Rods and Cones

Rods and Cones
          Rods and cones are the photoreceptors located in eyes, more specifically, retinas, the innermost layer of tissue. There are around 120 million rods located in the human retina, while there are only 6-7 million cones. Rods are more sensitive to light, so they are responsible for vision when there is little to no light. Cones, however, can detect color and shapes and sizes of objects under high light conditions. The ability to detect a shape is called spatial acuity. Therefore, rods have a low spatial acuity while cones have a high spatial acuity. The central fovea is the location of most cones, and only cones are allowed to be there. Rods are more numerous than cones in the periphery of the retina, which provides peripheral vision. Since rods are also better than cones at sensing motion, humans are able to detect motion through peripheral vision. Dimmer objects also appear more visible through peripheral vision because of the rods located in the periphery. These cells are comparable to neurons as their shapes resemble the long shape and they also have the synaptic terminal on the inner side of the cell. Their mitochondria and nucleus are located in the inner segment, and all their organelles are like the eukaryotic cells located in the human nervous system.

http://hyperphysics.phy-astr.gsu.edu/hbase/vision/rodcone.html
http://www.cis.rit.edu/people/faculty/montag/vandplite/pages/chap_9/ch9p1.html
https://faculty.washington.edu/chudler/retina.html


https://upload.wikimedia.org/wikipedia/commons/a/a0/Cone_cell_en.png

http://tridentmedia.org/wp-content/uploads/2015/06/eye-diagram.jpg

Lab: Sweetness in Carbs

          My partner and I began this experiment by writing down the structures and functions of 8 different carbohydrates- sucrose, glucose, fructose, galactose, maltose, lactose, starch, and cellulose. After we recorded the information regarding these carbs, we began the taste test. 
           Our hypothesis was that sucrose, glucose, fructose, galactose, and maltose would all taste sweet, while lactose, starch, and cellulose would not taste sweet. 
         From the small containers we were given, we used a spoon to dish out every carb into different locations on a paper towel with labels for our reference. When every carbohydrate was on the matting, we used the tips of our fingers to catch a small amount of each substance and taste it. The data we recorded included their names, their degree of sweetness from 0-200, their color, and their texture. 
         Sucrose, glucose, and fructose were granular and generally sweeter than the rest. Galactose, maltose, lactose, starch, and cellulose could be best described as powder in physical texture. The monosaccharides seemed to be sweeter, excluding galactose, and the disaccharides and polysaccharides were not very sweet at all, excluding sucrose. In general, the less rings in the structure of the carbohydrate, the sweeter it was. 
         This made a lot of sense because I find table sugar and fruits and juices to be sweeter than cornstarch and vegetables and other staple food items like potatoes.
         The tongue and the nose play key roles in allowing us to taste food. On the tongue, there are a lot of bumps called pappilae, and most of them have taste buds. These taste buds have sensitive microscopic hairs called microvilli. Every hair sends a message to the brain like a neuron when it tastes different tastes. The average person has around 10,000 taste buds, and although they are supposed to be replaced every 2 weeks, sometimes, they aren't. As people age, they lose taste buds, so that is one reason why people in our class could have had varying opinions on the sweetness levels of the samples in this lab. In our class, there are probably people with ages ranging from 15 to 18. In addition, the nose has olfactory receptors which are similar to the microvilli. When we eat, chemicals travel up our nose to contribute to our determination of each taste. However, if you are sick and your nose is plugged, the chemicals don't reach these receptors and that can also affect how you distinguish taste. Therefore, if there were people sick on the day of the lab, they could have also had different results on the sweetness levels. 

http://kidshealth.org/kid/talk/qa/taste_buds.html