The answers are as follows:
20. An organ for churning of food to chyme is THE STOMACH.
When food is ingested, it is moved down to the stomach. In the stomach, different types of enzymes and hydrochloric acid are secreted to act on the food. The movement of the smooth muscles of the stomach churn the food and turns it into chyme. Chyme refers to a thick, semi fluid, partially digested food material.
21. Wave of contraction passing along the gut is called PERISTALSIS.
Peristalsis is a wavelike contraction of the muscles, which moves food particles from one point to the other in the digestive tract. The process of peristalsis typically begin in the gullet when food are swallowed.
22. The type of teeth that grind food into smaller pieces is PREMOLARS.
Premolars are one of the four types of teeth that exist. An adult human being has 8 premolars, 4 at the top and 4 at the bottom. Premolars are big, strong and have ridges shapes, which make them perfect for grinding and crushing.
23. There are two types of digestion, mechanical and chemical digestion.
Mechanical digestion refers to the physical act of breaking down food into smaller pieces. A good example of this is chewing. Mechanical digestion is very important because it increase the surface area of the food particles; this aids proper digestion.
Chemical digestion refers to the breaking down of food by mean of enzymes, acids and other chemical products in the body. A good example of chemical digestion is the action of bile on fat during digestion.
24. Another structure in the human digestive system that is involved in mechanical digestion apart from the teeth is THE STOMACH.
In the stomach, peristaltic actions physically cause the churning of the chyme, this facilitates proper mixing of digestive enzymes and hydrochloric acid with the chyme.
