BIOL 2160 chapter 5

chemical signaling

direct communication is through ____ _______

gap junctions

a ____ is a protein channel that connects 2 cells in a gap junction

connexon

indirect communication is via ____ _______

chemical messengers

direct communication is good for ____ distance only and is very ____

short distance, fast

during indirect communication, a secretory cell releases a chemical messenger that binds to a receptor on a ____ ______

target cell

______ signaling involves 2 cells that are very close to each other but not touching

paracrine

_____ signaling is similar to paracrine signaling but the secretory cells will always be a nueron

neurotransmitter

in neurotransmitter signalling the target cell will be another ____, _____, or _____ and is very ______.

neuron, gland, or muscle, fast

_______ singaling involves a hormone being released into the bloodstream

endocrineen

endocrine signaling is good for ____ distances and is very ____ to take effect

long, slow

Paracrines, neurotrasmitters, and hormones are ____ that bind to receptors

ligands

is the endocrine messenger is ____ it will dissolve in the bloodstream

hydrophillic

the ____ ___ _______ determines where the receptor is found on the target cell

type of messenger

_____ _______ molecules such as steriods or hormones will bind on receptors inside of the cell

nonpolar signal

the receptor for ____ messegeners will be on the outside of the plasma membrane on a target cell

polar

receptor affinity is based on ____ and affinity is based on _____/______

shape, strength/charge

receptor activation depends on _____ of _____, adding more ligand increases liklihood that ligand will bind to receptor, once all receptors are bound adding more ligands will not have any effect

concentration of ligand

receptor activation depends on _______ ______ of receptors, adding more receptors will increase the chance of a ligand attaching

expression of receptors

receptor activation depends on _____ __ ______ ____ ______, increase the attraction, more likely for binding

affinity of receptor for ligand

how can the number of receptors change?

receptor synthesis or receptor turnover

______ means receptor synthesis is happening more quickly, ________ means receptor synthesis is happenign more slowly

upregulation, downregulation

usually the number of receptors is _________ the number of lignad. if there is more ligand the cell will _____________, if there is less ligand there will be _________________.

similar to, make extra receptors, less receptors made by the cell.

addictive drugs are __________ that bind ot receptors already in the body

artificial ligands

binding of an addictive drug to the receptors in the body activates a network of dopaminergic cells in the mesolimbic region of the brain that is involved in ______________, produces excessive ______. this is a _________________.

emotional reward, dopamine, postitive feedback mechanism

_____ are painkillers such as codeine, morphine, oxycodone, oxycontin, and heroin

opiates

opiates activate natural ________________ for endorphins in the brain. endorphin concetration is usually extremely ____.

G-protein coupled receptors, low

______ help with minor pain

endorphins

opiates in the body bind to ALL endorphin receptors which triggers receptor _______ and _____ because we arent supposed to be pain free

turnover and downregulation

____________ occurs from functional uncoupling of G-protein receptors to their effector molecule, this is what leads to people taking more opiates and becoming addicted

desensitization

nicotine has an extremly high affinity for _____ receptors and outcompetes ________ for these receptors

acetylcholine, acetylcholine

to combat nicotine, the cells that need acetylcholine for signalling respond by making more _____ and releasing more ______. this leads to addiction becuase you need more nicotine to get the same effect

receptors, acetylcholine

nicotine is also extremely addictive becuase your body gets better at breaking it down before it reaches the receptors, nicotine ________ _______ ______ for __________________.

upregulates cellular mechanisms for degrading the drug

_______ intolerance is the result of lower concetrations of a drug actually reaching the receptor, caused by degradation (opiates) or increased metabolism of the drug (nicotine)

pharmacokinetic

_________ tolerance is the cellular mechanism that results in receptor downregulation/turnover (opiates) or upregulation (nicotine)

pharmacodynamic

why is nicotine more addictive than heroine

nicotine results in both pharmacokinetic and pharmacodynamic tolerances, opiates are only pharmacokinetic

______ are lignads that bind to a receptor and cause a biological response, a normal physiological response

agonist

_____ is a ligand that bind to receptors and do not cause a biological response and may block a ____ from binding, descreasing cellular response

antagonist, agonist

______ ________ refers to intracellular mechanisms that mediate the response of target cells to the chemical messenger

signal transduction

_______ ______ are intracellular messengers produced by the binding of an extracellular messenger, carries the signal to the nucleus

second messengers

second messengers are not needed for ______/_______ messengers because they can cross the membrane and get to the nucleus

hydrophobic/lipophillic

______ messenger binds to a receptor directly in the cytoplasm or enters the nucleus directly - both produce the same response, the cell increases _____ / ______

lipophillic, gene expression/protein synthesis

in order for a receptor on the membrane to have an effect on the cell it has to be connected to some sort of pathway _______, ________or ________

fast linked ion channel, enzyme linked, or g-protein linked

in a ____________ ion channnel, when the ligand binds, the channel opens and allows ions to cross, the cellular response is ________________.

fast linked ion channel, changing the membrane potential of the cell.

calcium, sodium, chloride, and potassium cross the cell membrane through _____________.

fast linked ion channels

when a receptor is ________ linked, it is connected to the production of a second messenger, epecially _______

enzyme, kinase

_____ is an enzyme that adds a phosphate group to another protein and activates that protein

kinase

when the ligand binds to the enzyme linked receptor, it causes two more receptors to come together to form a ______, called ________. thsi activates the kinase which __________ many proteins in the cell that produce some effect in the cell

dimer, dimerization, phosphorylates

the receptor can be linked to ______ which are small intracellular proteins that link receptors with effector proteins

g-proteins

receptors linked to g-proteins are called __________ aka __________

g-protein coupled receptors, GPCRs

_____________ proteins bridge the gap between the receptor nad another protein inside the cell that does something

effector

the effector protein will either be an __________ or ____________ that produces a second messenger

ion channel or enzyme

effector proteins have three subunits _____, __________ and _________, and 3 types __________, _________, and ______

alpha, beta, and gamma; ion channel regulating, enzyme inhibiting, and enzyme stimulating

g-proteins are referred to as _________________ turned off or turned on depending on what the g-protein is attached to

molecular switches

when the g-protein is bound to _____ it can bind to the effector protein

GTP

for g-protein to turn off, it breaks down GTP to _____ and it cannot bind to the effector protein

GDP

g-protein linked __________ can open and close and do this _________ to stay open longer

ion channels, slowly

______________ channels can only be opened

fast ligand gated

when the effector protein is not an ion channel it is an ______ that controls the production of second messengers 

enzyme

the 5 major second messenger pathways regulated by g-proteins are _______, _______, _______, _____, and ______

cAMP, cGMP, IP3, DAG, and calcium