chapter 7 Flashcards
(38 cards)
hormone
chemical messenger released in response to a signal, released form tissue and travels to target cell through the blood
lipophilic hormones
hydrophobic
-steroids and thyroid hormones
-can easily pass membrane
lipophobic hormones
hydrophilic, polar or charged
-peptides and catacholamines
cannot pass membrane
what are the major classes of hormones
- amines
- peptides
- steroids
major classes of hormones
1. amines
amines: derivatives of tyrosine. lipophilic
a. thyroid hormones: triiodothyronine T3 and thyroxine T4
-synthesized from two tyrosines and iodine atoms
b. catacholamines: epinephrine, norepinephrin, dopamine
-modify the side groups of tyrosines
major classes of hormones
2. peptides
-amino acid chains
-ex. insulin and glucagon
-much larger, water soluble so they cannot enter the cell
-need an activation enzyme, open a channel, G- coupled pathway, or an integrin receptor to cause pathway
-typically activate 2nd messenger systems
major classes of hormones
3. steroids
steroids: derivatives of cholesterol, lipophilic. most are made on demand, not stored in the cell
a. adrenal hormones
b. gonadal hormones
major classes of hormones
3. steroids
a. adrenal hormones
a. adrenal hormones: on kidneys
-mineral corticoid: affect mineral metabolism ex. aldosterone
-glucocorticoid: affect glucose metabolism. ex. cortisol
-both called corticosteroids, on the cortex of the adrenal gland
major classes of hormones
3. steroids
b. gonadal hormones
b. testosterone, estradiol, progesterone
-don’t travel well in water and blood, need travel proteins
-readily diffuse into the membrane. lipophilic
describe the adrenal gland
-adrenal medulla: derivative of nerve tissues, releases catacholamines: epinephrine, nor-epi
-adrenal cortex: exterior layer. releases glucocorticoids, testosterone, and aldosterone
peptides and catacholamines traits
-water soluble, lipophobic
-easily degraded by enzymes so they have a short half life, causing the body to release them in large amounts
-must act on a extracellular receptor, typically activate 2nd messenger systems. fast
amine and steroid traits
-lipid soluble, lipophilic
-small amounts free in plasma, carried by transport proteins
-not easily degraded have longer half life
-diffuse directly through the membrane, usually alters DNA transcription, slow
what are ways hormone secretion can be controlled by
- change in plasma ion concentration
-ex. aldosterone secreted by adrenal cortex, increases Na resorption - change in plasma nutrient concentration
-ex. glucagon secreted by alpha cells raises blood pressure - neural input: nerual input causes secretion from a gland
- (neuro) hormonal input: neurohormone stimulates the release of another hormone
-ex. TSH controls the release of T3 and T4
example of change in ion concentration
parathyroid
-parathyroid releases parathyroid hormone which influences calcium levels.
-stimulus: low calcium levels in plasma
-parathyroid releases parathyroid hormone into the bloodstream
-hormone reaches kidney receptors: triggers reabsorption of calcium in urine
-bone: triggers bone resorption
-intestines: increases absorption
*promotes negative feedback loop
pituitary gland
composed of posterior and anterior sided. connected to the hypothalamus via the infundibulu,
anterior pituitary gland
-considered true endocrine gland
-other name: adenohypophysis
posterior pituitary gland
-extension of neural tissue
-other name: neurohypophysis
-extension of the brain that secretes neurohormones made in the hypothalamus
-first caused by action potentials that trigger the release of neurohormones out of neurons, then it enters capillaries.
-releases vasopressin (ADH) and oxytocin
posterior pituitary
vasopressin functions
-vasopressin: hormone that increases blood pressure, released during dehydration. other name, ADH antidiaretic hormones
- other functions: inhibits urine production, affects the kidneys
posterior pituitary
vasopressin pathway
kidneys:
1. stimulus: blood osm changes
2. osmoreceptors in the hypothalamus trigger the release of vasopressin
3. vasopressin reaches pituitary gland
4, vasopressin reaches kidney receptors and triggers water resorption
5. reach 300 mOSM
6. more water increases blood pressure
posterior pituitary
oxytocin
released during pregnancy in women
-during pregnancy increases fat in breasts. thickens the uterine wall to facilitate implantation. assists in parturition (smooth muscles contract to release milk in breasts)
tropic hormone
a hormone that stimulates the secretion of another hormone
short loop negative feedback
levels of H2 increase, binds to receptor on hypothalus and stops response
long loop negative feedbask
H3 feedbacks to hypothalamus and anterior pituitary to stop further release
pathways that include anterior pituitary have
tropic hormones
