A&P test 3

excitable cell

a cell with a plasma membrane that can hold a charge and propagate electrical signals

neurons

type of excitable cell, when they excite, they transmit electrical impulses

muscle cells

type of excitable cell, when they excite, they contract and produce force

all excitable membrane maintains a ____ resting membrane potential

non zero

neurons resting membrane potential

-70 mV

muscle cells resting membrane potential

-90 mV

efflux

going outside of the cell

influx

going inside the cell

K+ permeability at rest

relatively high K+ efflux through leak channels

Na+ permeability at rest

relatively low Na+ influx

Cl- permeability at rest

moderate influx

protein permeability at rest

proteins are too large to diffuse through membrane

nernest equation

calculates equilibrium potential

goldman-hodgkin-katz (GHK) equation

accounts for concentration gradient of nernest equation and selective permeability of membrane

gradients (do/don’t) change

gradients do NOT change (physiological assumption)

soma

cell body of neuron

dendrites

receiving end of neuron, graded potential

axon

conduct to transmit signals across distance, action potentials, part of neuron

terminal

part of neuron, convert electrical signal into chemical signal, release neurotransmitters

action potential

repeatable pattern of changing membrane voltage, all or nothing, when given electrical stimulus is applied and Vm reaches threshold this is generated

when does K+ efflux through leak channel

always

Na+ VG channel during resting membrane potential:

is closed (activation is closed and inactivation is open)

VG K+ channel during resting membrane potential

is closed

permeability and charge at resting membrane potential

Pk+ > Pna+, negative Vm (positive efflux)

VG Na+ channel at depolarization

open, both gates are open, Na+ influx

VG K+ channel at depolarization

is slowly opening, efflux is negligible