receptors and neurones

Question 1

what is an action potential

Answer 1

a nerve impulse

Question 2

what are the 3 types of neurones

Answer 2

1) sensory neurones
2) motor neurones
3) relay neurones

Question 3

what does a sensory neurone do

Answer 3

transmits nerve impulses from receptors to the CNS( the brain and spinal cord)

Question 4

what does a motor neurone do

Answer 4

transmits nerve impulses from CNS to effectors

Question 5

what does a relay neurone do

Answer 5

transmits nerve impulses between sensory and motor neurones

Question 6

what type of energy does a sensory receptor convert a stimulus into?

Answer 6

Electrical energy

sensory receptors act as transducers as they convert one energy from into another

Question 7

what is the potential difference when the cell is resting

Answer 7

resting potential

Question 8

what happens when a stimulus is detected:

Answer 8

• The cell membrane is excited and becomes more permeable, allowing more ions to move in and out of the cell which changes the potential difference.

Question 9

what potential is it ,when there is a change in potential difference due to stimulus

Answer 9

Generator potential:

greater stimulus= more permeable membrane as it gets more excited

this means bigger movement of ions which= bigger change in potential difference

WHICH MEANS GREATER GENERATOR POTENTIALPRODUCED

IF generator potential is big enough, an action potential is fired along the neurone, but its only fired if the generator potential reaches a certain level called threshold.

Question 10

what carries nerve impulses towards the cell body

Answer 10

The dendrites and dendrons

Question 11

what carries nerve impulses away from the cell body

Answer 11

axons

Question 12

Direction of impulse in a sensory neurone:

Answer 12

They have short dendrites and one long dendron
that carry nerve impulses from receptor cells to the cell body.

They have one short axon that carries nerve impulses from the cell body to the CNS.

Question 13

are motor neurones mylinated or non-mylinated

Answer 13

non-mylinated

Question 14

Direction of impulse in a motor neurone

Answer 14

motor neurones have dendrites that carry nerve impulses from the CNS to the cell body

There is one axon that carries nerve impulses from the cell body to the effector cells

Question 15

Direction of impulse in a relay neurone

Answer 15

Relay neurones have many short dendrites that carry nerve impulses from sensory neurones to the cell body

Then the axon carries nerve impulses from the cell body to the motor neurones

Question 16

when is the outside of the cell membrane positively charged

Answer 16

When the neurone is in its resting state

As there are more positive ions outside the cell than inside the cell

Question 17

what is the voltage of the membrane at resting potential

Answer 17

-70mV

Question 18

what does the sodium potassium pump do to the charge of the membrane

Answer 18

• Is found in the membrane of a neurone

Creates a resting potential and maintains it

Question 19

sodium potassium pumps… ( Na+) ACTIVE TRANSPORT

Answer 19

pump sodium ions out of the neurone
- sodium ions cant diffuse back into the neurone as the membrane isn’t permeable.

THIS CREATES a sodium ion electrochemical gradient

Question 20

sodium potassium pumps…(K+) FACILLITATED DIFFUSION

Answer 20

Pumps potassium ions into the neurone,
HOWEVER membrane of the neurone is permeable,

• so potassium ions diffuse back OUT through the potassium ion channel

which makes the outside of the cell more positively charged.