UNIT 3: Endocrine System (Mylab and Mastering)
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 (1) _______ stimulus. Insulin release is terminated when blood glucose (2) _______. This is an example of (3) _______ feedback.
(1) humoral (2) Falls (3) Negative (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.)
Focus Figure 16.2 Animation: Stress and the Adrenal Gland Drag and drop the labels to their appropriate structures in the diagram.
(The hypothalamus and pituitary gland are key structures in the brain. The pituitary gland is divided into two sections, or lobes: the anterior lobe and the posterior lobe. The anterior lobe of the pituitary gland is also known as the adenohypophysis and the posterior lobe is termed the neurohypophysis. Stressors targeting the hypothalamus result in an action potential traveling to the spinal cord, which then targets the adrenal gland. The adrenal gland has two primary regions: the cortex, or outer area, and the medulla, or inner area. Both are important in the production of hormones as we will see in this activity.)
Focus Figure 16.2 Animation: Stress and the Adrenal Gland Drag and drop the items below to the appropriate bin, depending if the item is associated with the short-term or long-term stress response.
(The long-term and short-term stress responses vary in their mechanisms: in the short-term response, stressful stimuli target the hypothalamus, which activates the sympathetic nervous system, ultimately impacting the adrenal medulla. The adrenal medulla releases the catecholamine hormones - epinephrine and norepinephrine - which result in many of the effects associated with the "fight or flight" mechanism. In the long-term response, stressors to the hypothalamus cause the release of corticotropin-releasing hormone, which targets the anterior pituitary gland. Adrenocorticotropic hormone travels in the blood and targets the adrenal cortex, resulting in the production of mineralocorticoids and glucocorticoids. The mineralocorticoids impact the kidney with increased sodium and water retention, while the glucocorticoids target the liver to increase production of glucose from fats and proteins, or mobilize them for energy.)
The word root _____ means feeding or eating.
-phag-
The word root _____ means attracted specifically to the specified organ or tissue.
-tropic
The word root _____ means urine.
-uria
As the adrenal gland releases glucocorticoids, which of the following effects may be observed? Select all the answers that apply. A. Increased blood levels of amino acids B. Increased blood glucose levels C. Increased water absorption in the kidney D. Decrease in immune system function E. Lipid breakdown in the liver will increase F. Decreased blood pressure and volume
A. Increased blood levels of amino acids B. Increased blood glucose levels D. Decrease in immune system function E. 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.)
What hormone also aids the stress response by promoting water retention and acting as a vasoconstrictor? A. ADH (vasopressin) B. cortisol C. angiotensin II D. aldosterone
ADH (vasopressin) (ADH increases water reabsorption in the distal tubule and collecting duct of the nephron and its secondary function is to act as a vasoconstrictor.)
Hyposecretion of the adrenal cortex.
Addison's disease
Hypocalcemia could be caused by the ______. A. apoptosis of parathyroid cells B. failure of osteoclasts to respond to PTH (parathyroid hormone/parathormone) C. malfunction of the parathormone receptors in kidney tubule cells D. 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.)
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?
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.)
Adult onset diabetes, diabetes type 2, can best be described using which of the following concepts? A. Constantly high blood sugar leads to high insulin release. High levels of insulin cause up-regulation of insulin receptors. B. Constantly high blood sugar leads to the release of glucagon. Glucagon causes gluconeogenesis, which makes blood sugar higher. C. Constantly high blood sugar leads to glucagon release. Glucagon is an antagonist to insulin, leading to a decrease in insulin. D. 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 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.)
Hypersecretion of the adrenal cortex.
Cushing's disease
Choose which condition has all of the following symptoms: hypertension, hyperglycemia, and a "moon face." A. Addison's disease B. Cushing's disease C. pheochromocytoma
Cushing's disease (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.)
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. FSH stimulates estrogen secretion by ovarian cells; therefore, it is not synthesized by males. B. FSH stimulates sperm production in the testes. C. A hormone made in the anterior pituitary cannot influence fertility. D. The man must be producing progesterone, which inhibits the synthesis of FSH.
FSH stimulates sperm production in the testes.
True or False: Steroid hormones are synthesized from amino acids.
False (Steroid hormones are lipid-based hormones synthesized from cholesterol.)
True or False: Water-soluble hormones are inactivated and removed from the blood by the liver.
False (Water-soluble hormones are rapidly removed from the blood by the kidneys.)
Insulin-like growth factors (IGFs) are intermediary hormones stimulated by which of the following hormones? A. prolactin (PRL) B. oxytocin C. thyroid hormones D. GH (growth hormone)
GH (growth hormone) (GH stimulates IGFs from the liver. IGFs are required for the growth effect of GH on bone and skin.)
An autoimmune problem involving the thyroid gland.
Graves disease
You may predict that iodized salt may be effective in preventing all EXCEPT which of the following? A. congenital hypothyroidism B. Graves' disease C. endemic goiter D. 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.)
Figure Animations: Regulation of Hormone Release Comparing the three Types of Stimuli for Hormone Release. Drag and drop each phrase below into the correct category.
Hormonal Stimuli 1. Involves tropic hormones 2. The most common type of stimul us for hormone release by the major endocrine glands 3. Hormone release caused by another hormone 4. Terminated by negative feedback by a hormone. 5. Example: Leutinizing hormone causes testosterone release Humoral Stimuli 1. Example: rising potassium levels caus e aldosterone release 2. Terminated by negative feedback by he regulated substance 3. Hormone released caused by altere d levels of certain critical ions or nutrients Neural stimuli 1. Hormone release caused by neural input 2. Not terminated by negative feedback 3. Example: Stress causes corticotropin releasing hormone (CRH) release from the hypothalamus
How do endocrine hormones reach their target cells?
Hormones are transported through the blood stream to target cells. (The blood stream allows hormones to be distributed throughout the body.)
Which second messenger causes the release of calcium from the endoplasmic reticulum?
IP3 (inositol trisphosphate releases calcium from intracellular storage sites.)
Thyroxine is a peptide hormone, but its mechanism is different from other peptide hormones. Which of the following statements is true concerning this difference? A. It causes positive feedback. B. It does not require a second messenger to cause a response. C. It is a stimulant of cellular metabolism and targets all cells. D. It is very specific in the cell type it targets.
It does not require a second messenger to cause a response.
Hyposecretion of the thyroid in adults.
Myxedema
Produces hormones that regulate glucose levels in the body.
Pancreas
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?
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 is the role of activated protein kinases?
Phosphorylate proteins. (Phosphorylation can activate different proteins causing the response of the cell to water-soluble hormone.)
The size and shape of a pea; produces hormones that stimulate other endocrine glands.
Pituitary gland (hypophysis)
Which hormone has only one known effect: to stimulate milk production by the breasts?
Prolactin
Which of the following is NOT a component of the cyclic AMP signaling mechanism? A. steroid B. hormone receptor C. G protein D. effector enzyme
Steriod
What do steroids and amino acid-based hormones have in common?
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.)
Which of the following hormones has the greatest effect on the overall metabolic rate? A. PRL B. TSH C. ACTH D. FSH
TSH (TSH is thyroid-stimulating hormone. The thyroid affects the metabolic rate of many organs and tissues of the body.)
How do steroid hormones and thyroid hormone affect change in their target cells?
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 statements is true of amino acid-based hormones? A. They require a receptor in the plasma membrane. B. They cross the plasma membrane. C. They are lipid soluble. D. They are synthesized from cholesterol.
They require a receptor in the plasma membrane.
Which of the following is a characteristic of thyroid hormone? A. Thyroid hormone activates the PIP2-calcium signaling mechanism. B. Thyroid hormone initiates the second-messenger cAMP. C. Thyroid hormone is lipid soluble. D. Thyroid hormone is a type of steroid hormone.
Thyroid hormone is lipid soluble. (Although thyroid hormone is composed of amino acids, it is lipid soluble and capable of crossing the plasma membrane.)
In______diabetes, no insulin is produced
Type 1
In______diabetes, target cells do not respond normally to insulin.
Type 2
Growth factor hormones, such as insulin, bind to which type of receptor?
Tyrosine Kinase receptors (Insulin binds to tyrosine kinase receptors and works without a second messenger.)
What is the role of the protein kinases in a cell?
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.)
Hypersecretion of growth hormone
acromegaly
Hypersecretion of growth hormone.
acromegaly
Which of the following is characteristic of water-soluble hormones? A. binding to intracellular receptors at their target cells B. exhibiting a long half-life in the blood C. acting through second messengers at their target cells D. 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.)
Which is the correct order of events for hormones activating G, proteins? A. activation of G protein, binding of GTP, activation of adenylate cyclase, conversion of ATP to cAMP B. activation of G protein, binding of GTP, activation of phospholipase C, activation of DAG and IP3 C. activation of a G protein, tyrosine kinase receptor, phosphorylation of intracellular proteins
activation of G protein, binding of GTP, activation of adenylate cyclase, conversion of ATP to cAMP (Gs proteins are stimulatory proteins that activate cAMP.)
Which endocrine gland produces cortisol?
adrenal gland (The adrenal cortex produces several corticotropic hormones, including cortisol.)
Is part of the sympathetic nervous system.
adrenal medulla
Targets the adrenal gland to release glucocorticoids and mineralocorticoids
adrenocorticotropic hormone (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.)
Secretion of __________ is increased in response to stress.
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.)
What tropic hormone stimulates cortisol from the adrenal gland?
adrenocorticotropic hormone (ACTH) (ACTH stimulates the adrenal cortex to produce cortisol. Stress and ACTH are the main stimuli for cortisol.)
Increased sodium and water absorption
aldosterone
Atrial natriuretic peptide secreted by the heart has exactly the opposite function of __________ secreted by the zona glomerulosa.
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.)
The word root _____ means blood or lymph vessels.
angio-
Upon the release of renin, ______ is produced and stimulates vasoconstriction and the release of aldosterone.
angiotensin II
Which hormone aids in water resorption?
antidiuretic hormone (Antidiuretic hormone (ADH) stimulates the kidney tubules to reabsorb water.)
Which of the following hormones helps the body avoid dehydration? A. atrial natriuretic peptide B. renin C. glucagon D. antidiuretic hormone
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 ________.
are usually synthesized from cholesterol
The second-messenger mechanism of hormone action operates by ________.
binding to specific receptors and employing the services of G proteins and cAMP
In______diabetes, glucose levels remain higher than normal.
both type 1 and type 2
How do glucocorticoids enable the body to deal appropriately with stress? A. by decreasing the heart rate, thus decreasing blood pressure B. by increasing blood glucose, fatty acid, and amino acid levels and enhancing blood pressure C. by releasing the neurotransmitters that prepare the body for the stress response D. by stimulating the pancreas to release insulin
by increasing blood glucose, fatty acid, and amino acid levels and enhancing blood pressure
The amplification of the signal from a water-soluble hormone is achieved through an increase in______
cAMP in the cytoplasm (Many cAMP can be generated as a second messenger to amplify the signal in response to hormone binding.)
What ion is sometimes used as a second messenger of amino acid-based hormones?
calcium
What is the target of thyroid hormones?
cells of the body (Thyroid hormones secreted by the thyroid gland target cells of the body to modulate metabolism.)
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? A. stimulating the target cell to divide by mitosis B. stimulating the target cell to secrete a product C. changing the structure of the target cell's cytoskeleton D. activating or deactivating enzymes in the target cell E. changing permeability of the target cell's plasma membrane
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.)
What is the function of the ventral hypothalamic neurons?
control secretion of thyroid stimulating hormone (TSH) (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 (ACT) and TSH)
Stimulates the anterior pituitary to release ACTH
corticotropin releasing hormone
Gluconeogenesis, the formation of glucose from fats and proteins, is due to the action of ________.
cortisol
Increased metabolic effects from the liver
cortisol
Hyposecretion of the thyroid in infants.
cretinism
In response to stress, which of the following changes would happen? A. decreased or difficulty breathing B. decreased cardiac output C. decreased sweating D. decreased insulin secretion
decreased insulin secretion (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 (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.)
Hyposecretion of the pancreas.
diabetes mellitus
Hormones often cause multiple responses in a cell. This is because ______.
during protein kinase activation, enzymes phosphorylate many other enzymes
Steroid hormones exert their action by ________.
entering the nucleus of a cell and initiating or altering the expression of a gene
Increased dilation of bronchioles and heart rate
epinephrine
Which of the following hormones is a part of the rapid response (rather than the prolonged response) to stress? A. cortisol B. ADH (vasopressin) C. aldosterone D. epinephrine
epinephrine (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.)
Which of the following pairs correctly matches the adrenal gland structure with the class of hormones it produces? A. medulla: glucocorticoidszona B. glomerulosa: mineralocorticoids C. zona reticularis: aldosteronezona D. fasciculata: catecholemines
glomerulosa: mineralocorticoids
FSH and LH are examples of ______ hormones, which target the ovaries or testes.
gonadotropic
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?
growth hormone
Hypersecretion of what hormone can produce the effects of gigantism, as seen in the individual in the center of this image?
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? A. low blood glucose B. cool, dry skins C. low heart rate D. heart palpitations
heart palpitations (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?
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 (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 ________.
hypophyseal portal system
Acromegaly may be caused by all EXCEPT which of the following? A. hypersecretion of GHRH (growth hormone-releasing hormone) B. pancreatic tumor C. lack of negative feedback by insulin-like growth factors D. 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. (Dopamine functions as a prolactin-release-inhibiting hormone (PIH). Thus, dopamine hyposecretion would allow excessive secretion of prolactin, resulting in hyperprolactinemia)
Where is antidiuretic hormone (ADH), also known as vasopressin, synthesized?
hypothalamus (ADH is synthesized mainly in the supraoptic nucleus of the hypothalamus. It is stored in the posterior pituitary in axon terminals.)
A release of parathyroid hormone (PTH) will trigger ________.
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 ______.
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 ______.
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 ________. A. it is unable to function as an endocrine tissue because it is actually part of the neural system due to its location B. it is only a hormone storage area that receives hormones from the hypothalamus for release C. embryonically it was an endocrine tissue, but in the adult human it is no longer functional D. 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
What property of a hormone would allow it to pass unassisted through a plasma membrane?
lipid-soluble (Hormones that are lipid-soluble can dissolve through the plasma membrane.)
If the anterior pituitary failed to produce LH appropriately, what might be the result?
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).)
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
What is the most important regulatory factor controlling the circulating levels of thyroid hormone?
negative feedback (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 hormones is regulated by a neuroendocrine ("letdown") reflex? A. oxytocin B. antidiuretic hormone (ADH) C. cortisol
oxytocin (suckling of the infant (or stretching of the uterus) increases release of oxytocin, which causes the milk let-down effect (or increased uterine contractions).)
Primary regulators of blood calcium levels.
parathyroid glands
The word root _____ means phosphate or phosphorus.
phospho-
An enzyme that degrades second messengers like cAMP or cGMP is ______.
phosphodiesterase
Cyclic AMP is degraded by __________.
phosphodiesterase (Phosphodiesterase degrades cyclic AMP into AMP.)
Which of the following enzymes are important in the deactivation of cAMP and termination of signaling? A. phosphodiesterase B. protein kinase C. G protein D. adenylate cyclase
phosphodiesterase (The increase in cAMP levels is usually short-lived because the enzyme phosphodiesterase is constantly present in the cytoplasm of the target cells.)
Which intracellular substance degrades cAMP, thus inactivating the response to a hormone? A. adenylate cyclase B. phosphodiesterase C. protein kinase C D. phospholipase C
phosphodiesterase (phosphodiesterase is an intracellular enzyme that degrades cAMP.)
Hyposecretion of growth hormone.
pituitary dwarfism
Water-soluble hormones affect target cells by binding to_________
plasma membrane receptors (Water-soluble hormones bind to specific receptors in the plasma membrane, whereas steroid hormones bind to cytoplasmic receptors.)
Overeating, or ______, is a sign associated with diabetes mellitus.
polyphagia
Overproduction of urine, or ______, is a sign of diabetes mellitus.
polyuria
Oxytocin ________.
release is an example of a positive feedback control mechanism
Virtually all amino acid-based hormones exert their signaling effects through intracellular ________.
second messengers
Antidiuretic hormone (ADH)_______
secretion is inhibited by alcohol
Thyroid hormone (a small iodinated amine) enters target cells in a manner similar to ________.
steroid hormones, because both diffuse easily into target cells
Which of the following is NOT a change typically produced by a hormonal stimulus? A. induces secretory activity B. activates or deactivates enzymes C. stimulates production of an action potential D. alters plasma membrane permeability
stimulates production of an action potential
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? A. summation B. synergism C. permissiveness D. antagonism
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 of the following can act on receptors inside the target cell that directly activate specific genes? A. calcitonin B. melatonin C. growth hormone D. testosterone
testosterone
Which organ is responsible for synthesizing the hormone atrial natriuretic peptide (ANP)?
the heart
What determines whether a particular cell is able to respond to a hormone?
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.)
The ability of a specific tissue or organ to respond to the presence of a hormone is dependent on ________.
the presence of the appropriate receptors on the cells of the target tissue or organ
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?
thymus
Produces the body's major metabolic hormones.
thyroid gland
The anterior pituitary gland does NOT produce __________.
thyroid hormone (Thyroid hormone, as its name implies, is produced by the thyroid gland.)
Glucagon ________.
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 ________.
up-regulation
What type of hormones bind to receptors located on the cell membrane?
water-soluble hormones, such as insulin and epinephrine (peptides and catecholamines are water-soluble hormones that cannot diffuse through the plasma membrane)
Dave has discovered a new lipid-soluble hormone. Which of the following is true regarding this hormone? A. will likely act through a second-messenger system B. can be stored in secretory vesicles C. receptor will be located on the plasma membrane D. will be bound to a transport protein in the blood
will be bound to a transport protein in the blood
Which of the following adrenergic receptors increase cAMP levels? A. β receptors B. α1 receptors C. α2 receptors
β receptors (these receptors are coupled to adenylate cyclase by Gs receptors that increase cAMP.)
