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Viscera includes organs of digestive system, respiratory system, urinary system and reproductive system. Mainly located in the chest cavity, abdominal cavity and pelvic cavity, it communicates directly or indirectly with the outside world through pipes.
1. Digestive system: the general term for digestive organs, which consists of digestive tubes and digestive glands.
2. Respiratory system: it is the general name of respiratory organs, which consists of respiratory tract and lungs. The respiratory tract is a passage for gas to enter and leave the lungs, which consists of nose, pharynx, larynx, trachea and bronchus.
3. Urinary system: A system consisting of a group of organs that produce, transport, store and excrete urine. Human urinary system includes kidney, ureter, bladder and urethra. When blood passes through the kidney, water and some substances (mainly metabolites) in the blood are filtered out through the glomerulus, and then stored in the bladder through the renal pelvis and ureter. When urinating, bladder muscles contract and urine is discharged through urethra.
4. Reproductive system: anatomical name. It is a general term for organs that reproduce offspring and continue races. The organs of the reproductive system are different between men and women, but they are all composed of gonads, reproductive ducts and accessory organs according to their functions. Reproductive organs can reproduce through their various activities, fertilization, pregnancy and other physiological processes.
Extended data:
According to its morphological structure, it can be divided into lumen organs and parenchymal organs. The lumen organs are connected with the outside world through pipelines; The parenchymal organs are mainly glands, and there are catheter openings on the wall of the lumen organs.
From the perspective of individual development, most digestive and respiratory systems are derived from endoderm; The respiratory organ is another tube protruding from the upper part of the primitive digestive tube to the ventral side.
The urinary and reproductive organs originated from the urogenital ridge of mesoderm and evolved into urinary and reproductive systems with different functions. But men still have common discharge tubes. Therefore, some people collectively refer to the urinary and reproductive systems as the urogenital system.