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Blood shift is a term used when blood flow to the extremities is redistributed to the head and torso during a breath-hold dive. Peripheral vasoconstriction occurs during submersion by resistance vessels limiting blood flow to muscles, skin, and viscera , regions which are " hypoxia -tolerant", thereby preserving oxygenated blood for the heart ...
Proteomic evidence also supports the universal ancestry of life. Vital proteins, such as the ribosome, DNA polymerase, and RNA polymerase, are found in everything from the most primitive bacteria to the most complex mammals. The core part of the protein is conserved across all lineages of life, serving similar functions.
Greenland ice sheet as seen from space. An ice sheet is a body of ice which covers a land area of continental size - meaning that it exceeds 50,000 km 2. [4] The currently existing two ice sheets in Greenland and Antarctica have a much greater area than this minimum definition, measuring at 1.7 million km 2 and 14 million km 2, respectively.
The transition from non-life to life has never been observed experimentally, but many proposals have been made for different stages of the process. The study of abiogenesis aims to determine how pre-life chemical reactions gave rise to life under conditions strikingly different from those on Earth today.
Anatomy is often described in planes, referring to two-dimensional sections of the body. A section is a two-dimensional surface of a three-dimensional structure that has been cut. A plane is an imaginary two-dimensional surface that passes through the body. Three planes are commonly referred to in anatomy and medicine: [1] [2]: 4
In normal anatomy, there is only one conduit for electrical conduction from the upper chambers to the lower chambers, known as the atrioventricular node. The physiologic cardiac skeleton forms a firewall governing autonomic /electrical influence until bordering the bundle of His which further governs autonomic flow to the bundle branches of the ...
Sexual reproduction appears to be an obligatory phase in the life cycle of diatoms, particularly as cell size decreases with successive vegetative divisions. [68] Sexual reproduction involves production of gametes and the fusion of gametes to form a zygote in which maximal cell size is restored. [ 68 ]
Faraday's ice pail experiment is a simple electrostatics experiment performed in 1843 by British scientist Michael Faraday [1] [2] that demonstrates the effect of electrostatic induction on a conducting container. For a container, Faraday used a metal pail made to hold ice, which gave the experiment its name. [3]