The excretory system refers to the continuous production of wastes that cannot be reused or even toxic in the metabolic process of animals. At the same time, excessive intake of water, salt and some toxic substances are taken into the body when the animals ingest food, and these substances must be continuously excreted. The endogenous metabolites, excess substances, and substances not required by the body are transported to the excretory organs through the blood circulation, and are excreted from physiological processes called excretion. This process is mainly done by the way the kidneys form urine. The excretory system also has a relatively stable function of regulating body water, salt metabolism, acid-base balance, and maintaining the internal environment while discharging urine.
Animals continue to produce waste that cannot be reused or even toxic during the metabolism process. At the same time, when the animal ingests food, excessive water, salt and some toxic substances are taken into the body, and these substances must be continuously excreted. The process of expelling the final metabolites and excess water and various foreign bodies entering the body is called excretion. This process is mainly done by the way the kidneys form urine. The excretory system also has a relatively stable function of regulating body water, salt metabolism, acid-base balance, and maintaining the internal environment while discharging urine. Protozoa complete the body's water balance and excretion with a balloon. The excretory organ of the flat animal is a flame cell. The kidney tube is a simple kidney-like excretory organ of annelids, mollusks, and other invertebrates. Vertebrates have concentrated kidneys and ureters and have a close relationship with the reproductive system. Mammalian excretory system Including the kidneys, ureters, bladder and urethra. In vertebrate animals, reptiles and birds are mainly uric acid; while fish, amphibians and mammals are mainly urea.
Urinary system consists of the kidney, ureter, bladder and urethra. Its main function is excretion. Excretion refers to the physiological processes that are produced in the body's metabolic process and are not transported to the body by substances that are utilized or harmful to the body.
The main function of the kidney is to eliminate waste from the blood by producing urine. They perform a variety of steady state functions such as:
Keep extracellular fluid.
Maintain ion balance in extracellular fluid.
Maintain the pH and osmotic concentration of the extracellular fluid.
Excretion of toxic metabolic by-products such as urea, ammonia and uric acid.
The ureter is connected to the renal pelvis and the lower bladder. It is a pair of slender tubes with a flat cylindrical shape with an average diameter of 0.5 to 0.7 cm. The adult ureter is 25 to 35 cm in length and is located in the retroperitoneum and descends vertically along the anterior aspect of the medial aspect of the psoas muscle into the pelvis. The ureter has three stenosis: one at the renal pelvis and the ureteral transition (the beginning of the ureter), one at the entrance to the small pelvis, and the last one inside the bladder wall. This stenosis are areas where stones, blood clots, and necrotic tissue are easily retained. The female ureter passes over the outside of the cervix to the bladder. The ureter - the bladder junction has a special structure, the valdalene sheath, which effectively prevents urine from flowing back into the ureter.
The biliary system mainly includes the gallbladder, the common hepatic duct and the common bile duct. The gallbladder is pear-shaped and located in the anterior part of the right longitudinal groove below the liver. It is connected to the common bile duct by the cystic duct. The part of the gallbladder that protrudes from the hepatic anterior border is called the gallbladder base. The surface projection is on the outer edge of the right rectus abdominis and the rib. Bow junction. The left and right hepatic ducts of the left and right hepatic lobe merge into the common hepatic duct, and the common hepatic duct and the cystic duct merge into the common bile duct. The common bile duct is about 6-8 cm long and descends from the duodenal bulb and the back of the pancreatic head in the hepatoduodenal ligament. The end and the pancreatic duct merge and expand into an ampulla, opening in the duodenum. In the opening, there is an Oddi sphincter around the opening.
Excretory system organ disease
Tonsillitis is an important cause of acute nephritis and an important cause of recurrent acute exacerbations of chronic nephritis and primary nephrotic syndrome. Active prevention and treatment of tonsillitis is of great significance for the treatment of glomerular diseases.
From the structure and function of the kidney, it is known that each kidney has 1 million nephrons, and the nephron is mainly composed of glomeruli, renal capsules, and renal tubules. The glomerulus has a filter membrane with good permeability filtration. The blood of the human body flows through the kidneys during the circulation. The glomerulus filters the water and medium and small molecules in the plasma to form the original urine. However, due to the negative charge of the glomerular filtration membrane, proteins in plasma also carry a negative charge. According to the principle of homosexuality, plasma proteins are left in the plasma and are not easily filtered. Only a very small amount of plasma protein will "leak the net", but when they are mixed in the original urine through the various tubules, they will be reabsorbed and returned to the circulating blood. The original urine filtered from the glomerulus reaches 180 liters per day, but it is reabsorbed and secreted by the renal tubules, and the final concentration is only about 1.5 liters per day. The protein content is about 40-100 mg, which cannot be determined by the qualitative method of urine protein.
1. Standring S.; et al. Gray's anatomy: the anatomical basis of clinical practice. London: Churchill Livingstone. 2008, pp. 1163, 1177, 1185–6