A&P II Lecture Exam 1 - Chapter 16

Describe the structure of the endocrine pancreas and its hormone-secreting cells.

Alpha cells secrete glucagon. Beta cells secrete insulin. Delta cells secrete somatostatin.

A patient has a tumor of the anterior pituitary gland that is found to secrete ACTH. Predict the effects this tumor will have on CRH and cortisol levels in the patient's blood. Explain your answers.

An ACTH-secreting tumor will increase the cortisol level in the blood, but the elevated cortisol level will decrease CRH secretion through negative feedback.

How is hormone secretion generally regulated?

As part of a negative feedback loop. Starts with a stimulus, followed by a receptor detecting deviations, and finishing with the stimulation of the control center (often endocrine cell) which increases or decreases secretion of particular hormone.

Compare and contrast how the endocrine and nervous systems control body functions.

Cells of the endocrine system secrete hormones into the bloodstream that affect distant targets, in contrast to the neurons of the nervous system, which come close to their target cells and work through the release of neurotransmitters into synapses.

Describe the stimulus for release, the target tissue, and the functional effect of each anterior pituitary hormone.

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Describe the stimulus for release, the target tissue, and the functional effect of each hormone released from the posterior pituitary.

Check page 640

A newly discovered hormone X is determined to be structurally similar to cholesterol. Predict how this new hormone interacts with its target cells.

Its structural similarity to cholesterol indicates that it is likely hydro- phobic, which means it may bind to receptors in the plasma membrane, in the cytosol, or in the nucleus.

What are the target tissues and effects of ADH?

Kidneys are the target tissue. The effects of ADH include. Antidiuretic hormone stimulates water reabsorbtion by stimulating insertion of "water channels" or aquaporins into the membranes of kidney tubules. These channels transport solute-free water through tubular cells and back into blood, leading to a decrease in plasma osmolarity and an increase osmolarity of urine.

What are the endocrine roles of the kidneys?

Kidneys produce: 1. Erythropoietin which targets red bone marrow. Increases rate of red blood cell formation. 2. Renin which targets enzymes activating anglotensinogen which is part of the renin-angiotensin-aldosterone system. 3. Vitamin D targets small intestine which stores vitamin D and prepares for conversion into calcium.

A pheochromocytoma (fee′-oh-kroh-moh-sy-TOHM-ah) is a tumor of the adrenal medulla that secretes large amounts of epinephrine and norepinephrine. Predict the effects of this kind of tumor.

Large amounts of epinephrine and norepinephrine will mimic a prolonged sympathetic response, leading to elevated heart rate and blood pressure, decreased digestive and urinary activity, elevated metabolic rate, and more.

A genetic mutation in mice leads to a dysfunctional leptin receptor in the hypothalamus that does not bind leptin. Predict the consequences of this mutation.

Leptin promotes satiety, and so the mice with this mutation are likely to always feel hungry and therefore to overeat. 3. The con- sequences will be wide-ranging and include a decrease in erythrocyte production due to decreased erythropoietin, a loss of bone mass due to lower levels of vitamin D (and so a decreased blood calcium ion con- centration), and disrupted blood pressure regulation due to abnormal renin secretion.

Individuals who live at extreme northern and southern latitudes experience winter with little to no periods of daylight and summer with little to no periods of darkness. Predict the effect these seasonal conditions will have on melatonin secretion and the sleep/wake cycle.

Melatonin secretion is stimulated by a decreasing light level. So when the light level is low all day, secretion will increase and individu- als might feel more tired than normal. When the light level is high all day, secretion will decrease and individuals might feel less able to fall asleep.

What are the target tissues and effects of melatonin?

Melatonin: targets reticular formation of the brainstem. Regulates sleep/wake cycle and promotes sleep.

Describe the stimulus for release, the target tissue, and the effects of the hormones produced by the pineal and thymus glands.

Melatonin: targets reticular formation of the brainstem. Regulates sleep/wake cycle and promotes sleep. Thymosin and thymopoletin: target T lymphocytes, promote T lymphocyte maturation.

Mr. Montez is a patient with type I diabetes mellitus. He presents with dizziness, rapid breathing, confusion, and weakness. You find out that he forgot to inject his normal dose of insulin this morning. Will his blood glucose concentration be normal? Explain. Your colleague suggests that Mr. Montez needs to ingest some sugar. Is this going to help him? Why or why not?

Mr. M's blood glucose level will be elevated (hypergylcemia) because glucose is not entering the cells. Ingesting sugar will not help because his cells cannot take in the glucose, and will simply lead to even more profound hyperglycemia.

What are parafollicular cells?

Neuroendocrine cells which secrete calcitonin (otherwise known as C-cells).

What are the target tissues and effects of calcitonin and parathyroid hormone?

Parathyroid hormone targets bone, kidneys, intestines to increase blood calcium levels. Calcitonin targets osteoclasts and inhibits their action so that calcium is retained in the bones, decreasing blood calcium levels.

What are the main functions of thyroid hormones?

Regulate metabolic rate and thermoregulation. Promotes growth and development.

Explain how releasing hormones, inhibiting hormones, and tropic hormones affect the secretion of other hormones.

Releasing hormones control the release of other hormones (tropic hormone). Inhibiting hormones prevent the release of other hormones (tropic hormone). Tropic hormones stimulate other endocrine glands by secreting releasing and inhibiting hormones.

A tumor increases the secretion of GHRH. Predict the effects of this tumor on secretion of GH and IGF. How would these effects differ in a child versus an adult?

Such a tumor would increase the secretion of GH and IGF, increasing their levels in the blood. In a child, this could lead to pituitary gigantism; in an adult, it could lead to acromegaly.

Renal failure is generally characterized by inability of the kidney cells to perform their many physiological functions. Predict those consequences of renal failure that extend beyond the urinary system.

Swelling of legs and feet due to water retention. Shortness of breath. Excessive fatigue or drowsiness.

What is the role of each of these hormones with respect to metabolic homeostasis?

T3 and T4 regulate body's metabolic rate when they are secreted (T3 more active but T4 is T3 precursor so found in higher concentrations). TSH regulates these hormones as well. Glucagon and insulin regulate blood glucose levels.

Which hormones control metabolic homeostasis?

T3 and T4, glucagon and insulin.

Describe the stimulus for release, the target tissue, and the effects of the glucocorticoids secreted by the adrenal cortex.

Target tissues are liver, muscle, adipose, and white blood cells. The effects include increasing gluconeogenesis in liver, increasing protein breakdown in muscle, and inhibiting inflammatory response.

Describe the target tissues and effects of growth hormone and IGF.

Target tissues: skeletal and cardiac muscle, adipose, liver, cartilage, bone. Effects: promotes fat breakdown, production of new glucose by liver, and inhibits glucose uptake by muscle fibers --> increasing concentrations of glucose and fatty acids. Long term, leads to indirect growth of bone and muscle.

What are the target tissues and effects of oxytocin?

Targets the uterus and mammary glands. The effects include labor contractions.

Mr. Dent is discovered to have an ADH-secreting tumor. Predict what will happen to the amount of aldosterone secreted by his adrenal cortex. What do you think will happen to the amount of ANP secreted by Mr. Dent's heart? Explain.

The ADH-secreting tumor will increase the blood volume and decrease the blood osmolarity. This will reduce secretion of aldosterone and stimulate the secretion of ANP in order to lower the blood volume (and blood pressure).

Ms. Prefect has a tumor of the hypothalamus that reduces its secretion of CRH. Will her body continue to secrete adrenal steroids and catecholamines as part of the stress response? Explain.

The amounts of adrenal steroids and catechol- amines might decrease slightly, but many other stimuli trigger secretion of these hormones. For this reason, the amounts secreted will not likely decrease significantly.

The condition called syndrome of inappropriate ADH secretion, or SIADH, is characterized by an abnormally increased secretion of ADH from the hypothalamus. Predict the effects of this condition.

The extra ADH will abnormally increase the amount of water in the body and decrease the osmolarity of the extracellular fluid.

Explain the negative feedback loops that regulate the production and release of anterior pituitary hormones.

The first tier of feedback control involves the neuroen- docrine cells of the hypothalamus, which secrete releasing and inhibiting hormones. These hormones stimulate or inhibit hor- mone production from the anterior pituitary, the second tier of control. The pituitary hormones then stimulate cells of their tar- get organs, many of them other glands, acting as the third tier of feedback control. The glands of the target organs secrete hor- mones that affect some homeostatic variable.

What are examples of secondary endocrine organs? Which organs are considered neuroendocrine?

The heart, kidneys, small intestines, and testes and ovaries and secondary organs. Neuroendocrine organs include the hypothalamus and pineal gland.

What is the hypothalamic-hypophyseal portal system?

The hypothalamic releasing and inhibiting hormones are delivered to the anterior pituitary by the hypothalamic-hypophyseal portal system.

How does the hypothalamus control the secretion of hormones from the anterior pituitary gland?

The hypothalamus released tropic hormones that affect the secretion of the anterior pituitary gland.

Ms. Reczkiewicz has her thyroid gland removed to treat hyper- thyroidism. Her condition is stable after surgery, but one day later she develops symptoms of severe hypocalcemia. What has happened? How would you correct this problem?

The parathyroid was removed with the thyroid so there is no parathyroid to stimulate an increase in blood calcium levels. To counteract this, patient must eat diet high in calcium, take calcium supplements and vitamin D supplements.

Mr. Scully, a patient with hypothyroidism, has had blood tests done to check his thyroid function. The lab technician reports that his TSH level is abnormally high, but forgets to record the levels of T3 and T4. Based on the TSH level, predict whether Mr. Scully's T3 and T4 levels will be elevated, normal, or decreased. Explain your answer.

The patient's levels of T3 and T4 are likely low. The low levels are causing the anterior pituitary to secrete extra TSH in an attempt to stimulate T3 and T4 production and secretion from the thyroid gland. However, the extra TSH is not effective, because of either iodine deficiency or Hashimoto's thyroiditis.

How do the anterior and posterior pituitary differ structurally and functionally?

The posterior pituitary does not secrete its own hormones, but acts as an extension of the hypothalamus, storing those hormones. The anterior pituitary secretes its own hormones (predominantly tropic hormones).

What are the primary organs of the endocrine system?

The primary endocrine organs include the anterior pituitary, thyroid, and parathyroid glands, the adrenal cortices, the thymus, and the endocrine pancreas.

Tumors of the parathyroid gland often secrete excessive parathyroid hormone. Predict the effects of such a tumor.

The result would likely be hypercalcemia and weakened bones due to excessive osteoclast activity.

Explain why drugs that activate or suppress the sympathetic nervous system have effects on the blood glucose concentration.

The signs and symptoms would be almost the exact opposite of those in question 1; Hypoglycemia would result from excess glucose uptake by target cells.

Predict the effects of a pancreatic tumor that secretes insulin. What signs and symptoms would you expect to see from such a condition?

The signs and symptoms would be almost the exact opposite of those in question 1; Hypoglycemia would result from excess glucose uptake by target cells.

Explain the relationship of the adrenal medulla to the sympathetic nervous system.

The sympathetic nervous system stimulates the adrenal medulla which then secretes epinephrine and norepinephrine (fight or flight response, adrenaline)

Describe the stimulus for release, the target tissue, and the effects of the mineralocorticoids secreted by the adrenal cortex.

The target tissue is the tubules of the kidneys. The effects include increasing sodium ion retention, increasing potassium ion loss in urine, and regulating blood pressure.

Explain the different types of chemical signaling used by the body.

The three types of chemical signaling are the endocrine, paracrine, and autocrine signals.

What are the two major classes of hormones, and how do they interact with their target cells?

The two types of hormones are amino acid-based hormones and steroid hormones.

Describe the causes, symptoms, and treatments for the two types of diabetes mellitus.

Type 1: immune system destroys beta cells which produce insulin. No matter how much glucose enters blood, it doesn't reach target cells which starves cells of glucose. Causes glucose to be overproduced in liver. Causes dehydration because so much glucose in blood creates gradient that draws water into kidney tubules causing excessive water loss and urination. Treatment is administration of insulin. Type 2: beta cells can respond to blood glucose changes but don't or are less responsive. Insulin resistance to glucose changes results in similar symptoms, but ketoacidosis does not develop (unlike type 1) because there is enough insulin to prevent it.

Which hormones are involved in the stress response?

Cortisol, epinephrine, norepinephrine

What two hormones are produced by the adrenal medulla? What are their target tissues and their effects?

Epinephrine and norepinephrine. Target every cell and cause fight or flight response.

Identify and describe the types of cells within the thyroid gland that produce thyroid hormone and calcitonin.

Follicular cells of the thyroid produce thyroid hormone. Calcitonin is produced by C-cells (parafollicular cells). They are neuroendocrine cells.

Hormone X appears to regulate the blood concentration of chemical Y via a negative feedback loop. a. Predict what happens to the secretion of hormone X when the blood concentration of chemical Y decreases. b. What effect will this likely have on the blood concentration of chemical Y? c. Predict what happens to the secretion of hormone X when the blood concentration of chemical Y increases.

a. Secretion of hormone X is likely to increase. b. Hormone X should increase the level of chemical Y back to its nor- mal range. c. The secretion of hormone X should decrease by negative feedback.

Certain drugs used to treat high blood pressure work by blocking the effects of aldosterone on the kidneys. Predict the effects these drugs would have on the: a. sodium and potassium ion concentrations in the blood. b. pH of the blood. c. solute concentration of the blood.

a. The sodium ion concentration could potentially decrease, and the potassium ion concentration could increase. b. Blocking aldosterone could increase the hydrogen ion concentra- tion of the blood, decreasing the pH. c. By decreasing water reabsorption, these drugs could cause the blood concentration of solutes other than sodium to increase slightly.

Which hormones primarily control fluid homeostasis?

antidiuretic hormone (ADH), aldosterone, renin, and atrial natriuretic peptide (ANP)

A hypothetical poison destroys the hypothalamic cells that produce TRH. Predict the effects of this poison on hormone secretion by the anterior pituitary and thyroid glands.

With low TRH, both TSH secretion and thyroid hormone secretion will decrease.

Define the terms hormone, endocrine gland (organ), endocrine tissue, and target cell.

Hormone - a regulatory substance produced in an organism and transported in tissue fluids such as blood or sap to stimulate specific cells or tissues into action. Endocrine gland - A gland that secretes a substance (a hormone) into the bloodstream. Endocrine tissue - tissue of an endocrine organ. Target cell - hormone usually affects only a limited number of cells, which are called target cells.

Describe the stimulus for release, the target tissue, and the effects of the hormones produced by the gonads, adipose tissue, the heart, and the kidneys.

Adipose tissue produces leptin, which targets brain and promotes satiety. Heart produces atrial natriuretic peptide which targets smooth muscle cells in blood vessels and kidney tubules. Causes relaxation of smooth muscles in blood vessels, promotes fluid loss in kidneys, and lowers blood pressure. Kidneys produce: 1. Erythropoietin which targets red bone marrow. Increases rate of red blood cell formation. 2. Renin which targets enzymes activating anglotensinogen which is part of the renin-angiotensin-aldosterone system. 3. Vitamin D targets small intestine which stores vitamin D and prepares for conversion into calcium.

What are the tropic hormones of the anterior pituitary gland? What glands do they affect?

-Thyroid stimulating hormone: stimulates development of the thyroid gland and its secretion of thyroid hormones. -Adrenocorticotropic hormone (ACTH): stimulates development of adrenal glands and their synthesis of steroid hormones. -Prolactin: affects mammary gland cells, which stimulate growth of mammary gland where milk is produced after childbirth. -LH: stimulate male and female gonads. In males, LH stimulates production of testosterone. In females, stimulates production of estrogens. -FSH: stimulates gonads. In males it concentrates testosterone; in females it triggers maturation of ovarian follicles that house developing eggs.

Which gland produces ADH and oxytocin, and from where are they secreted?

Both are produced by hypothalamus, released from posterior pituitary.

Describe the major chemical classes of hormones found in the human body, and compare and contrast the types of receptors to which each class of hormone binds.

1. Endocrine signals, which is secreted into the blood and affect distant tissues. 2.Paracrine signals, which are secreted by cells into the extracellular fluid to affect different nearby cells. 3. Autocrine signals, which are secreted by cells that target the same cell type in interstitial fluid.

What are the three types of stimuli that initiate hormone secretion? How do they perform this function?

1. Hormonal - some hormones initiate secretion of other hormones. 2. Humoral - changes in the concentration of certain ion or molecules in the blood or extracellular fluid. 3. Neural stimuli - signals from the nervous system.

What are the three zones of the adrenal cortex, and which hormones are produced by each zone?

1. Zona glomerulosa - produce mineralcorticoids. 2. Zona fasciculate and zona reticulares produce and secrete glucocorticoids and androgenic steroids.

How do the endocrine and nervous systems differ in the ways they maintain homeostasis? How are they similar?

Both the endocrine and nervous system respond to changes in homeostasis (using either chemical or electrical signals) to enable or inhibit responses that reestablish homeostasis. They differ in the speed at which they respond (nervous system is faster).

Predict the effects of a pancreatic tumor that secretes glucagon. What other disease would this condition resemble? Explain.

A glucagon-secreting tumor would cause hyperglycemia and ketosis, and thus resemble diabetes mellitus.

What is the role of each of these hormones with respect to fluid homeostasis?

ADH controls how much water is excreted by your kidneys. This regulates water levels in the body, preventing dehydration or excreting excess water. Aldosterone helps with sodium and potassium retention in the kidneys, and since sodium and potassium attract water, it leads to water retention as well. Renin releases aldosterone. Atrial natriuretic peptide regulates electrolyte concentrations in the body and therefore water levels.

A new diet guru claims hypersecretion of cortisol is the reason why so many people are obese. He is marketing a dietary supplement that is supposedly able to block cortisol secretion and lead to weight loss. How would cortisol hypersecretion cause weight gain? Would blocking normal cortisol secretion lead to weight loss? Why or why not?

Abnormal hypersecretion of cortisol does cause weight gain by increasing appetite and fluid retention and decreasing the metabolic rate. However, blocking normal cortisol secretion will not lead to weight loss because normal levels of cortisol do not cause weight gain.

You have read that aldosterone causes sodium ion retention from the kidneys. How would blocking aldosterone secretion decrease the amount of water retained from the fluid in the kidneys? (Connects to Chapter 3)

Blocking aldosterone will decrease the retention of sodium ions from the fluid in the kidneys. This will increase the solute concentration of this fluid, which will cause water to remain in the fluid due to osmosis. Overall, the amount of water retained by the kidneys will decrease.

Your friend is on a no-carbohydrate, all-fat diet, leading to essentially no intake of dietary glucose. Predict which hormones might be secreted in excess to compensate for the decreased level of blood glucose. How will these hormones compensate?

Glucagon secretion will increase in order to raise the concentration of glucose in the blood.

What has likely happened to the pH of Mr. Montez's blood? What does this mean about the hydrogen ion concentration in his blood? How will his buffer systems respond to this change in pH? (Connects to Chapter 2)

He is likely in diabetic ketoacidosis, meaning that his blood will have a high concentration of ketone bodies, increasing hydrogen ion concentration and lowering the pH of the blood. His buffer systems will respond by binding and removing the excess hydrogen ions from the blood, restoring the pH to normal.

Describe the major structures and functions of the endocrine system.

Hypothalamus, pituitary, thyroid, parathyroids, adrenals, pineal body, and the reproductive organs (ovaries and testes). They secrete hormones.

Explain how negative feedback loops regulate the production of thyroid hormones.

If the blood levels of thyroid hormones T3 and T4 reach a certain threshold, TRH secreting neurons in the hypothalamus are told to stop secreting TRH which stops secretion of T3 and T4.

Let's say that the dietary supplement in question 2 actually works and successfully blocks cortisol secretion. Could this drug potentially be harmful? Predict its effects on overall homeostasis.

If the supplement actually blocked normal cortisol secretion, it could lead to significant problems with glucose and other aspects of homeostasis, resulting in similar to those of Addison's disease (hypocortisolism).

Describe the stimulus for release, the target tissue, and the effects of thyroid hormone.

Low levels of iodine are detected by hypothalamus which tells anterior pituitary to release thyroid stimulating hormone. The iodide that entered the body gets converted to iodine and attach to thyroglobulin which enters colloid and is converted to T3 and T4. These are released into the blood where they regulate metabolic rate and thermoregulation. Also promote growth and development.

How does parathyroid hormone maintain calcium homeostasis?

PH stimulates osteoclasts and tells the small intestine to use Vitamin D stores, which have inactive form of calcium called calcitriol, to convert to calcium and release into blood. Also tells kidneys to reabsorb more calcium from liquids before converting them to urine.

What are the target tissues and effects of cortisol?

Same as glucocorticoids

What are the target tissues and effects of aldosterone?

Same as mineralocorticoids

What is the role of each hormone in the stress response? How do these hormonal effects tie in with the response of the sympathetic nervous system?

They all cause increase in heart rate, dilation of pupils, fight or flight.

Describe the locations of, as well as the anatomical and functional relationships between, the hypothalamus and the anterior and posterior pituitary glands.

They are connected by the infundibulum. The hypothalamus controls many of the functions of the anterior pituitary gland through the production and release of tropic hormones that affect its secretions. These hormones are called releasing and inhibiting hormones because they either stimulate or inhibit the release of hormones from the anterior pituitary.

Describe the stimulus for release, the target tissue, and the effect of catecholamines (epinephrine and norepinephrine).

They target nearly every cell in the body, causing increased heart rate, dilation of bronchioles, constriction of blood vessels to the digestive and urinary organs, and increased metabolic rate.

What are thyroid follicles, and how are they structured?

Thyroid follicles are composed of follicle cells which are epithelial cells which produce thyroid hormones. Filled with colloid which stores precursor of thyroid hormones.

Certain dietary supplements marketed for weight loss contain thyroid hormone. How would these supplements cause weight loss? Would these products generally be safe?

Thyroid hormone increases the metabolic rate, which could promote weight loss. Unfortunately, such a supplement could mimic the signs and symptoms of hyperthyroidism. It could also decrease the secretion of a person's own thyroid hormone through negative feedback, resulting, at best, in no effect.

What homeostatic imbalances may accompany hyperthyroidism and hypothyroidism?

With Graves' disease (hyperthyroidism) body will lose weight due to metabolic rate increase, heat tolerance will decrease, and heart rhythms are disrupted along with blood pressure. With hypothyroidism, there is weight gain, inability to manage cold temperatures, and low blood pressure and slow heart rate.

Describe the stimulus for release, the target tissue, and the effects of parathyroid hormone.

When blood calcium levels drop, parathyroid hormone stimulates osteoclasts in bones to release calcium ions into blood. It also increases absorption of dietary calcium ions by small intestine. Also tells kidneys to reclaim more calcium from fluid in tubules before converting it to urine.

Explain how insulin and glucagon work together to maintain the blood glucose level within the normal range.

When blood glucose gets too high, insulin brings it down. Once insulin brings it down past the threshold, glucagon steps in to help blood glucose levels rise.

Describe the stimulus for release, the target tissue, and the effect of glucagon.

When blood glucose levels drop, targets liver, muscle tissue, and adipose tissue. Breaks glycogen into glucose and forms glucose in liver by process of gluconeogenesis. Also releases fats from adipose tissue to gluconeogenesis and for additional source of fuel.

Describe the stimulus for release, the target tissue, and the effect of insulin.

When blood glucose levels rise, insulin targets liver, cardiac muscle, skeletal muscle, and brain. Insulin stimulates synthesis of glycogen in liver, uptake of glucose, synthesis of fat from lipids and carbohydrates, promotion of satiety.

How are thyroid hormones produced? How is this production regulated?

When exposed to cold, or levels of thyroid hormone fall, hypothalamus detects change and secretes TRH which tells anterior pituitary to release TSH. This stimulates thyroid to produce and secrete T3 and T4 which increases metabolic rate. This is regulated by negative feedback loop.

How do synergistic and antagonistic hormones differ?

When two or more hormones work together to produce a particular result, their effects are said to be synergistic. These effects may be additive or complementary. Hormones that act to return body conditions to within acceptable limits from opposite extremes.