Capillaries are the smallest of a body's blood vessels, measuring 5-10 μm. They connect arteries and veins, and most closely interact with tissues. Capillaries have walls composed of a single layer of cells, the endothelium. This layer is so thin that molecules such as oxygen, water and lipids can pass through them by diffusion and enter the tissues. Waste products such as carbon dioxide and urea can diffuse back into the blood to be carried away for removal from the body. Capillary permeability can be increased by the release of cer ...
The cannabis plant can be dried or otherwise processed to yield products containing large concentrations of compounds that have medicinal and psychoactive effects when consumed, usually by smoking or eating. Cannabis has been used for medical and psychoactive effects for thousands of years. Throughout the 20th century there was a massive upswing in the use of cannabis as a psychoactive substance, mostly for recreational purposes but to some extent for religious purposes. The possession, use, or sale of psychoactive cannabis pro ...
The Gray Wolf (Canis lupus; other forms: "Timber Wolf", "Wolf") is a mammal of the Canidae family. The wolf shares a common ancestry with the domestic dog (Canis familiaris), and, according to most experts, is likely the progenitor of all dogs as they exist today (in which case, the domestic dog would more accurately be classified as Canis lupus familiaris). Gray wolves were once abundant and distributed over much of North America, Eurasia, and the Middle East. Today, for a variety of human-caused reasons involving widespread habitat destruction and excessive hunting, wolves inhab ...
In the ovary, the corpus luteum secretes estrogens and progesterone, which are steroid hormones responsible for the thickening of the endometrium and its development and maintenance, respectively. If the egg is not fertilized, the corpus luteum stops secreting progesterone and decays (after approximately 12 days in humans). It then degenerates into a corpus albicans, which is a mass of fibrous scar tissue. The uterine lining sloughs off without progesterone and is either resorbed (in most animals) or expelled through the vagina (in humans and some great ...
Adipose tissue is an anatomical term for loose connective tissue composed of adipocytes. Its main role is to store energy in the form of fat, although it also cushions and insulates the body. It has an important endocrine function in producing recently-discovered hormones such as leptin, resistin and TNFα.
Adipose tissue - Anatomical features.
Adipose tissue is primarily located beneath the skin, but is also found around internal organs. In the skin, it accumulates in the deepest level, the subcutaneous la ...
Triglycerides (also known as triacylglycerols or triacylglycerides) are glycerides in which the glycerol is esterified with three fatty acids. They are the main constituent of vegetable oil and animal fats.
Triglyceride - Chemical structure.
CH2COOR-CHCOOR'-CH2-COOR"
where R, R', and R" are long alkyl chains; the three fatty acids RCOOH, R'COOH and R"COOH can be all different, all the same, or only two the same.
Chain lengths of t ...
Pain is an unpleasant sensation which may be associated with actual or potential tissue damage and which may have physical and emotional components. According to the International Association for the Study of Pain (IASP), one should distinguish between pain and nociception. The term "pain" is a subjective experience that typically accompanies nociception, but can also arise without any stimulus. It includes the emotional response. Nociception, on the other hand, is a neurophysiological term and denotes specific activity in nerv ...
An eye is an organ that detects light. Different kinds of light-sensitive organs are found in a variety of creatures. The simplest eyes do nothing but detect whether the surroundings are light or dark. More complex eyes are used to provide the sense of vision. Many complex organisms including some mammals, birds, reptiles and fish have two eyes which may be placed on the same plane to be interpreted as a single three-dimensional "image" (binocular vision), as in humans; or on different planes producing two separate "images" (monocular ...
Angiogenesis is the physiological process involving the formation of new blood vessels from pre-existing vessels. Though there has been some debate over this, vasculogenesis is the term used for spontaneous blood-vessel formation. Angiogenesis is a normal process in growth and development, as well as in wound healing. However, this is also a fundamental step in the transition of tumors from a dormant state to a malignant state.
Angiogenesis - Types of Angiogenesis.
Angiogenesis - Sprouting An ...
Muscle is a contractile form of tissue. It is one of the four major tissue types, the other three being epithelium, connective tissue and nervous tissue. Muscle contraction is used to move parts of the body, as well as to move substances within the body.
Muscle - Types.
There are three general types of muscle:
Cardiac muscle is a specialized kind of muscle found only within the heart. It cannot get tired and is "involuntary".
Skeletal muscle or "voluntary muscle" is anchored by tendons ...
Atherosclerosis is a disease affecting arterial blood vessels (as well as veins that have been surgically moved to function as arteries). Athēra is porridge in Greek, as the plaque changes have a foamy appearance under high-power light microscopy. Sclerosis denotes hardening; calcification within the oldest, outermost portion of atheroma increase wall stiffness.
Some sources draw a distinction between "Arteriosclerosis," "Atherosclerosis," and "Arteriolosclerosis". In these contexts, "Atherosclerosis" is used whe ...
In anatomy, the blind spot is the region of the retina where the optic nerve and blood vessels pass through to connect to the back of the eye. Since there are no light receptors there, a part of the field of vision is not perceived. The brain fills in with surrounding detail and with information from the other eye, so the blind spot is not normally perceived.
The presence of the blind spot can be demonstrated by drawing a small X on a piece of paper, then drawing a small circle about 12-15 centimetres to the right of the X:
The blood-brain barrier (BBB) is a membrane that controls the passage of substances from the blood into the central nervous system. It is a physical barrier between the blood vessels in the central nervous system, and most parts of the central nervous system itself, that stops many substances from traveling across it.
Blood-brain barrier - History.
The existence of such a barrier was first noticed in experiments by Paul Ehrlich in the late 19th century. Ehrlich was a bacteriologist who was studying s ...
Dinosaurs are vertebrate animals that range from reptile-like to bird-like.[1] Dinosaurs dominated the terrestrial ecosystem for over 160 million years, first appearing around 230 million years ago. 65 million years ago, at the end of the Cretaceous period, all non-avian dinosaurs became extinct. Dinosaurs still exist today in the line of birds (avian dinosaurs). Knowledge about dinosaurs is derived from both fossil and non-fossil records, includ ...
Benoît B. Mandelbrot (born November 20, 1924) is a Polish-born French mathematician and leading proponent of fractal geometry. He is Sterling Professor of Mathematical Sciences, Emeritus at Yale University and IBM Fellow Emeritus at the Thomas J. Watson Research Center.
Benoît Mandelbrot - Early years.
Born in Warsaw, Mandelbrot lived in France from the age of 12 to near the end of his college studies. He was born into a family with a strong academic tradition - his mother was a medical doctor and his unc ...
The Borg Collective is a group of telepathically-connected beings in the Star Trek fictional universe. They are known both within and beyond Star Trek fandom for their relentless pursuit of that which they wish to assimilate, their rapid adaptability to almost any defense, and their ability to continue functioning after what may seem a devastating or even fatal blow seemingly unaffected, and as such have become a powerful symbol in popular culture for any seemingly unstoppable force against which "resistance is futile".
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An atheroma (plural: atheromata) is an abnormal fatty deposit which develops within the walls of arteries over time. Veins do not develop atheromata, unless surgically moved to function as an artery, as in bypass surgery. In the context of heart or artery matters, atheroma is commonly referred to as "plaque."
Collectively, the process of atheroma development within an individual is called atherogenesis and the overall result of the disease process is termed atherosclerosis.
Atheroma - Stages.
...
An autopsy, also known as a post-mortem examination or an obduction, is a medical procedure that consists of a thorough examination of a corpse to determine the cause and manner of a person's death and to evaluate any disease or injury that may be present. It is usually performed by a specialized medical doctor called a pathologist.
A necropsy is a post-mortem examination performed on an animal and it is vulgar usage to apply this term to human beings.
Autopsy - General information. ...
Anton[1] van Leeuwenhoek (October 24, 1632 - August 30, 1723, full name Thonius Philips van Leeuwenhoek (pronounced 'Layewenhook') was a tradesman and scientist from Delft, Netherlands. He was known as "the Father of Microbiology". Born the son of a basket maker, at age 16 he secured an apprenticeship with a Scottish cloth merchant in Amsterdam. He is best known for his contribution to the improvement of the microscope and for his contr ...
