chapter 18 Flashcards
the endocrine system
regulates long term processes such as growth development and reproduction
nervous system releases
endocrine system releases
neurotransmitters; hormones
hormones will circulate through the blood and bind to receptors on
target cells
exocrine glands secrete products
into ducts
(sweat, oil, mucous and digestive glands)
endocrine glands secrete
hormones directly into interstitial fluid (no ducts)
endocrine glands include the
pituitary, thyroid, parathyroid, adrenal and pineal glands
what other organs secrete hormones?
hypothalamus, thymus, pancreas, ovaries, testes, kidneys, stomach, liver, skin, heart, placenta, adipose tissue, small intestine
what are the 3 classes of hormones
amino acid derivatives
peptide hormones
lipid derivatives
what causes down regulation of a receptor
high concentrations of hormone
what causes up regulation of a receptor
low concentrations of hormone
amino acid derivatives
small molecules structurally related to amino acids
what are the tyrosine derivatives
thyroid hormones
catecholamines (NE,E)
what are tryptophan derivatives
dopamine
seratonin
melatonin
what are the two classifications of hormones
lipid soluble (steroid) and non lipid soluble (non steroid)
peptide hormones are
chains of amino acids usually synthesized as prohormones
prohormones are
inactive molecules converted to active hormones before or after secretion
glycoproteins are
200+ amino acid chains with carb side chains
ie: TSH, LH, FSH
g protein is a
enzyme complex that is coupled to a membrane receptor
links first and second messenger
when the g protein is inactive
adenylate cyclase is activated and changes cAMP levels in the cell
increased cAMP levels accelerate
metabolic activity within the cell
can first and second messengers have direct effect on activities in the target cell
no they use an intracellular intermediary
activated g proteins trigger
- opening of calcium ion channels
- release of calcium ions intracellularly
- enzyme activation (phospholipase)
- receptor cascade to activate calmoudin
steroid and thyroid hormones and intracellular receptors can
alter DNA rate of transcription
affect metabolic activity and structure of target cekk
endocrine reflex are functional counterparts of _______ and controlled by ______________________
neural reflexes, negative feedback mechanisms
the trigger of endocrine reflexes produces
the production of a hormone and the effects of the hormone can reduce intensity of the stimulus
what can endocrine reflexes be triggered by and what do they miantain
maintain hormone homeostasis
triggered by humoral stimuli, hormonal stimuli and neural stimuli
local hormones
act locally without first entering the blood stream
paracrines act on
autocrines act on
neighboring cells
the same cell that secreted it
lipid soluble hormone examples
steroids, thyroid hormones, nitric oxide
water soluble hormone examples
peptides, proteins, glycoproteins and eicosanoids (amines)
Lipid soluble hormones binds to
water soluble hormones circulate in
transport proteins
plasma, in a free form
Actions of a lipid soluble hormone
L.S.H activate _________ in the cell and then alter ______________________ which create new __________ that create physiological responses
receptors, gene expression, proteins
Actions of Water Soluble Hormones
W.S.H alter cell functions by activating _________ ____________________, and bind to the ___ messenger. Then a ______ messenger is released where stimulus response takes place
plasma membrane receptors,1st, 2nd
common example is cyclic AMP
in cyclic AMP, the hormone will bind to the membrane receptor
then the receptor will activate a G protein,
which then turns on Adenylate cyclase,
which then converts ATP to cyclic AMP,
which activates protein kinases,
which phosphorylate enzymes
responsiveness of a target cell depends on
hormone concentration, hormone receptors
