The nervous system

Cards (27)

  • What does the human nervous system consist of?
    The central nervous system (CNS) and the peripheral nervous system.
  • What is in the central nervous system? (CNS)
    The brain and the spinal cord
  • What is the peripheral nervous system?
    Nerve cells that carry information to and from the CNS
  • What are nerves?
    Bundles of neurones.
  • What are neurones?
    Long cells which carry electrical impulse signals.
  • What is a synapse?

    A gap where 2 neurones meet.
  • How are electrical impulses passed?
    Chemically.
  • What are sense organs?
    Group of receptor cells (specialised) which produce electrical impulses.
  • What is the stimulus for skin?
    Temperature, pressure and pain.
  • What is the stimulus for tongue?
    Chemicals in the mouth.
  • What is the stimulus for nose?
    Chemicals in the air.
  • What is the stimulus for eye?
    Light.
  • What is the stimulus for ear?
    Sound.
  • What are effectors?

    Parts of the body, like glands/ muscles which produce a response to a detected stimulus.
  • What are 3 examples of effectors?
    1. A muscle contracting to move an arm
    2. A muscle contracting to alter pupil size
    3. a gland releasing a hormone into the blood.
  • What are the main stages in a reflex arc?
    1. Stimulus
    2. Receptor cells
    3. Electrical impulse along sensory neurone
    4. Synapse
    5. Relay neurone
    6. Synapse
    7. Motor neurone
    8. Effector
    9. Response
  • What is a reflex action?

    Usually protective, involuntary and fast.
  • What doesn’t a reflex response need?
    The brain- instead the spinal cord coordinates the response so that the electrical impulse can reach the effector quickly
  • How is light entering the eye controlled?
    By a reflex response through the muscles in the Iris. It changes in response to bright or dim light
  • What does the cornea?
    Clear part of sclera, refracts light
  • What does the lens do?
    Focuses light onto the retina
  • What does the optic nerve do?

    Carries impulses between retina and the brain
  • What is the sclera?
    White, tough, protective layer
  • What does the choroid do?
    Pigmented middle layer, absorbs light to avoid reflection
  • What is The blind spot?
    Where the optic nerve leaves the retina and lacks receptor cells
  • What is the pupil?
    A small hole at the centre of the iris, where light enters eye
  • How might reaction time be affected?

    Age and if the person has had stimulants (e.g caffeine)