Special Sense Book

Health Science 3

12/4/2016

Sight

Your eyes are the reason that you can see the world around you. Your eyes works in a similar way to a camera - light passes through the lens of your eye and is 'recorded' on the back of your eye which is called the retina. Except your eye takes pictures upside down and your brain turns the picture the right way up and tells you what you are looking at.

Astigmatism

Astigmatism is an imperfection on the surface of the cornea which causes light to spread over the retina rather than focusing on part of the retina. This can lead to blurry or fuzzy vision. Astigmatism can be treated by having glasses or contact lenses  or laser surgery can be performed on the eye.

Glaucoma

Glaucoma is a disease of the eye. Normally, our eyes stay wet because of a small chamber in front of the eye that fills up with fluid or liquid that washes and cleans the eye. When this fluid doesn’t drain out of the eye or there is too much of it, pressure builds up. This extra pressure is bad because it can hurt the optic nerve. The optic nerve sends messages to the brain about what the eye is seeing, so the problem needs to be fixed right away because if it isn’t it could lead to blindness.

Presbyopia

Presbyopia is farsightedness that is age related which means it is farsightedness that comes along with getting old. It is related to the inability of the aging lens to focus light rays properly due to light rays falling beyond the retina. Presbyopia usually affects people 40 or older and can be fixed by using reading glasses, bifocals or eye surgery.

Normal Eye

Conjunctivitis

Conjunctivitis

Conjunctivitis, is the inflammation or swelling of the conjunctiva, which is the pink lining of the inside of the eyelids. Normally the conjunctiva covers our eyes and helps protect them from things like dirt and dust, but if the lining is exposed to too much wind, sun, heat or cold it can become red and swollen.  A type of conjunctivitis is pink eye which causes the eye and the eyelids to become really red and itchy and is easily spread between people.

Myopia

Myopia is commonly called nearsightedness which means that people with this problem can see things that are up close but they have a hard time seeing things that are far away. Nearsightedness is caused by the eye being longer than it should be and this causes light entering the eye not to reach the retina in the eye. Nearsightedness can be fixed by using glasses, contact lenses or eye surgery.

Cataract

A cataract is a clouding of the center or lens of the eye. Usually this part of the eye is black and it helps focus on objects at various distances. This clouding of the eye is normally caused by getting old and is created very slowly in one or both eyes. A cataract causes blurred or cloudy vision, so people have a hard time seeing things.

Hearing

Your ears are the reason that you hear the world around you.

There are 3 main parts to your ears:

The Outer Ear: These are the parts we can see and the ear canal. They act like a funnel to catch sound waves and direct them to the ear drum.

The Middle Ear: This is a small air-filled space on the inside of the eardrum and the are 3 tiny bones in this part.

When the sound waves move the eardrum, these bones move and pass on the vibration to the much smaller oval shaped window of the cochlea. The hammer is touching the ear drum so it shakes when the sound comes through, and the movement goes right through the anvil to the stirrup, which is touching the window of the cochlea.

The Inner Ear: The cochlea has fluid in it, which moves due to the vibrations and bends hairs on the outside of cells lining the cochlea. 

Otitis

Otitis is an ear infection.  An ear infection is the inflammation of swelling of the inner, middle or outer parts of the ear.  An inner ear infection is called Otitis interna which is the swelling of the inner ear. An middle ear infection is an infection of the air-filled space behind the eardrum. A outer ear infection is usually called Swimmer's ear which is an infection of the outer ear canal. An ear infection can be fixed with medicine for pain, medicine for infection and medicine to decongest or drain out the area in the ear.

Meniere’s Disease:

Meniere’s Disease is a chronic or long lasting disease of the inner ear characterized by ringing in the ears, dizziness, hearing loss and a feeling of fullness in the ear. This disease usually affects people aged 40 to 60.  Acute or quick attacks can last from a few hours to several days with symptoms of nausea, vomiting, sweating and dizziness, medicines can help with controlling the symptoms.

Presbycusis:

Presbycusis is hearing loss due to getting old. The loss of hearing usually starts around the age of 50; first losing the hearing of high tones then losing hearing of lower tones. People with presbycusis might have a hard time hearing other people talking and talking might sound mumbled or hushed to them. To treat presbycusis in the beginning, people have to wear hearing aids but later on hearing aids might not help.

Hearing Aid

Otosclerosis

Otosclerosis is a condition in which the small bones of the middle ear become hardened. This causes those small bones to stop conducting vibrations from the eardrum to the inner ear, which causes hearing loss.  No one knows the cause of Otosclerosis but it happens to women under the age of 35. Otosclerosis is fixed by a stapedectomy which involves removing the hardened bones in the middle ear and replacing them with a prosthesis which is fake ones,

which helps the people hear better.

Taste

Your tongue is made up of lots of groups of muscles which run in different directions, so that your tongue can move in lots of different directions, and cope with all its different jobs.

On your tongue, you have lots of taste buds for picking up different tastes. Most of the ones that sense salty or sweet tastes are near the front of the tongue, the taste buds for sour tastes are mainly along the sides of the tongue, and the ones for bitter tastes are at the back of the tongue.

The nose and the tongue work as a team for tasting your food - smell is very important to tasting foods. If your sense of smell isn’t working properly, like when you have a cold, foods can taste very tasteless.