How are small intestines / ileum adapted/ suited to its function?

-They are long; to increase the surface area for digestion and absorption of food;
-They are highly coiled/ folded; to slow down movement of food to allow more time for digestion and absorption of digested food substances.
-Inner lining has numerous villi and micro-villi; to increase the surface area for digestion and absorption of food substances;
-Their walls have glands (crypts of Liberkurn) that secrete intestinal juice; which contains enzymes for digestion of food;
-Inner lining has goblet cells that secrete mucus; to lubricate food and protect their walls against digestion by enzymes; and lubrication of food;
-Are narrow/ has narrow lumen; to bring food into contact with intestinal walls/ blood vessels rapid/ faster absorption of food substances;
-The walls have smooth muscles which contract and relax; to facilitate peristalsis;
-They are highly vascularized/well supplied with blood capillaries; to create a steep/high concentration gradient hence faster diffusion of digested food/ for rapid and efficient of removal of absorbed products;
-They have lacteal vessels; for absorption of fatty acids and glycerol;
-They have thin epithelium; to reduce the distance travelled by digested food hence faster absorption;
-They have numerous mitochondria; to provide energy for absorption of food;