1. Sensing function
Living beings receive information through the senses and according to it, they produced a response. Thus they relate with the outside.
In the picture, we see that when we touch a tentacle of the snail, it responses shrinking.
The man has five senses: sight, hearing, taste, smell and touch. Each sense receives the direct action of the external environment. This information is transmitted through a nerve to the brain, where the response originates.
2. The sight
The sense of sight lets us know the color, shape, position and distance of the bodies. The main parts of the eye are:
- The eyebrow that prevent sweat drop on the eyes.
- The eyelash that prevents dust enters in the eye.
- The eyelids that close quickly to any hit or brush in the eye.
- The cornea is a transparent membrane in contact with the outside.
- The iris is the colored part of the eye.
- The pupil is in the center of the iris.
- The lens is a biconvex structure that focuses images.
- The retina is a light-sensitive membrane which is on the back of the eyeball. The optic nerve comes from it and gives information to the brain.
When much light comes, the pupil becomes smaller. When little light comes, the pupil dilates or enlarges.
According to the distance of the object, the lens can flatten or make convex in order to focus well and see the picture clear.
See the picture and note the similarity between the eye and a camera.
3. Answers with the appropriate part of the eye : eyebrows, eyelashes, eyelids, cornea, iris, pupil, lens or retina