B3.1 The nervous system

Question 1

What does the nervous system do?

Answer 1

detect + respond to changes in environment

Question 2

what is the nervous system needed for?

Answer 2

move, communicate, control internal processes + carry out higher order functions like memory + thinking

Question 3

what are neurones?

Answer 3

Specialised nerve cells which transmit electrical impulses around the nervous system

Question 4

What does the CNS contain?

Answer 4

Central nervous system - brain + spine

Question 5

How is the CNS linked to the rest of the body?

Answer 5

by neurones of the PNS (peripheral nervous system)

Question 6

What is a stimulus?

Answer 6

a change in the environment

Question 7

What do receptors do?

Answer 7

detect the stimulus

Question 8

what dies the CNS do?

Answer 8

co-ordinates how and where impulses are transmitted next

Question 9

What are the effectors?

Answer 9

muscles or glands

Question 10

What is the response?

Answer 10

a reaction to stimulus carried out by the effector

Question 11

5 main stages leading to a nervous response?

Answer 11

Stimulus –> Receptors –> CNS –> Effectors –> Response

Question 12

Draw a sensory neurone

Question 13

what are reflexes?

Answer 13

involuntary responses that occur without conscious thought - don’t have control over these responses

Question 14

are reflexes fast?

Answer 14

very fast - 0.2 seconds - need to be fast to protect us from harm

Question 15

What is a reflex arc?

Answer 15

pathway taken by the impulse during a reflex action

Question 16

describe the reflex arc when you tough something hot

Answer 16

1. Stimulus - touching hot pan
2. Receptor - temp receptors in skin
3. Sensory neurone
4. Spinal cord
5. motor neurone
6. Effector - bicep muscle contracts
7. Response - hand pulled away

Question 17

What is a synapse?

Answer 17

the gap between 2 neurones

Question 18

What happens in the synapse?

Answer 18

• elec impulses cant travel through
• chemicals (neurotransmitters) diffuse across the gap - diffusion across a synapse is sower than transmission of a nerve impulse along a neurone

Question 19

what is the iris responsible?

Answer 19

controlling size of pupil + therefore amount of light falling on retina

Question 20

where does light pass in the eye?

Answer 20

refracted by cornea and then through pupil to retina

• too much light = damage to light sensitive cells on retina
• too little light = not enough stimulus to cells

Question 21

What is the antagonistic muscle pair in the iris?

Answer 21

circular + radial

- bright light = smaller pupil - circular contracted, radial relaxed - lets less light in

Question 22

lens power (in eye) =

Answer 22

1 / focal length (m)

Question 23

what does the cerebrum do?

Answer 23

controls complex higher level functions - learning, memory, behaviour, conscious thought - lobes coordinates diff sensory + motor info

Question 24

what does the cerebellum do? (little brain!)

Answer 24

controls posture + balance - coordinates learned + fine movements

Question 25

what does the medulla do?

Answer 25

contains control centres for automatic processes - e.g. HR + breathing

Question 26

what does the hypothalamus do?

Answer 26

regulates body temp + water balance (homeostasis)

Question 27

what does the pituitary gland do?

Answer 27

stores + releases important hormones

Question 28

what does the corpus callosum do?

Answer 28

connects cerebral hemispheres to allow left + right brain to communicate

Question 29

Imaging techniques - CT & MRI

Answer 29

- CT - computed tomography - MRI - magnetic resonance imaging - provide real times images throughout brain

Question 30

CT scans

Answer 30

uses x-rays to create 3d images of inside brain + detect abnormalities - cant be done regularly - x-rays increase cancer risk

Question 31

MRI scans

Answer 31

use powerful magnets to identify abnormalities | - can identify areas of brain which are active during specific activities

Question 32

limitations of investigating brain function

Answer 32

- same area could be used for multiple functions - often many areas of brain are involved in a specific function - ethical issues - testing - patients must give consent for medical info to be shared - getting large enough sample of case studies to draw reliable conclusions

Question 33

label a motor neurone

Question 34

label a relay neurone

Question 35

label a sensory neurone

Question 36

draw a motor neurone

Question 37

draw a relay neurone

Question 38

label a picture of the eye

Question 39

label a picture of the brain

Question 40

`when focusing on near objects does the light need to be refracted more or less?

Answer 40

more

Question 41

what is accommodation in the eye?

Answer 41

Ability to change focal length of the lens by changing the curvature of the eye lens

Question 42

accommodation - distant object

Answer 42

ciliary muscle relaxed suspensory ligament tight lens pulled thin

Question 43

accommodation - near object

Answer 43

ciliary muscle contracts suspensory ligament slackens lens allowed to thicken

Question 44

Short sightedness - CAN see short

Answer 44

- eye cant focus on distant object - incorrect image forms in front of retina - because eyeball is too long OR lens is too powerful - ciliary muscles cant make lens thin enough to focus

Question 45

How do you correct short sightedness?

Answer 45

concave lens - bend light out before enter the eye

Question 46

Long sightedness - CAN see long

Answer 46

- eye cant focus on nearby objects - incorrect image is formed behind retina - eye lens cant thicken enough to focus on image on retina - caused by lens being too weak / eyeball being too short

Question 47

How do you correct long sightedness?

Answer 47

convex lens - bends light rays inwards before they enter the eye

Question 48

what are the two types of receptor cells in the eye?

Answer 48

rods and cones

Question 49

what do rods do?

Answer 49

respond to different light intensities - more sensitive to light than cones - help give good vision in low light

Question 50

what do cones do?

Answer 50

respond to different colours (wavelengths of light) - work best in relatively bright light

Question 51

What does the PNS consist of?

Answer 51

motor and sensory neurones

Question 52

damage to PNS neurones result in what?

Answer 52

- inability / reduced ability to detect pain - lack of 'feeling' - numbness - loss coordination of actions

Question 53

damage to the CNS result in what?

Answer 53

more severe - loss of control of body systems - partial or complete paralysis - memory loss - processing difficulties

Question 54

treating the PNS

Answer 54

- PNS neurones have some ability to repair themselves - damaged neurones often regenerate from the cell body end of neurone forming new axons - slow process - symptoms gradually fade overtime - severe cases - use nervous tissue skin grafts