L3 & L4: Hormones Flashcards
endocrine system
composed of glands and hormone secreting cells
signals sent by the endocrine system
longer delays, but last for greater lengths
a single endocrine gland __
may secrete multiple hormones
pancreas secretes
- insulin (lowers blood glucose levels)
- glucagon (increases blood glucose levels)
- somatostatin(inhibits secretion of pancreatic hormones)
single cell types ___
secretes only one hormone
two types of glands
exocrine and endocrine glands
exocrine glands
secrete their products into a duct, then to either exit or lumen of another organ
endocrine glands
ductless, secrete directly to interstitial fluid and blood
three major classes of endocrine hormones
amine hormones, peptides and proteins, steroids
amine hormones
derivatives of amino acid tyrosine, made by thyroid, adrenal medulla and hypothalamus
thyroid hormones, T3 and T4
contain iodine and are produced by the thyroid gland
epinephrine and norepinephrine
catecholamines, produced by adrenal medulla
dopamine
catecholamines, produced by hypothalamus
goiter
a greatly enlarged thyroid gland resulted from iodine deficiency
annual dose of iodine needed
50 mg
peptide hormones
large, inactive preproxhormones that include signal sequence, one or more copies of hormone, and additional peptide fragments
preproinsulin is cleaved into
proinsulin, then insulin and C-peptide
___ a marker of insulin secretion
C-peptide
secretory vesicles containing peptides __
are stored in the cytoplasm until the cell receives a signal for secretion
what happens when the cell receives a signal?
secretory vesicle releases its contents by Ca2+ dependent exocytosis into the extracellular space
the half-life of peptide hormones is ___
short
steroid hormones
lipids with ring-like structures
steroid hormones are derived from
cholesterol
aldosterone
stimulates Na+ & H2O reabsorption and K+ & H+ secretion in kidneys
cortisol
is secreted from the adrenal cortex and regulates metabolism during stress
sex hormones
testosterone and estradiol
what enzyme releases free cholesterol?
cholesterol esterase
how is cholesterol modified?
in a step-wise manner by a series of enzymes located in mitochondria and SER
most of the steroid hormone molecules found in blood are ___
bound to protein carrier molecules
some examples of protein carriers
corticosteroid-binding globulin, albumin
adrenal gland consists of
adrenal medulla (1/4), adrenal cortex (3/4)
adrenal medulla secretes
epinephrine and norepinephrine
adrenal cortex zonas
zona reticularis, zona fasciculata, zona glomerulosa
zona reticularis secretes
sex hormones
zona fasciculata secretes
glucocorticoids
zona glomerulosa secretes
aldosterone
hormone’s plasma concentration depends on
rate of secretion and rate of removal
how are hormones removed?
by liver and kidneys, by cell endocytosis, by break down by enzymes in blood and tissues
permissiveness
hormone B cannot exert its effect without hormone A
permissiveness example
thyroid hormones stimulates the synthesis of adrenergic receptors for epinephrine in adipose tissue
additive physiological effects
hormone A + hormone B + hormone C = sum of effects
synergistic physiological effects
hormone A + hormone B + hormone C > sum of effects
antagonistic effect
hormone A diminishes effects of hormone B
hormone secretion is under the control of __
three types of inputs:
1) ions or nutrients
2) neurotransmitters
3) other hormones
insuline secretion due to
increase of plasma glucose concentration
insulin secretion due to
signals from nervous system
insulin secretion due
GLP-1 stimulatory hormone
endocrine disease can result from
changes in secretion or responsiveness of target cells
type 2 diabetes (adult-onset)
hyporesponsiveness, cellular sensitivity to insulin is reduced
type 1 diabetes (juvenile)
hyposecretion, reduced number of active pancreatic beta cells
