72 terms

Endocrine system: Intro/overview

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hormones can be characterized by
basic chemical structure
hormonal effects are due to interaction with
receptors
hormones are chemicals released from ____ or _____ into the blood circulation to influence cell functions at remote location in the body
glands, specialized cells
what are chemicals secreted from neurons into the blood circulation to influence cell functions at remote location in the body
neuroendocrine hormones
______ and _______ are the major chemical messenger system in the body maintaining homeostasis
hormones, neurotransmitters
the majority of hormones (ADH, insulin, GH) are what classification
protein and polypeptide
what type of hormones are secreted by the adrenal cortex, ovaries, testes, and placenta
steroids
thyroid hormones, and E and NE from the adrenal medulla are classified as
derivatives of tyrosine
the pancreas, hypothalamus, pituitary, pineal, thyroid, adrenal, and gonads are the
major endocrine glands
endocrine glands are ______ and highly _______
ductless, vascularized
hormones can only affect cells with
receptors
amine hormones are synthesized from
tyrosine and tryptophan
hormones from the adrenal medulla, thyroid, and pineal glands are classified as
amines
amine hormones are synthesized form tyrosine by enzymes in the ________ compartment of the glandular cells
cytoplasmic
_________ synthesis occurs on the RER and is directed by specific mRNA (protein and peptide hormone synthesis)
preprohormone (no biological activity)
signal peptides are cleaved from the preprohormone producing a _________ which is transported to the Golgi for packing into secretory vessels (protein and peptide hormone synthesis)
prohormone (no biological activity)
the protein and peptide class of hormones are
water-soluble
steroid hormones are derivatives of
cholesterol
the steroid class of hormones are
lipid soluble
amines, and protein and peptide hormones are released by _______ into the blood
exocytosis
steroid hormones ______ out through the cell membrane into blood circulation
diffuse
there is no _________ in steroid-producing endocrine cells
hormone storage
carbohydrate bound long polypeptides (ex: FSH, LH)
glycoproteins
testosterone, estradiol, progesterone, and cortisol are examples of
steroids
hormones that are insoluble in water (lipophilic) are
nonpolar
non polar hormones use _____ receptors since they can enter target cells directly passing through the plasma membrane
intracellular
what 2 types of hormones are nonpolar
steroid and thyroid
_______ hormones can be taken orally in pill form
nonpolar
hormones that are water soluble (hydrophilic)
polar
since polar hormones cannot easily pass through membranes they require ________
membrane receptors
_____ hormones are usually injected if used as a drug
polar
______ are inactive hormones that must be cut and spliced to be active (ex. insulin)
prohormones
______ are inactive hormones that must be modified (ex. testosterone or vitamin D3)
prehormones
what is the most common thyroid hormone? (prehormone)
T4 (thyroxine)
what is the most active thyroid hormone
T3
which alpha subunit G protein activates adenylate cyclase
Gs
which alpha subunit G protein inhibits adenylate cyclase
Gi
Adenylate cyclase + ATP produces
cAMP
cAMP will activate
protein kinase
active protein kinase will trigger responses of the
target cell
what is the first messenger in the G protein pathway
hormone (or neurotransmitter)
what is the second messenger in the G protein pathway
cAMP
what is the most potent androgen
testosterone
when 2 or more hormones work together to produce a particular effect
synergistic
type of synergistic effect when norepinephrine and epinephrine both activate beta 1 receptors in heart
additive
type of synergistic effect when each hormone contributes to overall outcome (ex lactation requires estrogen, prolactin, and oxytocin)
complementary
when one hormone makes the target cell more responsive to a second hormone (ex estrogen makes uterus more responsive to progesterone)
permissive
when hormones produce opposite effects (ex. insulin stimulates lipogenesis, glucagon simulates lipolysis)
antagonistic
the time it takes for the concentration of a hormone to decrease in circulation by 1/2
hormone half life
most hormones are removed from the blood by what organ
liver
which hormone circulates for several days (long 1/2 life)
thyroid hormone
priming a receptor causes ____ regulation
up (increased responsiveness)
desensitization of a receptor causes ______ regulation
down (decreased responsiveness)
what are the 3 main ways to regulate the endocrine system
circulating hormone concentration, receptor regulation, feedback loops
if hormone concentration is too low there is
no effect
if hormone concentration is too high widespread effects occur due to ______ to receptors of related hormones or _____ to related hormones
binding, conversion
increased number or responsiveness of target cell hormone receptors is known as
priming (receptor up regulation)
decreased number or response of target cell hormone receptors is known as (caused by prolonged exposure to high concentrations of hormone)
desensitization (down regulation)
desensitization is avoided by the _________ secretion
pulsatile
the predominant mode of regulation in the endocrine system is
negative feedback
negative feedback caused by increasing levels of the circulating component is
physiological response-driven
negative feedback caused by increasing levels of the hormone secreted is
endocrine axis-driven
which hormone test starts with a primary antibody against the hormone and secondary antibody against primary immunoglobulin thats radio labeled
radioimmunoassay
radioimmunoassays will work best to ID which type of hormones
peptides (protein)
which type of hormones are not stored in tissues
steroid
thyroid hormones are stored as ________ in follicles
thyroglobulin
protein/peptide hormones are stored in endocrine cells in
membrane bound secretory granules
__________ are synthesized in the cytosol and secretory granules and do not readily cross cell membranes
catecholamines
where is the hormone receptor for proteins, peptide, E and NE hormones
in or on the surface of the cell membrane
where is the hormone receptor for steroid hormones
in the cytoplasm
where is the hormone receptor for thyroid hormones
in the cell nucleus
hormone levels are determined by
radioimmunoassay and ELISA
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