b10 - the nervous system

Question 1

homeostasis

Answer 1

the maintenance of a stable internal environment in response to changes in environment

Question 2

stimulus

Answer 2

a change in your environment that may require a response

Question 3

examples of stimuli

Answer 3

• temperature
• light
• sound
• chemical
• position
• pain
• pressure
• touch

Question 4

receptors

Answer 4

special cells that detect changes in the internal or external environment

Question 5

coordination centres

Answer 5

• areas that receive and process information from the receptors
• they then send out signals to coordinate the response of the body

Question 6

what does the CNS consist of?

Answer 6

the brain and the spinal cord

Question 7

effectors

Answer 7

• muscle or gland that carries out the response to the stimulus
• the response will restore the conditions to their optimum levels

Question 8

what does the human control system contain?

Answer 8

• receptors
• coordination centres
• effectors

Question 9

what is the purpose of the central nervous system?

Answer 9

enables humans to react to their surroundings and to coordinate their behaviour

Question 10

process of the body responding to stimuli

Answer 10

stimulus > receptor generates impulse after detecting a change in the environment > sensory neurone conducts impulses to spinal cord (CNS) > passes synapses between neurones > chemical stimulates

Question 11

why does homeostasis take place?

Answer 11

• an optimum environment is maintained to prevent the denaturing of enzymes
• denaturing reduces the enzyme’s ability to catalyse metabolic reactions

Question 12

which internal conditions need to be regulated?

Answer 12

• blood sugar
• water levels
• carbon dioxide levels
• urea conc (in urine)
• internal body temperature

Question 13

which type of neurone carries impulses to the central nervous system?

Answer 13

sensory neurone

Question 14

which type of neurone carries the impulses away from the central nervous system

Answer 14

motor neurone

Question 15

one factor that may affect reaction time

Answer 15

energy drinks/caffeine/exercise

Question 16

reflex actions

Answer 16

automatic and rapid reactions that do not require conscious parts of the brain

Question 17

where is the relay neurone found in the reflex arc?

Answer 17

spinal cord

Question 18

reflex pathway

Answer 18

stimulus > receptor > sensory neurone > relay neurone > motor neurone > effector > response

Question 19

synapses

Answer 19

the physical gap between neurones

Question 20

how is information passed through the synapse

Answer 20

via neurotransmitters

Question 21

neurotransmitters

Answer 21

chemicals that are released which travel through the synapse and bind to the receptor cells in the next neurone

Question 22

cerebral cortex

Answer 22

region in the brain which controls conscious activity, intelligence, memory and language

Question 23

cerebellum

Answer 23

region that co-ordinates muscle activity and balance

Question 24

medulla

Answer 24

region that controls automatic, unconscious activity

Question 25

name a method that scientists use to find out the functions of each part of the brain

Answer 25

- studying brain damage patients - use of electrical impulses to stimulate the brain - MRI scans

Question 26

function of the sclera

Answer 26

white outer layer to protect the eyeball

Question 27

function of the cornea

Answer 27

- transparent area at the front of the eyeball - allows light into the eye and then refracts/focuses it

Question 28

function of the iris

Answer 28

- controls the size of the pupil - can contract and relax to change the size of the pupil so as to control the amount of light focused on the retina

Question 29

hypothalamus

Answer 29

coordination centre in the brain

Question 30

pituitary gland

Answer 30

produces many different hormones (like ADH), which play a big part in coordinating and controlling body systems

Question 31

advantages of MRI

Answer 31

- non invasive - doesn't use ionic radiation - produces detailed images of the nervous system

Question 32

disadvantages of MRI

Answer 32

- claustrophobia - requires you to be in a small space for a long period of time - takes a while to acquire results - expensive

Question 33

lens

Answer 33

- held in place by the ciliary muscles and suspensory ligaments - fine tunes the focus of the light on the retina to produce a clear image

Question 34

function of the retina

Answer 34

filled with receptor cells which are sensitive to both the brightness and the colour of the light

Question 35

two main types of light receptor cells

Answer 35

rods and cones

Question 36

rods

Answer 36

sensitive to light intensity

Question 37

cones

Answer 37

produce colour vision

Question 38

what do the light sensitive cells do?

Answer 38

they send impulses to the brain along sensory neurones in the optic nerve

Question 39

optic nerve

Answer 39

sends impulses between the eye and the brain

Question 40

process of light being focused

Answer 40

light > cornea > bent onto the lens > falls on the retina > the light is focused by the process of refraction by the cornea

Question 41

process of the refraction of light

Answer 41

light refracted by the cornea and lens > cornea always refracts the same amount of light > the shape of the lens change to alter the amount of refraction > contraction of the ciliary muscles

Question 42

what happens to the pupils in bright light?

Answer 42

it constricts (becomes smaller) so as to limit the amount of light that enters the eye

Question 43

what happens to the pupil in dim light/darkness?

Answer 43

it dilates (becomes much bigger) because it needs to take in as much light as possible

Question 44

suspensory ligaments

Answer 44

a ring of fibres that connect the ciliary muscles to the lens

Question 45

ciliary muscles

Answer 45

a ring of smooth muscle that changes the shape of the lens to focus light

Question 46

pupil

Answer 46

a hole in the centre of the iris through which light passes to reach the retina

Question 47

accommodation

Answer 47

the process of the lens changing shape to focus on an object as its distance from the eye changes - this is done by the ciliary muscles and the suspensory ligaments

Question 48

focusing on a close object

Answer 48

- contraction of the ciliary muscles - loosening of the suspensory ligaments - causing the lens to become rounder and thicker - results in significant refraction

Question 49

focusing on a far object

Answer 49

- relaxation of the ciliary muscles - tightening of the suspensory ligaments - lens becomes flatter and thinner - results in less refraction

Question 50

hyperopia

Answer 50

long-sightedness - rays of light focus BEHIND the retina

Question 51

myopia

Answer 51

short-sightedness - rays of light focus IN FRONT of the retina

Question 52

reasons for myopia happening

Answer 52

lens too curved, long eyeball

Question 53

treatment options for myopia and hyperopia

Answer 53

contact lenses/laser eye surgery/glasses