Search results
Results from the WOW.Com Content Network
For the most part, vitamins are obtained from the diet, but some are acquired by other means: for example, microorganisms in the gut flora produce vitamin K and biotin; and one form of vitamin D is synthesized in skin cells when they are exposed to a certain wavelength of ultraviolet light present in sunlight.
This is an accepted version of this page This is the latest accepted revision, reviewed on 4 March 2025. List of organ systems in the human body Part of a series of lists about Human anatomy General Features Regions Variations Movements Systems Structures Arteries Bones Eponymous Foramina Glands endocrine exocrine Lymphatic vessels Nerves Organs Systems Veins Muscles Abductors Adductors ...
Metabolites produced from vitamin D 2 tend to bind less well to the vitamin D-binding protein. [3] Vitamin D 3 can alternatively be hydroxylated to calcifediol by sterol 27-hydroxylase, an enzyme coded for by gene CYP27A1, but vitamin D 2 cannot. [3] Ergocalciferol can be directly hydroxylated at position 24 by the enzyme coded for by CYP27A1. [3]
In vertebrates, the circulatory system is a system of organs that includes the heart, blood vessels, and blood which is circulated throughout the body. [ 1 ] [ 2 ] It includes the cardiovascular system , or vascular system , that consists of the heart and blood vessels (from Greek kardia meaning heart , and Latin vascula meaning vessels ).
Vitamin B 12 is produced in nature by certain bacteria, and archaea. [71] [72] [73] It is synthesized by some bacteria in the gut microbiota in humans and other animals, but it has long been thought that humans cannot absorb this as it is made in the colon, downstream from the small intestine, where the absorption of most nutrients occurs. [74]
The human body consists of many interacting systems of organs. These interact to maintain homeostasis, keeping the body in a stable state with safe levels of substances such as sugar and oxygen in the blood. [58] Each system contributes to homeostasis, of itself, other systems, and the entire body. Some combined systems are referred to by joint ...
Parts-per-million cube of relative abundance by mass of elements in an average adult human body down to 1 ppm. About 99% of the mass of the human body is made up of six elements: oxygen, carbon, hydrogen, nitrogen, calcium, and phosphorus. Only about 0.85% is composed of another five elements: potassium, sulfur, sodium, chlorine, and magnesium ...
In some parts of the world rheumatic heart disease is a major cause of valvular heart disease, typically leading to mitral or aortic stenosis and caused by the body's immune system reacting to a streptococcal throat infection.