What is absorption? Mention the absorption of nutrients and other substances in alimentary canal?

The passage of end products of digestion through the mucosal lining of alimentary canal into blood and lymph is called absorption. 90% of absorption takes place in small intestine and the rest in mouth, stomach and large intestine. 

1. Month: Absorption takes place through mucosa of mouth and lower side of tongue into the blood capillaries, e.g. Some drugs like certain painkillers. 

2. Stomach: Gastric mucosa is impermeable to most substances hence nutrients reach unabsorbed till small intestine. Little water, electrolytes, alcohol and drugs like aspirin get absorbed in stomach. 

3. Small Intestine: Glucose, fructose, galactose, amino acids, minerals and water-soluble vitamins are absorbed in blood capillaries in villi. Lipids and fatsoluble vitamins ( A, D, E, K) are absorbed in lacteals. 

4. Large Intestine: Absorption of water, electrolytes like sodium and chloride, drugs and some vitamins take place.