VILLI:villi are hair-like projections that cover the lining of small intestine.
MEDIASTINUM:mediastinum is a presised group of structures in thorax connected by loose connective tissue.
EPIGLOTTIS:epiglottis is a flap of cartilage located in the throat behind the tongue and in front of larynx.it prevents food and liquid from going into trachea.
*the functions of different types of blood vessels in the body are given below:-
1)arteries carry blood away from the heart.they carry oxygenated blood except for pulmonary artery.
2)veins bring blood to the heart.they carry de-oxy blood except for pulmonary vein
3)blood capillaries act as a passage where oxygen and other nutrients in the blood are delivered to the tissues in the body.
*pancreas,gall bladder and cells of endothelium secrete alkaline substances which buffer the acid in intestine before entering into small intestine.gastric juice in the stomach maintains the pH.