GI: The basics Flashcards
What are the major functions of the GI tract?
- mechanically disrupt food
- chemically digest food
- temporarily store food
- kill pathogens in the food
- to move food along the tracts
- to absorb nutrients
- to eliminate residual waste
What is the role of the stomach?
- stores food so we can eat faster than we digest
- receptive relaxation to prevent increased pressure
- secretes acid and proteolytic enzymes to break down food and disinfect
What are the muscle layers of the stomach wall?
Oblique, circular, longitudinal (innermost to outermost)
What are the 3 sections of the small intestine?
Duodenum, Jejunum, Ileum
What is the function of the small intestine?
Duodenum dilutes (permeable to water) and neutralises (alkali bile added) chyme. Digestive enzymes added from pancreas. Small intestine absorbs the majority of water
What are the sections of the large intestine?
Caecum, asc colon- (right hepatic flexure)- transverse colon- (left splenic flexure)- desc colon, sigmoid colon, rectum, anus
What is the function of the large intestine?
Recovery of water to form semi solid contents
Contents await expulsion in the rectum
Mass movement into the rectum around 3x daily
What is the neuronal control of the GI tract?
Somatic (striated muscle) is the mouth, first 1/3 of the oesophagus and the last sphincter of the anus
Autonomic NS controls the rest
Describe the fluid balance of the gut
Every day we injest about 1kg of food and 1L of liquids which is mixed in with 1.5L of saliva and 2.5L of gastric secretions. When the chyme is released from the stomach around 9L of fluid is added from the ECF.
The small intestine then absorbs ~12.5L of fluid and the large intestine absorbs 1.35L
What is the enteric NS?
A subdivision of the autonomic nervous system that controls the GI system. It is made up of 2 nerve plexuses
