The Senses Senses in Animals Survival Used for

The Senses

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

• 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

• 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

• 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

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

• 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

• 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

• 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

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

• 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

• 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

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

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

The Skin • 2 different layers for the skin – The epidermis –outside – The Dermis—inner part – 5 nerve cell types • • • Pain Pleasure Touch Heat Cold

• 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