Chapter 45 MB

DES is called an "endocrine disrupting chemical" because it structurally resembles, and interferes with, the endocrine secretions of the A) ovaries. B) thyroid gland. C) pancreatic islet cells. D) hypothalamus. E) adrenal medulla.

a

Growth factors are local regulators that A) bind to cell-surface receptors and stimulate growth and development of target cells. B) are produced by the anterior pituitary. C) convey messages between nerve cells. D) are found on the surface of cancer cells and stimulate abnormal cell division. E) are modified fatty acids that stimulate bone and cartilage growth.

a

In their mechanism of action, a difference between lipid-soluble and water-soluble hormones is that _____. A) lipid-soluble hormones bind to an intracellular receptor and this hormone-receptor complex binds to DNA B) water-soluble hormones cross the plasma membrane more readily than do lipid-soluble hormones C) water-soluble hormones bind reversibly to DNA D) lipid-soluble hormones activate a "second messenger" pathway E) the water-soluble hormones travel only in the blood, and the lipid-soluble hormones travel only in the lymphatic fluid

a

Suppose that substance X is secreted by one cell, travels via interstitial fluid to a neighboring cell, and produces an effect on that cell. All of the following terms could describe this substance except A) pheromone. B) neurotransmitter. C) prostaglandin. D) growth factor. E) paracrine signal.

a

Testosterone is an example of a chemical signal that affects the very cells that synthesize it, the neighboring cells in the testis, along with distant cells outside the gonads. Thus, testosterone is an example of A) an autocrine signal, a paracrine signal, and an endocrine signal. B) a paracrine signal. C) both an autocrine signal and a paracrine signal. D) an autocrine signal. E) an endocrine signal.

a

The amino acid tyrosine is a starting substrate for the synthesis of A) epinephrine. B) parathyroid hormone. C) vitamin D. D) steroid hormones. E) acetylcholine.

a

Which hormone is incorrectly paired with its action? A) insulin-stimulates glycogen breakdown in the liver B) thyroxine-stimulates metabolic processes C) oxytocin-stimulates uterine contractions during childbirth D) ACTH-stimulates the release of glucocorticoids by the adrenal cortex E) melatonin-affects biological rhythms, seasonal reproduction

a

All hormones A) elicit the same biological response from all of their target cells. B) are carried to target cells in the blood. C) are protein molecules. D) are lipid-soluble molecules. E) are produced by endocrine glands.

b

Correct and appropriate signal transduction processes are generally under strong selective pressure and are determined by the properties of the molecules involved, the concentrations of signal and receptor molecules, and the binding affinities between signal and receptor. Therefore, a hormone action is very specific in a species at any one point in time. However, there are examples of very diverse functions of a specific hormone between groups of organisms. For example, thyroxin, which is produced in all vertebrates and many invertebrates, can trigger growth, differentiation, metamorphosis, maturation, reproduction, behavior, temperature tolerance, osmoregulation, or seasonal adaptation depending on the organism in which it is produced. What is the most logical explanation for such different responses triggered by thyroxin in organisms? A) Thyroxin and its receptor molecules have a different binding affinity in different organisms. B) Receptor molecules for thyroxin are located on different tissues in different organisms. C) The concentration of thyroxin varies in different organisms. Invertebrate organisms do not have as much thyroxin as vertebrate organisms. D) The structure of thyroxin is substantially different in different organisms.

b

In a positive-feedback system where hormone A alters the amount of protein X, A) a decrease in A always produces an increase in X, which results in an increase in A. B) an increase in A always produces an increase in X, which results in an increase in A. C) a decrease in X always causes a decrease in A, which causes an increase in X. D) an increase in X always produces a decrease in A, which results in a decrease in X. E) it is impossible to predict how A and X affect each other.

b

Prostaglandins are local regulators whose chemical structure is derived from A) amino acids. B) fatty acids. C) steroids. D) nitric oxide. E) oligosaccharides.

b

The steroid hormone that coordinates molting in arthropods is A) thyroxine. B) ecdysteroid. C) growth hormone. D) oxytocin. E) glucagon.

b

Vertebrates have two major communication and control systems: the endocrine system and the nervous system. Choose the correct statement describing the coordination of these systems. A) The adrenal cortex secretes hormones in response to nervous stimulation. B) Epinephrine functions as a hormone in the endocrine system and as a neurotransmitter in the nervous system. C) The parathryroid gland is a fused endocrine and neuroendocrine gland.

b

Which of the following is the most likely explanation for hypothyroidism in a patient whose iodine level is normal? A) a decrease in the thyroid secretion of calcitonin B) hyposecretion of TSH C) hypersecretion of TSH D) hypersecretion of MSH E) greater production of T3 than of T4

b

Hormone X activates the cAMP second messenger system in its target cells. The greatest response by a cell would come from A) applying a molecule of cAMP to the extracellular fluid surrounding the cell. B) injecting a molecule of hormone X into the cytoplasm of the cell. C) applying a molecule of hormone X to the extracellular fluid surrounding the cell. D) injecting a molecule of cAMP into the cytoplasm of the cell. E) injecting a molecule of activated, cAMP-dependent protein kinase into the cytoplasm of the cell.

c

Hormones that promote homeostasis A) travel to target cells without passage in the plasma. B) are not found as members of antagonistic signaling mechanisms. C) usually operate as part of a negative feedback system. D) initiate signal transduction in the target cell without binding to receptors. E) utilize receptors that bind any hormone.

c

Select the correct statement about feedback regulation in endocrine systems. A) A hormone cascade pathway involves the hypothalamus, posterior pituitary, and endocrine gland. B) All hormones are regulated by negative feedback loops. C) Some homeostatic control systems rely on pairs of negatively regulated hormone pathways, each counterbalancing the other.

c

The reason that the steroid hormone aldosterone affects only a small number of cells in the body is that A) only its target cells get exposed to aldosterone. B) nontarget cells destroy aldosterone before it can produce any effect. C) only its target cells contain aldosterone receptors. D) nontarget cells convert aldosterone to a hormone to which they do respond. E) it is unable to enter nontarget cells.

c

This disorder typically arises prior to puberty and is generally treated by injections of the hormone missing from the affected individual's bloodstream. A) hypothyroidism B) hyperthyroidism C) Type I diabetes mellitus D) Type II diabetes mellitus E) cachexia

c

Which category of signal exerts its effects on target cells by binding to membrane-bound receptor proteins? A) neurohormones, estrogens, androgens, and vitamin D B) vitamin D C) neurohormones D) estrogens E) androgens

c

Epinephrine is an example of A) an androgen. B) a glucocorticoid. C) an estrogen. D) a catecholamine. E) a progestin.

d

For hormones that homeostatically regulate cellular functions, A) endocrine organs release their contents into the bloodstream via specialized ducts. B) the circulating level of a hormone is held constant through a series of positive feedback loops. C) both lipid-soluble hormones and water-soluble hormones bind to intracellular protein receptors. D) negative feedback typically regulates hormone secretion. E) it is impossible to also have neural regulation of that system.

d

Hormones are _____. A) signals that must interact with DNA in order to be effective B) are all under the control of the pituitary gland C) always proteins D) chemical signals between cells, transported in blood or hemolymph E) produced only in response to environmental stress

d

The anterior and posterior lobes of the pituitary differ in that _____. A) the anterior lobe of the pituitary is nervous tissue that connects directly to the brain whereas the posterior pituitary is derived from non-neural tissues B) the posterior lobe of the pituitary operates independently of the brain whereas the anterior lobe is directly dependent on brain activity C) the anterior lobe of the pituitary receives neuronal impulses from brain cells whereas the posterior lobe receives blood-borne hormones D) many anterior pituitary hormones regulate other endocrine glands whereas posterior pituitary hormones regulate nonendocrine tissues E) the posterior pituitary gland synthesizes oxytocin and antidiuretic hormone whereas the anterior lobe receives all of its hormone products in the blood

d

The counter-regulatory functions of the pancreas refer to the fact that it _____. A) releases one hormone that increases urine production and another hormone that reduces urine production B) releases one hormone that increases body temperature (fever) and another that decreases body temperature C) releases acetylcholine when a person is calm, and epinephrine when a person is frightened or exercising D) releases one hormone that reduces glucose levels in the blood and another that increases them E) releases one hormone that increases heart rate and another that decreases heart rate

d

The hypothalamus A) functions only as an endocrine target, by having lots of receptors on its cells. B) does not have any hormone receptors on its cells. C) functions only in neuronal transmission. D) includes neuronal cells that terminate in the posterior pituitary. E) secretes tropic hormones that act directly on the gonads.

d

A fantasy movie features a caterpillar that never matures into an adult, but simply gets larger and larger with each molt. It might be possible that the caterpillar did not mature into an adult because of A) a lack of juvenile hormone. B) a lack of melatonin. C) a lack of ecdysone. D) a decreased level of ecdysone. E) an increased level of juvenile hormone.

e

A tropic hormone from the anterior pituitary gland regulates the secretion of A) epinephrine. B) calcitonin. C) glucagon. D) parathyroid hormone. E) thyroxine.

e

Aspirin and ibuprofen both A) inhibit the release of nitric oxide, a potent vasodilator. B) stimulate vasoconstriction in the kidneys. C) stimulate the release of oxytocin. D) activate the paracrine signaling pathways that form blood clots. E) inhibit the synthesis of prostaglandins.

e

The body's reaction to PTH (parathyroid hormone), an increase in plasma levels of calcium, can be opposed by A) epinephrine. B) glucagon. C) growth hormone. D) thyroxine. E) calcitonin.

e

The hormone epinephrine causes opposite effects in two populations of target cells because _____. A) epinephrine crosses the membrane on one set of target cells but binds to membrane-bound receptors in the other set of target cells B) epinephrine activates biochemical pathways in one set of target cells but works only by changing gene expression in the other set of target cells C) the chemical form of epinephrine released by neurons is different from the epinephrine released by endocrine cells D) epinephrine can only reach target cells in adipose tissue, as it is fat-soluble E) each set of target cells has different receptor-transduction mechanisms

e