Endocrine System

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

Phosphodiesterase - Yes, phosphodiesterase is an intracellular enzyme that degrades cAMP.

What is the role of activated protein kinases? Convert ATP to cAMP by phosphorylation. Phosphorylate proteins. Phosphorylate ADP to ATP. Activate adenylate cyclase. Degrade cAMP to AMP.

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

Where is antidiuretic hormone (ADH), also known as vasopressin, synthesized? hypothalamus anterior pituitary kidney posterior pituitary

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

Where is thyrotropin-releasing hormone (TRH) made? anterior pituitary posterior pituitary hypothalamus follicular cells of the thyroid gland

hypothalamus - The hypothalamus regulates the release of several hormones by producing releasing and inhibitory hormones, including thyrotropin-releasing hormone (TRH).

Cyclic AMP is degraded by: AMP G proteins phosphodiesterase adenylate cyclase protein kinase

phosphodiesterase - Phosphodiesterase degrades cyclic AMP into AMP.

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

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: adenylate cyclase protein kinases plasma membrane receptors cAMP cytoplasmic receptors

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

Which of the following triggers the release of glucagon? prolonged fasting release of insulin release of somatostatin hyperglycemia

prolonged fasting - Glucagon acts to stimulate release of glucose into the blood to counteract falling levels.

Which of the following is NOT secreted by the thyroid? triiodothyronine thyroid-stimulating hormone thyroxine calcitonin

thyroid-stimulating hormone - Thyroid-stimulating hormone (TSH) is secreted by the anterior pituitary gland.

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

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

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

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

Which of the following adrenergic receptors increase cAMP levels? β receptors α2 receptors α1 receptors

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

Which of these would be an effect of an excess of thyroid hormones? B would release more TSH. The thyroid would swell and produce a goiter. A would release less TRH. More thyroid hormone would be produced.

A would release less TRH. - Excess thyroid hormone would have an inhibitory effect on A. This is a negative feedback mechanism.

Which hormone is produced in the hypothalamus? ADH ACTH LH GH

ADH

__________ is the adrenal hormone responsible for maintaining appropriate blood sodium levels. Cortisol DHEA Aldosterone Epinephrine

Aldosterone

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.

How do endocrine hormones reach their target cells? Hormones are released at synapses adjacent to target cells. Hormones are produced by endocrine cells that are adjacent to target cells. Ducts transport hormones directly to target cells. Hormones travel through the lymphatic system to target cells. Hormones are transported through the blood stream to 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? cAMP DAG IP3 tyrosine kinase

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

___ triggers secretion of aldosterone? Increased K+ Angiotensin II ANP Both A and B

Increased K+ and Angiotensin II

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

Increased blood glucose levels; Increased blood levels of amino acids; Decrease in immune system function; 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 is the significance of the slight swelling (called a goiter) in Krista's neck? It is unrelated to her condition. It is a sign that her thyroid gland is overactive. Her thyroid gland is producing but not secreting excessive amounts of thyroid hormone. The auto-antibodies of Graves' disease have caused inflammation of her thyroid gland.

It is a sign that her thyroid gland is overactive. - Goiters almost always occur in hyperthyroidism and result from increased cell numbers and cell size in the thyroid gland as thyroid hormone production increases.

Under normal conditions, increased levels of thyroid hormone in the blood will cause: a decrease in TSH levels no change in TSH levels an increase in TSH levels an increase in thyrotropin releasing hormone (TRH)

a decrease in TSH levels - Increased thyroid hormone levels will inhibit the release of TSH from the pituitary.

Which of the following would result from hypoparathyroidism? a decrease in the release of calcium from bones an increase in calcium ion in circulating blood an increase in calcium absorption from food an increase in calcium absorption in the kidney tubule

a decrease in the release of calcium from bones - Hypoparathyroidism leads to reduced osteoclast activity in bones. The resulting lack of calcium in the blood increases excitability of neurons and muscles, producing tingling sensations.

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

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.

What is the mechanism of action of lipid-soluble hormones? increasing protein kinases activation of genes, which increases protein synthesis in the cell phosphorylation of intracellular proteins

activation of genes, which increases protein synthesis in the cell - Yes, lipid-soluble hormones diffuse into the nucleus or they diffuse into the cytoplasm and then move into the nucleus, where they affect transcription and translation.

After a lipid-soluble hormone is bound to its intracellular receptor, what does the hormone complex do? phosphorylates a protein directly alters protein synthesis at the ribosome activates a protein kinase acts as a transcription factor and binds to DNA, activating a gene

acts as a transcription factor and binds to DNA, activating a gene - Yes, then mRNA is synthesized.

Where is the thyroid gland located? at the base of the brain near the hypothalamus posterior to the parathyroid glands in the neck posterior to the sternum in the thoracic cavity adjacent to the trachea in the neck

adjacent to the trachea in the neck - The thyroid is a butterfly or H-shaped gland in the anterior region of the neck just inferior to the larynx, with the lobes extending to each side of the trachea.

Secretions from the corticotrophs activate cells of ____ while secretions from the gonadotrophs affect cells of the ____ adrenal cortex; gonads thyroid; mammary glands gonads; adrenal cortex mammary glands; gonads

adrenal cortex; gonads

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

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

Hormones secreted into the hypophyseal portal system are detected by the posteriori pituitary anterior pituitary median eminence infundibulum

anterior pituitary

Which of the cell types would secrete their product if the blood glucose level was rising, as during digestion of a meal? beta cells pancreatic acinar cells alpha cells

beta cells - Beta cells secrete when the blood sugar rises. Their hormone allows body cells to take up glucose from the blood.

The amplification of the signal from a water-soluble hormone is achieved through an increase in: water-soluble hormone in the blood plasma membrane receptors phosphodiesterase in the cytoplasm adenylate cyclase in the plasma membrane cAMP in the cytoplasm

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

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

What keeps intracellular receptors from binding to DNA before a hormone binds to the receptor? transcription factors chaperone proteins (chaperonins) Receptors can't enter the nucleus until the hormone is bound to it.

chaperone proteins (chaperonins) - Yes, each receptor has two binding sites. The chaperone protein blocks the DNA binding site until a hormone binds at the hormone binding site.

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

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 has intracellular receptors? cortisol insulin epinephrine

cortisol - Yes, cortisol is one of the lipid-soluble steroid hormones. Thyroid hormones are also lipid soluble.

Occasionally, a female patient will experience hirsutism, or excessive facial hair growth. However, blood tests reveal that her levels of testosterone is normal for a female. Another cause could be hypersecretion of: catecholamines mineralocorticoids glucocorticoids gonadocorticoids

gonadocorticoids

Your patient has been diagnosed with Type I diabetes mellitus, and you are explaining how to administer insulin. Your patient states, "I don't want to do this. My brother-in-law has diabetes, and he just takes a pill and watches what he eats." What is your best response? "Your relative may have Type II diabetes. People with that condition can make insulin, but their cells don't respond to it properly. Your pancreas doesn't manufacture insulin." "Perhaps you can switch to pills and a special diet once your diabetes is under control." "Great. Maybe your relative can give you some tips on how to manage your condition." "I'll ask the doctor if you can try an oral pill and a low carbohydrate diet before using insulin."

"Your relative may have Type II diabetes. People with that condition can make insulin, but their cells don't respond to it properly. Your pancreas doesn't manufacture insulin." - A simple explanation of the differences between Type I and Type II diabetes may help your patient to understand the importance of the prescribed insulin regimen.

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

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

If a person's parathyroids are responding properly to a drop in blood calcium, which of the following should result? More calcium will be present in feces. Vitamin D levels in the blood will drop. Bone mass and density will increase. Less calcium will be excreted in the urine by the kidneys.

Less calcium will be excreted in the urine by the kidneys. - The kidneys would be encouraged by PTH to retain more calcium, which would result is less calcium in the urine.

Body cells that respond to insulin include Liver cells and muscle cells only. Liver cells, as well as most other cells of the body. Intestinal cells only. Muscle cells only. Liver cells only.

Liver cells, as well as most other cells of the body.

What cells in the body respond to glucagon by breaking down glycogen and releasing glucose? Liver cells. Liver cells and cells in the pancreas. Muscle cells. Intestinal cells. Cells in the pancreas.

Liver cells.

Your patient has been admitted to the intensive care unit with a severe head injury. As you monitor his urine output, you find that it has fallen sharply. Lab tests indicate that his serum osmolality is lower than normal (i.e., his plasma is too dilute). What should you suspect? Parathyroid hormone (PTH) Thyroid-stimulating hormone (TSH) Syndrome of inappropriate antidiuretic hormone (SIADH) Prolactin

Syndrome of inappropriate antidiuretic hormone (SIADH) - Antidiuretic hormone (ADH) is released from the posterior pituitary in response to rising serum osmolality. This causes the kidneys to preserve water, helping to restore normal solute/water balance. Your patient is retaining water despite a dilute plasma, suggesting that he is making "inappropriate" ADH. This problem may occur after head trauma or in some cancers.

Krista's treatment will likely involve destroying or surgically removing her thyroid gland. What effect will this have on her level of TSH? TSH will increase. TSH will decrease. It will have no effect because TSH is not secreted by the thyroid.

TSH will increase. - Destroying or removing the thyroid gland will cause thyroid hormone levels to plummet. This will cause an increase in the secretion of TSH from the pituitary.

A liver cell responds to insulin by Taking in glucose and converting it to glycogen. Breaking down glycogen and releasing glucose. Releasing insulin. Taking in glucose and converting it to glucagon. Releasing glucagon.

Taking in glucose and converting it to glycogen.

When blood glucose levels are low The pancreas releases insulin, which eventually causes blood glucose levels to increase. The pancreas releases insulin, which eventually causes blood glucose levels to decrease. Liver cells convert more glucose to glycogen. The pancreas releases glucagon, which eventually causes blood glucose levels to increase. The pancreas releases glucagon, which eventually causes blood glucose levels to decrease.

The pancreas releases glucagon, which eventually causes blood glucose levels to increase.

When blood glucose levels are high The pancreas releases glucagon. The pancreas releases insulin. The pancreas releases glucose. The liver releases glucagon. The liver releases insulin.

The pancreas releases insulin. - The pancreas responds to high blood glucose levels by releasing insulin.

Suppose Krista's hyperthyroidism was a result of a tumor that causes the anterior pituitary gland to become overactive. Which of the following would Krista's lab reports likely show? high thyroid hormone, low TSH low thyroid hormone, low TSH low thyroid hormone, high TSH high thyroid hormone, high TSH

high thyroid hormone, high TSH - An increase in TSH from the anterior pituitary will increase levels of thyroid hormone. The high levels of thyroid hormone will not be able to inhibit the anterior pituitary by negative feedback due to the presence of the tumor.

The body's tendency to maintain relatively constant internal conditions is called negative feedback. homeostasis. positive feedback. diabetes. None of the above.

homeostasis

What type of stimulation controls parathyroid release? humoral hormonal paracrine neural

humoral - The parathyroid is stimulated by the actual level of calcium in the blood rather than by neural or hormonal stimulus.

A patient is displaying high volumes of urine output and severe dehydration. The most likely cause is _________. hyposecretion of oxytocin hypersecretion of oxytocin hyposecretion of ADH hypersecretion of ADH

hyposecretion of ADH

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).

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.

The long bone growth-promoting effects of growth hormone are mediated by somatostatin somatotrophs insuling-like growth factors insulin

insuling-like growth factors

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.

Blood levels of hormones are kept within very narrow ranges by ____ mechanisms humoral neural hormonal negative feedback

negative feedback

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

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 hormones is regulated by a neuroendocrine ("letdown") reflex? oxytocin antidiuretic hormone (ADH) cortisol

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).

Pheochromocytoma produces symptoms of uncontrolled sympathetic nervous system activity. Which of the following is common to both adrenal chromaffin cells and adrenergic fibers of the sympathetic nervous system? the presence of axons capable of secreting substances that are capable of increasing heart rate secretion of epinephrine secretion of norepinephrine All of the listed responses are correct.

secretion of norepinephrine - Adrenal chromaffin cells are capable of releasing the hormones epinephrine and norepinephrine into the systemic circulation. Post-ganglionic neurons of the symphathetic nervous system also release norepinephrine.

All of the following conditions would stimulate the pancreas to release insulin EXCEPT one. Which one? a rise in blood glucose levels a rise in blood amino acid levels sympathetic activation acetylcholine release on the pancreatic cells

sympathetic activation - Sympathetic activation is designed to increase blood glucose levels, so it inhibits the release of insulin.

Which hormone's receptor is always bound to DNA, even when the receptor is empty? cortisol insulin thyroid hormone

thyroid hormone - Yes, thyroid hormones are lipid soluble and their receptors are bound to the response elements of the DNA.