1. Wake up! It’s Time to Learn!

2. Your Senses
A loud “boom!” is heard across the street. You turn quickly and duck slightly. Your senses are in action! The unexpected noise produces impulses in sensory receptors in your ears. These impulses travel to your brain, where they create a sense of awareness called a sensation. The sensory receptors in your eyes send impulses to your brain, which recognizes the sound as being a car crash.

3. The FIVE Senses
Sight
Touch
Hearing
Taste
Smell

4. The Human Eye
Your Sense of Sight!

6. Cornea
The cornea is a thin, clear membrane that covers the front of the eye
It protects the eye while allowing light to enter

7. Aqueous Humor The fluid behind the cornea
It is constantly replenished by the ciliary body
as it drains through the openings in the corner of the eye

8. Pupil
Light from the front of the eye enters through an opening called a pupil

9. Iris The pupil is surrounded by the iris, a ring of muscle
The iris is a muscle that controls the amount of light that enters the eye and gives the eye its color
In bright light, the iris contracts, which makes the pupil smaller in diameter
In dim light, the iris relaxes, which dilates the pupil to let in more light

10. Lens
The oval-shaped piece of clear, curved material behind the iris that bends light.
The lens refracts, or bends, the light rays and focuses the image, before sending it off to the retina in the back of the eye
Muscles in the eye change the shape of the lens in order to focus light onto the retina
When you look at objects that are close to the eye, the lens becomes more curved. It becomes flatter when you look at distant objects

11. Nearsightedness
If the lens focuses light in front of the retina, this results in nearsightedness
Cause: the cornea’s curvature is too steep for the shape of the eye, causing distant objects to appear blurry

12. Farsightedness
Here the person can see distant objects better than close up objects
It results from the lens focusing light behind the retina
Children with mild to moderate cases of farsightedness can see distances far and near without correction because the muscles and lens within the eye can overcome the farsightedness

13. To correct near or farsightedness you need to change the way the light is bent using contacts, eye glasses or surgery

14. Focusing the Light
Light travels in a straight line until it passes through the cornea and the lens.

15. Retina
A layer of light-sensitive cells, called photoreceptors, found in the back of the eye
They respond to light energy
These photoreceptors create electrical impulses
The brain perceives these impulses as light

16. Two Types of Photoreceptors
CONE CELLS
ROD CELLS
Retinal cells that are sensitive to dim light
Impulses from rod cells detect shades of grey and black
These cells are important in night vision
Light Impulse changed to an electrical impulse here and travels along axon to brain
Retinal cells that are very sensitive to bright light
Impulses from cones allow you to see detail and color
Light impulse changed to an electrical impulse here and travels along an axon to the brain

17. RETINAL CELLS Rod Cells allow you to see shades of grey and black
Cone Cells allow you to see colors

18. Vitreous Humor
The clear gel that fills the space between the lens and the retina
Unlike the aqeuous humor fluid in the front of the eye, it remains stagnant (does not move) and is not replenished

19. Located in the back of the eye
FOVEA
Located in the back of the eye
It is responsible for sharp, central vision necessary in reading, watching television, driving, or in any other activity that requires seeing detail

20. Optic Nerve
The impulse leaves the back of each eye through an optic nerve. The optic nerve carries the electrical impulses from the retinal cells to your brain, where the impulses are interpreted

21. What does 20/20 vision mean?
20/20 vision means that if you stand 20 feet away from an eye chart, you can see what the human eye is supposed to see at 20 feet away
20/40 vision means that you standing 20 feet away from the chart, you see what a normal human can see when standing 40 feet away
20/ 200 is the cut off for legal blindness

22. Glaucoma
An eye disease in which the vitreous fluid in the eye does not drain properly
If not treated, can lead to blindness
Pressure in the eye builds up and can damage the optic nerve
Can occur in people over 40 or in babies

23. Cataracts- a common disease that can lead to blindness if not treated
This is when your lenses become opaque, meaning that light does not pass through
Can occur in babies or adults
Cataracts can be removed with surgery
If corrected with surgery, then you need to wear strong contacts or glasses

24. Most people blink every 2-10 seconds
EYE FACTS
Most people blink every 2-10 seconds
Owls can see a mouse from 150 feet away in dim light
The reason cat and dog’s eyes glow at night is because of silver mirrors in the back of their eyes called, tapetum. This makes it easier for them to see at night.
A chameleon’s eyes can see in opposite directions at the same time
One in every 12 males is colorblind
A newborn baby sees things upside down because it takes time for baby’s brain to learn to turn the picture right side up

25. The Sense of Hearing (auditory processing)
The human ear is the most complex sensory system in the human body. Vision and smell are extraordinary, too, but they do not match the complexity of turning waves of sound pressure from air molecules banging against the ear drum in to the neural signals that get sent to the brain and interpreted as sound.

26. What is a Sound wave?
It is just a wave of sound. Music is just a bunch of sound waves, arranged in a nice pattern. A sound wave is comprised of the changes in tone of air pressure through compression and refraction.

27. The Human Ear

28. The Outer Ear
Sounds are pressure changes in the air that travel in waves.
The outer ear collects these waves which travel down your ear canal to enter the middle ear
The ear canal channels sound waves to your ear drum, a thin, sensitive membrane stretched tightly over your middle ear
The waves cause your ear drum to vibrate

29. Middle Ear
The middle ear lies between the tympanic membrane (ear drum) and the inner ear
Like the outer ear, the middle ear space is filled with air and contains three small bones called the ossicles: the hammer (malleus), anvil (incus), and the stirrup (stapes)
These bones amplify the pressure of waves from the vibrating tympanic membrane which provides an efficient transfer of sound energy to the fluid filled inner ear

30. The Inner Ear
1.The stirrup touches a liquid filled sac and the vibrations are passed on to the inner ear’s cochlea
2.The hollow channels of the inner ear are filled with fluid
The cochlea, semi-circular canals, and the auditory nerve make up the inner ear

31. Cochlea A snail-shaped organ of the inner ear filled with fluid
Inside the cochlea there are hundreds of special hair-like cells attached to nerve fibers, which can transmit information to the brain by changing sound waves to nerve impulses
The brain processes the sounds we hear and lets us distinguish between different types of sound

32. Auditory Nerve (sometimes called the cochlear nerve)
The waves are turned into a nerve impulse in the cochlea and sent to the brain for interpretation via the auditory nerve.

33. Exposure to too much noise can damage ear cells and lead to hearing loss. Hair cells in the cochlea do not replace themselves naturally, so take care of the healthy ones you have !
Damaged ear cells in the cochlea
Normal ear cells in the cochlea

34. The Inner Ear and Your Balance
The semi-circular canals in the inner ear help you maintain your balance
It is a fluid- filled organ with nerve cells that respond to the position of the fluid in it
It sends messages to the cerebellum, the base of the brain
The semi-circular canals works closely with the visual cortex and skeletal muscles to help maintain balance, which comes in handy when you walk, stand, and especially when your trying to juggle or do flips!

35. Semi-Circular Canals

36. The Eustachian Tube Tube that connects your middle ear to your throat
The tube allows air to pass between the tympanic cavity and the outside of the ear by way of the throat and mouth
It is important to maintain equal pressure on both sides of the ear drum, which is important for normal hearing
For example, if a person goes from a high altitude to a low one pressure on the outside of the ear gets greater and greater, pushing the eardrum inward, out of its normal position, and hearing may be impaired

38. TASTE
YOUR tongue and roof of your mouth are lined with tiny taste buds. When you eat something, the saliva in your mouth breaks down food. This causes receptor cells in your taste buds to send messages through sensory nerves to your brain. Your brain tells you what flavors you are tasting…
It can detect sweet, salty, sour, and bitter flavors…

39. TONGUE Taste buds change as you get older
They are most sensitive when you are a baby, as you had taste buds on the sides and roof of your mouth , and on your tongue.
As you get older you lose taste buds and are left with just the ones on your tongue, so they are less sensitive

40. Interesting Facts We have about 10,000 taste buds
Insects have the most highly developed sense of taste-they have taste organs on their feet, antennae, and mouthparts
Girls have more taste buds than boys do
Taste is the weakest of the five senses

41. Your Sense of Smell
Your nose smells, moistens, and filters the air that you breathe
Ever wonder how you are able to smell flowers, or the scent of a hot bowl of soup?
This is because millions of tiny odor particles float around in the air and are detected by cells in your nasal passageway called olfactory cells

42. Then the cells send signals along the olfactory nerve to the brain
OURSENSE OF SMELL
After passing through the nasal cavity, air reaches the olfactory cells which contain nerve cells
Smell particles are detected by the nerve cells there, and fit into them like a lock and key
Then the cells send signals along the olfactory nerve to the brain
The brain interprets the smell
Our sense of smell is well connected to our memories- the smell of cookies can remind us of a time we baked cookies with grandma
UMMMMM, the smell of a cup of hot coffee on a cold day!

43. You also have mucus produced that is sticky to trap in particles
Cilia and Mucus
You have tiny hairs in your nose called, cilia, that help to sweep out dust particles and bacteria that enter the nose
You also have mucus produced that is sticky to trap in particles
Together the cilia and mucus help prevent foreign material from entering the lungs
*Did you know that when you have a cold, you produce too much mucus that can get in the way of the smell molecules reaching the olfactory cells, making your sense of smell not as good

44. Interesting Smelling Facts
80% of taste is smell, so when you have a cold, food doesn’t taste as good
Dogs have one million olfactory cells per nostril and their smell cells are 100x larger than humans
Some people cannot smell! A condition called Anosmia
As you get older, your sense of smell isn’t as strong as it was when you were younger

45. Sense of touch Your sense of touch is located all over your body
Because your sense of touch originates in bottom layer of your skin, called the dermis
This layer of skin is lined with many tiny nerve endings that gives you information that body comes in contact with
They do this by sending this information to the spinal cord, which sends messages to the brain where the feeling is registered
Sense of touch

46. Nerve Receptors You have about twenty different nerve endings
The most common types of receptors in skin are cold, pressure, pain, and heat
Some parts of your body are more sensitive to pain because they have more nerve endings
Your tongue has many pain receptors, but is not as good at detecting heat, which is why it is easy to burn your tongue on hot foods! Ouch !

47. Interesting Facts…..
You have more pain nerve endings than any other type
Your fingertips, lips, face, hands, feet, and neck are very sensitive
You have about 100 touch receptors in your fingertips
The least sensitive part of your body is the middle of your back
Shivering is your body’s way of keeping you warm

48. Ever had your fingertips pricked?
A finger prick by a needle can measure blood glucose levels in diabetics- since the fingertips are one of the body’s most sensitive parts, it can be an unpleasant experience

49. Congenital Insensitivity to Pain with Anhidrosis (no sweating)
This is an extremely rare genetic mutation which prevents the sensation of pain, heat, and cold-it also prevents sweating making people with this condition prone to fever and heat stroke
It is caused by a mutation in a gene that prevents normal formation of nerve cells
Many people with this disease die before the age of three
For H.W.-State the pros and cons of not being able to feel pain, heat, or cold. End your paper by stating the importance of being able to feel pain…..