Neuro Ch5

what is the function of the nervous system

to produce and conduct electrochemical impulses in response to changes in ext and int environment

what gives neuron its electrical properties

its neural membrane

composed of lipids and proteins
critical for comms

of the neural membrane

what is the lipid bilayer

surrounds cell and separates cytoplasm from ECF

hydrophilic heads hydrophobic tails

of the neural membrane

what are intrinsic proteins

receptor and ion channel proteins within the membrane

gives neuron necessary properties for signaling

of the neural membrane

what kind of membrane is it

selectively permeable

of the neural membrane

what results from the membrane’s selective permeability

polarization

difference in electrical charge between inside and outside of cell

of the semipermeable membrane

what is the force of diffusion

ion flow from high to low concentration, along the concentration gradient

of the semipermeable membrane

what is electrostatic pressure

ion flow towards oppositely charged areas, electrical gradient

what is the resting potential

the difference in charge between the inside and outside of the membrane of a neuron at rest

typicall -65 mV

neuronal membranes are not permeable to what

big negatively charged proteins (anions)

neuronal membranes are selectively permeable to what

K+, freely enter and exit

what is the flow of K+ into the neuron

at rest, K+ flows into the negative cell, after it builds up it diffuses out

what are leak channels

ion channel proteins that stay open all the time

what are gated channels and what do they open and close in response to

ion channels

voltage changes (voltage-gated)
molecules binding (ligand-gated)
mechanical action

what are ion pumps

proteins that allow ions to pass membrane but require energy

what is the resting membrane potential caused by

the unequal distribution of ions on either side of the membrane

outside has mostly Na+ and CL-
inside is mostly K+ and organic anions

the membrane is slightly permeable to what so it slowly leaks in

Na+

what does the sodium potassium pump do

pumps 3 Na+ out and 2 K+ in to maintain resting potential

As graded potentials spread across the membrane, they do what

diminish like ripples in water

neurons can receive excitatory or inhibitory signals at the input zone, what do these mean and what are they called

excitatory- depolarize to get closer to threshold

inhibitory - hyperpolarize to get further away from threshold

these are graded potentials - action potential occurs if combo of graded exceed threshold

once the membrane reaches threshold and triggers action potential what happens to the cell

inside of cell becomes briefly positive

what is the all or none property of the action potential

neuron fires are full power or not at all

with increased stimulus strength, what happens to action potential

they increase in frequency

step by step of action potential

where do graded and action potentials occur

dendrites and soma are graded

hillock is where action potential occurs

step by step of action potential

at the axon hillock, what happens after the initial depolarization

Voltage-gated Na+ channels open to allow Na+ in then more and more open

step by step of action potential

what happens after all the Na+ channels open to let Na+ in

membrane potential hits +40 mV then the Na+ gates close

step by step of action potential

Once the inside of the cell becomes more positive due to the Na+ influx, what happens next

K+ channels open to let K+ out of the cell

what is the absolute refractory period

no more action potentials can be produced

what is the relative refractory period

only a strong stimulus can action potential

stronger than normal

what is the inactivation gate

“deadbolt” of the Na+ channel during the absolute refractory period

Myelin does what

increases conduction speed

1 m/s to over 120m/s

what is saltatory conduction

the action potential along the axon jumps from node of ranvier to node