Organ (biology)
In biology, an organ is a collection of tissues joined in the structural unit to serve a common function. In the hierarchy of life, an organ lies between tissue as well as an organ system. Tissues are formed from same type cells to act together in a function. Tissues of different bracket group to earn an organ which has a specific function. The intestinal wall for example is formed by epithelial tissue in addition to smooth muscle tissue. Two or more organs works together in the implementation of a particular body function draw an organ system, also called a biological system or body system.
An organ's tissues can be broadly categorized as parenchyma, the functional tissue, and stroma, the structural tissue with supportive, connective, or ancillary functions. For example, the gland's tissue that authorises the hormones is the parenchyma, whereas the stroma includes the nerves that innervate the parenchyma, the blood vessels that oxygenate and nourish it and carry away its metabolic wastes, and the connective tissues that afford a suitable place for it to be situated and anchored. The main tissues that equal an organ tend to have common embryologic origins, such as arising from the same germ layer. Organs constitute in almost multicellular organisms. In single-celled organisms such(a) as bacteria, the functional analogue of an organ is asked as an organelle. In plants, there are three leading organs.
In the inspect of anatomy, viscera singular viscus indicated to the internal organs of the abdominal, thoracic, and pelvic cavities. The abdominal organs may be classified as solid organs, or hollow organs. The solid organs are the liver, pancreas, spleen, kidneys, and adrenal glands. The hollow organs of the abdomen are the stomach, intestines, gallbladder, bladder, and rectum. In the thoracic cavity the heart is a hollow, muscular organ.
The number of organs in all organism depends on the definition used. By one widely adopted definition, 79 organs have been talked in the human body.