43. Endocrine System

The endocrine system relies on __________ that __________ all of the cells of the body.

A cell releases a cytokine, which binds to and acts on a neighboring cell. This represents an example of __________.

Which of the following examples is a true statement about the differences between hormones and neurotransmitters?

Which is an accurate statement regarding the difference between steroid and nonsteroid hormones?

Because most chemical signals are unable to pass through the plasma membrane, the cellular action they initiate results from __________.

What is the role of a second messenger in hormone action?

What result would you expect following the binding of epinephrine to an α-type epinephrine receptor?

Which of the following hormones is thought to act at the cellular level by inducing a change in gene expression?

Which of the following examples is a role of the local regulator nitric oxide (NO)?

Ibuprofen is known for its pain-relieving and anti-inflammatory properties because it inhibits the synthesis of __________.

Which of the following conditions in a silkworm moth would result in metamorphosis from pupa to adult?

In insects, ecdysteroid is released __________.

In the winter, the __________ of vertebrates is apt to produce __________ than in summer months.

Anabolic steroids, sometimes taken illegally by athletes and bodybuilders, are chemically related to natural __________ produced in the __________.

Which of the following is a problem with the long-term use of glucocorticoids, such as cortisone, to treat inflammation?

Which of the following hormones have antagonistic effects?

Which of the following endocrine glands releases steroid hormones?

Which of the following statements about the adrenal medulla is correct?

Which of the following statements about the catecholamines secreted by the adrenal medulla is correct?

How does parathyroid hormone affect levels of Ca²⁺ in the blood?

Which is a correct statement about the thyroid gland?

The mammary glands of a pregnant female will begin to produce milk in response to changes in the level of which of the following hormones?

The major tropic action of growth hormone is to signal the __________ to release __________.

How is the level of thyroxine in the blood regulated?

Hyperthyroidism, typically characterized by a high metabolic rate and high blood pressure, might be expected when __________.

A goiter may form because __________.

Which of the following endocrine organs only stores hormones produced by the hypothalamus?

As a young girl, Maria suffered a head injury that damaged her pituitary. An injury to the pituitary is particularly serious because of all the functions controlled by this gland. As Maria got older, she and her doctors found that all of the following except her __________ were affected.

A doctor might give an expectant mother __________ to stimulate uterine contractions and induce labor.

The regulation of water volume in the blood involves which hormone?

How does the hypothalamus control the secretion of growth hormone (GH) from the anterior pituitary?

Which of the following is a neurohormone secreted by the posterior pituitary?

Follicle-stimulating hormone (FSH) and luteinizing hormone (LH) are tropic hormones that are also known as __________.

Which is a correct statement about prolactin?

Which of the following hormones specifically act(s) to trigger secretion of hormones by another endocrine gland?

Which statement is accurate? (A) Hormones that differ in effect reach their target cells by different routes through the body. (B) Pairs of hormones that have the same effect are said to have antagonistic functions. (C) Hormones are often regulated through feedback loops. (D) Hormones of the same chemical class usually have the same function

Which hormone is correctly paired with its action? (A) oxytocin—stimulates uterine contractions during childbirth (B) thyroxine—inhibits metabolic processes (C) ACTH—inhibits the release of glucocorticoids by the adrenal cortex (D) melatonin—raises blood calcium level

Which of the following is not an accurate statement? a. Hormones are chemical messengers that travel to target cells through the circulatory system. b. Hormones often regulate homeostasis through antagonistic functions. c. Hormones of the same chemical class usually have the same function. d. Hormones are often regulated through feedback loops.

Complete this map, which presents some major concepts from this chapter.

How do steroid hormones differ from polypeptide hormones and most amino-acid-derived hormones? a. Steroid hormones are lipid soluble and cross plasma membranes readily. b. Polypeptide and amino-acid-derived hormones are longer lived in the bloodstream and thus exert greater signal amplification. c. Polypeptide hormones are the most structurally complex and induce permanent changes in target cells. d. Only steroid hormones bind to receptors in the plasma membrane.

The hypothalamus a. synthesizes all of the hormones produced by the pituitary gland. b. influences the function of only one lobe of the pituitary gland. c. produces only inhibitory hormones. d. regulates both reproduction and body temperature.

Which correctly matches a hormone to the gland from which it is produced and to its effect on target cells? a. thyroid hormone: anterior pituitary, regulates metabolism b. prolactin: anterior pituitary, raises blood calcium levels c. androgens: thyroid, promotes male characteristics d. None of the choices are correct.

What is a hormone-response element? a. a receptor for a steroid hormone b. a receptor for a polypeptide hormone c. a segment of DNA where a hormone–receptor complex binds d. an enzyme that is activated in response to hormone binding and produces a second messenger

Growth factors are local regulators that a. are produced by the anterior pituitary. b. are modified fatty acids that stimulate bone and cartilage growth. c. are found on the surface of cancer cells and stimulate abnormal cell division. d. bind to cell-surface receptors and stimulate growth and development of target cells.

The body is able to maintain a relatively constant level of thyroid hormone in the blood because a. thyroid hormone stimulates the pituitary to secrete thyroid-stimulating hormone (TSH). b. thyroid hormone inhibits the secretion of TSH-releasing hormone (TRH) from the hypothalamus. c. TRH inhibits the secretion of thyroid hormone by the thyroid gland. d. thyroid hormone stimulates the hypothalamus to secrete TRH.

Which of the following assertions regarding hormones is correct? Select True or False for each statement. T/F Growth and metamorphosis are controlled by hormones. T/F Cortisol stimulates the production of ACTH. T/F Hormones produced by the hypothalamus are considered neurohormones. T/F Hormonal changes during puberty and pregnancy are forms of endocrine disruption.

Which hormone is incorrectly paired with its action? a. oxytocin—stimulates uterine contractions during childbirth b. thyroxine—inhibits metabolic processes c. ACTH—stimulates the release of glucocorticoids by the adrenal cortex d. melatonin—affects biological rhythms and seasonal reproduction

Explain how the hypothalamus controls body functions through its action on the pituitary gland. How does control of the anterior and posterior pituitary differ?

True or False: In hormone systems, negative feedback occurs when the presence of a hormone inhibits release of the hormone.

What do steroid and peptide hormones typically have in common? a. their solubility in cell membranes b. their requirement for travel through the bloodstream c. the location of their receptors d. their reliance on signal transduction in the cell

List three ways endocrine glands are stimulated to release hormones.

Compare and contrast the modes of action of lipid-soluble and water-soluble hormones.

Which of the following is the most likely explanation for hypothyroidism in a patient whose iodine level is normal? a. greater production of T3 than of T4 b. hyposecretion of TSH c. hypersecretion of MSH d. a decrease in the thyroid secretion of calcitonin

In a glucose tolerance test, periodic measurements of blood glucose level are taken after a person drinks a glucose-rich solution. Using the hypothetical graph below, compare and contrast the results of the test for the diabetic and the healthy individual.

Why is the observation that one hormone may bind to more than one type of receptor important?

The relationship between the insect hormones ecdysteroid and PTTH is an example of a. an interaction of the endocrine and nervous systems. b. homeostasis achieved by positive feedback. c. homeostasis maintained by antagonistic hormones. d. competitive inhibition of a hormone receptor.

If a person has a pituitary tumor that is oversecreting TSH, would this person be likely to have goiter as a symptom? Explain.

Compare and contrast the structure and function of the anterior and posterior pituitary glands.

DRAW IT In mammals, milk production by mammary glands is controlled by prolactin and prolactin-releasing hormone. Draw a simple sketch of this pathway, including glands, tissues, hormones, routes for hormone movement, and effects.

Which two of the hormones listed below act upon the body with similar functions? Explain. a. glucagon b. oxytocin c. glucocorticoids d. ADH

Design a study to test the hypothesis that the symptoms of jet lag are caused by disruption of normal daily cortisol rhythms.

A strain of mice remains healthy as long as they are fed regularly. After they eat, their blood glucose level rises slightly and then declines to a homeostatic level. However, when these mice fast or exercise, their blood glucose drops dangerously. Which hypothesis best explains their problem? (Explain your choice.) a. The mice have insulin-dependent diabetes. b. The mice lack insulin receptors on their cells. c. The mice lack glucagon receptors on their cells. d. The mice cannot synthesize glycogen from glucose.

Suppose that during a detailed anatomical study of a marine invertebrate, you found a small, previously undescribed structure. How would you test the hypothesis that the structure is a gland that releases one or more hormones?

SCIENTIFIC THINKING The results of Tyrone Hayes's experiments (Module 26.3) were published in a top peer-reviewed journal, yet the validity of his experiments has since been challenged. Using external sources, find out who has challenged the results.

Scientists set out to test the hypothesis that the herbicide atrazine is an endocrine disruptor that feminizes male amphibians. They treated male amphibians with atrazine and then compared their circulating testosterone concentration with those of males and females that were not treated with atrazine (controls). The results are shown here (* signifies P<0.05). Was the hypothesis supported? Why or why not?

Ecotourism helps conserve wildlife by increasing the value of wildlife conservation for local people. In Argentina, the world's largest breeding colony of Magellanic penguins is visited by thousands of tourists every year, causing the penguins to become habituated to the presence of people. Has ecotourism affected the penguins' ability to respond to stressors? Has it affected the penguins' secretion of corticosterone? Corticosterone is a(n): a. neurohormone b. steroid hormone c. amino-acid-derived hormone d. polypeptide hormone

Ecotourism helps conserve wildlife by increasing the value of wildlife conservation for local people. In Argentina, the world's largest breeding colony of Magellanic penguins is visited by thousands of tourists every year, causing the penguins to become habituated to the presence of people. Has ecotourism affected the penguins' ability to respond to stressors? Has it affected the penguins' secretion of corticosterone? In what part(s) of a target cell would you expect to find corticosterone receptors?

Ecotourism helps conserve wildlife by increasing the value of wildlife conservation for local people. In Argentina, the world's largest breeding colony of Magellanic penguins is visited by thousands of tourists every year, causing the penguins to become habituated to the presence of people. Has ecotourism affected the penguins' ability to respond to stressors? Has it affected the penguins' secretion of corticosterone? If penguins in a colony are habituated to the presence of tourists, how would their corticosterone response to being visited by tourists compare to that of penguins in a colony not previously exposed to tourists?

Ecotourism helps conserve wildlife by increasing the value of wildlife conservation for local people. In Argentina, the world's largest breeding colony of Magellanic penguins is visited by thousands of tourists every year, causing the penguins to become habituated to the presence of people. Has ecotourism affected the penguins' ability to respond to stressors? Has it affected the penguins' secretion of corticosterone? Scientists tested the hypothesis that penguins habituated to tourists have a blunted stress response overall. They examined the corticosterone response of habituated and non-habituated penguins to another stressor—that of being captured and restrained for 30 minutes. They found that both habituated and non-habituated penguins secreted corticosterone in response to being captured and restrained, but that the level of corticosterone after 30 minutes differed between the groups. The results are shown here (* means P<0.05). Was the hypothesis supported? Explain.

Ecotourism helps conserve wildlife by increasing the value of wildlife conservation for local people. In Argentina, the world's largest breeding colony of Magellanic penguins is visited by thousands of tourists every year, causing the penguins to become habituated to the presence of people. Has ecotourism affected the penguins' ability to respond to stressors? Has it affected the penguins' secretion of corticosterone? In response to a visit by tourists, which penguins—habituated or non-habituated—would show a greater change in expression of genes for liver enzymes involved in converting amino acids to glucose? Explain.

Ecotourism helps conserve wildlife by increasing the value of wildlife conservation for local people. In Argentina, the world's largest breeding colony of Magellanic penguins is visited by thousands of tourists every year, causing the penguins to become habituated to the presence of people. Has ecotourism affected the penguins' ability to respond to stressors? Has it affected the penguins' secretion of corticosterone? Suggest at least two distinct physiological mechanisms that could be responsible for the difference in corticosterone response to a stressor in habituated and non-habituated penguins.