Neurones

Question 1

Why can receptors be considered transducers?

Answer 1

They convert one type of energy into an electrical impulse

Question 2

What is the charge of the inside and outside of a neurone?

Answer 2

Inside negative

Outside positive

Question 3

What is the resting potential of a neurone?

Answer 3

-70mV

Question 4

Draw a Pancinian Corpuscle

Answer 4

Sensory neurone with connecting tissue (lamellae)

Question 5

Explain how pressure on a Pancian C, causes an action potential

Answer 5

1. The shape of the corpuscle is changed
2. Causing Stretch mediated sodium channels in the neurone membrane to open
3. Sodium ions diffuse into the concentration gradient
4. Depolarising the membrane
5. Called a generator potential
6. The greater the pressure the more stretch mediated channels open causing a bigger generator potential
7. If threshold is reached an action potential develops and is transmitted along the neurone

Question 6

When is a action potential triggered?

Answer 6

When the generator potential reaches the threshold

Question 7

Explain adaptation in neurones?

Answer 7

When pressure is first applied impulses are transmitted along the neurone
With continuous pressure the frequency of the action potentials decreases, and then after a while may stop altogether
It prevents the nervous system from being overloaded with insignificant information

Question 8

What piece of equipment could be used to measure potential difference

Answer 8

Voltmeter

Question 9

Explain how testing potential is established and maintained

Answer 9

1. There is a higher concentration of sodium ions on the outside than on the inside and a higher concentration of potassium ions on the inside than the outside of the axon
2. The membrane is relatively impermeable to both K and Na but is less permeable to NA so more K diffuse out than Na in
3. This means there are more positive ions outside the membrane and the membrane is said to be “polarised”
4. The resting potential is maintained by the SODIUM POTASSIUM PUMP which pumps 3 Na out and pumps 2 K ions in

Question 10

What happens when a neurone is stimulated? (Simple)

Answer 10

A nerve impulse starts when the resting potential across the neurone membrane is converted into an action potential

Question 11

Draw a graph to correctly demonstrate how a membrane is stimulated

Answer 11

Include generater potential and restin and action, label with depolarisation and depolarisation and hyperpolarisation

Question 12

Explain how a neurone is depolarised

Answer 12

1. During an action potential, one section is depolarised
2. This depolarisation of one section of membrane causes local currents
3. These currents cause the voltage sensitive sodium ion channels to open, increasing the permeability if the membrane to sodium ions so causing depolarisation leading to the development of an action potential
4. The nerve impulse can only travel in one direction due to the hyperpolarisaton of the membrane

Question 13

Explain Saltatory conduction

Answer 13

In a myelinated nerve the depolarisation/ action potential jumps from node to node
The effect of the myelin sheath is to speed up conduction
Typical speed of conduction is 100ms-1

Question 14

What are the two nervous systems

Explain what they are

Answer 14

Nerves carry impulses to and from the rest of the body (Peripheral Nervous system)
Central Nervous system consisting of the brain and the spinal cord

Question 15

What do the Somatic Nervous system and the Autonomic Nervous System control?

Answer 15

Controls conscious actions like walking (somatic)

Controls unconscious actions like altering heart rate (autonomic)

Question 16

Draw a brain label parts of the brain

Answer 16

Should have 
Cerebrum
Hypothalamus 
Pituitary Gland 
Medulla 
Cerebellum 
Spinal Cord 
Corpus Collosum

Question 17

Functions of Pituitary gland

Answer 17

Controlled by the hypothalamus, this region releases hormones to stimulate other glands. This region is the connection between the nervous system and the hormonal system

Question 18

Cerebellum function

Answer 18

Has folded cortex and is underneath the cerebrum. It is responsible for muscle contraction, posture and balance

Question 19

Medulla oblongta function

Answer 19

Found at base of the brain and at the top of the spinal cord. Responsible for the automatic control of heart rate and breathing

Question 20

Hypothalamus function

Answer 20

Found in middle of the brain, it is responsible for temperature regulation and produces hormones that influence the pituitary gland

Question 21

Cerebrum function

Answer 21

Divided into two hemispheres and has a thin, folded outer layer, it is involved in hearing, learning, and thinking

Question 22

Draw a sensory neurone

Answer 22

Axon terminals
Axon 
Cell body in middle 
Dendron 
Dentrites

Question 23

Draw motor neurone 
Cell body with dendrites 
Axon 
Axon terminals 
With myelin sheath

Answer 23

Cell body with dendrites
Axon
Axon terminals
With myelin sheath

Question 24

Draw relay neurone

Answer 24

Cell body in middle

Question 25

State some structural and functional difference between motor neurone and sensory

Answer 25

Motor neurone 
Longer axon 
No dendron 
Cell body is at one end of the neurone 
Cell body is in the brain 
Cell body has dendrites 
Carries nerve impulses away from the spinal cord 
Carries nerve impulse to effectors 
(Make comparison points with sensory neurone)

Question 26

Draw a Schwann cell

Write a paragraph about it

Answer 26

Circle with snake around it
Schwann cell wraps itself around the axon
Myelin is composed of lipid and protein and has electrical insulating properties

Question 27

What is a reflex

Answer 27

A reflex is a rapid, involuntary, automatic response to a particular stimulus
Involuntary / no conscious decision to respond

Question 28

Explain what a spinal reflex is

Explain what a cranial reflex is

Answer 28

A fast automatic involuntary unlearned response to a stimulus
Coordinated by neurones passing to and from the spinal cord (spinal)
A fast automatic involuntary unlearned response to a stimulus
Coordinated by neurones to and from the brain

Question 29

Describe how the blinking reflex is coordinated in response to a puff of air into the eye

Answer 29

1. Stimulus is detected by sensory receptors, around the eyelids
2. If stimulus is above threshold
3. Impulses are transmitted to the brain I sensory neurones
4. Synapse between sensory neurones and relay neurones in the brain
5. Synapse between relay neurones and motor neurones in the brain
6. Impulses are transmitted from the brain in motor neurones
7. To effectors in eyelids which contract to lower eyelid
8. Impulses travel from the brain to both eyelids so that both respond