Monday, January 24, 2011

Science Form 2 Chapter 1.4, 1.5and 1.6

Hi there, we meet again and now we are going to continue our journey to success on science...

Chapter1.4 (Sense of Taste)
The tongue we know is use to taste the flavor of the food because the food contain chemicals that stimulate the receptors on our tongue called the taste buds.
The diagram above is the location of different receptors. The interesting part is that these tiny receptors (Taste Buds) can detect 4 kind of taste that is
  • Bitter
  • Sour 
  • Salty
  • Sweet
When we chew our food, the chemicals in the food is dissolve in the saliva. These dissolve chemicals stimulate the taste buds to send nerve impluse to the brain.

The other thing is, we don't only use our tongue to taste food but nose too! As you can see when u are having a cold you will felt that all food are almost tasteless. This is because the nose and the mouth is actually connected! So some of the chemical goes to the nose.


Chapter 1.5 (Sense of Hearing)
The ear has help us to hear . It has three main parts that are
  • Outer ear
  • Middle ear
  • Inner ear
Most part of the ear are located inside the skul so let's take a look at it!
The three smalls bone that are connected to the eardrum are also called Ossicles.
Ok, this is how the ear works...
  1. The Pinna directs sound into the ear.
  2. The sound is traveled down through the ear canal.
  3. The eardrum vibrates.
  4. The ossicles like speakers amplify it and transfer to the oval window.
  5. The oval window transfer the vibrations to the Cochlea.
  6. The Cochlea turns vibrations to nerve impluse.
  7. The auditory nerve carry the info to the brain.
TADA! Finish!
There are 2 more part of the ear I din't list out because it's not for hearing. They are:
  • Eustachian tube
  • Semicircular canals
Eustachian tube is use to balance the pressure in the ear to prevent the eardrum from damaging.
Semicircular canals are use to keep you walk upright. It detect movement and position of our head to keep our balance!

Chapter 1.6 (Sense of Sight)
The eye allowed us look at the beautiful lady (JKJK). The eye is slightly flattened but not as flat as roti canai! The eyelids, a layer of skin is use to protect our eye.This is how an eye look like.

The eye is made up of three coats, enclosing three transparent structures. The outermost layer is composed of the cornea and sclera. The middle layer consists of the choroid, ciliary body, and iris. The innermost is the retina, which gets its circulation from the vessels of the choroid as well as the retinal vessels, which can be seen in an ophthalmoscope.
Within these coats are the aqueous humor, the vitreous body, and the flexible lens. The aqueous humor is a clear fluid that is contained in two areas: the anterior chamber between the cornea and the iris and exposed area of the lens; and the posterior chamber, behind the iris and the rest. The lens is suspended to the ciliary body by the suspensory ligament, made up of fine transparent fibers. The vitreous body is a clear jelly that is much larger than the aqueous humor, and is bordered by the sclera, zonule, and lens. They are connected via the pupil.[2]
These are the functions of the eye:
  1. Sclera-Protect and maintain the shape of the eye ball
  2. Choroid-Absorbs light/prevent reflection of light/supplies nutrients and oxygen
  3. Retina-Detects light/porduce nerve impluse
  4. Lens-Focuses light
  5. Vitreous humour-Help refracting light/maintain shape of eyeball
  6. Suspensory ligaments-Hold the lens
  7. Ciliary body-Contracts and relaxes to change the thickness of lens
  8. Conjuntiva-Protect the cornea
  9. Aqueous humour-Helps refracting light/maintain the shape of eyeballs
  10. Cornea-Refract (bend) light onto Retina
  11. Pupil-control the amount of light enters
  12. Iris-Control Pupil
  13. Yellow Spot (fovea)-Detect light or images fall on it
  14. Blind spot-The shop where optic nerve leves the eyeballs
  15. Optic nerve-Carries nerve impluse.
How do we see images?


Ok...Finally the last part. When we see images, the images falls on the retina to produce nerve impluse to the brain and that's how we see things!

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