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55 terms

U9, Ch45 (Endocrine)

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endocrine system
the sum of all the body's hormone-secreting cells and tissues; hormones are released into the bloodstream and are broadcast throughout the body
homeostasis
how animals maintain a relatively constant internal environment even when the external environment changes significantly
negative feedback system
responds to the change in a way that counteracts it (uses antagonistic hormones)
antagonistic hormones
inverse hormones
positive feedback system
a change in some variable that triggers mechanisms that amplify rather than reverse the change
thermoregulation
how animals maintain their internal temperature within a tolerable range
osmoregulation
the process by which animals control solute concentrations and balance water gain and loss
ADH
important hormone in the regulation of water balance; produced in the hypothalamus and stored in and released from the pituitary gland; makes collecting ducts more permeable to water, so more water leaves the filtrate, resulting in more concentrated urine and reduced loss of water from the body
renin
an enzyme, is released in the kidney; activates angiotensin II if blood pressure or blood volume drop
angiotensin II
acts as a hormone and causes arterioles to constrict, which will raise blood pressure
aldosterone
causes the kidney to reabsorb more Na+, which increases retention of water and blood volume and pressure
endocrine glands
ductless and secrete hormones directly into body fluids
hormones
chemical signals that cause a response in target cells
cell-surface receptors
bind the hormone, and a signal transduction pathway is triggered, which consists of a series of molecular events that initiate a response to the signal
intracellular receptors
bound by hormones that are lipid-soluble; then acts as a transcription factor, causing a change in gene expression
hypothalamus
receives information from nerves throughout the body and from other parts of the brain and then initiates endocrine signals in response
posterior pituitary
an extension of the hypothalamus that stores and secretes oxytocin and ADH
oxytocin
causes contraction of the uterine muscles in childbirth and ejection of milk in nursing
anterior pituitary
consists of endocrine cells that synthesize and secrete several hormones
FSH
stimulates development of the ovarian follicles in females and promotes spermatogenesis in males by acting on the cells in the seminiferous tubules
luteinizing hormone
triggers ovulation in females and stimulates the production of testosterone by the interstitial cells of the testes
2 kinds of chemical signaling mechanisms
Steroids & peptides/proteins (non-steroids)
Steroid Signaling
passes through cell & nuclear membrane, binds w/ receptor in nucleus, & activates transcription that results in protein synthesis
Non-steroid (proteins/peptides) Signaling
binds to cell membrane surface, activates signal transduction which activates existing cytoplasmic proteins (process is faster than steroid response)
Hormone Creation Path
ribosomes in rough ER -> golgi apparatus (modified to final structure) -> secretory vesicles -> blood stream
Target Cells
cells equipped w/ the right receptors to respond to a certain hormone
If blood glucose is high:
pancreas releases insulin which stimulates cells to take up glucose & the liver to convert glucose into glycogen
If blood glucose is low:
pancreas releases glucagon which stimulates the liver to break down glycogen and release glucose into the blood stream
lining of digestive tract
in the stomach/small intestine; produces gastrin (-> stomach), secretin (-> pancreas) and cholecystokinin (-> gallbladder)
gastrin
(lining of digestive tract -> stomach) stimulates production of gastric juice (a mixture of pepsin & HCl)
secretin
(lining of digestive tract -> pancreas) stimulates release of pancreatic juice into the small intestine
cholecystokinin
(lining of digestive tract -> gallbladder) stimulates gallbladder to send bile to the small intestine
adrenal glands
adjacent to the kidneys; produces epinephrine and norepinephrine (-> various)
epinephrine and norepinephrine
(adrenal glands -> various) increases metabolic rate, breathing rate, glycogen breakdown rate in liver, and blood pressure; stimulates fat cells to release fatty acids; causes "fight/flight" response
pancreas
in abdominal cavity below stomach on left; produces insulin (-> body cells & liver) and glycogen (-> liver)
insulin
(pancreas -> body cells & liver) causes body cells to take up glucose from blood and the liver to remove glucose from the blood and store it as glycogen (decreases blood sugar levels)
glucagen
(pancreas -> liver) causes liver to break down glycogen and release glucose to blood (increases blood sugar levels)
parathyroid
4 glands embedded in thyroid; produces parathyroid hormone (-> bones & kidneys)
parathyroid hormone
(PTH) parathyroid -> bones & kidneys; increases blood calcium levels
thyroid
in neck region around pharynx; produces thyroxine (-> various) and calcitonin (-> bones and kidneys)
thyroxine
thyroid -> various; stimulates/maintains metabolic processes/metabolic rate; needs iodine to be made
calcitonin
thyroid -> bones and kidneys; decreases blood calcium levels
anterior pituitary
hangs just below hypothalamus; ACTH (-> adrenal cortex), thyroid stimulating hormone (-> thyroid), growth hormone (-> bones), prolactin (-> mammary glands) and follicle stimulating hormone/luteinizing hormone (-> testes and ovaries)
ACTH
(anterior pituitary -> adrenal cortex; regulates secretions of stress hormones (corticosteroids) by the adrenal cortex
thyroid stimulating hormone
(anterior pituitary -> thyroid); TSH; regulates secretion of thyroxine
Growth hormone
(anterior pituitary -> bones); GH; regulates proper growth of bones and cartilage
gigaintism
caused by too much growth hormone as a child
pituitary dwarfism
caused by too little growth hormone as a child
acromegaly
caused by too much growth hormone as an adult
prolactin
(anterior pituitary -> mammary glands); PRL; stimulates mammary gland growth and milk synthesis in mammals
follicle stimulating hormone and luteinizing hormone
(anterior pituitary -> tests & ovaries); FSH and LH
posterior pituitary
hangs just below the hypothalamus; produces oxytocine (-> mammary glands & uterine muscles), Antidiuretic hormone (->kidneys)
Antidiuretic hormone
posterior pituitary -> kidneys; ADH; regulates osmolarity of blood by influencing kidney filtration and urine production
oxytocine
posterior pituitary -> mammary glands & uterine muscles; stimulates uterus contractions and causes milk ejection during nursing
hypothalamus
part of cerebrum in lower center of brain; primary intersection between nervous system and endocrine system; produces releasing and inhibitory hormones (-> anterior pituitary); connected by blood to pituitary which allows for immediate and accurate regulation