Bergdahl- Chapter 20 Flashcards Preview

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Flashcards in Bergdahl- Chapter 20 Deck (68):

describe the ducts of the endocrine system

no ducts ! they secrete substances directly into extracellular spaces around the gland


what is a half-life ?

time required to reduce a hormone's blood concentration by a half, and gives an indication on how long its effect persists


how are steroid hormones different from amine and peptide hormones ?

they're not soluble in blood plasma


what are 4 ways that a hormone can specifically target a cell ?

1) modify rate of intracellular protein synthesis by stimulating nuclear DNA
2) change rate of enzyme activity
3) alter plasma membrane transport with a second-messenger system
4) induce secretion


what is the first step in initiating hormone action ?

hormone-receptor binding


what are the three things that a target cell's activation by a hormone depends on ?

1) hormone concentration in blood
2) number of target cell receptors for hormone
3) sensitivity or strength of union between hormone and receptor


what are 3 ways that a hormone can increase enzyme activity ?

1) stimulate its production
2) combine with it to alter its shape and ability to act, increasing or decreasing its catalytic effectiveness
3) activating inactive enzyme forms, therefore increasing total amount of active enzyme


what are 4 factors that determine plasma concentration of a hormone ?

1) quantity synthesized in host gland
2) rate of catabolism or secretion in blood
3) quantity of transport proteins present
4) plasma volume changes


what does "secreted amount" mean ?

the plasma concentration of a hormone
the sum of hormone synthesis and release by host gland, in addition to uptake by tissues and removal by liver and kidneys


can changes in plasma volume alter hormone concentration ?

yeah, independent of the host organ's secretion rate


what is hormonal stimulation ?

hormones influencing secretion of other hormones (eg ACTH)


what is humoral stimulation ?

changing levels of ions and nutrients stimulate hormone release (ADH, insulin)


what is neural stimulation ?

neural activity affects hormonal release (catecholamines)


what does a mean concentration of a hormone at a given time indicate ?

not much. the half-life and the pattern of release is much more significant


what controls the 6 releasing factors (hypothalamic hormones) ?

neural input to the hypothalamus from anxiety, stress, physical activity


what is growth hormone's main mission ?

to promote cell division and cellular proliferation throughout the body


in adults, what are the 3 ways that GH promotes protein synthesis ?

1) increase aa transport through membrane
2) stimulate RNA formation
3) activate ribosomes that increase protein synthesis


what energy sources does GH promote or inhibit?

less protein and carbs, more fat utilization


how does training affect GH?

extends GH's action on target tissues


what mediates GH's effects ?

Insulin-like Growth Factors


what is thyrotropin's main role ?

thyrotropin = thyroid-stimulating hormone
controls hormone secretion by thyroid gland


what is adenocorticotropic hormone's main use ?

acts directly to enhance fatty acid mobilization and stimulate protein catabolism and increase gluconeogenesis


what are the two hormones that mediate ACTH release ?

vasopressin and corticotropin-releasing hormone


what is prolactin's main role ?

initiates and supports milk secretion from mammary glands


how do prolactin levels change in exercise ?

increase at high intensities and return to baseline within 45 min during recovery


how is prolactin involved in training adaptations ?

exercise-induced release may inhibit ovarian function and contribute to menstrual cycle alterations


what is the main role of gonadotropic hormones ? what are they called ?

stimulate male and female sex organs to grow and secrete hormones at faster rate

follicle-stimulating hormone and luteinizing hormone


what are the two posterior pituitary hormones ?

ADH and oxytocin


what is the main role of ADH

anti-diuretic duh


what happens to ADH during physical activity ?

stimulus for secretion in order to help conserve body fluids


what does T4 do ?

raises metabolism of all cells except brain, spleen, sex, and thyroid gland


what does T3 do ?

facilitates neural reflex activity


how do thyroid hormones influence BP ?

by provoking an increase in adrenergic receptors in blood vessels


what are 4 effects of hyperthyroidism ?

1) increased VO2 and metabolic heat production at rest
2) increased protein catabolism
3) heightened reflex ability- irritability, insomnia
4) rapid HR


what are 4 effects of hypothyroidism ?

1) reduced metabolic rate
2) decreased protein synthesis
3) depressed reflex- sluggishness
4) slow HR


what does parathyroid hormone do ?

control blood calcium balance
decrease in calcium triggers PTH release


what hormones come out of the adrenal cortex ?

mineralocorticoids, glucocorticoid, and androgens


what does aldosterone do ?

a mineralocorticoid, regulates minerals like Na+ concentration, stimulates ion reabsorption


what does cortisol do ?

a glucocorticoid, promotes breakdown of energy sources


what are distinctly male and female hormones ?



what are the two hormones from the pancreas and where are they secreted ?

alpha cells: glucagon
beta cells: insulin


is pancreas endocrine or exocrine ?

both. islets are endocrine, acini are exocrine


how is GLUT 1 different from GLUT 4 in glucose transport ?

GLUT 1 moves glucose based on concentration difference
GLUT4 requires insulin to undergo a conformational change and transport glucose


what directly controls insulin secretion ?

blood glucose levels in pancreas


why does no excessive insulin release occur with a concentrated glucose feeding during physical activity ?

less blood flow to the pancreas since it's not a crucial organ


what does glucagon do ?

"insulin antagonist"
stimulates glycogenolysis and gluconeogenesis, and increases lipid use too.


does exercise training enhance GH secretion and conserve glycogen reserve ?

not really


how is blood GH different in trained individuals ?

endurance-trained people have less of a rise in blood GH levels because there is less exercise stress


how are women's GH levels different from men's in exercise ?

they're the same
women's are higher at rest


how does training affect ACTH release ? how does this change the metabolism ?

increases release
therefore increases fat catabolism and spares glycogen


how do prolactin levels differ in trained individuals ?

at rest, they're lower in male runners than in sedentary nonrunners


how does reproductive response vary with physical activity level ?

exercise depresses reproductive hormone response
lower testosterone levels for example
lower FSH and LH in women


what is the difference in LH and FSH levels between trained and untrained men ?

there is none
there's only lower levels in trained women


how does exercise impact aldosterone levels ?

it doesn't


how does exercise impact cortisol levels ?

levels increase less in trained people


when can adrenal gland enlargement occur ?

with repeated bouts of intense exercise training


how does catecholamine activity differ in trained individuals ?

in general there is a reduction in HR and BP, so lower levels
HOWEVER, relatively, there is a higher response that occurs following aerobic training


if there is a greater catecholamine output at the same relative exercise intensity following training, what 3 factors could explain the greater SNS activation ?

1) greater demand for substrate use
2) increased overall cardiovascular response
3) larger muscle mass activation


how does glucagon and insulin concentration vary with training status ?

with time, trained have less and requires less


what are 3 ways that exercise can improve insulin action ?

1) translocation of GLUT 4 from endoplasmic reticulium to cell surface
2) increase in total quantity of GLUT 4
3) increase in glycogen synthase activity and therefore storage


what tissue consumes the major amount of glucose transported in blood ?

skeletal muscle


how does intense exercise improve long term glycemic control ?

a bout decreases plasma glucose for a long time
the immediate effects increase the active muscles' insulin sensitivity, which causes long-term improvement in glycemic contol


what are the two primary hormones that affect adaptations to resistance training ?

GH and testosterone


what are 3 hormonal factors responsible for exercise induced changes in muscle size and function ?

1) changes in hepatic and extrahepatic hormone clearance rates
2) differential rates of hormone secretion
3) altered receptor site activation via neurohumoral control


what are short term effects of moderate and maximal exercise on the immune system ?

MODERATE: boosts natural immune function up to several hours

EXHAUSTIVE: severely depresses the body's first line of defense due to strenuous exertion


what are long term effects of aerobic exercise on immune system ?

positively affects natural immune function during weight loss


what 2 areas of improvement of immune system in long-term aerobic exercise ?

1) enhanced functional capacity of natural cytotoxic immune mechanisms
2) diminished age-related decrease in T-cell function


how does resistance training long term affect immune system ?

doesn't affect natural cytotoxic immune mechanisms