This preview shows page 1. Sign up to view the full content.
Unformatted text preview: Human Senses The senses are organs that connect the nervous system to the external environment. They are the sources of stimuli that cause a response in the nervous system, and they are the sources of all information to the human body. Eye In the human eye, the nerve cells are located in a single layer called the retina , located along the back wall of the eye. Light rays enter the eye through a curved, transparent structure called the cornea, then pass through the pupil, an opening in the eyeball. The iris regulates the size of the pupil. Next, the lens focuses the light on the retina, which contains two types of light-sensitive cells, rod cells and cone cells , which detect light. Cone cells, which detect color, are concentrated in the central portion of the retina, while rod cells, which permit vision in dim light, are concentrated at the...
View Full Document
This note was uploaded on 11/11/2011 for the course BIO 101 taught by Professor Pesthy during the Fall '07 term at Texas State.
- Fall '07