chemical regulators that are conveyed from one organ to another via the bloodstream
B)Is slower than regulation by neurotransmission
C)Differs from paracrine regulation in that endocrine regulators act on different cell types from those that secreted them, whereas paracrine regulators are secreted by the same cell type on which they act
D)Both refers to chemical regulators that are conveyed from one organ to another via the bloodstream and is slower than regulation by neurotransmission are correct
E)All of the choices are correct

Accepted Answer

Endocrine regulation refers to chemical regulators that are conveyed from one organ to another via the bloodstream and is slower than regulation by neurotransmission. It differs from paracrine regulation in that endocrine regulators act on different cell types from those that secreted them, whereas paracrine regulators are secreted by the same cell type on which they act. Therefore, choice D is the correct answer. Choice E is not completely accurate as choice C is not true.

Question 13

The enzyme in the mitochondria responsible for the modification of cholesterol that is important to the synthesis of steroid hormones is called
A)Cytochrome P450 enzyme
B)Tyrosine hydroxylase
C)Protein kinase
D)Cholesterol esterase
E)Lipase

Accepted Answer

The Cytochrome P450 enzyme, specifically the CYP11A1 enzyme found in the mitochondria, is responsible for converting cholesterol into pregnenolone, a precursor molecule in the synthesis of steroid hormones such as cortisol, aldosterone, and testosterone. Tyrosine hydroxylase is involved in the synthesis of catecholamines (such as dopamine, norepinephrine, and epinephrine), protein kinase is involved in phosphorylation and signal transduction, cholesterol esterase hydrolyzes ester bonds in cholesterol esters, and lipase breaks down lipids.

Question 14

The concentration of a hormone in plasma is determined by
A)Its secretion and clearance rates
B)Whether or not it binds to carriers and/or other plasma proteins
C)The kind of receptor to which it binds
D)Its secretion and clearance rates and whether or not it binds to carriers and/or other plasma proteins
E)Whether or not it binds to carriers and/or other plasma proteins and the kind of receptor to which it binds

Accepted Answer

The secretion and clearance rates of a hormone determine its concentration in plasma, as does whether or not it binds to carriers and/or other plasma proteins. Therefore, only choice D, which includes both of these factors, is correct. The kind of receptor to which it binds is important for the hormone's physiological effect, but does not directly determine its concentration in plasma.

Question 15

Cells that secrete steroid hormones
A)Store large amounts of hormone
B)Are characterized by abundant agranular endoplasmic reticulum
C)Are characterized by large and numerous mitochodria
D)Both store large amounts of hormone and are characterized by abundant agranular endoplasmic reticulum are correct
E)Both are characterized by abundant agranular endoplasmic reticulum and are characterized by large and numerous mitochondria are correct

Accepted Answer

The answer of Cells that secrete steroid hormones
A)Store large amounts...

Question 16

Secretion of hormones is controlled by
A)Concentration of mineral ions in the blood
B)Neural input
C)Tropic hormones
D)Concentration of mineral ions in the blood and tropic hormones
E)All of these things

Accepted Answer

Secretion of hormones is a complex process that involves various factors, such as the concentration of mineral ions in the blood, neural input, and tropic hormones. The endocrine system is tightly regulated to maintain homeostasis, and all of these factors can play a role in the control of hormone secretion.

Question 17

An endocrine cell that contains an abundance of granular endoplasmic reticulum,a large Golgi apparatus,and secretion granules is likely to
A)Secrete a peptide/protein hormone
B)Secrete by exocytosis
C)Secrete in an exocrine manner
D)Secrete a peptide/protein hormone and secrete by exocytosis
E)Do all of these things

Accepted Answer

Endocrine cells that contain an abundance of granular endoplasmic reticulum, a large Golgi apparatus, and secretion granules are likely to secrete a peptide/protein hormone and secrete by exocytosis.

Question 18

Which of the following statements about hormone synthesis is not correct?
A)Progesterone is a precursor of cortisol
B)Progesterone is a precursor of mineralocorticoid(s) and glucocorticoid(s)
C)Progesterone is a precursor for all steroid hormones
D)Tryptophan is a precursor for thyroid hormones
E)All of these are true statements

Accepted Answer

Tryptophan is not a precursor for thyroid hormones. Thyroid hormones are synthesized from tyrosine.

Question 19

Receptors for steroid hormones
A)Are proteins in the nucleus and/or cytoplasm
B)Undergo allosteric modulation when they bind to the hormone
C)Regulate gene transcription
D)Both are proteins in the nucleus and/or cytoplasm and regulate gene transcription are correct
E)All of the choices are correct

Accepted Answer

Steroid hormone receptors are proteins that are located in the nucleus and/or cytoplasm. When they bind to their hormone, they undergo allosteric modulation and regulate gene transcription.

Question 20

Some hormones are transported in plasma bound to proteins.These proteins function to
A)Maintain a stable high concentration of the hormone in the plasma and reduce its clearance rate from plasma
B)Reduce the binding of the hormone to its receptors in some cases
C)Make the hormone more soluble in aqueous plasma
D)Do all of these things
E)Do none of these things

Accepted Answer

Proteins that bind to hormones in the plasma serve multiple functions. They maintain a stable high concentration of the hormone in the plasma by reducing its clearance rate. They also make the hormone more soluble in aqueous plasma. In some cases, binding proteins can reduce the binding of the hormone to its receptors, modulating its activity. Therefore, choice D, "Do all of these things," is the best answer.

Quiz 11: The Endocrine System

Regarding the structure and synthesis of hormones,

A hormone may be

Which of the following statements is not true of the endocrine system?

Hormones(,)

Which of the following statements about hormone activation is true?

The liver participates in endocrine regulation by

Peptide hormones are

If a patient were given a drug that inhibited the actions of proteolytic enzymes in the blood plasma only (i.e.,not in cells) ,which of the following is most likely to result?

Rapidly acting chemical regulators generally

The main difference between the modes of action of peptide hormones and steroid hormones is that

Endocrine regulation

The enzyme in the mitochondria responsible for the modification of cholesterol that is important to the synthesis of steroid hormones is called

The concentration of a hormone in plasma is determined by

Cells that secrete steroid hormones

Secretion of hormones is controlled by

An endocrine cell that contains an abundance of granular endoplasmic reticulum,a large Golgi apparatus,and secretion granules is likely to

Which of the following statements about hormone synthesis is not correct?

Receptors for steroid hormones

Some hormones are transported in plasma bound to proteins.These proteins function to