the sensory system · sensory & motor neurons •carry messages from sense organs to the brain...
TRANSCRIPT
The Sensory System
Ms Rochford
Third Year Science
In this topic
• What does sensory system do?
• Our senses
• Central nervous system
• Motor and sensory neurons
• Responding to a stimulus
• The eye
How do we know something is living? Characteristics of living things:
1. Nutrition 3. Excretion
4. Growth
2. Respiration
5. Reproduction 6. Movement
7. Response
What does the sensory system do?
Response: the ability of an organism to gather information and respond to it
We have 5 senses
Sense Sense Organ
Sight Eyes
Hearing Ears
Smell Nose
Touch Skin
Taste Tongue
Central Nervous System • Made of the brain and spinal cord
• Brain
– Contains millions of nerve cells
– Neurons = nerve cells
• Spinal cord
– Contains neurons that carry messages to and from the brain
• The body’s neurons run to and from the central nervous system
Sense organs & Central Nervous System
• Neurons carry messages using electrical impulses
• Travel from sense organs to the brain
• Brain makes sense of the signal and responds
• It sends a signal to a muscle or group of muscles.
Sensory & Motor Neurons
• Carry messages from sense organs to the brain or central nervous system
1. Sensory Neurons
• Carry messages away from the brain or central nervous system to a muscle.
• Cause us to respond
2. Motor Neurons
Stimulus activates sense organ
Sensory neurons carry message
Brain
Sends message using motor
neurons
Muscle (s)
The Eye
Parts of the Eye
• Coloured part of eye
• Controls amount of light entering the eye
• Contracts let light in, expands to keep light out
Iris
Pupil
• Black circle in the eye
• Allows light into the eye
Parts of the Eye
• Flexible structure behind the iris
• Changes shape, depending on where we look
• Focuses light on the retina
Lens
Retina
• Light sensitive layer at back of eye
• Absorbs light which lets us see
Parts of the Eye
• Carries messages from eye to brain
Optic nerve
Cornea
• Transparent section of eye covering
• Allows light to pass into the eye
Ciliary muscle
• Contracts or relaxes to control the lens