ch. 45 part 1 Flashcards
steps of long-distance regulators
- regulator/monitor
- setpoint
- change in factor (controlling factor released)
- hormonal release
- circulation
- target cell
- receptor
- signal transduction
- balance restored
function of endocrine system
chemical signaling by hormones
endo
within
crine
secrete
nervous system
network of specialized cells (neurons) that transmit signals along dedicated pathways
what systems often overlap in function?
nervous and endocrine
where do endocrine cells secrete hormones
extracellular fluids
what are hormones picked up by
circulatory system
what does endocrine signaling do
- maintains homeostasis
- mediates responses to stimuli
- regulates growth/development
local regulators
molecules that act over short distances
- reach target cells by diffusion
2 types of local regulators
- paracrine signaling
- autocrine signaling
paracrine signaling
target cells lie near secreting cells
autocrine signaling
target cell is secreting cell
para
along side
auto
self
roles of paracrine/autocrine signaling
- blood pressure regulation
- nervous system function
- reproduction
prostaglandins
local regulators that mediate paracrine/autocrine signaling
where do prostaglandins function?
immune system and blood clotting
synaptic signaling
neurons form specialized junctions with target cells (synapses)
what are secreted at synapses?
neurotransmitters
neurotransmitters
secreted molecules that diffuse short distances and bind to receptors on target cells
neuroendocrine signaling
specialized neurosecretory cells secrete neurohormones that diffuse from nerve endings into the blood stream
pheromones
chemicals that are released into the environment
- used for communication
purpose of pheromones
- marking trails leading to food
- defining territories
- warning of predators
- attracting potential mates
what are prostaglandins composed of
modified fatty acids
what are local regulators composed of
polypeptides, gases, modified fatty acids
nitric oxide
gas that functions in body as both local regulator and neurotrnasmitter
function of NO
when level of oxygen in blood falls, activates enzyme that results in vasodilation
- increases blood flow to tissues
3 major classes of hormones
- polypeptides
- steroids
- amines
are polypeptides/amines water or lipid soluble
water-soluble
are steroid hormones water or lipid soluble
lipid-soluble
water-soluble hormones
- secreted by exocytosis
- travel freely in bloodstream
- bind to cell-surface receptors
lipid-soluble hormones
- diffuse across cell membranes
- travel in blood bound to transport proteins
- diffuse through membrane of target cell
- receptors in cytoplasm or nucleus of target cell
what does the binding of a hormone initiate
signal transduction
signal transduction
pathway leading to responses in cytoskeleton, enzyme activation, or change in gene expression (sometimes)
another name for epinephrine
adrenaline
epinephrine
regulates many organs in response to stressful situations
where does epinephrine bind
- receptors on plasma membrane of liver cells
- triggers release of messenger molecules that activate enzymes and result in a release of glucose into bloodstream
what 2 processes does epinephrine lead to
- glycogenolysis
- gluconegenesis
pathway of epinephrine
- binds to GPCR
- G protein with GTP activates adenyl cyclase
- ATP activates cAMP
- cAMP activates protein kinase A
- leads to inhibition of glycogen synthesis and promotion of glycogen breakdown
what is usually the response of a lipid-soluble hormone
change in gene expression
what happens when a steroid hormone binds to its cytosolic receptor
hormone-receptor complex moves into nucleus, then acts as transcriptional regulator of specific target genes
estradiol in female birds and frogs
form of estrogen that binds to a cytoplasmic receptor in liver cells
- then activates transcription of genes needed to produce egg yolk
