Digestion Intestine To Elimination

Small because it’s narrow consists of three parts where majority of absorption happens and pushes indigestible material to large intestine

Site of chemical digestion and releases hormones where auxiliary organ come into play including pancreas liver and gall bladder

Specialized for absorption

Does the last parts of absorbing

Chyme is pushed through the pycloic sphincter of the stomach into the duodenum once in the duodenum chyme moves via segmentation(chyme sloshes back and forth between segments of small intestine)

Chyme is very acidic so the duodenum secretes 3 hormones secretin, gastric inhibitory peptide (GIP) and cholecsyokinin (CCK)

Response to high acid levels the cells of the small intestine secrete a hormone into the bloodstream called secretin which goes to the pancreas causing it to secrete bicarbonate HCO which is a base so it neutralizes the acid from the stomach (pH of 2 to 8)

The amount of Chyme needs to be controlled because if not large macromolecules may not be broken down a hormone called gastric inhibitory peptide is secreted by the duodenum cells this hormone then travels to bloodstream to the stomach where is slows peristalsis and turns off the secretion of gastric juices

Choleccystokinin a hormone that stimulates the digestion of fats and proteins CCK is produced by duoedenum cells and sent to the pancreas to stimulate the production of pancreatic juices. These juices have enzymes that will assist the in digestion of various macromolecules CCK can affect gall bladder and liver

In addition to bicarbonate the pancreas secrets many enzymes into the duodenum that ate important in the chemical digestion of macromolecules

Trypsin and chymotrypsin continue where pepsin left off and breaks down the polypeptides into shorter peptides trypsin only works in basic environments. Another proteases are secreted by the pancreas are called peptidases these finish off the protein digestion by tiring the small pepyides into invidual amino acids

The digestion of starch began in the mouth with the salivary amylase much of the starch and disaccharide are still present in the chyme in the duodenum An enzyme secreted by the pancreas called pancreatic amylase continues to break down the leftover starch into smaller disaccharides then the cells of the small intestine secrete carbohydrases to break down and disaccharide into monosaccharides ( the jejenum absorbs this)

No lipid digestion has happpend at all so far When the fat is detected in the duodenum a hormone called gastric inhibitory CCK ins releases into the blood the CCK targets gall bladder and pancreas causing them to secrete digestive juices (gall bladder doesn’t produce but stores bile) Bile emulsifies the small intestine ( large fat droplets into smaller fat droplets) this increase surface area for chemical digestion. No chemical bonds are broken by the bile so this is considered mechanical digestion Once emulsified an enzyme is secreted by the pancreas called lipases and can chemically digest the fats into fatty acids and glycerol and get absorbed

DNA and RNA need to be broken apart into individual nucleotide the pancreas releases nucleases that chemically digest the Nucleic acids in order for absorption to make new dna in our cells

Made by liver from bile salts choresterol and substance called bilirubin which comes from recycled blood cells

Long finger like projections called vili line the walls of the small intestine this is it increase surface area for absorption by 10x inside vili are capillaries and the take in the nutrients to supply to the rest of the body

Each cell of the Vili have smaller projections call microvili that increase surface area even further

After all absorption is complete in the small intestine undigested material leaves the small intestine through a valve and enters the large intestine and chemical digestion is complete by the time it enters the large intestine. The large intestine absorbs excess water and water soluble vitamins and excess salts that are left after digestion. Colon is filled with many bacteria which aid in absorption and produce vitamins b 12 & k and some amino acids

When most water has been removed from the indicates material a solid waste matter call feces is what remains and peristalsis propels the feces through the large intestine finger shaped and into the rectum which is th last few inches of the large intestine feces is collected here and eliminated through anus.

Located near the junction of the small and large intestine finger shaped pouch which has no major function appendix can be removed if infected by bacteria

Monosaccharides and amino acids are absorbed by active transport into the capillaries and fats diffuse into lacteals where they go to the liver to be processed

Cholesterol in the bile can crystallize out of solution and these crystals are gallstones and are painful gallbladder can be removed and person can live without it