Nerves (from LOs)

Question 1

Define sensory receptor

Answer 1

Specialised cells that detect changes in our surroundings/ energy trasducers.

Question 2

Define polarised membrane

Answer 2

A membrane with a potential difference across it.

Question 3

Define depolarised membrane

Answer 3

When the potential difference has changed so that the inside of the cell is less negative compared to the outside.

Question 4

Define generator potential

Answer 4

A small depolarisation caused by sodium ions entering the cell.

Question 5

Was the energy transformation for a light receptor?

Answer 5

Light to electrical

Question 6

What’s the energy transformation for sound receptors?

Answer 6

Kinetic to electrical

Question 7

What is the energy transformation that occurs for olfactory receptors?

Answer 7

Chemical to electrical

Question 8

What is the energy transformation that occurs for taste receptors?

Answer 8

Chemical to electrical

Question 9

What is the energy transformation that occurs for pressure receptors?

Answer 9

Kinetic to electrical

Question 10

What is the energy transformation that occurs in pressure sensors?

Answer 10

Kinetic to electrical

Question 11

Explain how a membrane becomes polarised

Answer 11

Sodium potassium pump;
Actively transporting;
3 sodium ions out of the cell and 2 potassium ions into the cell;
Potassium ions diffuse out but sodium ions do not diffuse in
As the more permeable to potassium ions than sodium ions (sodium channels gated/ closed)

Question 12

Describe how a sensory receptor converts a stimulus into a nerve impulse.

Answer 12

When stimulus occurs, gated sodium channels open;
Sodium ions diffuse into cell;
Generator potential;
Above threshold value (-50mV) voltage gated sodium channels open
Many sodium ions diffuse in
Membrane depolarises to = 40mV
Action potential initiated.

Question 13

State the relationship between the size of the stimulus and the number of gated channels which open

Answer 13

The larger the stimulus, the more sodium channels open

Question 14

Define neurone

Answer 14

A nerve cell

Question 15

Define nerve

Answer 15

Tissue that consists of neurones

Question 16

Define CNS

Answer 16

The brain and spinal cord. Has overall control over the coordination of the nervous system.

Question 17

State the function of a sensory neurone

Answer 17

Carry the action potential from a sensory receptor to the CNS

Question 18

State the function of a motor neurone

Answer 18

Carry an action potential from the CNS to an effector such as a muscle or gland

Question 19

State the function of a relay neurone

Answer 19

Connect sensory and motor neurones

Question 20

Where is the cell body positioned in a sensory neurone?

Answer 20

Just outside CNS

Question 21

Where is the cell body positioned in a relay neurone?

Answer 21

Inside CNS

Question 22

Where is the cell body positioned in a motor neurone?

Answer 22

Inside CNS

Question 23

Does a sensory neurone have a myelin sheath?

Answer 23

Yes (most)

Question 24

Does a relay neurone have a myelin sheath?

Answer 24

No

Question 25

Does a motor neurone have a myelin sheath?

Answer 25

Yes ( most)

Question 26

What structure carries impulses to the cell body?

Answer 26

Dendrites/ dendron

Question 27

What is the structure that carries impulses away from the cell body?

Answer 27

Axon

Question 28

What is the length of dendron in sensory neurones?

Answer 28

Long singule dendron from receptor to cell body. Dendrites at end of axon.