Lecture 5

Question 1

What is it called when an ion channel event results in an increase in sodium conductance

Answer 1

Its called an excitatory local potential, where the intermediate regions voltage is altered, in this case to a more positive level. This will spread both ways out from the initial

Question 2

Describe local potentials

Answer 2

Small in comparison to AP (just a few mV). Graded rather than an all or nothing approach. Localised/non-conducted. They decrease in size as they spread and are capable of summation.

either excitatory or inhibitory

Question 3

How do local potentials spread if they aren’t propagated

Answer 3

they passively spread, dissipating exponentially with the distance it makes being determined by the properties of the cell. This is also known as electrotonic spread

Question 4

What are the 2 ways that local potentials can undergo summation

Answer 4

Summation in time(if the signals happen after one another) and summation in space(If they happen in close proximity

Question 5

Where do local potentials arise

Answer 5

Synapses, on the dendrites and the cell bodies of the neurons and at the sites of sensory reception such as the nerve endings of unipolar neurons in the skin and in internal organs

Question 6

What causes local potentials

Answer 6

The opening of ion channels, both mechanical and chemical