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The endothelium forms an interface between circulating blood or lymph in the lumen and the rest of the vessel wall. This forms a barrier between vessels and tissues and control the flow of substances and fluid into and out of a tissue. This controls the passage of materials and the transit of white blood cells into and out of the bloodstream.
Prokaryotes are able to subsist by allowing materials to enter the cell via simple diffusion. Intracellular transport is more specialized than diffusion; it is a multifaceted process which utilizes transport vesicles. Transport vesicles are small structures within the cell consisting of a fluid enclosed by a lipid bilayer that hold cargo. These ...
In cell biology, a vesicle is a structure within or outside a cell, consisting of liquid or cytoplasm enclosed by a lipid bilayer. Vesicles form naturally during the processes of secretion , uptake (endocytosis), and the transport of materials within the plasma membrane.
In muscle cells, a specialized smooth ER (sarcoplasmic reticulum) forms a membranous compartment (cisternal space) into which calcium ions are pumped. When a muscle cell becomes stimulated by a nerve impulse, calcium goes back across this membrane into the cytosol and generates the contraction of the muscle cell.
The transcellular fluid is the portion of total body fluid that is formed by the secretory activity of epithelial cells and is contained within specialized epithelial-lined compartments. Fluid does not normally collect in larger amounts in these spaces, [ 6 ] [ 7 ] and any significant fluid collection in these spaces is physiologically ...
Endocytosis is a cellular process in which substances are brought into the cell. The material to be internalized is surrounded by an area of cell membrane, which then buds off inside the cell to form a vesicle containing the ingested materials. Endocytosis includes pinocytosis (cell drinking) and phagocytosis (cell eating). It is a form of ...
The cell is the basic structural and functional unit of all forms of life. Every cell consists of cytoplasm enclosed within a membrane; many cells contain organelles, each with a specific function. The term comes from the Latin word cellula meaning 'small room'. Most cells are only visible under a microscope.
Light micrograph of a moss's leaf cells at 400X magnification. The following outline is provided as an overview of and topical guide to cell biology: . Cell biology – A branch of biology that includes study of cells regarding their physiological properties, structure, and function; the organelles they contain; interactions with their environment; and their life cycle, division, and death.