6.1 - Digestion And Absorption Flashcards
Mouth
- voluntary control of eating and swallowing
- mechanical digestion of food by chewing and mixing with saliva
- saliva contains lubricants and enzymes that start starch digestion
Esophagus
Movement of food by peristalsis from the mouth to the stomach
Stomach
Churning and mixing with secreted water and acid which kills foreign bacteria and other pathogens in food, plays initial states of protein digestion
Small intestine
Final stages of digestion of lipids, carbohydrates, proteins and nucleic acids, neutralising stomach acid, plus absorption of nutrients
Pancreas
Secretion of lipase, amylase and protease
Liver
Secretion of surfactants in bile to break up lipid droplets
Gall bladder
Storage and regulated release of bile
Large intestine
- re-absorption of water
- further digestion especially of carbohydrates by symbiotic bacteria, plus formation and storage of feces
What is peristalsis?
The contraction of circular and longitudinal muscle layers of the small intestine
Peristalsis (4)
- mixes food with enzymes and moves it along the gut
- muscle is smooth, short cells that exert continuous force of varying strength
- only occurs in one direction and when moved to the stomach occurs in one peristaltic wave
- in small intestine, moves at a few centimetres a time and its main role is to churn the chyme, accelerating digestion
Name the 6 structures found in the cross-section of a villus
- serosa
- circular muscle layer
- longitudinal muscle layer
- mucosa
- intestinal villi
- lumen
What is the mucosa?
Tissue with blood and lymphatic vessels below the epithelium
What is the epithelium?
Single layer of cells lining the small intestine
Muscles
Antagonistic
Smooth muscles which propel food along the gut
Inner circular, outer longitudinal
