What Is a Urinary Sphincter?
Sphincter refers to a ring-shaped muscle distributed in some luminal walls of humans and animals. It is often thickened. The sphincter in the human body is found in the digestive tract and urinary system.
- [kuò yu j]
- Chinese name
- Sphincter
- distribution range
- Some luminal walls in humans and animals
- Category
- Ring muscle
- Features
- Extra thick
- Common in the human body
- Digestive and urinary systems
- Influencing factors
- Vegetative innervation or hormonal regulation
- Sphincter refers to a ring-shaped muscle distributed in some luminal walls of humans and animals. It is often thickened. The sphincter in the human body is found in the digestive tract and urinary system.
- When the sphincter is contracted, the lumen can be closed, and when it is dilated, the lumen is opened, and it is usually in a contracted state. It is generally regulated by vegetative innervation or hormones.
- classification
- (1) The pyloric sphincter at the exit of the stomach, which can limit the amount of food discharged per gastric motility, and prevent the duodenal contents from flowing back into the stomach.
- (2) The ileocecal sphincter at the junction of the end of the ileum and the cecum can prevent the contents of the ileum from being discharged to the cecum; prevent the contents of the ileum from entering the large intestine too quickly, and extend the residence time of the chyme in the small intestine, which is conducive to the complete digestion of the contents And absorb and prevent the contents of the large intestine from flowing back to the ileum.
- (3) There is an internal urethral sphincter at the junction of the urethra and the bladder. When the urethra is contracted, the inner urethra can be closed to prevent urine leakage. The membrane of the urethra (urogenital septum) has urethral sphincter, which is composed of striated muscles and is controlled by consciousness.
- (4) At the anal canal, there is a strong muscle ring called anorectal ring, which is composed of internal anal sphincter, shallow anal external sphincter, deep, levator anus, and longitudinal rectum. This ring plays an extremely important role in enclosing the anal canal, and injury will cause fecal incontinence. The internal anal sphincter has no sphincter function, and only has the role of assisting defecation. The external anal sphincter is composed of striated muscles, subject to conscious control, and loosened during defecation.