Week 3 (Exam 1): Intro to Homeostasis, Endocrine System; Human Reproductive Cycles Flashcards
g protein-coupled receptors
a large family of cell-surface molecules composed of a single polypeptide chain w/ 7 transmembrane spanning regions; when activated, they associate with a G protein
how fast are cellular responses to the activation of a G protein-coupled receptor?
rapid
what did G protein-coupled receptors evolve from?
sensory receptors in unicellular eukaryotes
when are G protein-coupled receptors inactive?
in the absence of a ligand, and when it is bound to GDP
when are G protein-coupled receptors active?
when they are bound to a ligand, and when it is bound to GTP
what components are G proteins made up of?
alpha, beta, and gamma subunits
first step of the activation of G protein by a G protein-coupled receptor
when the alpha subunit is bound to GDP, the 3 subunits are joined together & G protein is inactive
second step of the activation of G protein by a G protein-coupled receptor
G protein associates w/ an activated receptor; GDP is released by GTP; beta & gamma subunits separate
third step of the activation of G protein by a G protein-coupled receptor
activated alpha subunit binds to & activates a target protein —> cell response
second messenger
an intermediate, cytosolic signaling molecule that transmits signals from a receptor to a target within the cell
first messenger
transmits signals from outside the cell to a receptor
first step of adrenaline signaling in heart muscle
activated adenylyl cyclase converts ATP into the 2nd messenger cAMP, which activates protein kinase A
second step of adrenaline signaling in heart muscle
activated protein kinase A phosphorylates proteins in the heart muscle, causing heart rate to increase
binding affinity
the tightness of the binding between the receptor & the signaling molecule
first step of termination
adrenaline detaches from the receptor, inactivating the receptor
second step of termination
an activated G protein deactivates itself by converting GTP to GDP
third step of termination
enzymes in the cytosol degrade to cAMP, which stops the phosphorylation & activation of target proteins by PKA
fourth step of termination
phosphatases remove phosphate groups from proteins, causing them to become inactive
homeostasis
the active regulation & maintenance of a stable internal physiological state in the face of a changing external environment
negative feedback
a process in which the output or product of a pathway opposes the initial stimulus, so that steady conditions are maintained
set point
a steady-state value in homeostatic regulation
thermoregulation
the ability to maintain a constant body temperature
endocrine system
a system of cells & glands that secretes hormones into the bloodstream & works w/ the nervous system to regulate an animal’s internal physiological functions
hormones
a chemical signal that influences physiology & development in both plants & animals; in animals, hormones are released into the bloodstream & circulate throughout the body
neurosecretory cells
a neuron in the vertebrate hypothalamus & the posterior pituitary gland that separates hormones into the bloodstsream
pituitary gland
an endocrine gland located at the base of the vertebrate brain that produces a number of different hormones & controls many other organs of the endocrine system
two kinds of hormones
hydrophilic & hydrophobic
peptide hormones
a short chain of linked amino acids
-hydrophilic
amine hormones
derived from a single aromatic amino acid such as tyrosine
-hydrophilic
steroid hormones
derived from cholesterol
-hydrophobic
1st set of signaling steps
passing of a signal from one endocrine gland to the next in a hormonal pathway
2nd step
signal transduction in a target cell
releasing hormones
peptide hormones that bind to receptors on cells in the anterior pituitary gland, leading that organ to release a much larger amount of the associated hormones
which hormone is released by the hypothalamus
releasing hormones (peptides)
what is the target gland of the releasing hormones
anterior pituitary gland
what is the action of the releasing hormones
stimulates secretion of anterior pituitary hormones
what hormones do the anterior pituitary gland release
-thyroid-stimulating hormone (TSH) (glycoprotein)
-follicle-stimulating hormone (FSH) (glycoprotein)
-luteinizing hormone (LH) (glycoprotein)
-adrenocorticotropic hormone (ACTH) (peptide)
-growth hormone (GH) (protein)
-prolactin (protein)
-melanocyte-stimulating hormone (peptide)
what gland secretes thyroid-stimulating hormone (TSH) (glycoprotein)
anterior pituitary gland
what gland secretes the follicle-secreting hormone (FSH) (glycoprotein)
anterior pituitary gland
what gland secretes the luteinizing hormone (LH) (glycoprotein)
anterior pituitary gland
what gland secretes the adrenocorticotropic hormone (ACTH) (peptide)
anterior pituitary gland
what gland secretes the growth hormone (GH) (protein)
anterior pituitary gland
what gland secretes the prolactin (protein)
anterior pituitary gland
what gland secretes the melanocyte-stimulating hormone (peptide)
anterior pituitary gland
what gland does the thyroid-stimulating hormone (TSH) (glycoprotein) target
the thyroid gland
what does the thyroid-stimulating hormone (TSH) (glycoprotein) do
stimulates synthesis and secretion of thyroid hormones by the thyroid gland
what organ does the follicle-stimulating hormone (FSH) (glycoprotein) target
gonads
what does the follicle-stimulating hormone (FSH) (glycoprotein) do
stimulates maturation of eggs in females; stimulates sperm production in males
what organ does the luteinizing hormone (LH) (glycoprotein) target?
gonads
what does the luteinizing hormone (LH) (glycoprotein) do?
stimulates production and secretion of sex hormones in ovaries (estrogen and progesterone) and testes (testosterone)
what gland does the adrenocorticotropic hormone (ACTH) (peptide) target?
adrenal glands
what organs do the growth hormone (GH) (protein) target?
the bones, muscles, and liver
what does the adrenocortico-tropic hormone (ACTH) (peptide) hormone do?
stimulates production & release of cortisol
what does the growth hormone (GH) (protein) do?
stimulates protein synthesis & body growth
what gland does the prolactin hormone (protein) target?
the mammary glands
what does prolactin do?
stimulates milk production
what does the melanocyte-stimulating hormone (peptide) target?
melanocytes
what do the melanocyte-stimulating hormones (peptides) do?
regulates skin and scale pigmentation
what hormones does the posterior pituitary gland secrete
oxytosin (peptide), and antidiuretic hormone (ADH) (peptide)
what organs does oxytosin (peptide) target?
uterus, breasts, brain
what does oxytosin (peptide) do?
stimulates uterine contractions & release of milk
what organs does antidiuretic hormone (ADH) (peptide) target?
kidneys, brain
what does the antidiuretic hormone (ADH) (peptide) do?
stimulates uptake of water from the kidneys
-involved in pair bonding
what hormones does the thyroid gland produce?
thyroid hormones (peptides) & calcitonin (peptide)
what organs do thyroid hormones (peptides) target?
many tissues
what do thyroid hormone (peptides) do?
stimulation & maintain metabolism for development & growth
what organ does calcitonin (peptide) target?
bone
what does calcitonin (peptide) do?
stimulates bone formation by osteoblasts
what hormones do the ovaries produce?
estrogen (steroid), progesterone (steroid)
what organ does estrogen (steroid) target?
uterus, breast, other tissues
what does estrogen (steroid) do?
stimulates development of female secondary sexual characteristics & regulates reproductive behavior
what organ does progesterone (steroid) target?
uterus
what does progesterone (steroid) do?
maintains female secondary sexual characteristics & sustains pregnancy
what hormone do the testes secrete?
testosterone (steroid)
what organ does testosterone target?
various tissues
what does testosterone (steroid) do?
-stimulates development of male secondary sexual characeristics
-regulates male reproductive behavior
-stimulates sperm production
what hormone does the adrenal cortex produce ?
cortisol (steroid)
what organ does cortisol (steroid) target?
liver, muscles, immune system
what does cortisol (steroid) do?
regulates response to stress by increasing blood glucose levels & reduces inflammation
what hormone does the adrenal medulla produce?
epinephrine (peptide)
what organ does epinephrine (peptide) target?
heart, blood vessels, liver
what does epinephrine (peptide) do?
stimulates heart rate, blood flow to muscles, & an elevation of blood glucose levels as part of a fight-or-flight response
what hormone do the parathyroid glands produce?
parathyroid hormone (PTH) (protein)
what organ does parathyroid hormone (PTH) (protein) target?
bone
what does parathyroid hormone (PTH) (protein) do?
stimulates bone resorption by osteoclasts to increase bone calcium levels
what hormones does the pancreas produce?
insulin (protein), glucagon (protein), somatostatin (peptide)
what organ does insulin (protein) target?
liver muscles, fat, other tissues
what does insulin (protein) do?
stimulates uptake of blood glucose & storage as glycogen
what organ does glucagon (protein) target?
liver
what does glucagon (protein) do?
stimulates breakdown of glycogen & glucose release into blood
what organ does somatostatin (peptide) target?
digestive tract
what does somatostatin (peptide) do?
inhibits insulin & glucagon release; decreases digestive activity
what hormone does the stomach release?
gastrin (peptide)
what organ does gastrin target?
the stomach
what does gastrin (peptide) do?
stimulates protein digestion by secretion of digestive enzymes & acid; stimulates contraction of smooth muscle in the stomach
what hormones does the small intestine produce?
cholecystokinin (peptide), secretin (peptide)
what organs does cholecystokinin (peptide) target?
pancreas, liver, gallbladder
what does cholecystokinin do?
secretion of digestive enzymes & products form liver & gallbladder
what organ does secretin (peptide) target?
pancreas
what does secretin (peptide) do?
stimulates bicarbonate secretion from pancreas
what hormone does the pineal gland produce?
melatonin (peptide)
what organs do melatonin (peptide) target?
brain, various organs
what does melatonin (peptide) do?
regulates circadian rhythms
chemical properties of peptide hormones
hydrophilic
chemical properties of amine hormones
hydrophilic
chemical properties of steroid hormones
hyddrophobic
general homeostatic process
stimulus —> sensor —> effector —> response —> inhibits sensor
how does glucagon affect blood glucose?
increases it
how does insulin affect blood glucose?
decreases it
how does countercurrent flow affect temperature gradients?
small gradients are maintained
how does concurrent flow affect temperature gradients?
large gradients disappear quickly
how is the pituitary gland divided?
into anterior and pituitary regions (think of them as two distinct glands)
how did the anterior pituitary gland form?
forms from epithelial cells that develop & push up from the roof of the mouth
how does the posterior pituitary gland form?
develops from neural tissue at the base of the brain
which region of the pituitary gland do neurosecretory cells communicate with?
anterior pituitary gland
how do the hypothalamus & posterior pituitary gland communicate?
via neurosecretory cells extending axons into the posterior pituitary gland
what do tropic hormones do?
control the release of other hormones
which hormones cause the ovaries to release estrogen & progesterone and the testes to release testosterone?
follicle-stimulating hormone (FSH) and luteinizing hormone (LH)
what does growth hormone do?
acts on the muscles, bones, & other body tissues to stimulate their growth
what does prolactin do?
stimulates milk production
what does oxytocin do?
causes uterine contractions & stimulates release of milk
what do antidiuretic hormones do?
act on the kidneys & control the water permeability of the collecting ducts
where is the thyroid gland located and what hormones does it produce?
-located in the front of the vertebrate neck
-releases thyroxine and triodothyronine
