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In biology, tissue is an assembly of similar cells and their extracellular matrix from the same embryonic origin that together carry out a specific function. [1] [2] Tissues occupy a biological organizational level between cells and a complete organ. Accordingly, organs are formed by the functional grouping together of multiple tissues. [3]
There are four basic types of animal tissues: muscle tissue, nervous tissue, connective tissue, and epithelial tissue. [5] [9] All animal tissues are considered to be subtypes of these four principal tissue types (for example, blood is classified as connective tissue, since the blood cells are suspended in an extracellular matrix, the plasma).
In animals, the plasma membrane is the outer boundary of the cell, while in plants and prokaryotes it is usually covered by a cell wall. This membrane serves to separate and protect a cell from its surrounding environment and is made mostly from a double layer of phospholipids , which are amphiphilic (partly hydrophobic and partly hydrophilic ).
Cells in animal tissues were observed later than those in plants because their tissues are fragile and difficult to study. Biologists believed that there was a fundamental unit to life, but until Henri Dutrochet were unclear what it was. Besides stating “the cell is the fundamental element of organization”, Dutrochet claimed that cells were ...
Cell junctions [1] or junctional complexes are a class of cellular structures consisting of multiprotein complexes that provide contact or adhesion between neighboring cells or between a cell and the extracellular matrix in animals. [2] They also maintain the paracellular barrier of epithelia and control paracellular transport. Cell junctions ...
These cozy breakfast recipes, like sweet potato toast and oatmeal, take under 20 minutes to prepare for a warm and nourishing meal to start your day.
This was ultimately concluded by plant scientist Matthias Schleiden [5] and animal scientist Theodor Schwann in 1838, who viewed live cells in plant and animal tissue, respectively. [ 3 ] 19 years later, Rudolf Virchow further contributed to the cell theory, adding that all cells come from the division of pre-existing cells. [ 3 ]
Four plays later, Mayfield threw a 9-yard scoring pass to Rachaad White that made it 10-10. Rookie Bucky Irving scored on 12-yard run that put Tampa Bay ahead 17-13 early in the fourth quarter.