Zusammenfassung der Ressource
The Nervous System
- Sense organs detect stimuli
- A stimulus is a change in your environment
- Light, sound, touch, pressure, chemical or
a change in position or temperature
- Five different sense organs eyes, ears, nose, tongue and skin
- contain different receptors. Receptors are
groups of cells which are sensitive to a
stimulus. They change stimulus energy
(light energy) into electrical impulses
- Sense organs and receptors dont get them
mixed up: The eye is a sense organ - it
contains light receptors. The ear is a sense
organ it contains sound receptors
- The five sense organs and the receptors that each contains:
- Eyes
- Light receptors - sensitive to
light. These cells have a
nucleus, cytoplasm and cell
membrane (just like animal
cells)
- Ears
- Sound receptors - sensitive to
sound. Also "balance" receptors -
sensitive to changes in position
- Nose
- Smell receptors - sensitive to chemical stimuli
- Tongue
- Taste receptors - sensitive to bitter,
salt, sweet and sour, plus the taste of
savoury things like monosodium
glutamate (MSG) - chemical stimuli
- Skin
- Sensitive to touch, pressure, pain and temperature change
- Neurones
- Sensory neurones
- The nerve cells that carry signals
as electrical impulses from the
receptors in the sense organs to
the central nervous system
- Relay neurones
- The nerve cells that carry signals
from sensory neurones to motor
neurones
- Motor neurones
- The nerve cells that carry signals from the
central nervous system to the effector muscles
or glands
- Effectors
- Muscles and glands are known
as effectors - they respond in
different ways. Muscles contract
in response to a nervous impulse,
whereas glands secret hormones
- The central nervous system coordinates a response
- The CNS is where all
the information from the
sense organs is sent and
where reflexes and
actions are coordinated.
This consists of the brain
and spinal cord
- Neurones (nerve cells) transmit the
information (as electrical impulses)
very quickly to and from the CNS
- Instructions from the CNS are sent
to the effectors (musles and
glands) which respond accordingly