Explain how the feeling of senses made possible
Sense is possible only when impulses from sense organs reach at the brain through the sensory nerves.The ends of sensory nerve from the brain act as the receptors inside the sense organs.
|
|
Receptors |
Stimulus |
Function |
|
Eye |
Photo
receptors in the retina (Rod & Cone cells) |
Light |
Vision |
|
Ear |
Auditory
receptors in the basilar membrane |
Sound |
Hearing |
|
Nose |
Olfactoiy
receptors |
Olfactory
particles |
Smelling |
|
Tongue |
Taste
receptors in the taste buds |
Taste
particles |
Tasdng |
|
Skin |
Receptors
for heat, cold, touch, pressure and pain |
Heat,
cold, touch, |
Heat,
cold, touch, |
Our eyes protected as follows
- Bony eye socket (orbit) - protects eye.
- External eye muscles - fixes the eye ball in the orbit.
- Eyelids - protect from dust and other particles.
- Eyelashes - protect from dust with out obstructing vision.
- Eyebrow - prevents perspiration or water reaching in to the eyes.
- Tears - clean and lubricate the anterior part, washes away the dust particles and destroys germs.
- Conjunctiva - secretes mucus to prevent the eye from being dry.
The enzyme contained in tears are called Lysozyme.
The 3 layers of human eye are as follows
- a. Sclera –The outermost, strong layer, that gives shape. Its transparent anterior portion is the cornea.
- b.Choroid- Middle layer of blood capillaries, which supply nutrients and oxygen. Its anterior dark screen with pupil is the iris. A convex lens is placed behind the iris.
- c. Retina- The innermost layer on which, the image forms. The optic nerve starts from the retina.