human nervous system Flashcards

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1
Q

what does the human nervous system consist of?

A
  • central nervous system
  • peripheral nervous system
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2
Q

what does the central nervous system contain?

A

the brain and the spinal cord

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3
Q

what does the peripheral nervous system contain?

A

all of the nerves in the body

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4
Q

what is information sent through the nervous system as?

A

electrical impulses

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5
Q

what are electrical impulses?

A

electrical signals that pass along nerve cells known as neurones

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6
Q

what are neurones?

A

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

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7
Q

what is a bundle of neurones known as?

A

a nerve

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8
Q

what does the CNS act as?

A

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

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9
Q

what does the CNS coordinate?

A

all of the nervous responses such as moving or reflexes

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10
Q

where are the nucleus and main organelles found in neurones?

A

in the cell body

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11
Q

what are axons and dendrites?

A

cytoplasmic extensions from this cell body

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12
Q

what is the axon?

A

the main long fibre of the neurone

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13
Q

what is the axon insulated by?

A

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

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14
Q

how does the electrical impulse travel down the axon?

A

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

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15
Q

where do dendrites extend out of?

A
  • the cell body of the neurone
  • at the far end of the axon
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16
Q

what do the dendrites do?

A

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

17
Q

what are the 3 main types of neurones?

A
  • sensory
  • relay
  • motor
18
Q

what do sensory neurones do?

A

carry impulses from sense organs to the CNS

19
Q

what do relay neurones do?

A

are found inside the CNS and connect sensory and motor neurones

20
Q

what do motor neurones do?

A

carry impulses from the CNS to effectors

21
Q

what do sensory neurones look like?

A
  • short
  • have a cell body branching off the middle of the axon
22
Q

what do relay neurones look like?

A
  • short
  • have a small cell body at one end with many dendrites branching off it
23
Q

what do motor neurones look like?

A
  • long
  • have a large cell body at one end with long dendrites branching off it
24
Q

how do impulses pass?

A
  • 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
25
Q

what does the nucleus of a neurone contain?

A

contains all the genetic information of the cell

26
Q

what is a dendrite?

A
  • tree like projections which connect to different neurones
  • one neurone can connect to many other neurones
27
Q

what does the cell body in a neurone do?

A
  • the main section of the cell
  • contains the nucleus
28
Q

what does the axon of a neurone do?

A
  • the long section
  • electrical impulses travel long distances through the axon
29
Q

what does the myelin sheath do?

A
  • insulates the axon
  • speeds up the transmission of the impulse
30
Q

where is a synapse formed?

A

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

31
Q

what is a synapse?

A

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

32
Q

what is at a synapse?

A

a very small gap between neurones

33
Q

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

A

the synaptic cleft or synaptic gap

34
Q

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

A
  • due to the synaptic cleft
  • electricity cannot jump the gap
35
Q

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

A

a chemical signal

36
Q

what process do neurotransmitters move by?

A

diffusion

37
Q

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

A

postsynaptic neurone

38
Q

how are electrical impulses passed along synapses?

A

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