The Senses

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The Senses

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• Senses in Animals
• Survival
• Used for survival to tell animals what is going
  on around them
• Sense organs
• Ears, nose, tongue, skin, eyes

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• Senses in Animals
• Planarian
• Lives in ponds, rivers, and lakes
• 2 sense organs
• Knobs used for detecting water currents
• Eyespots only able to tell light from dark

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• Senses in Animals
• Earthworms
• -light detectors
• -located just below the skin
• - Cricket
• Detects sound from the front of the leg
• Antennas detect feeling
• Uses a compound eye for seeing

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• Senses in Animals
• Snake
• Snakes eyes are similar to human eyes
• Snakes use their tongue to smell
• They shoot their tongue out and it catches air
  molecules
• They bring the air back into its mouth , where
  the sense of smell organ is located

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Human Sense Organs

• The Eye
• Path of light through the eye
• Sclera
• Iris
• Pupil
• Cornea
• Lens
• Retina
• Vitreous humor

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• The eye
• Light passes and bends first through the cornea
• Then light passes through the pupil and the lens
• The light bends again in the lens towards each
  other
• Light then passes through the vitreous humor
• The vitreous humor is clear. The light finally
  reaches the retina

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• The retina is made up of rods and cones
• Rods detect motion and light or dark
• Cones detect color
• Cones are nerve cells that detect color
• There are three types of cones, each type detects
  only one color-----red, green, or blue
• All the other colors are cones acting together

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• The optic nerve
• Carries the message from the eye to the vision
• Center of the brain
• 2 things happen at the vision center
• The brain interprets the message
• The image is rotated right-side up

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The Ear

• 3 parts
• Outer, Middle, Inner
• Outer Ear
• The only part that is visible of the entire ear
• The ear flap helps direct the sound waves into
  the ear
• Sound waves travel through the ear canal and bump
  against the ear drum

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• Middle Ear
• The vibration of the sound waves cause the anvil,
  hammer, and the stirrup to move
• The stirrup is also connected to a membrane that
  vibrates with the motion of the ear bones

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• Inner ear
• The cochlea contains nerve cells that are
  connected to the auditory nerve
• The auditory nerve takes the message to the brain
  to be interpreted
• Semicircular Cells
• Nothing to do with hearing
• Helps maintain balance

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The Tongue

• The tongue contains taste buds that detect taste
• They detect the chemical molecules in food
• 4 different types
• Sour
• Salty
• Sweet
• bitter

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The Nose

• Detects gas molecules in the air
• Neurons line the top of the nasal chamber
• There are 7 different types of nerve cells in the
  nose that detect a different odor
• The olfactory nerve takes messages to your brain
  and the cerebrum interprets the message

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The Skin

• 2 different layers for the skin
• The epidermis outside
• The Dermisinner part
• 5 nerve cell types
• Pain
• Pleasure
• Touch
• Heat
• Cold

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• Most nerve cells are found in the dermis
• But both the epidermis and the dermis share the
  pain cell
• From the skin, the nerve cells travel to the
  cerebrum to be interpreted
• They are perceived as cold, hot pain, pleasure,
  or touch