5.1 The Nervous System

Question 1

Why do animals need to be sensitive to their environment?

Answer 1

To detect food
To escape predators
To find a mate

Question 2

Receptors

Answer 2

Use specific receptors found in sense organs
They are transducers of energy—meaning they convert one form of energy into another (in the form of electric impulses)
Information is then processed by coordination centres and an effector will bring about a suitable response

Question 3

Effectors and response

Answer 3

Muscle: contract, e.g to move skeleton, change pupil size
Gland: secrete a substance, e.g sweat, saliva

Question 4

Different neurones

Answer 4

Sensory: has myelin sheath, very long axon, connected to receptors, peripheral nervous system
Relay: super small, tiny axon, no myelin, central nervous system
Motor: connected to muscle, long axon, myelin sheath, peripheral nervous system

Question 5

Central nervous system:

Answer 5

Receives huge amounts of information from all the sensory organs in your body via sensory neurones

CNS acts as the coordinator in the nervous system and determines the appropriate response to this sensory information, by sending impulses out along motor neurones to the effectors

Question 6

Reflex arc

Answer 6

Silly rabbits sometimes chew my ears! Really sore

Stimulus
Receptors
Sensory neuron
Coordinator
Motor neurone
Effector
Response
Synapses

Do not involve conscious part of the brain
Brain is made aware of every reflex action

Question 7

Synapses

Answer 7

Minute gap between neurones

1. An impulse arrives at the pre-synaptic neurone’s nerve ending
2. Causes a neurotransmitter (a chemical) to be released into the synapses
3. This diffuses across and binds to receptors on the post-synaptic neurone
4. This triggers and electrical impulse in the post-synaptic neurone

Question 8

BI: RP7: reaction time
Equipment

Answer 8

30 cm ruler
Chair
Table

Question 9

BI: RP7: reaction time
Method

Answer 9

2. Work with a partner to do this test. Choose who will be person 1 and Who will be person 2.
3. Each of you should use your dominant hand to do this experiment. if you are right-handed then your dominant hand is your right hand.
4. Person 1 sits down on the chair, with good upright posture and eyes looking across the room.
5. Person 1 puts the forearm of their dominant arm across the table with their hand overhanging the edge.
6. Person 2 holds a ruler vertically with the bottom end (the end with the 0 cm mark) in between person 1’s thumb and first finger.
7. Person 1 catches the ruler with their thumb and first finger as quickly as possible when Person 2
   drops it.
8. Record the number on the ruler that is level with the top of person 1’s thumb
9. Have a short rest, then repeat several times. Swap over and repeat.
10. Record your results in a suitable table. Use the conversion chart to convert ruler measurements into reaction time.

Question 10

Cerebral cortex

Answer 10

The big part of the brain

Conscious thought, decision making, language, sensory processing

Question 11

Cerebellum

Answer 11

The lil peanut shape at the bottom right

Motor learning

Question 12

Medulla

Answer 12

The long thing at the bottom going down next to the cerebellum

Breathing, heart rate

Question 13

Hypothalamus

Answer 13

The tiny section in the middle of the brain kind of between the cerebral cortex and the medulla

Temp regulation, appetite, sexual drive

Question 14

Pituitary gland

Answer 14

A little pebble thing hanging off the end of the hypothalamus
Releases hormones: TSH, FSH, LH, ADH

Question 15

Phineas Gage

Answer 15

Iron rod was blown through his skull—> personality changed
Prefrontal cortex damaged

Question 16

Electrical stimulation of the brain

Answer 16

Remove top of the skull
Stimulate different areas of the brain and see what effect it has on the subject, done when conscious
Brain has no pain receptors

Question 17

Eye—function: sclera

Answer 17

White outer layer of eye

Question 18

Eye—function: cornea

Answer 18

Transparent area in the front of the sclera

Question 19

Eye—function: iris

Answer 19

coloured part of the eye which controls the size of the pupil

Question 20

Eye—function: pupil

Answer 20

The hole through which light enters the eye

Question 21

Eye—function: lens

Answer 21

Clear disc that changes the direction of light rays to focus them

Question 22

Eye—function: suspensory ligaments

Answer 22

Attach the lens to the ciliary muscle

Question 23

Eye—function: ciliary muscle

Answer 23

Changes the shape of the lens through contraction/relaxation

Question 24

How the eye works

Answer 24

Light from an object passes through the cornea and the jelly in the eyeball, which changes the direction of the light rays (rafraction).
The light then passes through the lens, which focuses the light rays on the retina
Image formed upside down
Light sensitive cells in the retina send impulses along sensory neurones (found in the optic nerve) to the brain
Point where optic leaves the eye = blind spot

Question 25

Circular muscle and radial muscle in bright light vs dim light

Answer 25

Bright light:
Circular contract, radial relax
Pupil size contracts
Protects the retina from damage by decreasing the light entering

Dim light:
Circular relax, radial contract
Pupil dilates
Allows better vision by increasing light entering the eye