Rods and Cones

In our eyes, we have cells that make us able to see the world around us called photoreceptors. These photoreceptors are rods and cones. Rods and cones are both long cells but have slightly different structures. Rods and cones are long cells with three main sections: the synaptic terminal, the inner segment and the outer segment. The synaptic terminal has the nerve ending that send signals to the brain to communicate what it is seeing, so for rods it would be light or dark changes and general shapes, and for cones it would be sending color signals and making our vision clear. The inner segment contains the nucleus of the cells and the mitochondria. The outer segment, to put in a simple term, looks likes the teeth on a comb but made of plasma membranes. On rods, this section is longer and has disks within it making it larger and more rectangular. The cones look more triangular and don't contain those disks.

We have about 120 million rods in our eyes, mainly in our peripheral vision, and only 6-7 millions cones, mainly concentrated in the center of our eyes called the fovea. Even with the abundance of rods and cones we still have a blind spot in our eyes where light can't hit the photoreceptors. Rods and cones are classified as nervous tissue because they send signals to the brain about what they see.

Rod Cell:                                                                 Cone Cell:

 

Works Cited:

"Rods and Cones." The of the Human Eye. N.p., n.d. Web. 31 Aug. 2015.

"Neuroscience For Kids." - Retina. N.p., n.d. Web. 31 Aug. 2015.

Purves, Dale. "Functional Specialization of the Rod and Cone Systems."Functional Specialization of the Rod and Cone Systems. U.S. National Library of Medicine, n.d. Web. 31 Aug. 2015.

What is Sweetness?

According to PubMed Health, the sense of taste is caused by the chemicals in food coming in contact with sensory cells. When they come in contact, certain proteins in the food activate the nerves and transfer the exact taste to our brains through nerves. The taste buds on our tongues contain all of these sensory cells, and because they are bumpy, they increase the surface area of the tongue letting us taste even more. Many people were taught that the different parts of the tongue taste different things like sweetness, saltiness and bitterness but that is false, all parts of our tongue taste everything.

Sweet Science

In our lab today, we tasted different forms of sugar: sucrose, glucose, fructose, galactose, maltose, lactose, starch, and cellulose. These sugars all have slightly different structures, therefore they taste different, but a pattern that we noticed was that as the number of rings increased, the sweet taste disappeared. Sucrose is what we know as table sugar or just white granulated sugar used in baking. Fructose is used primarily as a sweetener since it takes very little to increase the sweetness of food products or even just your daily coffee. The rest of the sugars aren't your classic sugars as they do not taste very sweet; this is because they are disaccharides and polysaccharides. Maltose is the malt flavor in Maltesers and Whoppers or any other malt product. Lactose is in milk and is the primary source of carbohydrates for babies. Starch is in things like pasta, bread, potatoes, and much more and is our primary source of energy. Cellulose is primarily found in vegetables and is more commonly known as fiber. 

Even though all of these are technically sugars, they definitely don't all taste sweet but they do give us the energy to go about or lives.