Equilibrium, AP, Synapses Flashcards by Rachel Leigh

Homeostatic control has 3 components:

receptor, control center, effector

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what kind of solutes easily pass thru membrane

small hydrophobic

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hydrophilic solutes must cross membrane thru:

channels or pores

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conductance

permeability, depends on probability gate is open

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diffusion potential

generated by diffusion of ions

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equilibrium potential

diffusion potential that balances tendency for diffusion down [ ] grad

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electrochemical equilibrium

chemical and electrical driving forces on ion are equal and opposite

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membrane potential

intracellular potential relative to extracellular

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nernst equation will

convert a [ ] difference for ion into voltage

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inside of a cell is more +/- ?

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driving force

what is the charge separation (mem pot) at rest? and where would they like to be if allowed to flow freely?

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ionic current

movement of ions across membrane

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ions move thru channels when: (2)

1) ion has a driving force
2) membrane has conductance (channels open)

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resting membrane potential

about -70 mV

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which are excitable cells

nerve and muscle

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depolarization

process of making mem pot more positive

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hyperpolarization

process of making mem pot more negative

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inward current

flow of (+) charges into cell

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outward current

flow of (+) charge out of cell

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does inward current depol or hyperpol the cell?

depolarize

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does outward current depol or hyperpol the cell?

hyperpolarizes

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threshold potential

mem pot where an action potential is inevitable

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value of threshold potential

-55 mV

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overshoot

portion of AP where mem pot is (+)… goes above where it needs to

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undershoot (hyperpolarizing afterpotential)

portion of AP where mem pot is more(-) than at rest

refractory period

period where another AP cannot occur, absolute or relative... ions are in wrong places

lidocaine blocks...

Na+ channels, no AP...no sensation

at rest, activation gate is (open/closed) and inactivation gate is (open/closed)

idk help

absolute refractory period

entire duration of AP, another AP cannot occur, VG Na channel inactivation gate is closed

relative refractory period

overlaps w period of hyperpol, begins at end of absolute RP, AP can be generated only by a greater than usual depol current

accomodation

depolarization occurs too slowly for AP, Na inact gate stay closed, not enough open Na channels

axon is (good/poor) conductor of charge?

poor, is leaky to ions... AP continuously regenerated

conduction velocity is increased by (2)

1) incr nerve diameter 2) myelination

myelin is composed of

schwann cells

bare patches on the axon

nodes of ranvier, have ion channels

saltatory conduction

AP jumps from node to node

what ion is mediator of synaptic release

Ca2+

what kind of receptor do neurotransmitters often bind to on postsynaptic cell

chemically gated ion channels

what facilitates reuptake of NT

astrocytes or axon terminals

what facilitates degradation of NT

enzymes

ACh formed from

acetyl CoA and choline via enzyme choline acetyltransferase

types of synaptic arrangements (3)

one-to-one one-to-many (uncommon) many-to-one (common in brain)

synaptic fatigue

repeated stimulation causes smaller than normal response in postsynaptic cell, depletion of NT storage

only NT released at neuromuscular junction

Ach

choline acetyltransferase

combines choline + acetyltransferase = Ach

acetylcholinesterase

degrades Ach

dopamine beta-hydroxylase

converts dopamine into norepi

(PMNT) phenylethanolamine-N-methyltransferase

converts norepi into epi

catechol-O-methyltransferase (COMT)

degrades biogenic amines

monoamine oxidase (MAO)

degrades biogenic amines

COMT and MAO

common targets for behavioral meds

where can histamine be found

neurons of hypothalamus and mast cells

4 subtypes of glutamate

3- ionotropic (ligand-gated ion chan)... NMDA receptor 1- metabotropic (G-protein coupled chan)

GABA A receptor

ionotropic, directly linked to Cl- channel... hyperpolarizes targetted by benzos and barbiturates

GABA B receptor

metabotropic and coupled via G protein to K+ channel... hyperpolarizes huntington disease

only NT that is a gas

nitric oxide

neuropeptides may function as

neuromodulator, neurohormone, neurotransmitter

2 methods of release of neuromodulators

a) co-secreted w NT b) volume-transmission

purines

ATP and adenosine

ion channels

permit selective flow of ions across impermeable membranes

ionic disequilibrium

creates potential energy across membranes

synapses

spaces between 2 cells that allow for regulated release of substances to elicit physiologic response

neurotransmitters

diverse group of chemicals that act as chemical messengers... can stimulate APs (excitatory) or inhibit APs (inhibitory)