cell to cell comunication, hormones (ch6,7,23) Flashcards
(51 cards)
example of a paracrine signal
histamines, cytokines, NO (nitric oxide), eicosanoids
what does histamine do
it is secreted by basophils and mast cells in connective tissue nearby to injured areas and it makes the cells more permeable to immune cells and proteins that can interact with the pathogen
what are the types of neurocrine molecules & what is the difference b/w them
neurotransmitter (diffuses from a neuron to a target cell in which it triggers a rapid-onset effect)neuromodulator (acts as a paracrine/autocrine signal and triggers a slow effect)neurohormone (diffuses into the blood for long distance distribution)
what is the difference b/w cytokines and hormones?
- cytokines act mainly in a paracrine/autocrine manner but can also diffuse through the blood like hormones
- cytokines are produced by any nucleated cell/on demand, whereas hormones are produced by specialized cells and stored in advance (exception: steroid hormones)
what types of signal molecules are there (differentiated by what kind of receptors they bind to)
- lipophilic (bind to cytoplasmic receptors and trigger activation/inactivation of genes - slow)
- lipophobic (bind to membrane receptors)
how can an ion channel be modified (opened/closed)
- electrical signal (voltage-gated)
- chemical signal (ligand-gated) - this can in turn be: G protein activation, extracellular signal activation, intracellular signal molecule activation
two examples of GPCR pathways
GPCR-cAMP (G protein activates adenylyl cyclase=amplifier, which generates many cAMP molecules which activate protein kinases etc)
GPCR-PLC (phospholipase C) (G protein activates PLC which turns a membrane phospholipid into IP3 and diacylglycerol -> IP3 can trigger ER release of Ca2+ and DAG can activate protein kinases etc)
what is the tonic control of a system?
tonic control = response is gradual, proportional to the amount of signal that triggers it
what is the antagonistic control of a system?
a system that is antagonistically controlled has several pathways acting on it that have opposing effects
an output signal is produced by…
an efferent neuron or an endocrine cell that secretes a hormone
in an endocrine reflex, the endocrine cell is both…and…
the sensor and the integrating center
down regulation
decrease in receptor numbers
desensitization
reversible receptor modification to diminish response (drug tolerance)
up regulation
increase in receptor numbers
agonist
a competing ligand that triggers a response
antagonist
a competing ligand that blocks the receptor response
how can a signal be terminated
hormone or neurotransmitter
signal breakdown by enzymes (ACh breakdown into acetic acid and choline)
neurotransmitter transport to neighbouring cells (astrocytes)
endocytosis of the ligand-receptor complex
what does NO cause
vasodilation
what tissues does CO2 target
muscle and neural tissue
where is the adrenal gland
one on top of each kindey
what does the adrenal medulla secrete
catecholamines (mostly epinephrine)
what does the adrenal cortex secrete
steroid hormones (aldosterone, glucocorticoids, sex hormones)
the adrenal medulla is composed of
modified sympathetic ganglia
crossover effects
the effect of a structurally similar hormone binding a receptor for another hormone (ex: cortisol binding MR - mineralocorticoid receptors for aldosterone)
