Practice Test Chapter 45: Hormones and the Endocrine System

How is the level of thyroxine in the blood regulated? (Concept 45.2)

High levels of T3 and T4 inhibit the secretion of TRH and TSH. This is a negative feedback loop that maintains proper levels of TRH.

A goiter may form because __________. (Concept 45.2)

low blood levels of T3 and T4 inhibit the negative feedback loop, and an overload of TSH causes enlargement of the gland The hypothalamus continues to release TRH, causing the anterior pituitary to continue secreting TSH.

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

low concentration of juvenile hormone and high concentration of ecdysteroid Juvenile hormone promotes the retention of larval characteristics. When levels of juvenile hormone are low, ecdysteroid will stimulate formation of the pupal form and subsequent metamorphosis.

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

paracrine signaling Target cells in paracrine signaling are located close to the secreting cell.

Which statement below about the catecholamines secreted by the adrenal medulla is correct? (Concept 45.3) Epinephrine and norepinephrine are catecholamines. They are synthesized from the cholesterol. They decrease the rate of oxygen delivery to body cells. They decrease the rate of glycogen breakdown in the liver and skeletal muscles. They are released in response to FSH.

Epinephrine and norepinephrine are catecholamines.

Which is a correct statement about prolactin? (Concept 45.3)

It controls fat metabolism and reproduction in birds.

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

It relays a hormone's message inside a target cell. Most hormones are unable to cross plasma membranes. After binding to a surface receptor, a transduction event may result in the production of a second messenger within the cell.

Which example below is a true statement about the differences between hormones and neurotransmitters? (Concept 45.1) Neurotransmitters are secreted chemicals that diffuse a short distance, whereas hormones travel through the bloodstream to the target cell. Neurotransmitters produce slow, long-acting responses whereas hormones produce rapid, brief responses. Some endocrine glands release neurotransmitters, but no nervous tissue releases hormones. Neurotransmitters are released from ductless glands into the blood whereas hormones are secreted into synapses. All of the listed responses are correct.

Neurotransmitters are secreted chemicals that diffuse a short distance, whereas hormones travel through the bloodstream to the target cell. Neurotransmitters are local chemical signals that convey messages between neurons in the nervous system.

A doctor might give an expectant mother __________ to stimulate uterine contractions and induce labor. (Concept 45.3)

Oxytocin is released from the posterior pituitary as part of a positive feedback loop involving uterine contractions. Oxytocin is released from the posterior pituitary as part of a positive feedback loop involving uterine contractions.

Which is an accurate statement regarding the difference between steroid and nonsteroid hormones? (Concept 45.1) Nonsteroid hormones can pass through cell membranes; most steroid hormones cannot. Steroid hormones are lipids; nonsteroid hormones are made from one or more amino acids. Steroid hormones inactivate genes; nonsteroid hormones directly activate genes. Nonsteroid hormones attach to receptors in the cytoplasm; steroid hormones attach to membrane-bound receptors. Steroid hormones are produced by endocrine glands; nonsteroid hormones are produced by nervous tissue.

Steroid hormones are lipids; nonsteroid hormones are made from one or more amino acids. Steroid hormones are lipid-soluble, which allows them to pass through membranes.

Which of the following statements about the adrenal medulla is correct? (Concept 45.3)

The gland is stimulated by nerve signals carried from the brain. This provides a rapid, short-term response to stress

How does the hypothalamus control the secretion of growth hormone (GH) from the anterior pituitary? (Concept 45.3)

The hypothalamus produces a releasing hormone that stimulates the pituitary to secrete GH. Releasing hormones make the anterior pituitary secrete its hormones.

Which is a correct statement about the thyroid gland? (Concept 45.3) Thyroxine and triiodothyronine, two of the thyroid hormones, are steroid hormones. It produces steroid hormones. Fluorine is essential to proper thyroid function. Thyroid hormones trigger the change of an aquatic tadpole into a terrestrial bullfrog. Goiter is caused by hyperthyroidism.

Thyroid hormones trigger the change of an aquatic tadpole into a terrestrial bullfrog. Thyroid hormones are involved in bullfrog maturation.

How does parathyroid hormone affect levels of Ca2+ in the blood? (Concept 45.3)

When Ca2+ levels fall, PTH stimulates bone cells to decompose the matrix of bone and stimulates reabsorption of Ca2+ in the renal tubules. These two actions will build up the level of calcium in the blood.

Which example below is a role of the local regulator nitric oxide (NO)? (Concept 45.1) NO decreases the blood flow into the penis, producing an erection. When oxygen levels fall, nitric oxide activates an enzyme that relaxes smooth muscle. This dilates blood vessels and improves blood flow. When secreted by certain white blood cells, NO stimulates the reproduction of some bacteria and cancer cells. In the nervous system, NO serves as a cell surface receptor.

When oxygen levels fall, nitric oxide activates an enzyme that relaxes smooth muscle. This dilates blood vessels and improves blood flow. NO increases blood flow.

Which of the following endocrine glands releases steroid hormones? (Concept 45.3)

adrenal cortex The adrenal cortex, testes, and ovaries each secrete steroid hormones.

Which of the following hormones specifically act(s) to trigger secretion of hormones by another endocrine gland? (Concept 45.3)

adrenocorticotropic hormone (ACTH) The target of ACTH is the adrenal cortex.

Anabolic steroids, sometimes taken illegally by athletes and bodybuilders, are chemically related to natural __________ produced in the __________. (Concept 45.3)

androgens ... gonads Anabolic steroids are synthetic androgens that are similar to hormones produced by the adrenal cortex and gonads. Taking these steroids interferes with natural negative feedback mechanisms.

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.

blood sugar level Under normal circumstances, the hormones glucagon and insulin maintain blood sugar within its homeostatic range. These hormones are not controlled by the pituitary.

Which of the following hormones is thought to act at the cellular level by inducing a change in gene expression? (Concept 45.1) prostaglandin prothoracicotropic hormone (PTTH) epinephrine nitric oxide estrogen

estrogen Sex hormones such as estrogen are steroid hormones that can cross the plasma membrane and bind to receptors in the cytoplasm. The hormone-receptor complex has the proper conformation to bind to certain sites on DNA.

FSH (follicle-stimulating hormone) and LH (luteinizing hormone) are tropic hormones that are also known as __________. (Concept 45.3)

gonadotropins FSH and LH are called gonadotropins because they stimulate the activities of male and female gonads; the testes and ovaries.

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

hormones ... reach A hormone affects only cells with receptors for that particular hormone.

In insects, ecdysteroid is released __________. (Concept 45.1)

in response to prothoracicotropic hormone Endocrine glands located behind the brain are stimulated by prothoracicotropic hormone to release ecdysteroid.

Which of the following hormones have ANTAGONISTIC effects? (Concept 45.2)

insulin and glucagon These hormones decrease and increase blood sugar, respectively. It is important to note, however, that the mechanisms responsible for the effects are not opposite to one another.

The major tropic action of growth hormone is to signal the __________ to release __________. (Concept 45.2) hypothalamus ... thyroid-releasing hormone adrenal medulla ... epinephrine thyroid ... T3 and T4 liver ... insulin-like growth factors (IGFs) pancreas ... glucagon

liver ... insulin-like growth factors (IGFs) IGFs circulate in the blood and directly stimulate bone and cartilage growth.

Which of the following is a neurohormone secreted by the posterior pituitary? (Concept 45.3)

oxytocin The posterior pituitary releases oxytocin and antidiuretic hormone

In the winter, the __________ of vertebrates is apt to produce __________ than in summer months. (Concept 45.3)

pineal gland ... more melatonin Melatonin is secreted by the pineal gland in response to lack of daylight. Because there is less daylight in winter months, the pineal gland would release more melatonin.

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

posterior pituitary The posterior pituitary stores and secretes two hormones produced in the hypothalamus.

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? (Concept 45.3)

prolactin

Ibuprofen is known for its pain-relieving and anti-inflammatory properties because it INHIBITS the synthesis of __________. (Concept 45.1)

prostaglandins Among other roles, prostaglandins help induce fever and inflammation and intensify the sensation of pain

Which of the following is a problem with the long-term use of glucocorticoids, such as cortisone, to treat inflammation? (Concept 45.3)

suppression of the immune system Abnormally high levels of glucocorticoids administered as medication suppress certain components of the body's immune system.

Because most chemical signals are UNABLE to pass through the plasma membrane, the cellular action they initiate results from __________. (Concept 45.1)

the activation of a signal transduction pathway When a signal molecule binds to a surface receptor, it induces a specific intracellular response.

Hyperthyroidism, typically characterized by a high metabolic rate and high blood pressure, might be expected when __________. (Concept 45.2)

thyroid-stimulating hormone (TSH) concentration is high When TSH binds to specific receptors in the thyroid gland, a signal transduction pathway triggers the synthesis and release of T3 and T4. An excessive secretion of thyroid hormones, known as hyperthyroidism, produces such symptoms as sweating, high body temperature, weight loss, irritability, and increased blood pressure.

What result would you expect following the binding of epinephrine to an α-type epinephrine receptor? (Concept 45.1)

Blood flow to the intestines decreases. When epinephrine binds to the α-type receptor, found in the intestinal blood vessels, the vessels constrict and thus decrease blood flow.

The regulation of water volume in the blood involves which hormone? (Concept 45.3)

ADH- Antidiuretic hormone (ADH) is secreted by the posterior pituitary and acts on the kidneys, increasing water retention and thus decreasing urine volume.