How tubular digestive system is more efficient than sac like digestive system? or Differentiate between sac like system and tube type digestion.
The tubular digestive system of cockroach is more efficient system than sac like digestive system of Hydra or Planaria, in having specialized organs or partitions for efficient digestion and absorption of food. Sac-like digestive has a single opening which is used both as mouth as well as anus.
What are the main parts of digestive system in the direction of passage of food in man?
The main parts in the direction of passage of food, are the oral or buccal cavity, oesophagus, stomach, small intestine (duodenum, jejunum and ileum), large intestine (ascending colon, transverse colon, descending colon, caecum and rectum).
What is the function of water and mucus found in saliva?
Water and mucus together make a slimy liquid which serves to moisten and lubricate the food so that it can be chewed efficiently and passed through the esophagus smoothly.
What is the function of sodium bicarbonate and other saits found in saliva?
Sodium bicarbonate and some other salts are slightly antiseptic but their main function is to stabilize the pH of food. Fresh saliva is alkaline with a pH nearly 8 quickly loses carbon dioxide and gets to pH 6.