Neuronal Signals start as Local Potentials

Question 1

local potentials

Answer 1

local potentials are generated at receptors, synapses where nerve endings synapse with muscles or interneurons

Local potentials can be excitatory or inhibitory

only small changes in voltage

Question 2

generator potentials

Answer 2

stationary depolarization of a receptor that occurs in response to a stimulus and is graded according to its intensity and that results in an action potential when the appropriate threshold is reached aka receptor potenial

Question 3

threshold potential

Answer 3

threshold potential
= voltage needed to activate sodium channels
and active potential

Question 4

synaptic potentials

Answer 4

the difference in voltage between the inside and outside of a postsynaptic neuron. In other words, it is the “incoming” signal of a neuron. Synaptic potential comes in two forms: excitatory and inhibitory.

Question 5

Synaptic transmission = chemical synapses

Answer 5

Receptor/channel combinations determine transmitter effects

Type #1: directly-gated ion channels
- Receptor is part of the ion channel - receptor opens up ion channel which causes depolarization
- Allows fast post-synaptic potentials
eg cardiac muscle is electrically stimulated and
have electrical transmission >receptors open up an ion channel which causes depolarisation

Question 6

membrane potential graph - depolarisation

Answer 6

increase curve in the graph

Excitatory local potential (sodium channel opened and sodium comes in) - GLUTAMATE RELEASESD

Question 7

membrane potential graph - hyperpolarisation

Answer 7

dip in the curve

IF GABA RELEASED = CHLORIDE IONS MOVE IN AND ARE - CHARGED

Question 8

AP

Answer 8

A depolarising local potential triggers action potentials if it reaches the initial segment.

Question 9

Why do we need action potentials?

Answer 9

• local potentials are small and decay over distance -no way they could make it along an axon
• action potentials are self propagated along axons -domino effect

Question 10

Local potentials travel further when:

Answer 10

• leakage increases ie
• radius increases
• myelination
• fewer channels open
• imternal resistance decreases
• large diameter axon

Question 11

denrites

Answer 11

LARGE DENDRITES ALLOW LOCAL POTENTIAL TO FLOW TOWARDS AXON
DENDRITES BECOME LARGER THE MORE YOU USE THEM
Local potentials in thin dendrite are less likely to make it all the way to initial segment