nerve/mm/cell communication Flashcards
(42 cards)
what is endocrine signaling? example?
source of the signal is distant from the target, signal travels in blood, insulin
what is paracrine signaling?
cells release signals that affect neighboring cells
examples of paracrine signaling (2)
1- vascular endothelial cells secrete vasodilators and vasoconstrictors that act on the neighboring smooth muscle
2- tumor derived growth factors bind nearby epithelial cells to trigger blood vessel formation
what is juxtracrine signaling? example?
cells in very close proximity or direct contact, glial cells guiding axons during nervous system development
what is autocrine signaling?
cell responds to a signal that it has generated
what is an example of autocrine signaling?
stimulation of the EGFR receptor leads to increased levels of VEF, VEGF leaves the cell and binds to different receptors on the same cell
what is intracrine signaling? what type of receptor is required?
cell responds to a signal that it generated without the signal leaving the cell, intracellular receptor is required
what is an example of intracrine signaling?
estrogen-like molecules enter cell and encounter enzymes in the cell that change the molecules into signals that active receptors inside the cell
what are the 4 basic steps of signal transduction
signal released
signal binds receptor
transduction
response
what are ligand gated ion channels?
ligand binds to receptor causing a conformational change that opens or closes the ion channel
describe the GABA receptor
GABA is an inhibitory neurotransmitter, when GABA binds to GABA receptors, it opens Cl- channel, Cl- enters the cell and hyperpolarizes
describe IP3
IP3 binds IP3 channel on SER in smooth muscle, this allows Ca to leave SER and enter cytoplasm
describe RyR
RyR is on SER, when activated it causes release of Ca from RER to increase cytosolic Ca
describe K(ATP)
K(ATP) channel is inhibited when ATP binds, this leads to depolarization that allows for Ca release, that causes insulin release from b-cells
what is the neurotransmitter in skeletal muscle?
acetylcholine
what receptors do ACh bind on skeletal muscle?
nicotinic ACh receptors
describe what happens when ACh binds nicotinic receptors on skeletal muscle
ACh binds nicotinic receptors, this opens the Na channels in the receptor and Na flows into cell causing depolarization, wave of depolarization travels on membrane to T-tubule where it contacts DHP receptor, DHP receptor is activated and it activates RyR-1 receptor (which is physically linked) and RyR-1 opens to release Ca from SER, Ca binds to troponin-C allowing for the myosin-binding sites on actin to be exposed
3 general ways that signal termination occurs with ligand-gated ion channels
inactivation of receptors, inactivation of ion channels and membrane transporters (like SERCA)
describe the basic structure of a G-protein receptor
7 membrane spanning domains, g protein with 3 subunits (a,b,y)
describe general action of g-protein linked receptor
signal binds to G-protein receptor on membrane, G-protein receptor activated G-protein by GDP –> GTP, activated G-protein dissociates from receptor, a-GTP and By subunits dissociate, a-GTP and By subunits associate with effectors, a-catalyzed hydrolysis of GTP–>gdp inactivates a and promotes reassembly of aBy trimer
what is the neurotransmitter and receptor for GaS?
epinephrine and B-adrenergic receptor
explain the steps of GaS
epinephrine binds to B-adrenergic receptor
receptor is activated and it exchanges GDP–GTP to activate G-protein
G-protein interactions with adenylyl cyclase (effector)
activated adenylyl cyclase forms cAMP from ATP
increased cAMP levels activate protein kinase A
what is the “effector” in GaS?
adenylyl cyclase
what is the 2nd messenger in GaS?
cAMP
