The Endocrine System (ch18) Flashcards
what are the physiological signals
electrical signals and chemical signals
electrical signals
changes in the membrane potential of a cell
chemical signals
- molecules secreted by cells into extracellular fluid
- reponsible for most communication within the body
- chemical signals act as ligands that bind to proteins to initiate a response
molecules in nervous system
neurotransmitters released locally in response to nerve impulses
molecules in endocrine system
hormones delivered to tissue throughout body by blood
site of action for nervous system
close to site of release, at synapse; binds to receptors in postsynaptic membrane
site of action for endocrine system
- far from site of release (usually); binds to receptors on or in target cells
types of target cells in nervous system
- muscle cells, gland cells, other neurons
types of target cells in endocrine system
- cells throughout body
duration of action in nervous system
generally briefer
duration of action in endocrine system
generally longer
exocrine glands
secrete their products into ducts to be excreted to external environment
endocrine glands
do not have ducts, secret hormones
receptors are constantly being _____ and ______
synthesized and broken down
down regulation makes cells
less receptive
up-regulation makes cells more receptive
up-regulation makes cells more receptive
lipid soluble hormones
steroid hormones, thyroid hormones, nitric oxide
water soluble hormones
amine hormones, peptide hormones, eicosanoid hormones
steriod hormones
derived from cholesterol
thyroid hormones
although a protein, they behave like a lipid
nitric acid
gas produced by endothelial cells
amine hormones
decarboxylation of selected Amino Acids
peptide hormones
small to large proteins
eicosanoid hormones
- fatty acids that behave like proteins
- classified as autocrine/paracrine hormones
most water-soluble (hydrophilic) hormones circulate in _________
free form
what does preprohormone and prohormone refer to
inactive precursors
how often are peptide hormones release
- released in burst frequently throughout day.
mechanism of lipid-soluble hormones
- diffuse through the cell membrane
- bind to receptors in the cytosol or nucleus
cytoplasmic and nuclear receptors lead to what types of response
genomic response - which activate and represses gene transaction
thyroid hormones
- behaves like steroid hormone
T3 and T4 transported in blood by
- thyroid-binding globulin (TBG)
- transthyretin
- albumin
which hormones cannot cross the plasma membrane, so they must bind to the surface membrane receptors
- amine, peptide, protein
g- protein once activated will….
- open an ion channel in the membrane
- turns on amplifier enzyme
______ converts ATP into cyclic AMP
Adenylyl cyclase
2nd messenger and function
Cyclic AMP
- alter ion channels
- activated protein kinase A
1st messenger and function
hormone
- binds to surface cell receptors
amplifier enzyme is most common in
G-protein
synergistic effect
something is better when combined than each individual item
permissive effect
hormone cannot fully work without the permission from another hormone
antagonist effect
one hormone opposing the action of another hormone
humoral stimuli
changes in composition of extracellular fluid
ex) rise in blood glucose levels triggers the pancreatic release of insulin
hormonal stimuli
release of a hormone in response to another hormone
neural stimuli
stimulates endocrine glands to release hormones
simple endocrine reflex
cell senses a change in environment and then secrets a hormone in response
complex neuroendocrine reflexes
- involves two or more hormones
-one organ typically releases hormones that control the release of additional hormones from another part of the body
2 major groups of neurohormones
- catecholamines
hypothalamic neurohormones
neurohypophysis stores and releases what
- antidiuretic hormone ADH
- oxytocin
antidiuretic hormone ADH
-promotes H2O conservation by kidneys
- elevates BP
- contraction of blood vessels
oxytocin
- stimulates contractions of uterus during parturition
- ejection of milk during breast feeding
pars intermedia secrets _______ (MSH)
Melanocyte-Stimulating Hormone
increase in production of melanin helps with….
- provides pigmentation to hair, eyes and skin
when is MSH produced
- mainly during fetal development
adenohypophysis
produces and secrets majority of the hormones of pituitary gland
function of IGF and growth hormone
- increase growth of muscle, bone and soft tissue
- decreases protein breakdown
- enhances lipolysis and decrease glucose uptake
hormones that use short look negative feeback
- ACTH
- prolactin
- growth hormone
what is hypersecretion
- excess hormone
- caused by exogenous administration or tumors
- too much hormone is secreted
prolonged exogenous exposure may cause?
glands to shrink, lose ability to regain normal function when exogenous use stops
hyposecretion
- amount of hormones that is released is to low
- caused by decreased trophic hormone synthesis or atrophy of a gland
primary hypersecretion
problem occurs at adrenal gland
secondary hypersecretion
problem occurs with the enzyme
tertiary hypersecretion
problem occurs at the hypothalamus
primary hyposecretion
something wrong with adrenal gland
secondary hyposecretion
something wrong with the pituitary gland
tertiary hyposecretion
something wrong wtih hypothalmus
cortex secretes ______
steroid hormones called corticosteroids
different classes of hormones in cortex
mineralocorticoids, glucocorticoids, androgens
mineralocorticoids
regulate mineral homeostasis
glucocorticoids
affect glucose homeostasis
androgens
produce weak masculinizing effects
medulla secrets ____?
neurohormones
subgroups of mineralocorticoids
aldosterone and desoxycorticosterone
aldostrone secretion controlled by (in order)
- blood K+ levels
- Renin
- blood Na+ levels
- ACTH
what is renin
hormone produced by kidneys
action of aldostrone
- renal extraction of K+ and H+
- reabsorbs Na+ and water to maintain blood pressure and blood volume
subgroups of glucocorticoids
- cortisol
- corticosterone
- cortisone
action of cortisol
- gluconeogenesis in liver
- causes breakdown of skeletal muscle proteins
- enhances lipolysis
- suppress immune system
- causes negative Ca+ balance
- influences brain function
how much epinephrine and norepinephrine does the medulla secret
80% epinephrine
20% norepinephrine
eustress
- positive stress
distress
- negative stress
what is hypercortisolism
when body produces too much cortisol
cause of hypercortisolism
adrenal or pituitary tumors
what does hypercortisolism lead to
- hyperglycemia (mimics diabetes)
- muscle breakdown (tissue wasting)
- redistribution of body fat
