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[4] [5] Pericytes help in the maintainenance of homeostatic and hemostatic functions in the brain, where one of the organs is characterized with a higher pericyte coverage, and also sustain the blood–brain barrier. [6] These cells are also a key component of the neurovascular unit, which includes endothelial cells, astrocytes, and neurons.
A biological barrier is a natural selectively permeable membrane that protects certain organs or tissues by allowing some substances to pass through them, and blocking entry of other substances.
Invertebrates have several other types of specific junctions, for example septate junctions (a type of occluding junction) [4] or the C. elegans apical junction. In multicellular plants, the structural functions of cell junctions are instead provided for by cell walls. The analogues of communicative cell junctions in plants are called ...
Examples of tight epithelia include the distal convoluted tubule, the collecting duct of the nephron in the kidney, and the bile ducts ramifying through liver tissue. Other examples are the blood-brain barrier and the blood cerebrospinal fluid barrier; Leaky epithelia do not have these tight junctions or have less complex tight junctions. For ...
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 ...
A few elements have been found to have a pharmacologic function in humans (and possibly in other living things as well; the phenomenon has not been widely studied). In these, a normally nonessential element can treat a disease (often a micronutrient deficiency). An example is fluorine, which reduces the effects of iron deficiency in rats.
The main intravascular fluid in mammals is blood, a complex mixture with elements of a suspension (blood cells), colloid , and solutes (glucose and ions). The blood represents both the intracellular compartment (the fluid inside the blood cells) and the extracellular compartment (the blood plasma). The average volume of plasma in the average ...
Cell–cell interaction refers to the direct interactions between cell surfaces that play a crucial role in the development and function of multicellular organisms. These interactions allow cells to communicate with each other in response to changes in their microenvironment. This ability to send and receive signals is essential for the ...