Mechanisms Of Hormonal Regulation, Ch. 20 Mccance

Front 1

Hormones are chemical messengers that work with what to maintain communication and control?

Back 1

The nervous system

Front 2

Most hormone levels are regulated by nega¬tive feedback, in which tropic hormone secretion

Back 2

raises the level of a specific hormone.

Front 3

The elevated level of the specific hormone then causes

Back 3

negative feedback, decreasing secre¬tion of the tropic hormone.

Front 4

Endocrine feedback is described in terms of

Back 4

short and long feedback loops.

Front 5

Water-soluble hormones circulate throughout the body in unbound form, whereas lipid-soluble hormones (i.e., ste¬roid and thyroid hormones) circulate throughout the body bound to

Back 5

carrier proteins.

Front 6

Hormones serve as first messengers and affect only target cells with appropriate receptors and then act on

Back 6

those cells to initiate specific cell functions or activities.

Front 7

Hormones have two general types of effects on cells

Back 7

direct effects, or obvious changes in cell function, and permis¬sive effects, or less obvious changes that facilitate cell function.

Front 8

Water-soluble hormones act as first messengers, binding to

Back 8

receptors on the cell’s plasma membrane.

Front 9

The signals ini¬tiated by hormone receptor binding are then transmitted into

Back 9

the cell by the action of second messengers.

Front 10

Second messengers that have been identified include

Back 10

cAMP, cGMP, and calcium, which associates with IP3 and DAG to produce physiologic effects.

Front 11

For cells that have cAMP as their second messenger, a series of interactions within the plasma membrane must activate

Back 11

adenylyl cyclase.

Front 12

Cells that have cGMP as their second messenger are acti¬vated by the enzyme

Back 12

guanylyl cyclase.

Front 13

For cells that have calcium as their second messenger, an increase in intracellular calcium concentration causes

Back 13

cal¬cium to bind with calmodulin, a regulatory protein.

Front 14

This then initiates

Back 14

other intracellular processes.

Front 15

Lipid-soluble hormones (including steroid and thyroid hormones) may have rapid effects by

Back 15

binding to a plasma membrane or receptor or crossing the plasma membrane through diffusion.

Front 16

These hormones then either bind to cytoplasmic proteins or

Back 16

diffuse directly into the cell nucleus and bind to nuclear receptors.

Front 17

Hormones have direct effects or permissive effects. What do these mean?

Back 17

Direct: facilitate the effects of other hormones, permissive: specific changes in cell func¬tion.

Front 18

The pituitary gland is connected to the central nervous system through the

Back 18

hypothalamus.

Front 19

The hypothalamus regulates anterior pituitary func¬tion by

Back 19

secreting releasing hormones into the portal circulation.

Front 20

Hypothalamic hormones include the following:

Back 20

dopamine, TRH, CRH, substance P, ADH, and oxytocin

Front 21

Dopamine does what?

Back 21

inhibits prolactin secretion

Front 22

TRH does what?

Back 22

affects release of thyroid hormones

Front 23

CRH does what?

Back 23

facilitates release of ACTH and endorphins

Front 24

substance P does what?

Back 24

inhibits ACTH release and stimulates release of a variety of other hormones.

Front 25

ADH and oxytocin are synthesized in the hypothalamus and stored and secreted by the

Back 25

posterior pituitary.

Front 26

The posterior pituitary stores and secretes ADH, also called

Back 26

arginine vasopressin

Front 27

ADH controls what?

Back 27

serum osmolality, increases the permeability of the renal tubules to water, and causes vasoconstriction when administered pharmacologically in high doses. ADH also may regulate some central nervous system functions.

Front 28

Oxytocin causes uterine contraction and lactation in women and may have a role in

Back 28

sperm motility in men.

Front 29

In men and women, oxytocin has what effect similar to that of ADH?

Back 29

Antidiuretic

Front 30

Hormones of the anterior pituitary are regulated by the following:

Back 30

(1) secretion of hypothalamic-releasing hormones or factors; (2) negative feedback from hormones secreted by target organs; and (2) mediating effects of neurotransmitters.

Front 31

Hormones of the anterior pituitary include

Back 31

ACTH, MSH, somatotropic hormones (GH and prolactin), and glycopro¬tein hormones (FSH, LH, and TSH).

Front 32

Growth hormone

Back 32

stimulates bone growth, increased pro¬tein metabolism in muscles, and lipolysis. Its effects are mediated in part by IGFs.

Front 33

Prolactin functions to

Back 33

produce milk during pregnancy and lactation.

Front 34

The pineal gland produces

Back 34

melatonin, which affects sleep, immune function, and aging.

Front 35

The two-lobed thyroid gland contains

Back 35

follicles, which secrete some of the thyroid hormones, and C cells, which secrete calcitonin and somatostatin.

Front 36

Regulation of TH levels is complex and involves the

Back 36

hypo¬thalamus (TRH), anterior pituitary (TSH), thyroid gland, and numerous biochemical variables.

Front 37

TH secretion is regulated by TRH through a negative feedback loop that involves the

Back 37

anterior pituitary and hypothalamus.

Front 38

TSH, which is synthesized and stored in the anterior pitu¬itary, stimulates secretion of TH by activating intracellular processes, including

Back 38

uptake of iodine necessary for the syn¬thesis of TH.

Front 39

Synthesis of TH depends on the glycoprotein thyroglobu¬lin, which contains

Back 39

a precursor of TH, tyrosine.

Front 40

Tyrosine then combines with iodide to form

Back 40

precursor molecules of the thyroid hormones T4 and T3.

Front 41

When released into the circulation, T3 and T4 are bound by carrier proteins in the plasma that

Back 41

store these hormones and provide a buffer for rapid changes in hormone levels.

Front 42

Thyroid hormones alter protein synthesis and have a wide range of

Back 42

metabolic effects on proteins, carbohydrates, lip¬ids, and vitamins.

Front 43

TH also affects

Back 43

heat production and car¬diac function.

Front 44

Parafollicular cells or C cells

Back 44

secrete calcitonin and lower serum calcium concentration by inhibiting bone-resorbing osteoclasts.

Front 45

The paired parathyroid glands normally are located

Back 45

behind the upper and lower poles of the thyroid gland.

Front 46

These glands secrete PTH, an important regulator of

Back 46

serum calcium and phosphate levels.

Front 47

PTH secretion is regulated by

Back 47

levels of ionized calcium in the plasma and by cAMP within the cell.

Front 48

Some other substances— hormones, neurotransmitters, and ions—affect PTH secre¬tion by

Back 48

inhibiting cAMP or by changing calcium levels.

Front 49

In bone, PTH causes

Back 49

bone breakdown and resorption.

Front 50

In the kidney, PTH

Back 50

increases reabsorption of calcium, decreases reabsorption of phosphorus and bicarbonate, and stimulates synthesis of vitamin D.

Front 51

Parathyroid hormone–related peptide (PTHrP) has prop¬erties similar to those of PTH and plays a role in

Back 51

placental calcium transport, lactation, and fetal tooth development.

Front 52

The endocrine pancreas contains the islets of Langerhans, which secrete

Back 52

hormones responsible for much of the carbohy¬drate metabolism in the body.

Front 53

The islets of Langerhans consist of

Back 53

alpha cells, beta cells, delta cells, and F cells.

Front 54

Beta cells synthesize

Back 54

insulin, a hormone that regulates blood glucose concentration and overall body metabolism of fat, protein, carbohydrates, and amylin.

Front 55

Alpha cells produce

Back 55

glucagon, which is secreted inversely to the blood glucose concentration and stimulates glycogenoly¬sis, gluconeogenesis, and lipolysis.

Front 56

Incretin hormones are produced by

Back 56

endocrine cells of the gastrointestinal tract that promote glucose-dependent insulin secretion, inhibit glucagon synthesis, and delay gas¬tric emptying.

Front 57

Amylin promotes

Back 57

glucose-dependent insulin secretion, inhibits glucagon synthesis, and delays gastric emptying, producing an antihyperglycemic effect.

Front 58

Delta cells secrete

Back 58

somatostatin, which inhibits glucagon, insulin, and polypeptide secretion.

Front 59

F cells secrete pancreatic polypeptide, which stimulates

Back 59

Y receptors, promotes gastric secretion, and antagonizes cholecystokinin.

Front 60

The paired adrenal glands are situated on the

Back 60

kidneys.

Front 61

Each gland consists of an adrenal medulla, which secretes

Back 61

cat¬echolamines,

Front 62

Each gland has an adrenal cortex, which

Back 62

secretes steroid hormones.

Front 63

The steroid hormones secreted by the adrenal cortex are all synthesized from

Back 63

cholesterol. These hormones include glu¬cocorticoids, mineralocorticoids, and adrenal androgens and estrogens.

Front 64

Glucocorticoids directly affect carbohydrate metabolism by

Back 64

increasing the blood glucose concentration through gluco¬neogenesis in the liver and by decreasing the use of glucose. Glucocorticoids also inhibit immune and inflammatory responses, inhibit bone formation and ADH secretion, and stimulate gastric secretion.

Front 65

Cortisol secretion is related to secretion of

Back 65

ACTH, which is stimulated by CRH.

Front 66

ACTH binds with receptors of the adrenal cortex, which

Back 66

activates intracellular mechanisms (specifically cAMP) and leads to cortisol release.

Front 67

Mineralocorticoids, especially aldosterone, are steroid hor¬mones that

Back 67

directly affect ion transport by epithelial cells, causing sodium retention and potassium and hydrogen loss.

Front 68

Aldosterone secretion is controlled by the what and acts by?

Back 68

renin-angiotensin-aldosterone system and acts by binding to a site on the cell nucleus and altering protein production within the cell.

Front 69

Its principal site of action is the kidney, where it causes

Back 69

sodium reabsorption and potassium and hydrogen excretion.

Front 70

Androgens and estrogens secreted by the adrenal cortex act in the same way as those secreted by the

Back 70

gonads.

Front 71

The adrenal medulla secretes the

Back 71

catecholamines epineph¬rine and norepinephrine. Catecholamines are synthesized from the amino acid phenylalanine.

Front 72

Their release is stimu¬lated by

Back 72

sympathetic nervous system stimulation, ACTH, and glucocorticoids.

Front 73

Catecholamines bind with various target cells and are taken up by

Back 73

neurons or excreted in the urine.

Front 74

They cause a range of metabolic effects that generally are characterized as

Back 74

the flight-or- fight response.

Front 75

What two systems act together to respond to stressors, providing an inte¬grated and protective response?

Back 75

The endocrine system acts together with the nervous and immune systems

Front 76

Several assay methods are used to measure levels of

Back 76

hor¬mones in the plasma.

Front 77

RIA compares the proportion of

Back 77

radiolabeled and nonradiolabeled hormone against stan¬dard reference curves.

Front 78

ELISA is a method similar to RIA, but uses a

Back 78

radiolabeled enzyme rather than a radiolabeled hormone.

Front 79

Bioassays use graded doses of hormone in a reference prep¬aration and then compare the results with

Back 79

an unknown sample to determine the hormone level.

Front 80

Endocrine changes that may be associated with aging include

Back 80

altered biologic activity of hormones, altered cir¬culating levels of hormones, altered secretory responses of endocrine glands, altered metabolism of hormones, loss of circadian control of hormone release, and changes in secre¬tion of hypothalamic regulatory hormones.

Front 81

What may con¬tribute to endocrine gland dysfunction or alterations in the responsiveness of target organs?

Back 81

Cellular damage associated with aging, genetically pro¬grammed cell change, and chronic wear and tear

Front 82

Aging apparently causes atrophy of the

Back 82

thyroid gland and is associated with infiltrative glandular changes.

Front 83

Secretion of thyroid hormones may (what) with age.

Back 83

diminish

Front 84

Aging causes pancreatic fat deposition and is associated with a decrease in insulin

Back 84

secretion and in insulin sensitivity.

Front 85

Growth hormone levels do what with aging, leading to decreased bone and muscle mass?

Back 85

Decrease

Front 86

Aging is associated with alterations in calcium steady states, which may be related to

Back 86

alterations in PTH secretion from the parathyroid glands.

Front 87

Age-related changes in adrenal function include

Back 87

decreased clearance of glucocorticoids and a decrease in levels of adre¬nal androgens.

Front 88

The effects of these changes, however, are offset by

Back 88

feedback mechanisms that maintain glucocorti¬coid levels and by gonadal secretion of androgens.