6.1 Flashcards
(21 cards)
What happens in digestion in the mouth?
Food is mechanically mixed and amylase is secreted
What happens in digestion in the esophagus?
Peristalsis
What happens in the stomach in digestion?
Food is mixed with gastric juice, which contains HCL and protease is secreted, producing chyme and polypeptides, and bacteria are killed
What happens in the pancreas in digestion?
Amylase, lipase and endopeptidase are secreted, digesting food into monomers
What happens in the large intestine in digestion?
Vitamins are reabsorbed and undigested polysaccharides are fermented to produce energy
What happens in the small intestine in digestion?
Neutralisation occurs, lipase and amylase are secreted and most of the absorption takes place
What is peristalsis?
The wave of contraction and relaxation of the longitudinal and circular muscles of the alimentary canal, by which the contents are forced ahead
Where does peristalsis take place?
In the esophagus to the stomach
What happens to the muscles in peristalsis?
The longitudinal and circular muscles work antagonistically, so the longitudinal contracts to widen the lumen, whilst the circular contracts to constrict the lumen
How long is the small intestine?
6-7m in humans
How much does villi increase the small intestines surface area by?
30-60 fold
What are the layers of the small intestine, starting from the outside going in?
Serosa, muscle layers, mucosa, sub mucosa, villi
Where do enzymes come from in the small intestine?
The wall
What does the small intestine produces?
Monosaccharides, amino acids, fatty acids and glycerol, vitamins, mineral ions
Where does absorption of actual food molecules are place?
Over the epithelium
What is directly absorbed by the villi?
- bases and phosphates from nucleic acids
- fatty acids and glycerol
- amino acids
- monomeric carbohydrates
Where are food molecules, minerals and vitamins absorbed into?
The blood or the lymph
Where do food molecules, minerals and vitamins from the blood pass into the small intestine?
They need to pass through capillaries of villus
Where do fats from the lymph pass through the small intestine?
They circulate into the lacteal
How do monosaccharides enter the epithelium?
By sodium- glucose channels in facilitated diffusion
How do amino acids enter the epithelium?
Pumped against the concentration gradient
