HLTH1030 Lecture 18: HTLH1030-Lecture 18
Document Summary
Catabolic process that breaks macromolecules down into chemical building blocks (monomers) by enzymes so they are small enough for absorption across wall of small intestine. Process of moving substances from lumen of gut through apical membrane of epithelial cells into the body through basolateral membrane. Most nutrients are absorbed before chyme reaches ileum. Occurs via diffusion, facilitated transport, osmosis and active transport. Modifications of mucosa & submucosa reflects function => achieve maximal digestion and absorption: small intestine length. Stretches from pyloric sphincter to ileocecal valve. Allows for sufficient time for digestion and absorption: plicae circulares. Permanent circular folds of mucosa & submucosa. Form transverse to spiral ridges, ~1 cm deep circul. > force chyme to slowly spiral through lumen. Absent from the first few cm of the duodenum, then all the way to the middle of the ileum. Increase surface area ~ 3 fold: plicae circulares, villi and crypts. Each of the plicae circulares contains many villi: