B3.1 - Nervous system

Question 1

What does the nervous system do

Answer 1

• detects change in external environment and sends it to the brain

Question 2

what are the three stages of a nervous response?

Answer 2

1) stimulus (change in environment)
2) sensory detector (detects stimulus)
3) effector (responds to an impulse)

Question 3

how to glands respond to a stimuli?

Answer 3

release hormones

Question 4

where are receptor cells found?

Answer 4

sense organs (eyes, ears, nose, tongue, skin)

Question 5

what do receptor cells do?

Answer 5

change the stimuli to electric impulses to travel along neurone to CNS

Question 6

what is the CNS made of?

Answer 6

brain and spinal cord

Question 7

how is the spinal cord protected?

Answer 7

by the vertebrae column (backbone)

Question 8

what is the stimulus for skin?

Answer 8

pressure, heat

Question 9

what is the role of sensory neurones?

Answer 9

carry electric impulses from receptor cells to CNS

Question 10

what is the role of motor neurones?

Answer 10

carry electric impulses from CNS to effectors

Question 11

what is the nervous system made of?

Answer 11

• brain
• -spinal cord
• neurones

Question 12

what are effectors?

Answer 12

muscles or glands that respond to the change in environment

Question 13

what are synapses?

Answer 13

gaps between neurones which allows nerve impulses to travel

Question 14

how do synapses work? (5)

Answer 14

• electrical impulse reaches the end of neurone
• triggers the release of chemicals called neurotransmitters from vesicles
• neurotransmitters diffuse (move down a concentration gradient) across the synapse.
• neurotransmitters bind to receptors on the next neurone.
• presence of the neurotransmitter causes the production of an electrical impulse in the next neurone.

Question 15

how do reflex actions help?

Answer 15

allow us to respond to dangerous situations rapidly and automatically

Question 16

give three examples of reflex actions

Answer 16

blinking, sneezing, flinching from a hot pan

Question 17

what is a stimulus?

Answer 17

change in the environment to which the body needs to respond

Question 18

describe the response arc

Answer 18

• stimulus detected by a receptor
• sensory neurone carries signal (through impulse) to CNS
• motor neurone carries electrical impulse from the CNS to an effector.
• effector (a muscle or gland) produces the response to the stimulus

Question 19

what can effect human reaction time?

Answer 19

caffeine, exercise

Question 20

what is the role of the brain?

Answer 20

processes all the information collected by body and produces a co-ordinated response

Question 21

medulla

Answer 21

unconscious activities (breathing, heart rate)

Question 22

cerebellum

Answer 22

muscle coordination (posture, balance, speech)

Question 23

cerebral cortex

Answer 23

conscious thought (memory, language)

Question 24

Why is it hard to treat brain damage or problems in the brain?

Answer 24

we don’t understand it enough, easy to make mistake and cause irreversible damage

Question 25

name some of the techniques used in neuroscience (3)

Answer 25

- fMRI - CT scans/electrical stimulation - MRI scanners

Question 26

what are the 4 different ways you can damage your PNS or CNS?

Answer 26

- injury - disease - genetic condition - ingesting a toxic substance (lead)

Question 27

what does damaging the nervous system cause?

Answer 27

prevents impulse being passed through nervous system effectively

Question 28

effects of peripheral nervous system damage? (3)

Answer 28

- inability to detect pain - numbness - lack of co-ordination

Question 29

how can PNS damage be fixed? (2)

Answer 29

- limited ability to regenerate (minor nerve damage reveals), and symptoms gradually decrease - severe nerve damage treated through surgery

Question 30

how can nerve damage be treated through surgery?

Answer 30

sections of nervous tissue can be drafted over damaged tissue (restoring electric conduction path for impulse)

Question 31

can the CNS regenerate

Answer 31

no, unless corrected by surgery

Question 32

why is it difficult to repair the spinal cord?

Answer 32

- 1.5 cm in diameter | - so identifying and repairing damage to an individual nerve fibre without damaging others is difficult

Question 33

why is damage to the interior of the brain difficult to repair?

Answer 33

it is difficult to diagnose, not many different treatments available as hard to test, as may kill person

Question 34

optic nerve

Answer 34

Transmits visual information, in the form of electrical impulses, from the retina to the brain

Question 35

cornea

Answer 35

The transparent frontal portion of the eye responsible for refracting light

Question 36

sclera

Answer 36

The white of the eye; the opaque protective outer layer (all around the eye) - even in a cross-sectional diagram, would see it on outer edge

Question 37

retina

Answer 37

- Packed with receptor cells - sensitive to both the brightness - colour of light

Question 38

pupil

Answer 38

A hole in the centre of the iris through which light passes to get to the retina

Question 39

iris

Answer 39

controls pupil dilation and therefore quantity of light reaching retina

Question 40

ciliary muscles

Answer 40

- ring of smooth muscle | - change shape of lens (to focus light)

Question 41

suspensory ligaments

Answer 41

- ring of fibres, connect ciliary muscle to lens

Question 42

what is the process of changing lens shape in order to focus on an object at its distance from the eye changes?

Answer 42

accommodation

Question 43

What happens when our eyes focus on a distant object?

Answer 43

- minor refraction of light rays - ciliary muscles relax - lens become flatter and thinner - suspensory ligaments tighten

Question 44

what controls how our eyes adapt to different light levels?

Answer 44

iris

Question 45

what is hyperopia, and treatment?

Answer 45

- longsightedness - lens too thin - eyeball too short - light ends up behind retina - convex lens (fat one)

Question 46

what is myopia and treatment?

Answer 46

- short sightedness - lens too thick - eyeball too long - light in front of retina - concave lens (inwards),

Question 47

what causes colour blindness?

Answer 47

- defects in the photoreceptors

Question 48

focusing on a close object?

Answer 48

contraction of the ciliary muscles and loosening of the suspensory ligaments.

Question 49

focusing on a far object?

Answer 49

loosening of the ciliary muscles and contraction of the suspensory ligaments.

Question 50

as people get older, the lens in the eye becomes less flexible and cannot change shape easily. This means they cannot focus clearly on near objects. Explain why.

Answer 50

- lens cannot become fat | - light is focused behind retina

Question 51

what is a CT scan and what does it show?

Answer 51

- computed tomography - uses X-rays to create 3D images of inside of body - but cannot be used regularly (X-rays can cause cancers) - only show still images

Question 52

what is MRI scanning and how does it work? (3)

Answer 52

- magnetic resonance imaging - use powerful magnets to identify brain abnormalities - see which areas of brain are active

Question 53

what is fMRI scanning and how does it work?

Answer 53

- functional magnetic resonance imaging - produces images in real time by sending magnetic radiation - radiation bounces back and can see the properties/density of tissue ie. whether it is oxygenated or not - areas are active when increased blood flow during a specific activity

Question 54

how does electrical stimulation work?

Answer 54

- electrodes places inside animal/human brains | - electrodes transmit electrical impulses + result in movement

Question 55

draw a neurone out | label with - nucleus, cell body, axon, dendrites

Answer 55

nucleus - little circle cell body - area around little circle axon - the body - long bit dendrites - sticky out bits around cell body

Question 55

what does the cerebrum control?

Answer 55

complex behaviour (memory/learning/personality/conscious thought)