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Human teeth function to mechanically break down items of food by cutting and crushing them in preparation for swallowing and digesting. As such, they are considered part of the human digestive system. [1] Humans have four types of teeth: incisors, canines, premolars, and molars, which each have a specific function. The incisors cut the food ...
Macular degeneration, also known as age-related macular degeneration (AMD or ARMD), is a medical condition which may result in blurred or no vision in the center of the visual field. [1] Early on there are often no symptoms. [1] Over time, however, some people experience a gradual worsening of vision that may affect one or both eyes. [1]
Xerophthalmia (from Ancient Greek xērós (ξηρός) meaning "dry" and ophthalmos (οφθαλμός) meaning "eye") is a medical condition in which the eye fails to produce tears. It may be caused by vitamin A deficiency, [ 1 ] which is sometimes used to describe that condition, although there may be other causes.
Studies have shown that incidence of dry eyes increases with age, [84] [85] especially among women. [86] Tear film stability (e.g. tear break-up time) is significantly lower among women than among men. In addition, women have a higher blink frequency while reading. [87] Several factors may contribute to gender differences. One is the use of eye ...
Vitamin C and B vitamins are water soluble, so we pee out what we don’t need in a matter of days. Vitamins A, D, E, and K are fat soluble, so we can store extra in our tissues. It’s easier to ...
The macula (/ˈmakjʊlə/) [1] or macula lutea is an oval-shaped pigmented area in the center of the retina of the human eye and in other animals. The macula in humans has a diameter of around 5.5 mm (0.22 in) and is subdivided into the umbo, foveola, foveal avascular zone, fovea, parafovea, and perifovea areas.
In humans, the molar teeth have either four or five cusps. Adult humans have 12 molars, in four groups of three at the back of the mouth. The third, rearmost molar in each group is called a wisdom tooth. It is the last tooth to appear, breaking through the front of the gum at about the age of 20, although this varies among individuals and ...
By targeting the USAG-1 gene, researchers believe that they can help people without a full set of teeth regrow teeth. The team says that humans have a third set of teeth available as buds, ready ...