In course of swallowing the food, frog depresses the eyes.These areas are the bulging of eye balls. The roof of buccal cavity shows two large oval and somewhat pale areas, behind the vomerine teeth.By these internal nares, the nasal cavities open into buccal cavity.Just in front of vomerine teeth, the roof of buccal cavity contains anteriorly, a pair of small openings of internal nares.The change of pressure in large sublingual lymph sac causes the protrusion of tongue.The slimy surface of tongue facilitates in capturing the prey.This free end can be flicked out and retracted immediately after catching the prey.The anterior end of tongue is attached to the inner border of lower jaw.In frogs, tongue is large, muscular, sticky and protrusible.It is filled with a soft nourishing pulp, containing connective tissues, blood vessels, nerve and odontoblast cells that produces new material for the growth of tooth.Tooth contains a central pulp cavity open at the side.Enamel is a very hard, resistant and glistening substance.It is made up of dentine (a hard ivory-like substance), which is traversed by numerous fine canals or canaliculi.But teeth are attached to the jaw bone by a broad base made of a bone-like substance.The nature of teeth is homodont (similar), acrodont (not set in a socket).The function of teeth is to simply hold the prey and prevent it from slipping out.Vomers (two small bones in the roof of the mouth) also consists of two groups of vomerine teeth.However, teeth occur in a row of either side on the premaxillae and maxillae bones of the upper jaw.These mucous glands secrete mucus that helps in lubricating the food.It has ciliated columnar epithelial lining that contains mucous glands.Buccal cavity is large, wide and shallow.it can move up and down to close or open the mouth. Two bony jaws bound the mouth, and the jaws are covered by immovable lips.It extends from one side of the snout to the other. It is the beginning to the alimentary canal.Digestive system consists of digestive tract or alimentary canal along with the associated digestive glands.The undigested solid waste moves into the rectum and passes out through cloaca.Digestive system of frog: Anatomy and Physiology of digestion Digestive system of Frog: parts and functions Absorption : Digested food is absorbed by the numerous finger like folds in the inner wall of intestine called villi and micro villi. Final digestion takes place in intestine. Bile emulsifies fat and panecreatic juices digest carbohydrates and proteins. The duodenum receives the bile from gall bladder and pancreatic juices from the pancreas through a common bile duct. Chyme is passed from stomach to the first part of the intestine, the duodenum. Digestion of food takes place by the action of HC1 and gastric juices secreted from the walls of the stomach. Digestion process in frog : Food is captured by the bilobed tongue. Cloaca opens towards the exterior through ventor cloacal opening situated at the posterior end of the body. Cloaca : It is a small saclike structure and receives the openings of anus and urine genital apertures. Large Intestine : Ileum opens into large intestine. Digestion and absorption of digested food occurs in small intestine. The hepatic duct and cystic ducts join to form a common bile duct which runs through pancreas and opens into the duodenum.Ileum : It is the longest and coiled part of alimentary canal. Liver and Pancreas : Bile juice and pancreatic juice. It secretes pancreatic juice that possesses digestive enzymes. Liver and Pancreas are accessory digestive glands. Duodenum curves upwards to form a āUā with the stomach. The pyloric end of stomach is constricted and its opening into small intestine is guarded by a sphincters, (a circular ring like muscule) Small intestine is divided into duodenum and illeum. The anterior larger part is called cardiac stomach and the posterior narrow part is called pyloric stomach. It is long, broad and slightly curved as cavity. Stomach : It is located on the left side in the body cavity. Oesophagus is a short tube due to absence of neck. The mouth opens into the buccal cavity that leads to the oesophagus through pharynx. The alimentary canal is short because frogs are carnivores and hence the length of intestine is reduced. Solution The digestive system of frog consists of alimentary canal and digestive glands.
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