Ch.16 Endocrine System

Hypocalcemia could be caused by the ______. apoptosis of parathyroid cells. failure of osteoclasts to respond to PTH (parathyroid hormone/parathormone). malfunction of the parathormone receptors in kidney tubule cells. All of the listed responses are correct.

All of the listed responses are correct. Parathyroid hormone (parathormone) is secreted in response to hypocalcemia. It functions to stimulate osteoclast activity, enhances the reabsorption of calcium by the kidneys, and increases absorption of calcium ions by the intestinal mucosal cells.

1. In type 2 diabetes, target cells do not respond normally to insulin. 2. In type 1diabetes, no insulin is produced. 3. In both type 1 and type 2diabetes, glucose levels remain higher than normal.

Answer is on the front

What ion is sometimes used as a second messenger of amino acid-based hormones? chlorine iron sodium calcium

CALCIUM

Adult onset diabetes, diabetes type 2, can best be described using which of the following concepts? Constantly high blood sugar leads to glucagon release. Glucagon is an antagonist to insulin, leading to a decrease in insulin. Constantly high blood sugar leads to high insulin release. High levels of insulin cause up-regulation of insulin receptors. Constantly high blood sugar leads to high insulin release. High amounts of insulin lead to down-regulation of insulin receptors. Constantly high blood sugar leads to the release of glucagon. Glucagon causes gluconeogenesis, which makes blood sugar higher.

Constantly high blood sugar leads to high insulin release. High amounts of insulin lead to down-regulation of insulin receptors. High levels of insulin cause the down-regulation of insulin receptors. Type 2 diabetes is sometimes called insulin insensitivity because of the lack of insulin receptors.

Choose which condition has all of the following symptoms: hypertension, hyperglycemia, and a "moon face." Cushing's disease Addison's disease pheochromocytoma

Cushing's disease Yes, a patient with Cushing's would have hypertension, increased blood glucose, and an unusual fat distribution on the face, known as a "moon face." These symptoms are due to increased levels of cortisol and can also be seen in patients after long periods of steroid treatment.

Cortisol: Increased metabolic effects from the liver Aldosterone: Increased sodium and water absorption Corticotropin-releasing hormone: Stimulates the anterior pituitary to release ACTH Epinephrine: Increased dilation of bronchioles and heart rate Adrenocorticotropic hormone: Targets the adrenal gland to release glucocorticoids and mineralocorticoids

Each of these hormones plays a distinctive role in the body. Epinephrine, along with norepinephrine, target the cardiovascular and respiratory systems, producing increases in heart rate and blood pressure, along with increased dilation of the respiratory bronchioles. Blood glucose and metabolic rate increases are also important functions of epinephrine. Corticotropin-releasing hormone and adrenocorticotropic hormone are tropins; that is, their target organs are other endocrine glands. Corticotropin-releasing hormone targets the anterior pituitary, causing the release of adrenocorticotropic hormone; this, in turn, affects the adrenal cortex to release glucocorticoids and mineralocorticoids. Lastly, cortisol and aldosterone are the chief secretions of the glucocorticoids and mineralocorticoids, respectively; cortisol targets the liver for various metabolic effects, while aldosterone impacts the kidneys, causing them to retain more sodium and water

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. A hormone made in the anterior pituitary cannot influence fertility. FSH stimulates sperm production in the testes. FSH stimulates estrogen secretion by ovarian cells; therefore, it is not synthesized by males. The man must be producing progesterone, which inhibits the synthesis of FSH.

FSH stimulates sperm production in the testes.

Steroid hormones are synthesized from amino acids. True False

False Steroid hormones are lipid-based hormones synthesized from cholesterol.

Water-soluble hormones are inactivated and removed from the blood by the liver. True False

False Water-soluble hormones are rapidly removed from the blood by the kidneys.

Glucose levels in the blood are tightly controlled. An important hormone for controlling blood glucose is insulin, which is released by the pancreas. Increases in blood glucose cause insulin release. This is an example of a hormone released in response to a humoral stimulus. Insulin release is terminated when blood glucose falls. This is an example of negative feedback.

Glucose is a critical nutrient in the blood. Its blood levels directly control release of the hormone insulin from the pancreas, so this is an example of a humoral stimulus for hormone release. In this case, a rise in blood glucose levels causes insulin release, and a fall in blood glucose terminates insulin release. This is an example of negative feedback.

You may predict that iodized salt may be effective in preventing all EXCEPT which of the following? congenital hypothyroidism. Graves' disease. endemic goiter. myxedema.

Graves' disease Graves' disease is an autoimmune disorder which results in hyperthyroidism. The condition is caused by autoantibodies which mimic the action of TSH (thyroid-stimulating hormone). Iodized salt cannot prevent Grave's disease.

A patient is being treated by her urologist for a fourth episode of kidney stones. Analysis of the stones shows that they are composed of calcium oxalate. The urologist orders an assay of which hormone? Aldosterone Parathyroid hormone (PTH) Cortisol Glucagon

Parathyroid hormone (PTH) Inappropriately high levels of PTH may result in excess calcium in the blood, which might precipitate in the urine. The result is renal lithiasis, or kidney stones.

What do steroids and amino acid-based hormones have in common? Both steroids and amino acid-based hormones may directly activate intracellular receptors responsible for activating specific genes within the cell. Steroids and amino acid-based hormones are both lipid soluble and able to cross the plasma membrane. Steroids and amino acid-based hormones both initiate the formation of second-messenger systems. Steroids and amino acid-based hormones are secreted by endocrine glands.

Steroids and amino acid-based hormones are secreted by endocrine glands. Although most hormones secreted by endocrine glands are amino acids, gonadal and adrenocortical hormones, both steroids, are also produced by endocrine glands.

How do steroid hormones and thyroid hormone affect change in their target cells? The hormone diffuses across the membrane through a protein carrier and binds to ribosomes to activate protein synthesis. The hormone passes through the cell membrane and activates intracellular receptors that enter the nucleus to activate genes. The hormone remains outside the cells and activates plasma membrane receptors to begin a second-messenger cascade. The hormone phosphorylates enzymes by adding a phosphate group to either increase or decrease the enzyme's activity.

The hormone passes through the cell membrane and activates intracellular receptors that enter the nucleus to activate genes. Steroid hormones may cross the plasma membrane and bind to intracellular receptors. This receptor-hormone complex may then directly bind to DNA in the nucleus.

Which of the following is a characteristic of thyroid hormone? Thyroid hormone initiates the second-messenger cAMP. Thyroid hormone activates the PIP2-calcium signaling mechanism. Thyroid hormone is a type of steroid hormone. Thyroid hormone is lipid soluble.

Thyroid hormone is lipid soluble. Although thyroid hormone is composed of amino acids, it is lipid soluble and capable of crossing the plasma membrane.

What is the role of the protein kinases in a cell? When activated, they phosphorylate other proteins, including other enzymes. Once activated, they serve as a second messenger within the cell. When activated, they produce a second messenger such as cAMP. When activated by a hormone, they, in turn, activate a G protein.

When activated, they phosphorylate other proteins, including other enzymes. Protein kinases are enzymes that, when activated by a second messenger, phosphorylate (give a phosphate group to) other proteins. This may activate or inhibit various cellular processes.

Which of the following is a characteristic of water-soluble hormones? binding to intracellular receptors at their target cells. exhibiting a long half-life in the blood. acting through second messengers at their target cells. circulating in the blood bound to protein carriers.

acting through second messengers at their target cells Water-soluble hormones exert their signaling effects through intracellular second messengers generated when the hormone binds to a receptor in the plasma membrane.

Secretion of __________ is increased in response to stress. follicle-stimulating hormone. thyroid-stimulating hormone. adrenocorticotropic hormone. luteinizing hormone.

adrenocorticotropic hormone Stress is the primary trigger for the secretion of CRH from the hypothalamus, which in turn signals the anterior pituitary to secrete more adrenocorticotropic hormone (ACTH), which targets the adrenal cortex to promote the release corticosteroid hormones, most importantly glucocorticoids. Glucocorticoids elevate blood nutrient levels and blood pressure to ensure adequate nutrient delivery to the body during a prolonged stress response.

Atrial natriuretic peptide secreted by the heart has exactly the opposite function of __________ secreted by the zona glomerulosa. antidiuretic hormone epinephrine aldosterone calcitonin

aldosterone Aldosterone signals the kidneys to conserve salt and water in response to low blood volume and pressure. It promotes increased reabsorption, and thus decreased urinary excretion, of salt and water. In contrast, atrial natriuretic peptide (ANP) is secreted in response to elevated blood volume and pressure. It promotes increased urinary excretion of salt and water, mainly by inhibiting the secretion of aldosterone from the adrenal cortex.

Which hormone aids in water resorption? adrenocorticotropic hormone. parathyroid hormone. antidiuretic hormone. thyroid hormone.

antidiuretic hormone Antidiuretic hormone (ADH) stimulates the kidney tubules to reabsorb water.

Which of the following hormones helps the body avoid dehydration? antidiuretic hormone. renin. atrial natriuretic peptide. glucagon.

antidiuretic hormone As blood volume and pressure drop, antidiuretic hormone (ADH) secretion increases. ADH signals the kidney tubules to reabsorb and conserve water, resulting in small volumes of highly concentrated urine. Along with consuming water, this helps the body avoid dehydration.

Hormones that bind to plasma proteins ________. must also bind to plasma membrane receptors. are usually synthesized from cholesterol. are usually made of amino acids. are usually water soluble.

are usually synthesized from cholesterol.

How do glucocorticoids enable the body to deal appropriately with stress? by increasing blood glucose, fatty acid, and amino acid levels and enhancing blood pressure by decreasing the heart rate, thus decreasing blood pressure by stimulating the pancreas to release insulin by releasing the neurotransmitters that prepare the body for the stress response

by increasing blood glucose, fatty acid, and amino acid levels and enhancing blood pressure

What is the target of thyroid hormones? cells of the body anterior pituitary thyroid hypothalamus

cells of the body Thyroid hormones secreted by the thyroid gland target cells of the body to modulate metabolism.

Gluconeogenesis, the formation of glucose from fats and proteins, is due to the action of ________. secretin aldosterone insulin cortisol

cortisol

In response to stress, which of the following changes would happen? decreased sweating. decreased or difficulty breathing. decreased cardiac output. decreased insulin secretion.

decreased insulin secretion Yes, insulin decreases plasma glucose and during stress we need an increase in plasma glucose as well as other body fuels. Therefore, insulin secretion would be decreased, in turn increasing plasma glucose.

Aldosteronism will cause ______. decreased secretion of renin. decreased secretion of ANP (atrial naturetic peptide). decreased loss of K+ in the urine. None of the listed responses is correct.

decreased secretion of renin Aldosteronism is due to oversecretion of aldosterone. The kidneys release renin, which is converted into angiotensin II, which stimulates aldosterone release. Decreased renin secretion reduces aldosterone secretion.

Which of the following hormones is a part of the rapid response (rather than the prolonged response) to stress? ADH (vasopressin) aldosterone epinephrine cortisol

epinephrine Yes, epinephrine is part of the immediate or rapid response to stress. Epinephrine is released from the adrenal medulla as a result of the increase in the sympathetic nervous system. In fact, the chromaffin cells in the adrenal medulla act like modified postganglionic neurons.

Johanna, a 7-year-old girl, is significantly shorter than normal for her age. Her doctor recommends treatment with a hormone before her growth plates ossify in her long bones. Which hormone is recommended? parathyroid hormone. growth hormone. thyroid stimulating hormone. cortisol.

growth hormone

Hypersecretion of what hormone can produce the effects of gigantism, as seen in the individual in the center of this image? aldosterone thyroid-stimulating hormone (TSH) thyroid hormones (TH) growth hormone (GH)

growth hormone (GH) Growth hormone has effects on metabolism as well as growth. Hypersecretion can lead to gigantism.

Which of the following are symptom(s) of pheochromocytoma? low blood glucose heart palpitations slow heart rate cool, dry skin

heart palpitations Yes, due to the increase in epinephrine, heart rate would be increased and you would feel like your heart was pounding or racing.

What is directly required for the production of anterior pituitary gland hormones? humoral stimuli hormonal stimuli neural stimuli All of the listed responses are correct.

hormonal stimuli The anterior pituitary requires hormonal stimuli from the hypothalamus.

Low blood glucose concentration and high blood potassium concentration are examples of __________ stimuli for an endocrine gland. humoral antagonistic hormonal neural

humoral Some endocrine glands secrete their hormones in direct response to changing blood levels of certain critical ions (such as K+) and nutrients (such as glucose). These stimuli are called humoral stimuli (from the Latin term humor, which refers to bodily fluids).

Several hormones are synthesized in the hypothalamus and transported to the anterior pituitary gland. The mechanism of transportation from hypothalamus to anterior pituitary gland is through the ________. hepatic portal system. feedback loop. hypophyseal portal system. general circulatory system.

hypophyseal portal system

Acromegaly may be caused by all EXCEPT which of the following? hypersecretion of GHRH (growth hormone-releasing hormone). pancreatic tumor. lack of negative feedback by insulin-like growth factors. hyposecretion of GH in adulthood

hyposecretion of GH in adulthood Acromegaly is a disorder resulting from excessive GH secretion after epiphyseal plates have closed. There are usually no adverse effects of GH hyposecretion in adults. However, GH hyposecretion in children slows the growth of long bones and, unless treated, results in pituitary dwarfism. Growth hormone secretion is stimulated by GHRH (growth hormone-releasing hormone).

Hyperprolactinemia may be caused by ______. hyposecretion of dopamine. negative feedback by gonadotropins on the anterior pituitary. hypersecretion of milk. negative feedback by PIH (prolactin-inhibiting hormone) on the anterior pituitary

hyposecretion of dopamine Dopamine functions as a prolactin-release-inhibiting hormone (PIH). Thus, dopamine hyposecretion would allow excessive secretion of prolactin, resulting in hyperprolactinemia.

A release of parathyroid hormone (PTH) will trigger ________. increased osteoblast activity. a reduction of calcium reabsorption in the kidney tubules. a drop in blood calcium levels. increased activation of vitamin D by the kidney.

increased activation of vitamin D by the kidney

Adrenocortical androgens are normally converted in females into estrogens. However, in adrenogenital syndrome, females develop a beard and a masculine pattern of body hair distribution; this occurs due to ______. negative feedback that inhibits estrogen production. conversion of estrogens into testosterone. insufficient level of enzymes that convert androgens into estrogens. increased testosterone secretion

insufficient level of enzymes that convert androgens into estrogens During the end steps of sex hormone, synthesis androstendione is converted into either testosterone or estrogen. If the body lacks the enzyme to convert androstendione to estrogen, the remaining pathway to testosterone will predominate.

A blow to the head may cause diabetes insipidus by ______. triggering the hypersecretion of hypothalamic-inhibiting hormones. triggering the hyposecretion of hypothalamic-inhibiting hormones. interfering with the normal transmission of nerve impulses to the posterior pituitary. interfering with the normal transmission of nerve impulses from the posterior pituitary.

interfering with the normal transmission of nerve impulses to the posterior pituitary Specialized neurons called neurosecretory cells produce anti-diuretic hormone in the paraventricular nuclei of the hypothalamus. This hormone is then transported down the axons of these neurons and stored in their axon terminals, which are located in the posterior pituitary. The hormone is released from the axon endings when associated neurons fire action potentials, and it passes down the axon to the axonal terminals.

The posterior lobe of the pituitary gland is NOT a true endocrine gland because ________. it is strictly a part of the neural system and has little or nothing to do with hormonal release. it is only a hormone storage area that receives hormones from the hypothalamus for release. it is unable to function as an endocrine tissue because it is actually part of the neural system due to its location. embryonically it was an endocrine tissue, but in the adult human it is no longer functional.

it is only a hormone storage area that receives hormones from the hypothalamus for release.

Upon landing at the airport in Lagos, Nigeria, Eric feels wide awake even though the local time is 11pm. Which synthetic hormone supplement could he administer to help adjust to the new time zone? melatonin growth hormone insulin glucagon

melatonin

Which hormone has only one known effect: to stimulate milk production by the breasts? progesterone prolactin estrogen oxytocin

prolactin

Oxytocin ________. is an anterior pituitary secretion. controls milk production. exerts its most important effects during menstruation. release is an example of a positive feedback control mechanism.

release is an example of a positive feedback control mechanism.

Antidiuretic hormone (ADH) ________. increases urine production. promotes dehydration. secretion is inhibited by alcohol. is produced by the anterior pituitary.

secretion is inhibited by alcohol

Which of the following occurs in situations where different hormones produce the same effects at the same target cell and their combined effects are amplified? synergism antagonism permissiveness summation

synergism Synergism occurs when more than one hormone produces the same effects at the target cell and their combined effects are amplified. For example, let's say both hormone "A" and hormone "B" cause the liver to release glucose into the blood. When they act together, the amount of glucose released might be 150% of what is released if each hormone acts independently.

Which organ is responsible for synthesizing the hormone atrial natriuretic peptide (ANP)? the kidney the spleen the heart the skin

the heart

What determines whether a particular cell is able to respond to a hormone? the structure of the hormone. the location of the cell. the gland that releases the hormone. the presence of a specific hormone receptor.

the presence of a specific hormone receptor Any cell that has a specific receptor for a specific hormone is a target cell of that hormone. Binding of the hormone to the receptor triggers a response from the target cell.

At age 85, Lyle's immune system does not respond to vaccines as well as it did when he was younger. The atrophy of which endocrine gland is likely responsible for this? thyroid anterior pituitary thymus adrenal

thymus

Glucagon ________. triggers gluconeogenesis. is considered a hypoglycemic hormone. stimulates the absorption of glucose from the blood. triggers the conversion of glucose into glycogen.

triggers gluconeogenesis

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 ________. sensitivity increase. up-regulation. a stressor reaction. cellular affinity.

up-regulation

Dave has discovered a new lipid-soluble hormone. Which of the following is true regarding this hormone? will be bound to a transport protein in the blood. will likely act through a second-messenger system. receptor will be located on the plasma membrane. can be stored in secretory vesicles

will be bound to a transport protein in the blood.

Which of the following pairs correctly matches the adrenal gland structure with the class of hormones it produces? medulla: glucocorticoids zona reticularis: aldosterone zona fasciculata: catecholemines zona glomerulosa: mineralocorticoids

zona glomerulosa: mineralocorticoids The zona glomerulosa produces mineralocorticoids

As the adrenal gland releases glucocorticoids, which of the following effects may be observed? Select all the answers that apply. Increased water absorption in the kidney. Increased blood levels of amino acids. Decrease in immune system function. Increased blood glucose levels. Lipid breakdown in the liver will increase. Decreased blood pressure and volume.

-Increased blood levels of amino acids. -Decrease in immune system function. -Increased blood glucose levels. -Lipid breakdown in the liver will increase. With long-term stress, the glucocorticoid hormones, chiefly cortisol, are instrumental in the body. The primary targets include the liver, resulting in increased gluconeogenesis and increased catabolism of lipids and proteins. In larger amounts, the depression of the immune system can result.

Which of the following hormones has the greatest effect on the overall metabolic rate? 1.TSH 2.FSH 3.ACTH 4. PRL

1. TSH TSH is thyroid-stimulating hormone. The thyroid affects the metabolic rate of many organs and tissues of the body.

Which of the following statements is true of amino acid-based hormones? 1. They require a receptor in the plasma membrane. 2. They cross the plasma membrane. 3. They are lipid soluble. 4. They are synthesized from cholesterol.

1. They require a receptor in the plasma membrane.

Which endocrine gland produces cortisol? 1. adrenal gland 2.parathyroid glands 3. kidney 4. ovary

1. adrenal gland The adrenal cortex produces several corticotropic hormones, including cortisol.

The second-messenger mechanism of hormone action operates by ________. binding to specific receptors and employing the services of G proteins and cAMP altering gene expression in the nuclear DNA synthesizing more than one hormone at a time increasing the basal metabolic rate in the target organ

1. binding to specific receptors and employing the services of G proteins and cAMP.

The amplification of the signal from a water-soluble hormone is achieved through an increase in _______. 1. cAMP in the cytoplasm 2. plasma membrane receptors. 3. phosphodiesterase in the cytoplasm. 4. adenylate cyclase in the plasma membrane. 5. water-soluble hormone in the blood

1. cAMP in the cytoplasm Many cAMP can be generated as a second messenger to amplify the signal in response to hormone binding.

What is the function of the ventral hypothalamic neurons? 1. control secretion of thyroid stimulating hormone (TSH). 2. control secretion of oxytocin. 3. control secretion of antidiuretic hormone (ADH). 4.control secretion of thyroid hormones.

1. control secretion of thyroid stimulating hormone (TSH). Yes, neurohormones from the ventral hypothalamic neurons, known as releasing (RH) and inhibiting (IH) hormones, control the release of anterior pituitary hormones such as adrenocorticotropic hormone (ACTH) and TSH.

Which of the following hormones is regulated by a neuroendocrine ("letdown") reflex? 1. oxytocin 2. antidiuretic hormone (ADH) 3.cortisol

1. oxytocin Yes, suckling of the infant (or stretching of the uterus) increases release of oxytocin, which causes the milk let-down effect (or increased uterine contractions).

How do endocrine hormones reach their target cells? 1. Hormones are produced by endocrine cells that are adjacent to target cells. 2. Hormones are transported through the blood stream to target cells. 3. Ducts transport hormones directly to target cells. 4. Hormones travel through the lymphatic system to target cells. 5. Hormones are released at synapses adjacent to target cells.

2. Hormones are transported through the blood stream to target cells. The blood stream allows hormones to be distributed throughout the body.

What is the role of activated protein kinases? Select the best answer. 1. Degrade cAMP to AMP. 2. Phosphorylate proteins. 3. Phosphorylate ADP to ATP. 4. Convert ATP to cAMP by phosphorylation. 5. Activate adenylate cyclase.

2. Phosphorylate proteins. Phosphorylation can activate different proteins causing the response of the cell to water-soluble hormone.

Steroid hormones exert their action by ________. 1. binding cell receptors and initiating cAMP activity. 2. entering the nucleus of a cell and initiating or altering the expression of a gene. 3. activating the hypothalamic release of regulating hormones 4. entering the cell and activating mitochondrial DNA.

2. entering the nucleus of a cell and initiating or altering the expression of a gene.

Which intracellular substance degrades cAMP, thus inactivating the response to a hormone? 1. protein kinase C. 2. phosphodiesterase. 3. phospholipase. 4. C adenylate cyclase.

2. phosphodiesterase Yes, phosphodiesterase is an intracellular enzyme that degrades cAMP.

Virtually all amino acid-based hormones exert their signaling effects through intracellular ________. 1. deactivating ions 2. second messengers 3. nucleotides 4. calcium

2. second messengers

Which of the following is NOT a component of the cyclic AMP signaling mechanism? 1. G proteins 2. steroid 3. effector enzyme 4. hormone receptor

2. steroid

Which of the following is NOT a change typically produced by a hormonal stimulus? 1. alters plasma membrane permeability. 2. stimulates production of an action potential. 3. activates or deactivates enzymes. 4. induces secretory activity

2. stimulates production of an action potential

The ability of a specific tissue or organ to respond to the presence of a hormone is dependent on ________. 1. the membrane potential of the cells of the target organ. 2. the presence of the appropriate receptors on the cells of the target tissue or organ. 3. the location of the tissue or organ with respect to the circulatory path 4. nothing—all hormones of the human body are able to stimulate any and all cell types because hormones are powerful and nonspecific.

2. the presence of the appropriate receptors on the cells of the target tissue or organ.

What type of hormones bind to receptors located on the cell membrane? 1. lipid-soluble hormones, such as thyroid hormones and cortisol. 2. water-soluble hormones, such as insulin and epinephrine.

2. water-soluble hormones, such as insulin and epinephrine Yes, peptides and catecholamines are water-soluble hormones that cannot diffuse through the plasma membrane.

Jeremy has been feeling tired and cold for the last week. His roommate offers Jeremy his bottle of thyroid hormone supplements and promises that they will make him feel better (they don't). Suppose that Jeremy's thyroid hormone levels were normal to start with, and that the supplements actually did contain active thyroid hormones. After taking these supplements for a week, how do you think Jeremy's blood levels of thyroid-stimulating hormone (TSH) and thyrotropin-releasing hormone (TRH) would compare to normal levels? 1. TSH would be lower, but TRH would be higher than normal. 2. TSH would be higher, but TRH would be lower than normal. 3. Both TSH and TRH would be lower than normal. 4. Both TSH and TRH would be higher than normal.

3. Both TSH and TRH would be lower than normal Thyroid hormone release follows the pattern of a hormonal stimulus for hormone release. When thyroid hormone levels go up, there is increased negative feedback on both TRH from the hypothalamus and TSH from the anterior pituitary, so blood levels of these hormones decrease.

Thyroxine is a peptide hormone, but its mechanism is different from other peptide hormones. Which of the following statements is true concerning this difference? 1. It is very specific in the cell type it targets. 2. It is a stimulant of cellular metabolism and targets all cells. 3. It does not require a second messenger to cause a response. 4. It causes positive feedback.

3. It does not require a second messenger to cause a response.

Which is the correct order of events for hormones activating Gs proteins? 1. activation of G protein, binding of GTP, activation of phospholipase C, activation of DAG and IP3 2. activation of a G protein, tyrosine kinase receptor, phosphorylation of intracellular proteins 3. activation of G protein, binding of GTP, activation of adenylate cyclase, conversion of ATP to cAMP

3. activation of G protein, binding of GTP, activation of adenylate cyclase, conversion of ATP to cAMP Yes, Gs proteins are stimulatory proteins that activate cAMP.

Hormones bring about their characteristic effects by altering target cell activity, increasing or decreasing the rates of normal cellular processes. Which of the following is NOT a typical effect brought on by hormones? 1. activating or deactivating enzymes in the target cell. 2. stimulating the target cell to secrete a product. 3. changing the structure of the target cell's cytoskeleton. 4. stimulating the target cell to divide by mitosis. 5. changing permeability of the target cell's plasma membrane.

3. changing the structure of the target cell's cytoskeleton. Changing the structure of the target cell's cytoskeleton is not a typical effect brought on by hormones. A hormone typically produces one or more of the following changes: alters plasma membrane permeability or membrane potential, or both, by opening or closing ion channels; stimulates synthesis of enzymes and other proteins within the cell; activates or deactivates enzymes; induces secretory activity; and/or stimulates mitosis.

Hormones often cause multiple responses in a cell. This is because ______. 1. The receptors bind to several hormones at the same time. 2. there are thousands of receptors on the cell membrane. 3. during protein kinase activation, enzymes phosphorylate many other enzymes. 4. The protein kinases are rapidly metabolized into functional amino acids.

3. during protein kinase activation, enzymes phosphorylate many other enzymes.

What property of a hormone would allow it to pass unassisted through a plasma membrane? 1. charged. 2. bound to a protein complex. 3. lipid-soluble. 4. protein-based.

3. lipid-soluble Hormones that are lipid-soluble can dissolve through the plasma membrane.

Cyclic AMP is degraded by __________. 1. protein kinase 2. adenylate cyclase 3. phosphodiesterase 4. G proteins 5. AMP

3. phosphodiesterase Phosphodiesterase degrades cyclic AMP into AMP.

Which of the following can act on receptors inside the target cell that directly activate specific genes? 1. melatonin 2. calcitonin 3. testosterone 4. growth hormone

3. testosterone

The anterior pituitary gland does NOT produce __________. 1. follicle-stimulating hormone. 2. adrenocorticotropic hormone. 3.thyroid hormone 4. prolactin

3. thyroid hormone Thyroid hormone, as its name implies, is produced by the thyroid gland.

Growth factor hormones, such as insulin, bind to which type of receptor? 1. intracellular receptors. 2. G proteins. 3. tyrosine kinase receptors.

3. tyrosine kinase receptors Yes, insulin binds to tyrosine kinase receptors and works without a second messenger.

Which of the following adrenergic receptors increase cAMP levels? 1. α2 receptors. 2. α1 receptors. 3. β receptors.

3. β receptors Yes, these receptors are coupled to adenylate cyclase by Gs receptors that increase cAMP.

Insulin-like growth factors (IGFs) are intermediary hormones stimulated by which of the following hormones? 1. oxytocin. 2. thyroid hormones. 3. prolactin (PRL). 4. GH (growth hormone).

4. GH (growth hormone) Yes, GH stimulates IGFs from the liver. IGFs are required for the growth effect of GH on bone and skin.

Which second messenger causes the release of calcium from the endoplasmic reticulum? 1. DAG 2. cAMP 3. tyrosine kinase 4. IP3

4. IP3 Yes, inositol trisphosphate releases calcium from intracellular storage sites.

Where is antidiuretic hormone (ADH), also known as vasopressin, synthesized? 1. anterior pituitary 2. kidney 3. posterior pituitary 4. hypothalamus

4. hypothalamus Yes, ADH is synthesized mainly in the supraoptic nucleus of the hypothalamus. It is stored in the posterior pituitary in axon terminals.

If the anterior pituitary failed to produce LH appropriately, what might be the result? 1. poor milk production in nursing women. 2. cretinism 3. dwarfism 4. lowered levels of testosterone or ovarian hormones

4. lowered levels of testosterone or ovarian hormones Gonads are the sex organs: ovaries and testes. If adequate LH is not produced, the gonads will not produce normal levels of estrogen and progesterone (females) or testosterone (males).

What is the most important regulatory factor controlling the circulating levels of thyroid hormone? 1. thyrotropin-releasing hormone (TRH). 2. a circadian rhythm of release. 3. thyroid-stimulating hormone (TSH). 4. negative feedback

4. negative feedback Yes, negative feedback controls the levels of circulating thyroid hormone. If levels are high, negative feedback will decrease thyroid-stimulating hormone (TSH) (and thyrotropin-releasing hormone (TRH) to some degree), thus decreasing the thyroid hormones.

Which of the following enzymes are important in the deactivation of cAMP and termination of signaling? 1. adenylate cyclase 2. G protein 3. protein kinase 4. phosphodiesterase

4. phosphodiesterase The increase in cAMP levels is usually short-lived because the enzyme phosphodiesterase is constantly present in the cytoplasm of the target cells.

Water-soluble hormones affect target cells by binding to __________. 1.cAMP 2. adenylate cyclase 3. protein kinases 4. plasma membrane receptors 5. cytoplasmic receptors

4. plasma membrane receptors Water-soluble hormones bind to specific receptors in the plasma membrane, whereas steroid hormones bind to cytoplasmic receptors.

Thyroid hormone (a small iodinated amine) enters target cells in a manner similar to ________. 1. growth hormone, because the thyroid works synergistically with thyroid hormone. 2. glucagon, because the structure of glucagon is similar to that of thyroid hormone. 3. insulin, because insulin is a small peptide. 4. steroid hormones, because both diffuse easily into target cells.

4. steroid hormones, because both diffuse easily into target cells

What tropic hormone stimulates cortisol from the adrenal gland? 1. growth hormone (GH). 2. thyroid stimulating hormone (TSH). 3. luteinizing hormone (LH) and follicle stimulating hormone (FSH). 4.adrenocorticotropic hormone (ACTH).

4.adrenocorticotropic hormone (ACTH) Yes, ACTH stimulates the adrenal cortex to produce cortisol. Stress and ACTH are the main stimuli for cortisol.

What hormone also aids the stress response by promoting water retention and acting as a vasoconstrictor? ADH (vasopressin) cortisol aldosterone angiotensin II

ADH (vasopressin) Yes, ADH increases water reabsorption in the distal tubule and collecting duct of the nephron and its secondary function is to act as a vasoconstrictor.