Jessica Stermanns Blog September 19/07

Sept. 19/07

Jessica’s Blog

Today in Biology class we had a test on the brain. We needed to label the brain and know where the major parts are located. We also had to know the location and functions of the occipital, temporal, parietal, and frontal lobes.In the second half of class we filled out a fill in the blanks sheet about the eye. It listed the major internal structures. A worksheet was assigned for homework “Pathway of light through the eye”. It’s based on the information we learned previously in class today about the eye.

The question came up today in class about if dogs are color-blind. I did some research and found the answer: (http://ask.yahoo.com/20020902.html) resource

A dog's world is not all black and white. To understand what dogs can see, it helps to have some basic knowledge of vision for example the facts we learned today in class. Our vision is optimized for seeing in bright light, while dogs, like many other predators, see best in dimmer light. There are two types of photoreceptor cells in the retina which are rods and cones. Rods process visual information in dim light, while cones handle color and detail. Human vision is trichromatic meaning we have three types of cones that recognize different portions of the color spectrum.

Dogs have only two types of cones -- their dichromatic color vision is similar to that of a human with red-green color-blindness. In addition, a dog's retina contains a much smaller ratio of cones to rods than ours does. So even though dogs don’t have the color range and focus like us, their night vision is superior, thanks to a reflective structure behind their retina called the tapetum lucidum, dogs see objects in the dark as if lit by an eerie glow.

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