Topic 2 – Cells and Control-The Nervous System

Question 1

What is the central nervous system?

Answer 1

Brain and spinal cord

Question 2

what is the spinal cord?

Answer 2

long thin structure, composed of neurones that extend from medulla oblongata down spine

Question 3

what is function of spinal cord?

Answer 3

connects peripheral nervous system to brain

Question 4

describe structure of brain

Answer 4

consists of 3 main regions:
cerebrum
cerebellum
medulla oblongata

Question 5

describe structure of cerebrum?

Answer 5

largest region of brain

divided into 2 hemispheres

Question 6

what is function of cerebrum?

Answer 6

intelligence
language
memory
emotion
visual and sensory processes

Question 7

what is function of left hemisphere?

Answer 7

receives sensory information from right side of body, controls muscle coordination on right

Question 8

what is function of right hemisphere?

Answer 8

receives sensory information from left side of body, controls muscle coordination on left

Question 9

where is cerebellum located?

Answer 9

lower region of brain

Question 10

what is function of cerebellum?

Answer 10

involved in:
coordination of muscles
voluntary movement e.g. walking
non-voluntary movement e.g. balance

Question 11

what is function of medulla oblongata?

Answer 11

controls automatic processes in body e.g. breathing rate, heart rate, peristalsis

Question 12

what methods are used by doctors to observe brain?

Answer 12

CT scan

PET scan

Question 13

what is CT scan?

Answer 13

procedure that uses X-rays to produce 3D cross sectional image of brain

Question 14

describe how CT scans are useful to investigate brain function?

Answer 14

CT scans show damaged regions of brain e.g. areas of swelling bleeding
observations of patient symptoms can enable scientists to determine function of damaged region

Question 15

what does a PET scan

Answer 15

radioactive substance injected into patient bloodstream, taken up by tissues in brain
radiation emitted by tissues, enabling identification of active and inactive regions of brain

Question 16

describe how PET scans are useful to investigate brain function

Answer 16

show which areas of brain are active and not
comparisons of brain activity in healthy patients, and patient with brain damage, allow to determine functions of inactive regions.

Question 17

why is it difficult to treat damage to CNS?

Answer 17

damage to neurons is permanent and cannot be repaired
hard to reach some areas in brain
risk of permanent damage to other areas of CNS during surgery

Question 18

what is function of nervous system?

Answer 18

allows organism to rapidly react to environmental and internal changes

Question 19

what are neurones?

Answer 19

nerve cells adapted to quickly transmit nerve impulses, they are functional units of the nervous system.

Question 20

what is function of axon?

Answer 20

carry impulse away from cell body

enable transmission of nerve impulse over long distance

Question 21

what is function of dendrites and dendrons?

Answer 21

carry impulse towards cell body

dendrites provide large surface area to receive impulses

Question 22

what is role of myelin sheath?

Answer 22

electrically insulating layer

surrounds axon and increases speed of impulses

Question 23

outline function of sensory neurone

Answer 23

carry impulse from receptors to CNS

Question 24

describe structure of sensory neurone

Answer 24

long dendron carry impulse from receptors to cell body
cell body found part way along neurones
short axon carry impulse from cell body to CNS

Question 25

outline function of motor neurone

Answer 25

carry impulse from central nervous system to effectors

Question 26

describe structure of motor neurone

Answer 26

short dendrites carry impulse from CNS to cell body
cell body found at one end of neurones
long axons carry impulses from cell body to effectors

Question 27

outline function of relay neurone

Answer 27

carry impulse from sensory neurones to motor neurones within CNS

Question 28

describe structure of relay neurone?

Answer 28

short dendrites carry impulse from sensory neurone to cell body
short axon carry impulses from cell body to motor neurones

Question 29

describe how the CNS coordinates a response to stimulus?

Answer 29

1: stimulus
2: sensory receptor detect stimulus
3: sensory receptor sends impulse along sensory neurone to CNS
4: CNS coordinates response
5: CNS sends information to effector along motor neurone
6: effector produces response to stimulus

Question 30

what is a synapse?

Answer 30

small gap between neurones across which nerve impulse is transmitted via neurotransmitters.

Question 31

how are nerve impulses transmitted across synapse?

Answer 31

nerve impulse reaches presynaptic neurone
triggers release of neurotransmitters
bind to receptors on postsynaptic neurone
stimulates impulse in postsynaptic neurone

Question 32

why do synapses slow down transmission of nerve impulses?

Answer 32

takes time for neurotransmitters to diffuse across synapse and bind to receptors on postsynaptic neurone

Question 33

what is a reflex?

Answer 33

automatic response to a stimulus by body
involuntary-does not involve conscious part of brain
protective mechanism e.g a withdrawal reflex is intimated when hot object touched to prevent burns

Question 34

describe reflex arc

Answer 34

Stimuli → sensory receptor → sensory neurone → relay neurone → motor neurone → effector → response