Frog Digestive System Short Notes | Free Biology Notes

In this article we will discuss about the frog digestive system

Frog Digestive System

• The function of the frog digestive system is digestion and absorption
• Frog digestive system consists of alimentary canal along with digestive glands

Alimentary canal

• Alimentary canal is long, complete and coiled tube
• Alimentary canal consist of mouth, buccal cavity, pharynx, oesophagus, stomach, intestine, rectum, cloaca

Mouth

• Frog digestive system starts with the mouth
• Two bony jaws bound the mouth, and the jaws are covered by immovable lips
• Mouth helps in consumption of food. This process is known as ingestion.

Buccal cavity of frog

• Mouth opens into buccal cavity
• Buccal cavity has glandular epithelial lining that secrete mucus, helps in lubricating the food.
• Frog lacks salivary glands

Teeth

• Teeth occur in a row of maxillae bones in the upper jaw
• Function of teeth is to simply hold the prey and prevent it from slipping out
• The nature of teeth is homodont (similar), acrodont (not set in a socket), polyphyodont (replaced several times)
• The lower jaw lacks teeth
• Vomerine teeth are two rough bumps on the roof of the frog’s mouth. These function in holding and capturing prey.

Tongue

• Tongue is large, muscular and sticky
• Anterior end of tongue is attached to the inner border of lower jaw
• Posterior end is free and bifid

Pharynx

• The buccal cavity reaches short pharynx
• The pharynx tapers behind to lead to oesophagus through the gullet
• Gullet is the wide opening that leads to oesophagus

Oesophagus

• Oesophagus is short, wide and muscular tube
• Some alkaline digestive juice is secreted by the glandular lining of oesophagus
• The oesophagus opens into the stomach

Stomach

• Large and thick muscular sac like structure
• Anterior end of stomach is called cardiac end while the posterior end is called pyloric end
• The walls of stomach are muscular and glandular
• Stomach secrete HCL & proteolytic enzyme
• HCL makes the acidic PH of food & it is bacteriolytic
• In stomach, digestion of protein of food is started

Small intestine

• Small intestine is a long, coiled and narrow tube
• It comprises of two parts: anterior duodenum and posterior ileum
• The ducts from liver and pancreas open into the duodenum
• Bile juice emulsifies fat and pancreatic juices digest carbohydrates and proteins
• Digested food is absorbed by ileum

Rectum

• Large intestine is short and wide tube
• Its inner lining forms numerous folds
• In rectum undigested food material is stored which is ready to expel from cloaca

Cloaca

• The anus and the urinogenital apertures open into cloaca
• Cloaca opens to outside by the vent or cloacal aperture, lying at the hind end of body.
• Cloaca remove undigested food material.

Digestive glands of frog

Liver

• The largest gland of the body
• Bile is a greenish alkaline fluid secreted by liver
• Bile is stored sac called as gall bladder
• It changes the PH of food from acidic to alkaline
• Hepatic ducts joins the pancreatic duct to form a hepatopancreatic duct
• Ultimately opens into duodenum

Pancreas

• Pancreas is long and irregularly lobed gland
• It secrete pancreatic juice
• Pancreatic juice poured into duodenum through hepatopancreatic duct
• Pancreatic juice help digestion of ingested food

How Digestive System Works In Frog?

• Frog feeds on insects, worms, crustaceans, molluscs, small fish and even small frogs and tadpoles
• The prey is caught by rapid flicking of tongue and is swallowed as a whole
• Salivary glands are absent in case of frogs, the food is lubricated by the mucus secreted from the lining of buccal cavity and oesophagus
• The food is now passed to stomach
• Food remains in the stomach for up to 2-3hrs
• Gastric juice is secreted by the gastric glands of stomach wall
• Now acidic chyme enters the duodenum
• Three important substances mix with the food in intestine
• They are derived from three different sources: bile, pancreatic juice and intestinal juice
• Digestion is accomplished in the small intestine
• The faecal matter passes into cloaca