3. A system that controls all of the activities of the body. The nervous system is made of: The brainThe spinal cord The nervesThe senses

4. The nervous system also allows you to react to a stimulus. A stimulus is a change in the environment. Example: A hot stove Or… tripping over a rock

5. Your reactions are automatic. Automatic means that you do not have to think about your reactions. Example: If a bug flies by your eye, you will blink.

6. An organ that controls your emotions, your thoughts, and every movement you make.

7. The Central Nervous System is made of the brain and the spinal cord. The Central Nervous System controls everything in the body.

8. The Outer Nervous System is made of the nerves and the sense organs. Nerves Sense organs

9. Messages carried throughout the body by nerves.

10. You have a nerve along your whole arm. The “funny bone” is the only place on the arm where the nerve is not protected. The “funny bone” is on the elbow.

12. * The Central Nervous System controls all of the body’s activities. * The Central Nervous System is made of two main organs. 1. The brain 2. The spinal cord

13. * The spinal cord sends messages to the brain. * The spinal cord is the part of the nervous system that connects the brain to the rest of the nervous system.

14. * The brain controls everything in the body. * The brain is made of more than 10 billion nerves! * The brain is divided into three parts and is protected by the skull.

15. * The Brain has three main parts… 1. The Cerebrum 2. The Cerebellum 3. The Brain Stem

16. * The Cerebrum is the largest part of the brain. 1. The cerebrum controls your thinking. 2. The cerebrum controls your memory. 3. The cerebrum controls your speaking. 4. The cerebrum controls your movement and identifies the information gathered by your sense organs.

17. * The cerebellum is below and to the back of the cerebrum. 1. The cerebellum controls you balance. 2. The cerebellum controls your posture.

18. * The Brain Stem connects the brain to the spinal cord. * The nerves in the brain stem control your heartbeat, breathing, and blood pressure.

19. * The vertebrae are the many bones that protect the nerves in the spinal cord.

21. * The Outer Nervous System’s job is to connect the Central Nervous System to the rest of the body. * The outer nervous system carries messages between the central nervous system and the rest of the body.

22. * The outer nervous system is made of the nerves and the sense organs. Ear Eye Skin Nerves Tongue

23. * An automatic reaction that happens without thinking about it. * A reflex happens quickly in less than a second.

24. * The outer nervous system controls the body’s activities that you don’t think about. * The outer nervous system controls activities in your small intestine, your breathing, and your heartbeat. controls

25. * This is just for emphasis sake to remind us how the brain receives the information We should note that these messages are sent in the form of chemical and electrical transmissions

26. *Firstly our receptors receive the stimuli and the information is sent as impulses through the sensory neurons (nerves) *These messages are then sent to the brain where the information is processed and an appropriate response is constructed *The brain the sends the response as impulses to the motor neurones which in turn causes the effectors (muscles) to react to the stimuli

28. Sense organs carry messages about the environment to the central nervous system.

29. The eyes, ears, nose, tongue, and skin are examples of sense organs. The sense organs gather information (light, sound, heat, and pressure) from the environment.

30. The environment is everything outside the body. The sense organs gather information from outside the body, then send the messages to the brain.

31. Vision is your ability to see. Vision involves the eye and the brain.

32. The eye is one of your sense organs. The eye is made of the iris and the pupil. The eye gathers pictures and sends them to the brain.

33. The colored part of the eye is the iris. The black part of the eye is the pupil. The pupil becomes larger and smaller as it controls the light coming into the eye. Iris Pupil

35. Parts of the eye Function Choroid Contains lots of blood vessels Sclera Tough white fibrous coat protecting the eye ball Retina Contains light sensitive cells Iris Controls the amount of light entering the eye Optic nerve Carries impulse from retina to brain Ciliary muscles Alters the shape of the lens Suspensory ligaments Attach lens to Ciliary muscles Lens Focuses light unto the retina Pupil Allows the light to enter the eye Cornea Bends rays of light on entering the eye Conjunctiva Protects the cornea

36. How does the human eye work? The individual components of the eye work in a manner similar to a camera. Each part plays a vital role in providing clear vision. So think of the eye as a camera with the cornea, behaving much like a lens cover. As the eye's main focusing element, the cornea takes widely diverging rays of light and bends them through the pupil, the dark, round opening in the center of the colored iris. The iris and pupil act like the aperture of a camera. The individual components of the eye work in a manner similar to a camera. Each part plays a vital role in providing clear vision. So think of the eye as a camera with the cornea, behaving much like a lens cover. As the eye's main focusing element, the cornea takes widely diverging rays of light and bends them through the pupil, the dark, round opening in the center of the colored iris. The iris and pupil act like the aperture of a camera.

37. Lets compare the camera and the eye Light sensitive areas: retina and the film Focusing : both camera and eye has lens to focus Amount of light entering : diaphragm and shutter….eye lids and iris

38. How does the human eye work? Next in line is the lens which acts like the lens in a camera, helping to focus light to the back of the eye. Note that the lens is the part which becomes cloudy and is removed during cataract surgery to be replaced by an artificial implant nowadays. Next in line is the lens which acts like the lens in a camera, helping to focus light to the back of the eye. Note that the lens is the part which becomes cloudy and is removed during cataract surgery to be replaced by an artificial implant nowadays.

39. Eye defects Accommodation is the adjustment of the thickness of the lens of the eye to see near of far Accommodation is the adjustment of the thickness of the lens of the eye to see near of far Shortsightedness (myopia) Shortsightedness (myopia)

40. Shortsightedness (myopia) What is myopia? What is myopia? Myopia, also known as short sightedness or near sightedness, is the condition in which distant objects appear blurry. A shortsighted person may have good vision at close range, but will usually experience difficulties seeing details or objects that are far away. Myopia, also known as short sightedness or near sightedness, is the condition in which distant objects appear blurry. A shortsighted person may have good vision at close range, but will usually experience difficulties seeing details or objects that are far away.

41. With myopia, light entering the eye focuses in front of the retina. This occurs because either the eye has grown too long, or the focusing components of the eye are too strong. A diagram of a normal eye v a shortsighted eye. As you can see, in the diagram of the normal eye, light enters the eye, and focuses perfectly onto the back of the eye (the retina). With a shortsighted eye, the light focusses in front of the retina, and causes the image that forms on the retina to be blurred. Thus, causing distance vision to be blurred.

42. Longsightedness (hypermetropia) What is hypermetropia? Hypermetropia, also known as long-sightedness or far- sightedness, is the condition in which close objects appear blurry. A longsighted person may have good distance vision but will have trouble with close objects.

43. With hypermetropia, light entering the eye focuses in behind the retina. This occurs because either the eye is too short (in length), or the focusing components of the eye are too weak. With hypermetropia, light entering the eye focuses in behind the retina. This occurs because either the eye is too short (in length), or the focusing components of the eye are too weak. A diagram of a normal eye v a longsighted eye. A diagram of a normal eye v a longsighted eye. As you can see, in the diagram of the normal eye, light enters the eye, and focuses perfectly onto the back of the eye (the retina). With a longsighted eye, the light focuses in beyond the retina, and causes the image that forms on the retina to be blurred. This causes near vision to become blurred. As you can see, in the diagram of the normal eye, light enters the eye, and focuses perfectly onto the back of the eye (the retina). With a longsighted eye, the light focuses in beyond the retina, and causes the image that forms on the retina to be blurred. This causes near vision to become blurred.

44. When a sound is made, the air around the sound vibrates. Hearing starts when some of the sound waves go into the ear.

45. There are nine main parts of the ear. 1. Pinna 2. Ear canal 3. Ear drum 5. Anvil 6. Stirrup 7. Cochlea 4. Hammer8. Eustachian tube 9. Auditory nerve

46. The ear canal is the tube between the outside of the ear and the ear drum. The ear drum is in the middle ear. It vibrates when sound waves hit it. The pinna is the part of the ear that you can see.

48. The three smallest bones in the body, the hammer, the anvil, and the stirrup, are in the middle ear. The hammer gets the vibrations from the eardrum, then sends them to the anvil. The anvil passes the vibrations to the stirrup. The stirrup passes the vibrations to the inner ear.

49. The inner ear is made of the cochlea and liquid. The cochlea is in the inner ear. The cochlea looks like a shell. The Eustachian tube controls the amount of pressure in the ear. The auditory nerve carries the hearing information to the brain and the brain tells us what we heard.

50. The ear works with the brain to control your balance. All of your movements are controlled by balance and muscles. The liquid in your inner ear is responsible for your balance. The liquid in your ear moves when we move. The liquid movement sends information to the brain to tell it how we are moving.

51. The sense of touch is located in the skin. The nerves in the skin allow us to feel texture, pressure, heat, cold, and pain. Texture is how something feels.

52. The nose controls your sense of smell. The nose is able to smell 80 different kinds of smells.

53. Your sense of taste comes from the taste buds in the tongue. Taste buds are the parts on the tongue that allow us to taste. The four kinds of taste buds are sweet, sour, bitter, and salty.

54. Tastes and smells work together to make flavors. Flavors are the tastes of food and drinks.