Humans, and piglets, and bears, oh my! Preventing dangerous blood clots
"Don't poke the bear," they said. But that's exactly what a team of scientists have been doing to discover the secrets of blood clotting.
Apr 13, 2023
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"Don't poke the bear," they said. But that's exactly what a team of scientists have been doing to discover the secrets of blood clotting.
Apr 13, 2023
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(Medical Xpress)—A team of researchers working at the University of Toronto in Canada may have found the answer to the question of why we humans tend to have little to no memory of the first few years of our lives. In their ...
(Medical Xpress)—Apes, including humans, lack an enzyme called uricase that breaks down uric acid. Because we lack uricase, we are predisposed to developing gout. After reconstructing ancient versions of the enzyme found ...
A new study by researchers at the Stanford University School of Medicine could help pinpoint ways to counter the effects of the antibiotics-driven depletion of friendly, gut-dwelling bacteria.
Sep 1, 2013
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(Medical Xpress)—Researchers at the University of California, San Francisco (UCSF) have identified the lynchpin that activates brown fat cells, which burn fat molecules instead of storing them, making them the focus of ...
Oct 19, 2012
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It might be possible for human-to-human airborne transmissible avian H5N1 influenza viruses to evolve in nature, new research has found. The findings, from research led by Professor Derek Smith and Dr Colin Russell at the ...
Jun 21, 2012
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In mammals, including humans, scar tissue forms after injury to the spinal cord as part of the healing process. In mammals, however, this has a serious drawback: the scar tissue cannot be penetrated by regrowing nerves. As ...
Nov 10, 2023
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Whether a mouse is a good or bad parent can be traced back to imprinted genes in key neurons in the "parenting hub" in the brain, according to a new study by Anthony Isles of Cardiff University and colleagues, published October ...
Oct 19, 2023
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Trying to finish your homework while the big game is on TV? "Visual-movement" neurons in the front of your brain can help you stay focused, according to a new study from neuroscientists in the Perelman School of Medicine ...
Aug 9, 2023
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University of Queensland research has revealed features of early human brain development are mimicked in the brains of marsupials.
May 23, 2023
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Mammals (formally Mammalia) are a class of vertebrate animals whose females are characterized by the possession of mammary glands while both males and females are characterized by sweat glands, hair, three middle ear bones used in hearing, and a neocortex region in the brain.
Mammals are divided into three main categories depending how they are born. These categories are, monotremes, marsupials and placentals. Except for the five species of monotremes (which lay eggs), all mammal species give birth to live young. Most mammals also possess specialized teeth, and the largest group of mammals, the placentals, use a placenta during gestation. The mammalian brain regulates endothermic and circulatory systems, including a four-chambered heart.
There are approximately 5,400 species of mammals, distributed in about 1,200 genera, 153 families, and 29 orders (though this varies by classification scheme). Mammals range in size from the 30–40-millimetre (1.2–1.6 in) Bumblebee Bat to the 33-metre (110 ft) Blue Whale.
Mammals are divided into two subclasses, the prototheria, which includes the oviparous monotremes, and the theria, which includes the placentals and live-bearing marsupials. Most mammals, including the six largest orders, belong to the placental group. The three largest orders, in descending order, are Rodentia (mice, rats, and other small, gnawing mammals), Chiroptera (bats), and Soricomorpha (shrews, moles and solenodons). The next three largest orders include the Carnivora (dogs, cats, weasels, bears, seals, and their relatives), the Cetartiodactyla (including the even-toed hoofed mammals and the whales) and the Primates to which the human species belongs. The relative size of these latter three orders differs according to the classification scheme and definitions used by various authors.
Phylogenetically, Mammalia is defined as all descendants of the most recent common ancestor of monotremes (e.g., echidnas and platypuses) and therian mammals (marsupials and placentals). This means that some extinct groups of "mammals" are not members of the crown group Mammalia, even though most of them have all the characteristics that traditionally would have classified them as mammals. These "mammals" are now usually placed in the unranked clade Mammaliaformes.
The mammalian line of descent diverged from an amniote line at the end of the Carboniferous period. One line of amniotes would lead to reptiles, while the other would lead to synapsids, including mammals. The first true mammals appeared in the Triassic period. Modern mammalian orders appeared in the Palaeocene and Eocene epochs of the Palaeogene period.
This text uses material from Wikipedia, licensed under CC BY-SA