human nervous system

Question 1

what does the human nervous system consist of?

Answer 1

• central nervous system
• peripheral nervous system

Question 2

what does the central nervous system contain?

Answer 2

the brain and the spinal cord

Question 3

what does the peripheral nervous system contain?

Answer 3

all of the nerves in the body

Question 4

what is information sent through the nervous system as?

Answer 4

electrical impulses

Question 5

what are electrical impulses?

Answer 5

electrical signals that pass along nerve cells known as neurones

Question 6

what are neurones?

Answer 6

specialised cells adapted to rapidly carry electrical charges called nerve impulses from one end of the body to the other

Question 7

what is a bundle of neurones known as?

Answer 7

a nerve

Question 8

what does the CNS act as?

Answer 8

a central coordinating centre for the impulses that come in or are sent out to any part of the body

Question 9

what does the CNS coordinate?

Answer 9

all of the nervous responses such as moving or reflexes

Question 10

where are the nucleus and main organelles found in neurones?

Answer 10

in the cell body

Question 11

what are axons and dendrites?

Answer 11

cytoplasmic extensions from this cell body

Question 12

what is the axon?

Answer 12

the main long fibre of the neurone

Question 13

what is the axon insulated by?

Answer 13

a fatty myelin sheath with small insulated sections along its length (called nodes)

Question 14

how does the electrical impulse travel down the axon?

Answer 14

it does not travel down the whole axon- it jumps from one node to the next

Question 15

where do dendrites extend out of?

Answer 15

• the cell body of the neurone
• at the far end of the axon

Question 16

what do the dendrites do?

Answer 16

the neurones can connect to many other neurones and receive impulses from them, forming a network for easy communication

Question 17

what are the 3 main types of neurones?

Answer 17

• sensory
• relay
• motor

Question 18

what do sensory neurones do?

Answer 18

carry impulses from sense organs to the CNS

Question 19

what do relay neurones do?

Answer 19

are found inside the CNS and connect sensory and motor neurones

Question 20

what do motor neurones do?

Answer 20

carry impulses from the CNS to effectors

Question 21

what do sensory neurones look like?

Answer 21

• short
• have a cell body branching off the middle of the axon

Question 22

what do relay neurones look like?

Answer 22

• short
• have a small cell body at one end with many dendrites branching off it

Question 23

what do motor neurones look like?

Answer 23

• long
• have a large cell body at one end with long dendrites branching off it

Question 24

how do impulses pass?

Answer 24

• impulses from receptors pass along sensory neurones until they reach the CNS
• impulses pass to relay neurones in the CNS
• impulse is then passed to effectors along motoe neurones

Question 25

what does the nucleus of a neurone contain?

Answer 25

contains all the genetic information of the cell

Question 26

what is a dendrite?

Answer 26

- tree like projections which connect to different neurones - one neurone can connect to many other neurones

Question 27

what does the cell body in a neurone do?

Answer 27

- the main section of the cell - contains the nucleus

Question 28

what does the axon of a neurone do?

Answer 28

- the long section - electrical impulses travel long distances through the axon

Question 29

what does the myelin sheath do?

Answer 29

- insulates the axon - speeds up the transmission of the impulse

Question 30

where is a synapse formed?

Answer 30

when the dendrites of 2 neurones meet- to make a connection between the neurones

Question 31

what is a synapse?

Answer 31

the point where the axon of one neurone connects with the dendrite of another or an effector- they help coordinate activities and are unidirectional

Question 32

what is at a synapse?

Answer 32

a very small gap between neurones

Question 33

at a synapse what is the small gap between neurones called?

Answer 33

the synaptic cleft or synaptic gap

Question 34

why can electrical impulses not travel directly from one neurone to the next?

Answer 34

- due to the synaptic cleft - electricity cannot jump the gap

Question 35

what is the electrical impulse converted to that can cross the synaptic cleft?

Answer 35

a chemical signal

Question 36

what process do neurotransmitters move by?

Answer 36

diffusion

Question 37

where are receptors that are complementary in shape to neurotransmitters located?

Answer 37

postsynaptic neurone

Question 38

how are electrical impulses passed along synapses?

Answer 38

1) an electrical impulse travels along an axon 2) this triggers the nerve-ending of a neuron to release chemical messengers called neurotransmitters 3) these chemicals diffuse along the synapse and bind with receptor molecules on the membrane of the next neurone 4) the receptor molecules on the 2nd neuron bind only to the specific chemicals released from the first neuron- this stimulates the second neuron to transmit the electrical impulse