The change of seasons is sensed by organisms in a variety of ways, but one of the most influential for humans is the increase or decrease in day length. Although various factors likely contribute to variations of SAD, changes in daylight and a disruption of the melatonin/serotonin balance is key. Some of us, based on our genetic disposition, are very sensitive to the changes in daylight that occur with the change in seasons.

Overall skin coloration is determined by the degree to which cells in the skin called melanocytes produce the pigment melanin. Melanin is also responsible for hair and eye coloring. The subtype pheomelanin is responsible for red hair, while the subtype eumelanin is responsible for grey, black, yellow, and brown hair. People with certain ancestries have the genetic coding to create a lot of melanin in their skin and therefore have dark skin. Albinism occurs in individuals who produce no melanin. Freckles are small bunches of melanin that are visible on ...

Our tongue senses only five different tastes- sweet, sour, bitter, salty, and a fifth called umami. The umami responds to salts of glutamic acid, which would be associated with meat broth or aged cheese. Taste receptors function through either a transmembrane ion channel (sour and salty) or a G-protein-coupled receptor (sweet and bitter) and are bundled in groups of 50-150 to form taste buds. Each taste bud probably has a few representatives from each of the five taste classes, but receptors for each of these tastes are focused in different ...

We all know that feeling- from running too far, too fast. Or from pedaling a bike up a hill really hard. (If you don’t, you might want to get out more….) That nauseating feeling in your muscles that makes you stop and lingers for a short while is due to the build-up of lactic acid, which is simply a byproduct of the muscular metabolic process.
Muscle contraction begins with a signal from your brain, which propagates through your nervous system and causes the release of the neurotransmitter acetylcholine at the neuromuscular ...

Vitamin D is a critical nutrient for our bodies. It is responsible for the maintenance of normal blood levels of calcium and phosphorus. By aiding in the absorption of calcium, vitamin D plays a vital role in the maintenance of bone strength. The diseases that caused by a lack of vitamin D are rickets in children (skeletal deformities) and osteomalacia in adults (weak bones and muscles). Recently, vitamin D has been found to protect against diseases such as osteoporosis, hypertension, cancer, and some autoimmune conditions.

Well, it tries… and succeeds in its own way. However, success on the part of the immune system may actually contribute to the permanence of a tattoo.
Skin is an incredible organ. It represents approximately 7% of one’s body mass and is responsible for very important tasks such as regulating body temperature, restricting water loss, and protecting all of our other organs from bacteria and chemicals. In order to maximize its ability to ward off invading pathogens and particles, the skin is immunologically robust. In the skin, the immune system primarily ...

Asparagus-induced aromatic pee is an event that has always amazed me because it happens so quickly. When you eat asparagus, it goes into the stomach to be broken down by acids in the stomach, just like any other food. The nourishing elements of the meal are absorbed into the blood stream and the food molecules travel through the bloodstream to the liver and kidneys for purification. This is all normal and good. Waste that is collected in the kidneys is excreted in urine. Asparagus, unlike other vegetables, contains asparagusic acid. ...

An intrauterine device (IUD) is a type of contraception that is used all over the world. In the United States, there are two different versions.
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Hair can be considered in two separate sections, the root and the shaft. The hair root is located inside of the follicle and exists below the portion of the skin while the shaft is the portion of hair that extends out from the skin. The root of the hair receives nutrients from the blood through the dermal papilla. The nutrients that are supplied to the root of the hair through the dermal papilla, combined with oil from the sebaceous gland, can contribute to hair’s strength. This strength of the hair ...

Your dog can actually eat a little bit of chocolate, but if they eat about an ounce of milk chocolate per kilogram of body weight or as little as a couple of mouthfuls of cocoa mulch, there will be trouble.
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