Ch. 4 Flashcards
How does the endocrine system maintain homeostasis?
through hormones
What is the neuroendocrine system?
endocrine + nervous system
How is the endocrine system defined?
all tissues or glands that secrete hormones
The endocrine system secretes hormones directly to where?
the blood
Where are hormones transported to?
to specific target cells that have specific hormone receptors
Where are the main hormones from the endocrine system around?
metabolism, electrolytes, and fluid
Where are steroid hormones derived from?
cholesterol
Why are steroid hormones able to diffuse through membranes?
they’re lipid soluble
What are the four major glands that secrete steroid hormones?
adrenal cortex, ovaries, placenta, and testes
How are steroid hormones derived from cholesterol?
they have a chemical structure similar to cholesterol
Nonsteroid hormones are not?
lipid soluble so they cannot cross membranes
What two groups are nonsteroid hormones divided into?
protein/peptide hormones and amino-acid derived hormones
What type of hormone are most nonsteroid hormones?
protein/peptide hormones
Where are protein/peptide hormones from?
the pancreas and pituitary gland
What are some amino-acid derived hormones?
thyroid and adrenal medulla hormones
How are hormones secreted?
in bursts (pulsatile)
What is secretion regulated by?
negative feedback
Hormone release causes what in the body?
changes
High level of downstream changes the secretion by?
decreasing it
Low level of downstream changes the secretion by?
increasing it
What is the primary mechanism through which the endocrine system maintains homeostasis?
negative feedback
What is downregulation?
a decrease in the number of receptors during high concentration (DESENSITIZE)
What is upregulation?
an increase in the number of receptors during high plasma concentration (SENSITIVE)
If there is no hormone receptor on a cell’s surface then?
there is no hormone effect
Hormones only affects what kind of tissues?
tissues with a specific receptor
What is the hormone-receptor complex?
when a hormone binds to a receptor
What is sarcopenia
muscle loss
Where are steroid hormone receptors found?
in the cytoplasm or nucleus of the cell
What is direct gene activation?
when a hormone receptor binds to DNA and activates certain genes
Where are nonsteroid hormone receptors found?
on the cell membrane
What are some common second messengers?
cyclic adenosine monophosphate (cAMP), cyclic guanine monophosphate (cGMP), inositol triphosphate (IP3)
What do second messengers do?
relay signals and intensify the strength of the signal
How do nonsteroid hormones form second messengers?
they bind to its receptor and triggers a series of reactions to form second messengers
What does cyclic AMP (cAMP) do?
controls specific physiological responses
What other hormones employ cAMP as a second messenger?
epinephrine, glucagon, and luteinizing hormone
What class are prostaglandins?
third class hormones
What do prostaglandins do?
they act as local hormones
What area do prostaglandins affect?
the immediate area where it’s secreted
What triggers prostaglandin release?
other hormones or a local injury
What do prostaglandins mediate?
inflammation and pain
In an injury, what can a prostaglandin do?
increase vascular permeability (swelling) and vasodilation
What are two important functions of the endocrine glands and their hormones?
to regulate metabolism during exercise and regulate body fluids and electrolytes
What are the major endocrine glands responsible for metabolic regulation?
anterior pituitary gland, thyroid gland, adrenal glands, and the pancreas
What do the glands responsible for metabolic regulation affect?
the metabolism of carbohydrates and fats during exercise
Where does the pituitary gland come from?
the inferior hypothalamus
What hormone does the pituitary gland release?
the growth hormone (GH)
What does the pituitary gland do?
secretes hormones in response to hypothalamic hormone factors
What is the growth hormone?
a potent anabolic agent
GH release is proportional to?
exercise intensity
The pituitary gland secretes six hormones in response to what?
releasing factors or inhibiting factors secreted by the hypothalamus
What does GH utilize
fats
What does GH promote?
muscle growth (hypertrophy)
Outside of the GH, what other hormone is released by the pituitary gland?
thyrotropin
Thyrotropin is also known as?
TSH (thyroid stimulation hormone)
What increases TSH release?
acute exercise
What does short term exercise do to T3 and T4?
it creates a delayed response causing T4 to increase first then T3
What does prolonged exercise do to T3 and T4?
decrease in T3 and T4
What makes more T3 and T4 be secreted in the thyroid gland?
TSH
What are signs of hyperthyroid?
low weight, arrythmia, shaky
What is happening with thyroid hormones if hyperthyroid is present?
there is an decrease in TSH causing T3 and T4 to increase
What is happening with thyroid hormones if hypothyroid is present?
there is an increase in TSH causing T3 and T4 to decrease
What are signs of hypothyroid?
weight gain and fatigue
What releases catecholamines?
the adrenal medulla
What causes the adrenal medulla to release catecholamines?
stimulation by the sympathetic nervous system
What is the percentage of catecholamines that is secreted from the adrenal medulla?
80% epinephrine and 20% norepinephrine
Epinephrine is also known as what?
adrenaline
What does catecholamine release increase?
glycogenolysis, FFAs into the blood, and blood flow to working muscles
When do plasma norepinephrine concentrations increase?
they increase significantly at intensities above 50% of VO2max
When do epinephrine concentrations increase?
until the exercise intensity exceeds 60% to 70% VO2max
When do blood concentrations of epinephrine and norepinephrine increase together?
during long-duration steady-state exercise
What does epinephrine do after exercise ends?
returns to resting concentrations within a few minutes of recovery
What does norepinephrine do after exercise ends?
it can stay elevated for several hours
What releases corticosteroids?
the adrenal cortex
What is a major glucocorticoid?
cortisol
What does cortisol increase?
gluconeogenesis, FFA mobilization, and protein catabolism
Anabolic means?
build up
Catabolic means?
break down
What secretes insulin?
the pancreas
What is the function of insulin?
lowers blood glucose
What does insulin counter?
it counter hyperglycemia
What is hyperglycemia?
when plasmaglucose is elevated and makes you lethargic
What does insulin oppose?
glucagon
What does insulin increase?
glucose transport into cells and synthesis of glycogen to fat
What does insulin inhibit?
gluconeogenesis
What is the function of glucagon?
raises blood glucose
What is hypoglycemia?
when plasma glucose falls below normal concentration
What type of diabetes appears before the age of 40?
type 1 diabetes
What is happening in the body for those who have type 1 diabetes?
their body can’t produce insulin
What is the cause of type 1 diabetes?
unknown cause but most likely a viral or environmental trigger
What type of diabetes appears after the age of 40?
type 2 diabetes
How does type 2 diabetes develop?
when the body produces insulin but not enough or it doesn’t work properly
What causes type 2 diabetes?
family history, low activity levels, poor diet, excess body weight
What are some causes of metabolic syndrome?
high triglyceride levels, low HDL cholesterol, high BP (140/90), insulin resistance
What is glucogenolysis?
when glycogen is broken down into glucose
What is gluconeogenesis?
when fats or proteins are used to create glucose
Adequate glucose during exercise requires?
release by the liver and uptake by the exercising muscle
What hormones increase circulating glucose?
glucagon, norepinephrine, epinephrine, and cortisol
What hormone increases during the first 30-45 minutes of exercise?
cortisol
Cortisol increases protein catabolism in the liver to do what?
gluconeogenesis
The amount of glucose released from the liver depends on what?
muscle usage and exercise (intensity + duration)
As exercise intensity increases what do the catecholamines do?
they increase
As exercise duration increases what is happening within the body?
more liver glycogen is utilized, release/uptake, as glycogen stores decrease, glucagon levels increase
Insulin enables what in the muscle?
glucose uptake
FFAs are stored as what and where in the body?
they’re stored as triglycerides in adipose tissue and within muscle fibers
Lipolysis is stimulated by what hormones?
decrease of insulin, elevation of catecholamines, cortisol, and GH
What are the hydration hormones?
antidiuretic hormone, aldosterone, and kidneys
What is osmolality?
relationship between solutes to fluid
What is high osmolality?
high solutes but low fluid in concentration
What is low osmolality?
low solutes but high fluid in concentration
What is hemoconcentration?
a decrease in plasma volume that causes a simultaneous increase in the concentration of red blood cells
A high hemoconcentration means there is also what kind of osmolality?
high
What is the normal value of osmolality?
300 mOsm/kg
If compartment osmolality is high, then water is?
drawn in
Why is water drawn in if osmolality is high?
because there’s not enough fluid but a lot of solute
If compartment osmolality is low, then water is?
drawn out
The posterior pituitary gland secretes what two hormones?
antidiuretic hormone (ADH) and oxytocin
What does antidiuretic hormone promote?
water conservation by increasing water reabsorption by the kidneys
What is the primary stimulus for antidiuretic hormone release?
high osmolality
What hormone does the adrenal cortex secrete?
mineralocorticoids
What is a major mineralocorticoid for exercise?
aldosterone
What does aldosterone promote?
renal reabsorption of sodium making the body retain sodium
When sodium is retained, what else is being retained?
water
Aldosterone also promotes what to be excreted?
potassium
What stimulates aldosterone release?
increased potassium concentrations, decreased blood volume, decreased plasma sodium
What two hormones do the kidneys release?
renin and erythropoietin (EPO)
What does renin do?
it is released into circulation to convert angiotensinogen to angiotensinogen 1
What is angiotensinogen?
protein from the liver
What happens once angiotensinogen converts to angiotensinogen 1?
it converts to angiotensinogen 2
What enzyme helps angiotensinogen 1 convert to angiotensinogen 2?
angiotensin-converting enzyme (ACE)
What is angiotensin-converting enzyme?
an enzyme from the liver
What happens after angiotensinogen 1 becomes angiotensinogen 2?
it goes to the adrenal cortex and triggers aldosterone to be released
Explain the renin-angiotensin-aldosterone mechanism.
renin converts angiotensinogen to angiotensinogen 1, ACE converts angiotensinogen 1 to angiotensinogen 2, then angiotensinogen 2 goes to the adrenal cortex and triggers the release of aldosterone
What happens after angiotensinogen 2 triggers the release of aldosterone?
blood vessels will vasoconstrict to increase blood pressure
What triggers the kidneys to release renin?
dehydration because it causes blood pressure to decrease
ADH and aldosterone effects persists how much longer after exercise?
48 hrs
Where does erythropoietin (EPO) come from?
kidneys
What does erythropoietin (EPO) do?
regulates red blood cell production by stimulating bone marrow cells
What hormones suppress hunger?
cholecystokinin (CCK), GLP-1, peptide YY, insulin, leptin
What hormone increases hunger?
ghrelin
Where does cholecystokinin (CCK) come from?
the stomach (GI tract)
Where does GLP-1 and peptide YY come from?
large and small intestines
Where does insulin come from?
pancreas
Where does leptin come from?
fat cells
How is ghrelin transmitted?
through the blood to the brain and crosses the blood-brain barrier
What does leptin act on?
receptors in the hypothalamus to decrease hunger
What is the appetite control center of the brain?
the hypothalamus
Why is adipose a endocrine organ?
it secretes the hormone leptin
What two hunger hormones act in opposing ways?
leptin and ghrelin
What type of exercise suppresses appetite?
acute moderate-to-vigorous intensity exercise
What does acute moderate-to-vigorous intensity exercise do to hunger hormones?
it decreases ghrelin and increases GLP-1 and peptide YY secretion
Suppressed appetite only occurs with aerobic exercise, NOT?
resistance exercise
What are the effects of chronic exercise on satiety hormones?
calorie deficit, increased hunger, increase in peptide YY = satiety
What hormone is secreted during a person’s adaptation to training in altitude?
Erythrocytes
