A&P CH11 PT3

What membrane potential must generally be met in order to achieve threshold?

-55 mV

Salatory conduction occurs when

Myelin sheath is present

The presence of a synaptic cleft between cells is characteristic of __________.

chemical synapse

Voltage-gated sodium channels have both an activation gate and a(n) ________ gate.

inactivation gate

Which statement best describes the all or none principle

An action potential happens completely, or it doesn't happen at all.

The majority of synapses in the nervous system are

Chemical

During repolarization of a neuron

Returns to a negative state/resting membrane potential

Repolarization begins as

Sodium channels close and potassium opens

What happens when Voltage gated sodium channels are activated

Sodium ions enter and depolarization happens

During the absolute refractory period

no stimulus of any strength will trigger a new action potential

A neuron that receives neurotransmitter from another neuron is called

postsynaptic neuron

Action potential order

Top to bottom 4,2,5,1,3 1.)Local potential depolarizes the axolemma of a trigger zone to threshold 2.) voltage gated sodium ions enter and axon section depolarizes 3.) sodium channels inactivate and voltage gated potassium ions active are. Sodium stops entering and potassium leave, beg reploarization 4.) sodium returns to resting state and repolarization continues 5.) as postassium ion channels return to resting state, axolemma May hyperpolarize b4 re but to resting membrane pot

Which type of fiber has the largest diameter?

Type A

Determine the fiber type in which propagation of an action potential will occur most quickly.

Type A myelinated

When is the generation of an action potential impossible, no matter the strength of the stimulus?

absolute refractory period

What is more likely to promote an action potential?

depolarization