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IGCSE Biology > Topic 9 Nervous System > Flashcards

Topic 9 Nervous System Flashcards

1
Q

What is part of the central nervous system?

A

brain and spinal cord and linked to sense organs by nerves

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2
Q

What is a neurone?

A

Nerve cell
Many neurones make a nerve

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3
Q

What is a sensory neurone?

A

Transfers nerve impulses from receptors to CNS

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4
Q

What is a relay neurone?

A

In the CNS, transmits nerve impulses from sensory neurone to motor neurone

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5
Q

What is a motor neurone?

A

Sends nerve impulse from CNS to effector (eg muscle or gland)

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6
Q

What is the function of the cell body?

A

Contains nucleus

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7
Q

What is the function of the dendrons/dendrites?

A

Extensions of cell body which carries nerve impulses towards the cell body

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8
Q

What is the function of the axon?

A

Carries nerve impulses away from the cell body

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9
Q

What is the function of the myelin sheath?

A

Fatty material which insulates cell extensions + speeds rate of transmission of electrical impulses

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10
Q

What is the receptor?

A
  • receptor cell in sense organ detects change + generates nerve impulse -> passes along a sensory neurone into CNS
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11
Q

What is the coordinator?

A

Relay neurones take impulse through spine, brain and transmit to correct neurone

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12
Q

What is the effector?

A

Motor neurone takes impulse out of CNS to correct effector organ (muscles)

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13
Q

What is the response?

A

A reaction that happens eg muscle contraction

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14
Q

What is a reflex action?

A

An involuntary action
Happens automatically + rapidly in response to stimuli

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15
Q

What are the characteristics of a reflex action?

A
  • helps protect body from damage
  • brings about a rapid response by involving few neurones, so few synapses
  • involves brain + spinal cord but not conscious thought
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16
Q

What is the nerve pathway for a voluntary action?

A

Receptor senses stimuli from surroundings

Sensory neurone -> relay neurone in spinal cord

Brain receives impulses from spinal cord + sends out new impulses -> motor neurone -> effector

17
Q

What is the nerve pathway for involuntary action?

A

Receptor senses stimuli from surroundings

Sensory neurone -> relay neurone -> motor neurone -> effector

18
Q

What is a synapse?

A

Gap between two neurones (needs to be crossed to or from CNS)

19
Q

How is a synapse crossed?

A
  1. Electrical signal travels along axon + triggers neurotransmitters in nerve ending of neurone 1 to be released
  2. These diffuse across gap and stimulate neurone 2 to re transmit electrical impulse (they attach to membrane of 2nd neurone)
    Broken down by enzyme once impulse has been transmitted
20
Q

What are the differences between the nervous and endocrine systems?
- signal carried by…
- type of signal….
- speed of signal…
- signal carried in…
- area of response…
- duration of message…

A

N: signal carried by neurones, E: hormones

N: electrical signal, E: chemical signal

N: fast, E: slow

N: signal carried in neurones, E: blood

N: area of response localised, E: widespread

N: duration of message short E: long

21
Q

What is the function of the cornea?

A

Refracts light as it enters eye

22
Q

What is the function of the iris.

A

Controls how much light enters the eye

23
Q

What is the function of the pupil?

A

Allows light to enter eye

24
Q

What is the function of the lense?

A

Refracts light to focus onto retina

25
Q

What is the function of the ciliary muscles?

A

Adjust shape of lense to make it more or less curved
This increases/decreases refraction of light

26
Q

What is the function of the suspenders ligaments?

A

Slacken or stretch as ciliary muscles contract or relax to adjust thickness / curvature of lens

27
Q

What is the function of the retina?

A

Contains light receptors which trigger electrical impulses to send to brain when light is detected
Contains light receptors rods (sensitive to dim light, black and white) cones (colour)

28
Q

What happens to the eye in bright light?

A
  1. Circular muscles contract
  2. Radial muscles relax
  3. Pupil constricts
29
Q

What happens to the eye in dim light?

A
  1. Circular muscles relax
  2. Radial muscles contract
  3. Pupil dilates
30
Q

What happens when focusing on a distant object? (Accommodation reflex)

A
  1. Ciliary muscles relax
  2. Suspenseful ligaments pulled tight
  3. Lens flat
  4. Less refraction
31
Q

What happens when focusing on a nearby object?

A
  1. Ciliary muscles contract
  2. Suspenders ligaments are slack
  3. Lens -> more rounded
  4. More refraction

IGCSE Biology (22 decks)

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