Zusammenfassung der Ressource
The Nervous System
- Sense organs
- Detect stimuli
- Change in environment which you may need
to react to
- Eyes
- Light receptors
- Cells have a nucleus, cytoplasm
and cell membrane
- Ears
- Sound receptor
- Balance receptors - sensitive to
changes in position
- Nose
- Smell receptors - sensitive
to chemical stimuli
- Tongue
- Taste receptors
- Sensitive to bitter, salt, sweet, sour
and savoury - chemical stimuli
- Skin
- Sensitive to touch,
pressure, pain and
temperature change
- Central nervous system
- Sensory neurones
- Nerve cells carry signals
as electrical impulses
from the receptors in the
sense organs to the CNS
- Motor neurone
- Nerve cells carry signals
from the CNS to the
effector muscles or glands
- Relay neurones
- Nerve cells carry signals
from sensory neurones to
motor neurones
- Effector
- Muscles and glands
- Muscles contract in response
to a nerve impulse
- Glands secrete hormones
- Where all the information
from sense organs are sent
and where reflexes and
actions are coordinated
- Neurones transmit
information as electrical
impulses quickly to and
from the CNS
- Instructions
from CNS are
sent to effectors
which respond
- Brain and spinal cord only
- Synapses
- Connection between
two neurones
- Nerve signal is transferred by
chemicals which diffuse
across the gap
- Reflexes
- Prevent injury
- Automatic responses to certain stimuli
- Eg. bright lights make your
pupils automatically get
smaller for less light to enter
- Reflex arc
- Stimulus is
detected by
receptors,
impulses are
sent along a
sensory neurone
to the CNS
- When impulses reach a
synapse between the
sensory and a relay,
they trigger chemicals
to be released - these
cause impusles to be
sent along the relay
- When impulses reach
a synapse between
the relay and motor,
chemicals are
released and impulses
are sent along the
motor
- Impulses travel along the
motor to the effector
- Muscle then contracts