The Endocrine System Ch. 16 Module 5: Section 16.09-16.10 Dynamic Study Module Flashcards

Associated with drowsiness at night

Ex.

Melatonin is associated with drowsiness at night.

Melatonin concentrations in the blood rise and fall in a diurnal (daily) cycle. Peak levels occur during the night and make us drowsy, and lowest levels occur around noon. Recent evidence suggests that melatonin also controls the production of protective antioxidant and detoxification molecules within cells.

Increased production of a pigment in skin, called melanin (not melatonin), results in skin darkening. Melanin and melatonin are commonly confused terms.

The hormone ANP is responsible for decreases the amount of sodium in the extracellular fluid. The result of this decrease is then a drop in blood volume (and blood pressure).

Uterine contractions are stimulated by oxytocin, not by melatonin.

Additional Learning:

The tiny, pinecone-shaped pineal gland hangs from the roof of the third ventricle in the diencephalon. Its secretory cells, called pinealocytes, are arranged in compact cords and clusters. Lying between pinealocytes in adults are dense particles containing calcium salts. These salts are radiopaque, making the pineal gland a handy landmark for determining brain orientation in X rays.

Although many peptides and amines have been isolated from this minute gland, its only major secretory product is melatonin, an amine hormone derived from serotonin.

The pineal gland indirectly receives input from the visual pathways (retina S suprachiasmatic nucleus of hypothalamus S superior cervical ganglion S pineal gland) concerning the intensity and duration of daylight. In some animals, mating behavior and gonadal size vary with relative lengths of light and dark periods, and melatonin mediates these effects. In children, melatonin may have an antigonadotropic effect. In other words, it may affect the timing of puberty and inhibit precocious (too early) sexual maturation.

Epinephrine

Ex.

The adrenal medulla produces epinephrine.

The spherical medullary chromaffin cells in the adrenal medulla are modified postganglionic sympathetic neurons. The cells synthesize the catecholamines epinephrine and norepinephrine (NE) via a molecular sequence from tyrosine to dopamine to NE to epinephrine.

Aldosterone is secreted by the adrenal gland, but by the adrenal cortex, not medulla.

Insulin is secreted by another organ within the abdominal cavity, not by any region of the adrenal gland.

Growth hormone is secreted by the anterior pituitary gland, not by any region of the adrenal gland.

Antidiuretic hormone is released from the posterior pituitary. It is not secreted by any region of the adrenal gland.

Additional Learning:

When a short-term stressor activates the body to fight-orflight status, the sympathetic nervous system is mobilized. Blood vessels constrict and the heart beats faster (together raising the blood pressure), and blood is diverted from temporarily nonessential organs to the heart and skeletal muscles. Blood glucose levels rise, and preganglionic sympathetic nerve endings weaving through the adrenal medulla signal for release of catecholamines, which reinforce and prolong the fight-or-flight response.

epinephrine release from the adrenal medulla

Ex.

One of the short-term stress responses is epinephrine release from the adrenal medulla.

When a short-term stressor activates the body to fight-or-flight status, the sympathetic nervous system is mobilized. Blood vessels constrict and the heart beats faster (together raising the blood pressure), and blood is diverted from temporarily nonessential organs to the heart and skeletal muscles. Blood glucose levels rise, and preganglionic sympathetic nerve endings weaving through the adrenal medulla signal for release of catecholamines (epinephrine and norepinephrine), which reinforce and prolong the fight-or-flight response.

Glucocorticoid release from the adrenal cortex is part of the long-term stress response.

Immune system suppression is a result of the long-term stress response.

Release of ACTH from the anterior pituitary is a result of the long-term stress response.

Addison's disease

Ex.

The homeostatic imbalances that usually results from deficits in both glucocorticoids and mineralocorticoids is Addison’s disease.

Addison’s disease, the major hyposecretory disorder of the adrenal cortex, usually involves deficits in both glucocorticoids and mineralocorticoids. Affected individuals tend to lose weight; plasma glucose and sodium levels drop, and potassium levels rise. Severe dehydration and hypotension are common. Corticosteroid replacement therapy is the usual treatment.

Diabetes insipidus results from a deficiency of ADH. That hormone is not a glucocorticoid or mineralocorticoid.

Cushing’s syndrome is caused by excess secretion of glucocorticoids, not a deficit. Mineralocorticoids are also not affected by Cushing’s syndrome.

Grave’s disease is caused by an excess secretion of thyroid hormone. That hormone is not a glucocorticoid or mineralocorticoid.

Adrenal cortex

Ex.

The adrenal cortex would produce the hormone needed to restore homeostasis when you have loss of Na⁺ from profuse sweating.

The adrenal cortex synthesizes well over two dozen steroid hormones, collectively called corticosteroids. The essential function of mineralocorticoids is to regulate the electrolyte (mineral salt) concentrations in extracellular fluids, particularly of Na⁺ and K⁺. Their regulation is the primary job of aldosterone, the most potent mineralocorticoid. Aldosterone reduces excretion of Na⁺ from the body. Its primary target is the distal parts of the kidney tubules, where it stimulates Na⁺ reabsorption (increasing blood volume and blood pressure).

The anterior pituitary secretes many hormones. But, none of them play a direct role in maintaining Na⁺ homeostasis.

The parathyroid gland is involved in maintaining homeostasis of a critical ion. But, that critical ion is not Na⁺.

The posterior pituitary stores a hormone that is involved in water homeostasis. But, while it may assist in restoring water balance, it will not directly help restore Na⁺ homeostasis.

The pancreas produces two hormones that are involved in glucose homeostasis. Neither of those hormones plays a role in Na⁺ homeostasis.

Additional Learning:

The single most abundant cation in extracellular fluid is Na⁺, and the amount of Na⁺ in the body largely determines the volume of the extracellular fluid—where Na⁺ goes, water follows. Changes in Na⁺ concentration lead to changes in blood volume and blood pressure. Moreover, the regulation of Na⁺ is coupled to the regulation of many other ions, including K⁺, H⁺, HCO₃– (bicarbonate), and Cl^– (chloride). The extracellular concentration of K⁺ is also critical—it sets the resting membrane potential of all cells and determines how easily action potentials are generated in nerve and muscle. Not surprisingly, Na⁺ and K⁺ regulation are crucial to overall body homeostasis.

Renin – angiotensin II – aldosterone

Ex.

In a mechanism designed to increase blood volume/blood pressure, the correct sequence that would result in increased absorption of Na⁺ (and water) is renin – angiotensin II – aldosterone.

The renin-angiotensin-aldosterone mechanism influences both blood volume and blood pressure by regulating the release of aldosterone and therefore Na⁺ and water reabsorption by the kidneys.

1. When blood pressure (or blood volume) falls, specialized cells of the juxtaglomerular complex in the kidneys are excited.
2. These cells respond by releasing renin into the blood.
3. Renin splits off part of the plasma protein angiotensinogen, triggering an enzymatic cascade that forms angiotensin II, which stimulates the glomerulosa cells to release aldosterone.

Renin must be released first in order to initiate the subsequent cascade of events.

Though renin must be released first, it does not directly stimulate the release of aldosterone.

Renin must be released first in order to initiate the subsequent cascade of events.

Renin must be released first in order to initiate the subsequent cascade of events.

mineralocorticoids

Ex.

The cell clusters in the zona glomerulosa produce mineralocorticoids.

The adrenal cortex synthesizes well over two dozen steroid hormones, collectively called corticosteroids. The cell clusters forming the zona glomerulosa produce mineralocorticoids, hormones (such as aldosterone) that help control the balance of minerals and water in the blood.

The zona glomerulosa is a region in the adrenal gland. Glucagon is secreted by another organ within the abdominal cavity, not by any region of the adrenal gland.

The zona glomerulosa is a region in the adrenal gland. Insulin is secreted by another organ within the abdominal cavity, not by any region of the adrenal gland.

Glucocorticoids are produced by the adrenal gland, but by a different region (not the zona glomerulosa).

Androgens are produced by the adrenal gland, but by a different region (not the zona glomerulosa).

glucocorticoids

Ex.

The cell region termed the zona fasciulate produces glucocorticoids.

The adrenal cortex synthesizes well over two dozen steroid hormones, collectively called corticosteroids. The cell clusters forming the zona fasciculata mainly produce the metabolic hormones called glucocorticoids (such as cortisol). Both the zona fasciculata and zone reticularis share production of glucocorticoids and gonadocorticoids, although each layer predominantly produces one type.

The zona fasciculata is a region in the adrenal gland. Glucagon is secreted by another organ within the abdominal cavity, not by any region of the adrenal gland.

The zona fasciculata is a region in the adrenal gland. Insulin is secreted by another organ within the abdominal cavity, not by any region of the adrenal gland.

Mineralocorticoids are produced by the adrenal gland, but by a different region (not the zona fasciculata).

Androgens are produced by the adrenal gland, but primarily by a different region (not the zona fasciculata).

Aldosterone

Ex.

If you have a homeostatic imbalance of excessive loss of Na⁺ in extracellular fluids, aldosterone will help restore that balance.

The adrenal cortex synthesizes well over two dozen steroid hormones, collectively called corticosteroids. The essential function of mineralocorticoids is to regulate the electrolyte (mineral salt) concentrations in extracellular fluids, particularly of Na⁺ and K⁺. Their regulation is the primary job of aldosterone, the most potent mineralocorticoid. Aldosterone reduces excretion of Na⁺ from the body. Its primary target is the distal parts of the kidney tubules, where it stimulates Na⁺ reabsorption (increasing blood volume and blood pressure).

Glucagon is involved in glucose balance and plays no role in restoring Na⁺ homeostasis.

Insulin is involved in glucose balance and plays no role in restoring Na⁺ homeostasis.

Antidiuretic hormone (ADH) helps regulate water balance. And, though water and Na⁺ are closely related, ADH does not directly help restore Na⁺ homeostasis.

Parathyroid hormone is involved in Ca²⁺ balance and plays no role in restoring Na⁺ homeostasis.

Additional Learning:

The single most abundant cation in extracellular fluid is Na⁺, and the amount of Na⁺ in the body largely determines the volume of the extracellular fluid—where Na⁺ goes, water follows. Changes in Na⁺ concentration lead to changes in blood volume and blood pressure. Moreover, the regulation of Na⁺ is coupled to the regulation of many other ions, including K⁺, H⁺, HCO₃– (bicarbonate), and Cl^– (chloride). The extracellular concentration of K⁺ is also critical—it sets the resting membrane potential of all cells and determines how easily action potentials are generated in nerve and muscle. Not surprisingly, Na⁺ and K⁺ regulation are crucial to overall body homeostasis.

adrenal cortex

Ex.

Glucocorticoids are produced by the adrenal cortex.

The adrenal cortex synthesizes well over two dozen steroid hormones, collectively called corticosteroids.

The cells of the middle layer, the zona fasciculata, mainly produce the metabolic hormones called glucocorticoids.

The adrenal medulla is close to the correct answer. Glucocorticoids are produced by a specific region, but that region is not in the adrenal medulla.

The anterior pituitary secretes multiple hormones, one of which targets the cells that produce glucocorticoids. But, glucocorticoids are not produced the in anterior pituitary.

The pancreas secretes two hormones that are involved in blood glucose homeostasis. Although glucocorticoids do play a role in glucose metabolism, they are not produced by the pancreas.

Increases Na⁺ reabsorption in the kidneys

Ex.

The function of aldosterone is that it increases Na⁺ reabsorption in the kidneys.

Aldosterone reduces excretion of Na⁺ from the body. Its primary target is the distal parts of the kidney tubules, where it stimulates Na⁺ reabsorption (increasing blood volume and blood pressure) and causes K⁺ secretion into the tubules for elimination from the body.

Aldosterone does not play a role in regulating the body’s metabolic rate. That is the responsibility of other hormones, primarily thyroid hormone.

Aldosterone does not play a role in glucose metabolism or regulation. Facilitating glucose transport into cells is the primary role of another hormone, produced by the pancreas.

Another hormone secreted by the adrenal cortex is responsible for increasing glucose formation from fats and proteins in times of stress. Aldosterone does not influence glucose formation.

Increase blood levels of glucose, fatty acids, and amino acids during stress

Ex.

The function of the glucocorticoids is to increase blood levels of glucose, fatty acids, and amino acids during stress.

The glucocorticoids influence the energy metabolism of most body cells and help us resist stressors. Under normal circumstances, they help the body adapt to intermittent food intake by keeping blood glucose levels fairly constant, and help maintain blood pressure.

The dramatically higher output of glucocorticoids during stress is essential for negotiating the crisis. Cortisol provokes a marked rise in blood levels of glucose, fatty acids, and amino acids, making resources readily available for body cells.

Another hormone produced by the adrenal cortex is responsible for producing masculinizing effects when produced in large quantities.

Another hormone produced by the adrenal cortex is responsible for regulating Na⁺ reabsorption by the kidneys.

Although glucocorticoids do function to help maintain blood pressure, another hormone released from the adrenal medulla has a more direct influence in heart rate.

Additional Learning:

Cortisol’s prime metabolic effect is to provoke gluconeogenesis, that is, the formation of glucose from fats and proteins. In order to “save” glucose for the brain, cortisol mobilizes fatty acids from adipose tissue and encourages their increased use for energy. Under cortisol’s influence, proteins are broken down to provide building blocks for repair or to make enzymes for metabolic processes.

Gonadocorticoids

Ex.

Androgens secreted by the adrenal cortex belong to the gonadocorticoids category of hormones.

Most gonadocorticoids secreted by the adrenal cortex are weak androgens, or male sex hormones, such as androstenedione and dehydroepiandrosterone (DHEA). Most are converted in tissue cells to more potent male hormones, such as testosterone, and some are converted to estrogens.

Mineralocorticoids are also secreted by the adrenal cortex, but by a different group of cells. Androgens do not belong to the mineralocorticoid category.

Glucocorticoids are also secreted by the adrenal cortex, but by a different group of cells. Androgens do not belong to the glucocorticoid category.

Gonadotropins are secreted by the anterior pituitary gland, not the adrenal cortex.

Additional Learning:

The amount of gonadocorticoids produced by the adrenal cortex is insignificant compared with the amounts made by the gonads during late puberty and adulthood. The exact role of the adrenal sex hormones is still in question, but we know that they contribute to axillary and pubic hair development. In adult women adrenal androgens are thought to contribute to the sex drive, and they largely account for the estrogens produced after menopause when ovarian estrogens are no longer produced. Control of gonadocorticoid secretion is not completely understood. ACTH stimulates their release, but the gonadocorticoids do not appear to exert feedback inhibition on ACTH release.

Adrenal medulla

Ex.

The part of the adrenal gland indicated by "E" is the adrenal medulla.

Letter E is indicating the deepest region of the adrenal gland. The zona glomerulosa is more superficial than what letter E is indicating.

Letter E is indicating the deepest region of the adrenal gland. The zona fasciculata is more superficial than what letter E is indicating.

Letter E is indicating the deepest region of the adrenal gland. The zona reticularis is more superficial than what letter E is indicating.

The capsule is the most superficial layer of the adrenal gland. Letter E is indicating the deepest region of the adrenal gland.

epinephrine

Ex.

Sympathetic nerve stimuli are responsible for the release of epinephrine.

The spherical medullary chromaffin cells of the adrenal medulla are modified postganglionic sympathetic neurons. The cells synthesize the catecholamines epinephrine and norepinephrine (NE) via a molecular sequence from tyrosine to dopamine to NE to epinephrine.

When a short-term stressor activates the body to fight-or-flight status, the sympathetic nervous system is mobilized. Blood vessels constrict and the heart beats faster (together raising the blood pressure), and blood is diverted from temporarily nonessential organs to the heart and skeletal muscles. Blood glucose levels rise, and preganglionic sympathetic nerve endings weaving through the adrenal medulla signal for release of catecholamines, which reinforce and prolong the fight-or-flight response.

Estrogen is released in response to gonadotropic hormones secreted from the anterior pituitary gland. The sympathetic nervous system plays no role in estrogen release.

Aldosterone is produced in response to a complex mechanism that helps regulate blood pressure. Though blood pressure will increase with sympathetic impulses, aldosterone is not released in response to nervous stimuli.

Insulin is released in response to levels of glucose in the bloodstream, not in response to nervous stimuli.

Additional Learning:

Unequal amounts of the two hormones are stored and released. Approximately 80% is epinephrine and 20% norepinephrine. With a few exceptions, the two hormones exert the same effects. Epinephrine is the more potent stimulator of metabolic activities and bronchial dilation, but norepinephrine has a greater influence on peripheral vasoconstriction and blood pressure. Epinephrine is used clinically as a heart stimulant and to dilate the bronchioles during acute asthmatic attacks.

Unlike hormones from the adrenal cortex, which promote long-lasting body responses to stressors, catecholamines cause fairly brief responses.

Produce masculinizing effects when produced in large quantities

Ex.

A function of gonadocorticoids is that they produce masculinizing effects when produced in large quantities.

The exact role of the adrenal sex hormones is still in question, but we know that they contribute to axillary and pubic hair development. In adult women, adrenal androgens are thought to contribute to the sex drive, and they largely account for the estrogens produced after menopause when ovarian estrogens are no longer produced. Since androgens predominate, hypersecretion of gonadocorticoids causes adrenogenital syndrome (masculinization). In adult males, elevated gonadocorticoid levels may not be noticeable since testicular testosterone has already produced masculinization, but in prepubertal males and in females, the results can be dramatic.

A hormone produced by the adrenal cortex plays a primary role in regulating Na⁺ reabsorption by the kidneys. Though gonadocorticoids are also produced by the adrenal cortex, they have no effect on Na⁺ reabsorption.

The hormones that regulate functions of gonads in both sexes are gonadotropins, not gonadocorticoids.

A hormone produced by the adrenal cortex plays a primary role in increasing blood levels of glucose, fatty acids, and amino acids during stress. Though gonadocorticoids are also produced by the adrenal cortex, they have no role in the stress response.

Zona reticularis

Glucocorticoids

Ex.

Cortisol belongs to the glucocorticoids category of hormones.

The glucocorticoids influence the energy metabolism of most body cells and help us resist stressors. Under normal circumstances, they help the body adapt to intermittent food intake by keeping blood glucose levels fairly constant, and help maintain blood pressure. Glucocorticoid hormones include cortisol (hydrocortisone), cortisone, and corticosterone, but only cortisol is secreted in significant amounts in humans. As with all steroid hormones, glucocorticoids act on target cells by modifying gene activity.

Mineralocorticoids are secreted by the same gland as cortisol, but by a different group of cells. Cortisol does not belong to the mineralocorticoid category.

Gonadocorticoids are secreted by the same gland as cortisol, but by a different group of cells. Cortisol does not belong to the gonadocorticoid category.

Gonadotropins are secreted by the anterior pituitary gland. Cortisol is secreted by a different gland.

Aldosterone

Ex.

The hormone secreted by the adrenal cortex is aldosterone.

Epinephrine is secreted by the inner portion of the adrenal gland, the adrenal medulla, not by the adrenal cortex. Insulin is secreted by the pancreas.

Epinephrine is secreted by the adrenal gland, but not by the adrenal cortex.

Insulin is secreted by another gland in the abdominal cavity, but not the adrenal cortex.

Antidiuretic hormone (ADH) is made by the posterior pituitary gland.

Additional Learning:

The adrenal cortex synthesizes well over two dozen steroid hormones, collectively called corticosteroids. The multistep steroid synthesis pathway begins with cholesterol, and involves varying intermediates depending on the hormone being formed. Unlike the amino acid–based hormones, steroid hormones are not stored in cells. Consequently, their rate of release depends on their rate of synthesis.

Cortisol

Ex.

The hormone secreted by the adrenal gland is cortisol.

The adrenal cortex synthesizes well over two dozen steroid hormones, collectively called corticosteroids.

The cells of the middle layer, the zona fasciculata, mainly produce the metabolic hormones called glucocorticoids (such as cortisol).

Melatonin is secreted by the pineal gland, not the adrenal gland.

ACTH (adrenocorticotropic hormone) targets the adrenal gland, but it is secreted by the anterior pituitary gland.

Insulin is secreted by another gland in the abdominal cavity. It is not secreted by the adrenal gland.

Melatonin

Atrial natriuretic peptide

Ex.

Atrial natriuretic peptide would be released in response to a rise in blood pressure.

Atrial natriuretic peptide, a hormone secreted by the heart when blood pressure rises, fine-tunes blood pressure and sodium-water balance of the body. One of its major effects is to inhibit the renin-angiotensin-aldosterone mechanism. It blocks renin and aldosterone secretion and inhibits other angiotensin-induced mechanisms that enhance water and Na⁺ reabsorption. Consequently, ANP’s overall influence is to decrease blood pressure by allowing Na⁺ (and water) to flow out of the body in urine (natriuretic = producing salty urine).

Aldosterone stimulates an increased Na⁺ reabsorption. Water follows that Na⁺ and the result is an increase in blood volume and pressure. That would not be a healthy response to a rise in blood pressure as it would just make the blood pressure increase more.

Renin is released in response to a drop in blood pressure, not a rise.

ADH (anti-diuretic hormone) stimulates the kidneys to retain water. This increase in water would result in an increase in blood volume and blood pressure. That would not be a healthy response to a rise in blood pressure as it would just make the blood pressure increase more.

The hormone ANP is responsible for decreases the amount of sodium in the extracellular fluid. The result of this decrease is then a drop in blood volume (and blood pressure).

Zona glomerulosa

Ex.

The part of the adrenal gland indicated by "B" is the zona glomerulosa.

The adrenal medulla is the deepest region of the adrenal gland. Letter B is indicating a layer more superficial.

The zona reticularis is deeper than what letter B is indicating.

The zona fasciculata is deeper than what letter B is indicating.

The capsule is the most superficial layer of the adrenal gland. Letter B is indicating a deeper layer in the adrenal gland.

increases heart rate and metabolic rate

Ex.

The function of epinephrine is that it increases heart rate and metabolic rate.

The spherical medullary chromaffin cells in the adrenal medulla are modified postganglionic sympathetic neurons. The cells synthesize the catecholamines epinephrine and norepinephrine (NE) via a molecular sequence from tyrosine to dopamine to NE to epinephrine.

When a short-term stressor activates the body to fight-orflight status, the sympathetic nervous system is mobilized. Blood vessels constrict and the heart beats faster (together raising the blood pressure), and blood is diverted from temporarily nonessential organs to the heart and skeletal muscles. Blood glucose levels rise, and preganglionic sympathetic nerve endings weaving through the adrenal medulla signal for release of catecholamines, which reinforce and prolong the fight-or-flight response.

Epinephrine is released by the adrenal medulla. There is a hormone released from the adrenal gland that increases Na⁺ reabsorption in the kidneys; however, that hormone is secreted by adrenal cortex (not medulla).

Epinephrine is released by the adrenal medulla. The hormone that facilitates glucose transport into cells is secreted by cells in the pancreas.

Epinephrine is released by the adrenal medulla. There is a hormone released from the adrenal gland that stimulates gluconeogenesis; however, that hormone is secreted by adrenal cortex (not medulla).

Additional Learning:

Unequal amounts of the two hormones (epinephrinen and norepinephrine) are stored and released. Approximately 80% is epinephrine and 20% norepinephrine. With a few exceptions, the two hormones exert the same effects. Epinephrine is the more potent stimulator of metabolic activities and bronchial dilation, but norepinephrine has a greater influence on peripheral vasoconstriction and blood pressure. Epinephrine is used clinically as a heart stimulant and to dilate the bronchioles during acute asthmatic attacks.

Unlike hormones from the adrenal cortex, which promote long-lasting body responses to stressors, catecholamines cause fairly brief responses.

Zona fasciculata