Chapter 16 Flashcards

Question

Nervous system modulation: Nervous system can override...

Answer 1

normal endocrine controls - Ex: under severe stress, hypothalamus and sympathetic nervous system override insulin to allow blood glucose levels to increase - Prepare body for “fight or flight”

Answer 2

receptors to which hormone binds - ex: ACTH receptors are found only on certain cells of adrenal cortex, but thyroxin receptors are found on nearly all cells of body

Answer 3

1. ) Blood levels of hormone 2. ) Relative number of receptors on/in target cell 3. ) Affinity (strength) of binding between receptor and hormone

Answer 4

free or bound - Steroids and thyroid hormone are attached to plasma proteins; others don’t require carriers

Answer 5

1. ) Rate of release | 2. ) Speed at which it is inactivated and removed from body

Answer 6

- Degrading enzymes or - Kidneys or - Liver Half-life: time required for level of hormone in blood level to decrease by half - Varies anywhere from fraction of a minute to a week, depending on hormone

Answer 7

- Up-regulation: target cells form more receptors in response to low hormone levels - Down-regulation: target cells lose receptors in response to high hormone levels (Desensitizes the target cells to prevent them from overreacting to persistently high levels of hormone)

Answer 8

- Permissiveness - Synergism - Antagonism

Answer 9

One hormone cannot exert its effects without another hormone being present - Ex: reproductive hormones need thyroid hormone to have effect

Answer 10

More than one hormone produces same effects on target cell, causing amplification - Ex: glucagon and epinephrine both cause liver to release glucose

Answer 11

One or more hormones oppose(s) action of another hormone | - Ex: insulin and glucagon

Answer 12

stalk called infundibulum

Answer 13

eight major hormones

Answer 14

- Posterior pituitary: composed of neural tissue that secretes neurohormones - Anterior pituitary: consists of glandular tissue

Answer 15

a downgrowth of brain

Answer 16

Two neurohormones (oxytocin and ADH) - Hormones are stored in axon terminals in posterior pituitary and are released into blood when neurons fire

Answer 17

- Strong stimulant of uterine contractions released during childbirth - Also acts as hormonal trigger for milk ejection - Both are positive feedback mechanisms - Acts as neurotransmitter in brain

Answer 18

- Hypothalamus contains osmoreceptors that monitor solute concentrations - If concentration too high, posterior pituitary triggered to secrete ADH - Targets kidney tubules to reabsorb more water to inhibit or prevent urine formation

Answer 19

six hormones - all are peptide hormones - All but two are tropic hormones (tropins) that regulate secretion of other hormones - Growth hormone (GH) - Thyroid-stimulating hormone (TSH) (tropic) - Adrenocorticotropic hormone (ACTH) (tropic) - Follicle-stimulating hormone (FSH) (tropic) - Luteinizing hormone (LH) (tropic) - Prolactin (PRL)

Answer 20

Has direct actions on metabolism and indirect growth-promoting actions - Direct actions on metabolism: (Triggers liver to break down glycogen into glucose Increases blood levels of fatty acids for use as fuel and encourages cellular protein synthesis) - Indirect actions on growth: (GH stimulates most cells to enlarge and divide, but major targets are bone and skeletal muscle)

Answer 21

- In children results in gigantism (Can reach heights of 8 feet) - In adults results in acromegaly (Overgrowth of hands, feet, and face)

Answer 22

- In children results in pituitary dwarfism (May reach height of only 4 feet) - In adults usually causes no problems

Answer 23

Hypothalamus releases TRH (thyrotropin releasing hormone) Anterior pituitary releases TSH (thyroid stimulating hormone) Thyroid gland releases Thyroid hormones (T3/T4) - The main functions of the thyroid hormones are to increase basal metabolic rate and body heat production. - Low levels of TH can stimulate TRH release. TRH can also override the negative feedback in emergency situations, such as exposure to extreme cold (particularly in infants).

Answer 24

- Body’s major metabolic hormone - Found in two forms: T4 (thyroxine): major form secreted and in blood Must be converted to T3 at tissue level T3 (triiodothyronine): different structure; more active 10x more active than T4 at receptors. - Hormones carried in blood by thyroxine-binding globulins (TBGs)

Answer 25

- increasing basal metabolic rate and body heat production, by turning on transcription of genes concerned with glucose oxidation. this is the hormones calorigenic effect - regulating tissue growth and development. TH is critical for normal skeletal and nervous system development and maturation and for reproductive capabilities - maintaining blood pressure by increasing the number of adrenergic receptors in blood vessels

Answer 26

- Lack of iodine decreases TH levels, which triggers increased TSH secretion, triggering thyroid to synthesize more and more unusable thyroglobulin - Thyroid enlarges even though TH levels are low

Answer 27

Called ‘myxedema’ Symptoms: - Low metabolic rate - Lethargy - Feeling cold/chilly - Edema - Dry skin Overweight is often secondary to low metabolism.

Answer 28

Called ‘Graves’ disease’ Symptoms: - Elevated metabolic rate - Excess sweating - Nervousness - Irregular heartbeat - Exopthalmos Elevated metabolic rate causes weight loss despite adequate food.

Answer 29

- ACTH stimulates adrenal cortex to release corticosteroids Regulation of ACTH release: - Triggered by hypothalamic corticotropin-releasing hormone (CRH) in daily rhythm - Highest levels in morning - Internal and external factors that alter release of CRH include fever, hypoglycemia, and stressors

Answer 30

Paired, pyramid-shaped organs atop kidneys Structurally and functionally, it is two glands in one - Adrenal cortex: synthesizes and secretes several different hormones - Adrenal medulla: nervous tissue that is part of sympathetic nervous system

Answer 31

Three layers of cortical cells produce the different corticosteroids: - Mineralocorticoids (glomerulosa cells) - Glucocorticoids (fasciculata cells) - Gonadocorticoids (reticularis cells)

Answer 32

Regulate electrolyte concentrations (primarily Na+ and K+) in ECF - Importance of Na+: affects ECF volume, blood volume, blood pressure. - Importance of K+: sets resting membrane potential of cells Aldosterone: most potent mineralocorticoid - Stimulates Na+ reabsorption by kidneys - Results in increased blood volume and blood pressure - Stimulates K+ elimination by kidneys

Answer 33

hypersecretion usually due to adrenal tumors Results in two major problems: 1. ) Hypertension and edema due to excessive Na+ 2. ) Excretion of K+, leading to abnormal low plasma levels and nonresponsive neurons and muscle

Answer 34

Hormone: Glucocorticoid (cortisol) Regulation of Release: stimulated by ACTH, inhibited by feedback back inhibition exerted by cortisol Target Organ and Effects: body cells; promote gluconeogenesis and hyperglycemia; mobilize fats for energy metabolism; stimulate protein catabolism; assist body to resist stressors; depress inflammatory and immune repsonses Effects of Hypersecretion vs Hyposecretion: Hyper is cushing's syndrome. Hypo is addison's disease

Answer 35

Short-term stressors cause SNS activation and include the release of E and NE from the adrenal medulla. Long-term/prolonged/chronic stress also causes the endocrine system to exert more of an effect by causing CRH and ACTH release, which leads to mineralo- and gluco-corticoid release. Cortisol exerts negative feedback on CRH and ACTH release. This long-term stress response can lead to chronic hypertension (due to increased blood volume and sodium levels) as well as diabetes (increased blood glucose levels) and increased risk of infection due to immunosuppression.

Answer 36

the hypothalamus activates the adrenal medulla via neural stimuli short-term stress response helps the body successfully respond to a short-term emergency (running from fire)

Answer 37

the hypothalamus activates the adrenal cortex via hormonal stimuli. this greatly reinforces the continuing short-term stress response long-term stress response helps the body successfully deal with some long-term stressors (starvation). if the stress response is prolonged, it can become detrimental. it may lead to high BP, muscle loss, altered immune function, etc.

Answer 38

Depresses cartilage/bone formation and immune system; inhibits inflammation; disrupts neural, cardiovascular, and gastrointestinal function - Causes: tumor on pituitary gland or adrenal cortex; overuse of corticosteroids - Treatment: removal of tumor, discontinuation of drugs Glucocorticoid drugs can control symptoms of many inflammatory diseases (arthritis, allergies) but can also cause undesirable effects.

Answer 39

- Usually involves deficits in both glucocorticoids and mineralocorticoids - Decrease in plasma glucose and Na+ levels - Weight loss, severe dehydration, and hypotension are common - Treatment: corticosteroid replacement Early sign is characteristic bronzing of skin due to high levels of ACTH which triggers melanin production in melanocytes

Answer 40

Triangular gland located partially behind stomach - Acinar cells (exocrine) produce enzyme-rich juice for digestion - Pancreatic islets (islets of Langerhans) contain endocrine cells - Alpha cells produce glucagon (hyperglycemic hormone) - Beta cells produce insulin (hypoglycemic hormone)

Answer 41

Secreted when blood glucose levels increase Insulin lowers blood glucose levels: - Enhances membrane transport of glucose into fat and muscle cells - Inhibits breakdown of glycogen to glucose - Inhibits conversion of amino acids or fats to glucose Insulin also triggers cells to: - Catalyze oxidation of glucose for ATP production: first priority - Polymerize glucose to form glycogen - Convert glucose to fat (particularly in adipose tissue)

Answer 42

pancreas beta cells secrete insulin when stimulated by: - elevated blood glucose levels - rising blood levels of amino acids and fatty acids - acetylcholine released by parasympathetic nerve fibers - hyperglycemia hormones, this effect is indirect and occurs because all of these hormones increase blood glucose levels activation of sympathetic NS inhibits insulin release

Answer 43

Release triggered by decreased blood glucose levels, rising amino acid levels, or sympathetic nervous system Raises blood glucose levels by targeting liver to: - Break down glycogen into glucose (Glycogenolysis) - Synthesize glucose from lactic acid and other noncarbohydrates (Gluconeogenesis) - Release glucose into blood

Answer 44

hormone secretion from the pancreas

Answer 45

Hyposecretion of insulin: Type 1 Hypoactivity of insulin: Type 2

Answer 46

Polyuria: large urine output Glucose acts as osmotic diuretic Polydipsia: excessive thirst From water loss due to polyuria Polyphagia: excessive hunger and food consumption Cells cannot take up glucose and are “starving”