Nervous system Flashcards

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1
Q

What is the nervous system made up of

A
  • Central nervous system
  • Peripheral nervous system
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2
Q

What is the central nervous system

A
  • Consists of brain and spinal cord
  • Functions as a coordination centre that processes information
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3
Q

What is the myelin sheath

A
  • Covers most long fibres
  • Insulates nerve fibres
  • Increases transmission speed of nerve impulses
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4
Q

What is a dendron

A
  • Transmits nerve impulses towards neurone cell body
  • End branches are called dendrites
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5
Q

What is an axon

A
  • Transmits nerve impulses away from neurone cell body
  • End branches are called axon terminals
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6
Q

What are the Nodes of Ranvier

A

Regions where myelin sheath is absent

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7
Q

What happens when nerve impulses reach the axon terminals

A
  • Neurones are not physically attached to receiving cells
  • There is a gap between a neurone and effector called the synapse
  • Neurotransmitter is released into the synapse when nerve impulses reach the axon terminals
  • Activity of receiving cells is altered
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8
Q

Describe the structure and function of the sensory neurone

A
  • Circular cell body
  • Long dendron, short axon
  • Dendron and cell body outside CNS, axon inside CNS
    Functions: Transmit nerve impulses from receptors to CNS
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9
Q

Describe the structure and function of the motor neurone

A
  • Irregular cell body
  • Long axon, dendrites
  • Cell body and dendrites inside CNS, axon outside CNS
    Functions: Transmit nerve impulses from relay neurone to effector
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10
Q

Describe the structure and function of the relay neurone

A
  • Circular or irregular cell body
  • Whole neurone inside CNS
    Functions: Transmit nerve impulses from sensory neurone to motor neurone or to another relay neurone
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11
Q

Define a reflex

A

A reflex is any immediate response to a specific stimulus that occurs without any conscious effort

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12
Q

Define a simple reflex

A

Simple reflexes are built-in, unlearned responses, and they have protective functions

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12
Q

Define a reflex arc

A

A reflex arc is the shortest pathway by which impulses travel from the receptor to the effector

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13
Q

Define a conditioned reflex

A

Conditioned reflexes are acquired from past experiences of learning with a stimulus which was originally not effective in producing a response

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14
Q

What are the types of simple reflexes

A

Spinal reflex
- Spinal cord is reflex centre

Cranial reflex
- Brain is reflex centre

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15
Q

How does withdrawal reflex occur

A
  • Stimulus stimulates pain receptor on finger, generating nerve impulses
  • Nerve impulses travel along sensory neurone to spinal cord
  • Neurotransmitters released across synapse between sensory and relay neurone
  • Nerve impulses flow along relay neurone to motor neurone
  • Neurotransmitters released across synapse between relay and motor neurone
  • Nerve impulses leave the spinal cord along the motor neurone to the effector
  • Effector is bicep muscles, which contract to cause withdrawal action
16
Q

Which neurones have myelin sheath

A

Motor
Sensory