small intestine and liver and gallbladder and pancreas

majority of:

digestion and absorption happens here

villi

finger-like projections in the small intestine which all contain a bunch of capillaries

microvilli

each villi has thousands of microvilli, which increase the surface area even more.

lymphatic vessels 

lacteals - nutrients are absorbed into the lymphatic system, which absorbs fats, defends against disease, and controls fluid balance.

small intestine 3 reigons

duodenum - 25 cm long 

jejunum 250 cm long 

ileum 300 cm long 

pH of small intestine

8

duodenum

majority of chemical digestion happens here:

ducts from gallbladder and pancreas join and empty into the duodenum 

jejunum 

food is broken down and some absorption of nutrients occurs 

ileum

absorption of nutrients and pushing remaining chyme into the large intestine

Pancreas functions 

release bicarbonate ions - neutralize hydrochloric acid from the stomach, bringing the pH up from 2 to 8

enzymes secreted from the pancreas

carbohydrases - break down carbohydrates

• ex. pancreatic amylase (like salivary amylase) 

proteases - breaks down proteins 

• ex. chymotripson and trypsin 

lipases - breaks down lipids 

nucleases - breaks down nucleic acids 

liver functions

makes blood, hormones, and bile

bile

bile is made of bile salts and bile pigments. Bile emulsifies fats, breaking lipids down into small droplets, increasing surface area.This is a mechanical digestion

how does bile and lipases work together 

bile increases surface area for lipids, mechanically digesting lipids 

lipases use the broken down lipid droplets and deconstruct them 

the liver stores glucose in the form of…

glycogen

gallbladder function

stores bile - in the presence of lipids, the gallbladder releases bile into the duodenum

segmentation

the back and forth peristalsis-like motion that sloshes chyme back and forth between the small intestine.This movement isn’t for moving the chyme, it’s to break it down. When the chyme is broken down to smaller bits, it moves forwards.