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    Frog Digestive System Short Notes | Free Biology Notes

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    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

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