Phagocytes are the white blood cells that protect the body by ingesting
(phagocytosing) harmful foreign particles, bacteria and dead or dying
cells. They are essential for fighting infections, and for subsequent
immunity. Phagocytes are important throughout the animal kingdom, and
are highly developed in vertebrates. One liter of human blood contains
about six billion phagocytes. Phagocytes were first discovered in 1882
by Ilya Ilyich Mechnikov while he was studying starfish larvae.
Phagocytes of humans and other animals are called professional or
non-professional, depending on how effective they are at phagocytosis.
The professional phagocytes include cells called neutrophils,
monocytes, macrophages, dendritic cells, and mast cells. The main
difference between professional and non-professional phagocytes is that
the professional phagocytes have molecules called receptors on their
surfaces that can detect harmful objects, such as bacteria, that are
not normally found in the body. Phagocytes are therefore crucial in
fighting infections, as well as in maintaining healthy tissues by
removing dead and dying cells that have reached the end of their
life-span. During an infection, chemical signals attract phagocytes to
places where the pathogen has invaded the body.
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Today's selected anniversaries:
Spainish Conquistador Gonzalo Jiménez de Quesada founded a European
urban settlement in what is today Bogotá, Colombia.
The Holy Roman Empire was dissolved by its last emperor Francis II
during the aftermath of the War of the Third Coalition.
World War II: The U.S. Army Air Force bomber Enola Gay dropped an
atomic bomb named Little Boy on Hiroshima, Japan, killing as many as
British computer programmer Tim Berners-Lee first posted files
describing his ideas for a system of interlinked, hypertext documents
accessible via the Internet, to be called a "World Wide Web".
Mauritanian President Sidi Mohamed Ould Cheikh Abdallahi was ousted
from power by a group of high ranking generals that he had dismissed
from office several hours earlier.
Wiktionary's word of the day:
1. To fill cracks or holes with a plastic paste.
2. To fill gaps with something; to speckle
Wikiquote quote of the day:
I hold it true, whate'er befall;
I feel it, when I sorrow most;
'Tis better to have loved and lost
never to have loved at all.