Category: Ya-Yz

A narrow tube present in the early embryo that connects the midgut of the embryo to the yolk sac outside the embryo through the umbilical opening. Later in development, the yolk stalk is usually obliterated, but a remnant of it may persist: most commonly as a finger-like protrusion from the small intestine known as Meckelis diverticulum. Found in 2 to…

An acute systemic (bodywide) illness caused by a virus called a Flavivirus. In severe cases, the viral infection causes a high fever, bleeding into the skin, and necrosis (death) of cells in the kidney and liver. The damage done to the liver from the virus results in severe jaundice which yellows the skin. Hence, the “yellow” in “yellow fever.” Yellow fever…

Overgrowth of yeast can affect the skin (yeast rash), mouth (thrush), digestive tract, esophagus, vagina (vaginitis), and other parts of the body. Yeast infections occur most frequently in moist areas of the body. Although Candida albicans and other Candida yeasts are the most frequent offenders, other yeast groups are known to cause illness, primarily in immunocompromised patients. These include Torulopsis, Cryptococcus, Malassezia, and Trichosporon…

A group of single-celled fungi that reproduce by budding. Most yeast are harmless (some are used in baking and brewing). Yeast is commonly present on normal human skin and in areas of moisture, such as the mouth and vagina, usually without causing any problems. However, yeast can produce disease in people. For example, the yeast Candida (once called Monilia) causes thrush (oral…

Yard.

Involuntary opening of the mouth with respiration, breathing first inward, then outward. Yawning is often caused by the power of suggestion. Repeated yawning may be a sign of drowsiness. It can also sometimes be a sign of depression.

Involuntary opening of the mouth, accompanied by slowly breathing inward and then outward. Repeated yawning can be a sign of drowsiness, boredom, or depression. The yawn helps to open tiny air sacs (alveoli) in the lungs that can collapse during shallow breathing.

The use of a YAG (yttrium-aluminum-garnet) laser to do surgery. One use for a YAG laser in surgery is to punch a hole in the iris to relieve increased pressure within the eye from acute angle-closure glaucoma. In this type of glaucoma, there is a sudden (acute) increase in pressure in the anterior (front) chamber of the eye due…

Inheritance of genes on the Y chromosome. Since only males normally have a Y chromosome, Y-linked genes can only be transmitted from father to son. Y-linked inheritance is also called holandric inheritance. A number of genes were are known to be Y-linked including:

The sex chromosome that is found, together with an X chromosome, in most normal males. The Y chromosome contains the unique male-determining gene and the male fitness genes that are active only in the testis and are responsible for the formation of sperm. Other genes on the Y chromosome have counterparts on the X chromosome, are active in…