Digestive System of Frog – With Diagram

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Digestive System Of Frog

  • Frogs’ digestive tract includes the alimentary canal , or digestive tract as well as the digestive glands.
  • The system consists of digestive glands and the alimentary canal.
  • The alimentary canal processes like digestion, absorption, and mastication occur. the digestive glands create enzymes that cause the digestion of the food item that is consumed.
  • The alimentary canal is comprised of the buccal cavities, pharynx, duodenum, the oesophagus and the rectum that leads to the cloaca. It is opened to the outside through the Cloacal aperture.
  • The mouth’s wide opening opens to the buccal cavity.
  • In the buccal cavity is the large, muscularly sticky tongue. It is attached in the front and free behind. Free edge is forked.
  • If the frog spots an insect, it flicks its tongue, and the insect is glued to the sticky tongue. The tongue disappears immediately and the mouth is closed.
  • A small row of pointed maxillary teeth can be located in the middle in the jaw’s upper region.. In the same way, vomerine teeth are found in two groups with one on each side of the nostrils’ internals. Lower jaws are completely devoid of teeth.
  • The mouth is opened into the buccal cavity, which leads to the oesophagus via the pharynx.
  • Oesophagus is a narrow tube that is opened to the stomach, and then extends into the intestine, the rectum, and then finally it opens out through the Cloaca.

Alimentary Canal

In frogs, the digestive canal is thought to be fully developed. The canal is a coiled long tube with different diameters , extending from the mouth and the cloaca. It consists of:

  • Pharynx
  • Buccal cavity
  • Oesophagus
  • Stomach
  • Small intestinal
  • Large intestine
  • Cloaca

1. Mouth

  • The alimentary canal begins at the mouth. It’s a large space that runs from one end of the snout to opposite.
  • The two jaws of bony are located inside the mouth. Both jaws are covered by impermeable lips.
  • Upper jaws are fixed and the jaw below is movable and is able to move up and down to open and close the mouth.
diagram of frog digestive system
diagram of frog digestive system | Image Source: www.flinnprep.com

2. Buccal Cavity

  • The mouth opens to the buccal cavity that is large, wide and shallow.
  • It consists of a columnar epithelial lining with ciliated cells that contains mucous glands. These glands produce mucus that aids in the lubrication of food.
  • Frogs don’t have salivary glands.

a. Teeth

diagram of frog digestive system
diagram of frog digestive system | Image Source: www.mramphibian.com
  • The lower jaw doesn’t have teeth. It is however located in a row on each side of the premaxillae and maxillae bones that are located on the jaw’s upper.
  • Teeth point in the opposite direction.
  • There are two additional tooth-like patches visible either side of the median line that forms the buccal cavity, also known as the vomerine teeth.
  • Vomers also include two sets of teeth from the vomerine teeth. These teeth aren’t utilized to chew , but rather to check the escape of the captured prey.
  • The upper jaw is adorned with rows of aligned even, small and hooked-like pointed teeth.
  • Teeth have a similar shape, and they are homodont. The teeth are curved inwards and is joined to bones instead of being attached to sockets.
  • Each tooth is conical in appearance and has two parts : the crown (front portion of the tooth) and the base. The base is attached by the jawbone, and contains bone-like material.
  • Thus, teeth aren’t intended to be chewed, they serve as a means of holding the prey in place and stopping it from sliding out. Dentine is traversed by a number of fine canals, and it covers the top of the tooth.
  • It is hard solid, glistening and resistant particle.
  • The tooth has an inner pulp cavity that opens to the sides. They contain soft and nourishing pulp that is surrounded by connective tissues, blood vessels and nerves as well as odontoblasts creating new materials for tooth’s development. The teeth of frogs have to be replaced numerous times during their lifetime.
diagram of frog digestive system
diagram of frog digestive system | Image Source: www.mramphibian.com

b. Internal Nostrils

  • Its roof is located near the teeth of the vomerine. The buccal cavity consists of two passageways – the internal or posterior nasal cavities, through which breathing gases flow to and out of the buccal cavity during respiration.

c. Tongue

  • The tongue of frogs is massive, sticky, strong and protruding.
  • It is located near the base of the mouth oral cavity.
  • The anterior part of it is connected to the inner part of the jaw’s lower border. the posterior portion is bifid, and free.
  • The surface of the tongue contains taste buds, which form tiny papillae as well as mucous glands of which secretions make the tongue sticky.
  • Digestive enzymes are not produced by mucous glands, nor by the taste buds.
  • The tongue may protrude and then retracted abruptly to engulf and catch insects. It is believed that the dislodging of the tongue is the result of an abrupt flow of squeezed lymph that is contained within the lymph sac. This is transferred to the opposite side, as the result of muscle contraction.
  • But, swallowing is accomplished through elevating the buccal cavity’s level where the hyoid cartilage, which is flat, is inserted.

d. Orbit-Bulging

  • Behind the vomerine teeth the the buccal cavity contains two large, oval regions, the bulgings from the eyes.
  • In the process of eating food, the eyes are compressed down the mouth cavity. This pushes the contents of the mouth into.

3. Pharynx

  • The buccal cavity tapers off behind the pharynx.
  • Then, it expands through the gullet to the oesophagus.
  • The pharynx and buccal cavity are often sometimes referred to as the buccopharyngeal space.
  • On the top of the pharynx, on each one of its lateral edges an extensive Eustachian tube is located and an opening that connects with middle ears.
  • The glottis is an opening in the pharynx that is behind the tongue, protecting the entrance into the lung.
  • When breathing, the mouth remains open and closes after swallowing.
  • In the lower jaw’s angle in the lower pharynx’s floor of male frogs, two openings in the vocal sacs develop as well. They are used as resonators in the croaking.

4. Oesophagus

  • Gullet leads to a large short and muscular portion that is part of the canal for eating, referred to as the Oesophagus.
  • This portion of the alimentary canal is quite narrow due to the neck’s absence, but they are extremely slender due to their inner lining. many longitudinal folds, which allows sufficient to expand the oesophagus at the moment of passage of the food that is consumed through it into the stomach.
  • They expand to the stomach, and no demarcation line is formed between your stomach and Oesophagus.

5. Stomach

  • It is situated in the lower left-hand side of the cavity that is connected to the dorsal wall of the body through mesogaster.
  • The digestion of food happens with the help of digestive enzymes that are produced through the digestive tracts located within their wall. They take the form of tubes that are wide and curving that are located between the intestine as well as the the oesophagus.
  • The stomach is divided into two distinct parts: the small, narrow posterior pyloric stomach, and the larger, more spacious anterior heart stomach.
  • The lining of the stomach is lined with many longitudinal folds that allow for the stomach to expand in the event of need.
  • The mucous epithelium that they have contains multicellular gastric glands that produce pepsinogen enzymes.
  • Hydrochloric acid secreted by the oxyntic glands that are unicellular. The pyloric portion of the stomach narrows.
  • Their entrance into the small intestine is protected by a circular ring-like muscle, the sphincter. It regulates the flow of food through the stomach and into the small intestine.
diagram of frog digestive system
diagram of frog digestive system | Image Source: www.studyread.com

6. Intestine

The stomach flows into the tubular long and coiled structure called the intestine, which is connected to the body’s dorsal wall via mesentery. It is composed of two parts:

  • Small intestinal
  • Large intestine

a. Small intestine

  • It is present in many loops that are braced by mesentery, a membrane that resembles a fan.
  • The anterior portion of the small intestinal tract curves upwards to form an U when it meets the stomach . This is known as the duodenum.
  • The other portion is the ileum that is wrapped in a coil.
  • The hepatopancreatic duct is a common opening into the duodenum through the pancreas and the liver that brings the pancreatic as well as the Bile juice.
  • The mucous lining inside is placed in the lower transverse folds.
  • The mucosal lining in the small intestine, in addition to the intestinal glands, comprise two kinds of cells –
    1. Goblet cells – Goblet cells are large cells that have granular substances, and oval vacuoles which produce mucus. The nucleus can be found within them near the center of the cell.
    2. Absorbing cells – Absorbing cells are identified as tiny cells with nuclei located near the base.

b. Large intestine

  • The ileum is a narrow long, coiled tube, where its lower portion is directed towards part of the intestinal structure, the rectum.
  • The mucous lining inside the ileum creates numerous long-distance folds.
  • The glands, the true villi, and the crypts of vertebrates of the higher vertebrates aren’t visible. In this area that digestion and absorption of food happens.
  • The lower terminal is connected to the cloaca through using the sphincter. Their mucosal lining continues to form the lower longitudinal fold.

7. Cloaca

  • They are small sac-like structures which receive the openings in the anus as well as the urinary apertures.
  • The cloaca is connected to the outside via the cloacal opening or vent that is located on the posterior side of the body.

Histology of the Alimentary Canal

Histologically speaking, The wall that forms the alimentary canal in vertebrates, including frogs, is composed from four concentric, distinct layers. They are found in the order listed below from inwards to outwards:

  1. The mucosa
  2. The submucosa
  3. The muscles The muscularis
  4. the serosa, or the visceral peritoneum.

1. Mucosa

  • It is the ugliest layer, or mucous membrane.
  • It stays folded, forming numerous pits and different kinds of glands.
  • It’s about digestion and absorption of digested foods, etc.
  • It is also composed from the layers below:

(i) Epithelium

  • It is the outermost layer made up of simple epithelium columnar (glandular as well as ciliated) built on the basement membrane, which is thin and.

(ii) Lamina Propria

  • It is a fine connective tissue layer that contains blood capillaries, lymph and nerves.

(iii) Muscularis Mucosae

  • It is a thin smooth muscle layer that houses both outer and inner circular muscles.

2. Submucosa

  • It’s a thin layer of protection made up of connective tissue with coarse texture, flexible fibers, fat lymph vessels and blood vessels as well as nerve cells.
  • It has glands in mammals.
  • It also contains the Meissner plexus, which is composed of fibers and nerve cells.

3. Muscularis

  • It is made up of the outer longitudinal and inner round smooth muscles that form spirals.
  • Between these two layers of muscle there is an additional layer of connective tissue with a web of nerve cells as well as nerve fibres from the myocentric autonomic ganglions of the Auerbach plexus.

4. Visceral Peritoneum or Serosa

  • The outermost layer, which is not present in the oesophagus.
  • It is made up of a small connective tissue layer, and the outermost layer is made of cells that have been flattened.
  • It is connected to the peritoneum lining in the body cavity known as mesentery.
  • There are a few variations that can be observed in various parts in the canal’s alimentary tract as the layers mentioned above especially the mucosa change drastically in various parts of the canal’s alimentary tract to allow that area to take on specific roles.

a. Oesophagus

Histologically speaking, the oesophagus is more than not has the same shape, but it is distinct from the other alimentary canal by the following ways:

  • There is no visceral peritoneum since it is just outside of the coelom.
  • It is home to both involuntary and voluntary fibres in its wall . There are also the fibres of striated or voluntary muscle in its upper region.
  • Its mucous membrane lining consisted of stratified epithelial cells, not columnar cells.
  • It contains goblet cells that make mucus, which makes the food slippery. Mucous epithelium invaginates into submucosa, which forms tubular branched glands which secrete an enzyme called pepsin that aids in digestive digestion of protein.

b. Stomach

The stomach’s wall is very thick and consists of the typical components that comprise the canal’s alimentary tract i.e. mucosa, submucosa and muscularis as well as serosa. It has two distinctive features:

  • Stomach Wall is thick longitudinally folded inside. It is not folded when the stomach is stretched. The mucous epithelium consists of columnar mucous secreting gland cells. The glands are embedded within the connective tissues that make up the lamina propria. Glands are a result of invaginations to the mucous epithelium. They are tubular structures with elongation placed very close to each other, and are often more or less branched. They are also known as gastric glands.
  • These glands vary in shape and structure in different parts in the stomach. The gastric glands that are located in the heart region of the stomach are known as cardiac glands as well as those in the fundus region and pyloric regions are referred to by the names of fundic and pyloric.
  • They are long with large mouths. However, the glands of the fundic and pyloric are not as deep and are much smaller. The pyloric and cardiac glands release mucus only from the cells on the surface. The fundic glands (or the cardiac glands in certain) contain three types of cells: mucous neck cells create mucus. and oxyntic cells create hydrochloric acid and may be present in the heart region too, and zymogen cells or peptic cells create pepsin. Pepsin is made as inactive propepsin or pepsinogen that converts quickly into active pepsin through the hydrochloric acid.
  • Villi is absent.

c. Small Intestine or Duodenum

  • It is covered with all four normal coats that cover the canal’s alimentary tract; however, its mucosa is thick and thick. It forms irregular transverse folds with branches that increase the absorptive area of the canal’s alimentary tract.
  • It is made up of columnar epithelial cells that have glands that secrete mucus. The mucosa of the small intestine gets divided into many folds; however, there aren’t any villi or definite glands, nor crypts from higher vertebrates.
  • The mucosae of the Muscularis mucosae is very thin. The remaining layers are normal.


  • It also comes with the usual four coats.
  • Mucosa is split into many folds with different sizes. they are inserted in the intestinal lumen, which decreases its size.
  • Mucosa is a tall columnar epithelial cell that is in one row, within which absorptive and goblet cells are dispersed.
  • The muscle layers are not as developed. Muscularis mucosa is tinier and consists of only one layer of muscle fibers. Villi is true, but crypts do not exist.

d. Large Intestine or Rectum

  • It also consists of the four coats of the alimentary canal.
  • The mucosae of muscularis is less developed, while the muscular coat is thick, and both are stuffed with voluntary muscle fibres.
  • The mucosa is dense and has longitudinal folds. It includes numerous tubular goblet cells, which secrete mucus. Mucosa epithelium is stratified near anus.

Digestive glands of frog

The two large glands of digestion, along with those located within the stomach as well as the small intestinal tract, are also present within the frog. These glands are the liver and the pancreas.

Digestive glands of frog
Digestive glands of frog

1. Liver

  • It is the biggest reddish brown gland that is located in the front inside the abdominal cavity, close to the lungs and the heart.
  • It is composed of two lobes – the left and the right. Both lobes are linked with one another via the narrow connection of the liver.
  • The left lobe has been subdivided into two parts. Between the left and right lobes, a thinly walled, oval greenish sac, known as the gallbladder is located. It acts as a reservoir for the bile secreted by liver cells.
  • The bile is able to pass into the gallbladder via cystic ducts, and straight into the bile tract by tiny liver conduits.
  • The cystic and hepatic ducts connect to create a common bile duct that flows through the pancreas, and then opens to the duodenum.
  • The common bile tract is known as the hepatopancreatic drain as it connects to the fine ducts of pancreas as it travels to the duodenum.
  • Bile lacks digestive juices. Bile is a lubricant that emulsifies fats. Therefore, the liver isn’t an actual digestive organ.

Histology of Liver

  • The liver is composed of a variety of tubules or lobules that not only branch, but also join to create a network of interconnected cells as a result of which it is often referred to as the retinal gland.
  • The lobules are distinguished from one another by connecting tissue, which contains liver ducts, bile capillaries as well as blood sinuses and capillaries.
  • Each lobule is composed of many polyhedral, glandular hepatic cells that have nuclei and cytoplasm , as well as protein granules, drops of glycogen, fats and, in most cases, dark or black brown pigment particles.
  • The hepatic cells are located in columns between capillaries in the bile that facilitate the development of larger hepatic tracts.
  • Hepatic ducts eventually open into cystic ducts which are directly linked to the gallbladder.
  • The hepatic ducts from different cystic ducts and lobes join to form the bile tract.
  • The liver receives blood through the hepatic arterial vein and the portal vein of the hepatic. These blood vessels reach the liver and supply the necessary material for the production of the bile.
  • The bile continuously secreted by liver cells is released into capillaries, from which it is absorbed into the gallbladder through cystic ducts, for temporary storage or through the digestive tract through the bile drain.

Functions of Liver

The liver is responsible for the following essential functions:

  1. The liver secretes alkaline, watery bile that includes bile salts, bile pigments cholesterol, lecithin, cholesterol as well as water. Bile salts include bicarbonate taurocholate, and glycocholate from sodium. Bicarbonate from sodium reduces the pH of food items in the intestine. The two other bile salts work to activate the pancreatic lipase. They also lower the friction of fats to ensure that they are able to be blended.
  2. It does not contain digestive enzymes however it adds water to food items and assists in the digestion of fats through mixing them.
  3. The body stores sugar excess in glycogen, which is created by the alteration to the glucose (glycogenesis). It is stored as a food reserve, but it is also converted to glucose (glycogenolysis) as its concentration drops in blood.
  4. It helps maintain the level of protein in blood. The amino acids that are not used up rather than being stored are transformed into ammonia in the liver, that is then reacted with carbon dioxide before being transformed into urea and various nitrogenous wastes through the actions by enzymes (deamination) which are later eliminated through the kidneys.
  5. It also gets rid of other excretory materials that are released with the intestines and excreted through the Feces.
  6. In embryos, the liver creates red blood corpuscles. However, as an adult, it destroys worn and old out erythrocytes through its Kupffer cells.
  7. It stores iron and copper and also forms vitamin A.
  8. It creates prothrombin and fibrinogen that are vital for blood clotting. Heparin is also produced which hinders blood clotting within blood vessels.
  9. It kills bacteria, and removes foreign substances from the blood.
  10. Prussic acid forms in the body , as an unintended by-product. It is hazardous. Liver converts it to harmless potassium sulphocyanide.

2. Pancreas

It is an irregularly branching, flattened, and pale-colored gland with the endocrine and exocrine glands that is held by mesentery between stomach and the duodenum. It is connected to the common bile drain into which pancreatic ducts are opened, and is known as the hepatopancreatic duct.

a. Exocrine Part

  • It is divided into a variety of parts and lobules joined by connective tissue. In it are pancreatic ducts as well as lymph vessels, blood vessels, and nerves.
  • The lobules contain many tubules that branch, or alveoli or acini.
  • Each alveolus is composed from pancreatic pancreatic glands with pyramidal structures in a central cavum.
  • These alveoli connect with each by ductules that in turn join together to form larger ducts, and finally create the pancreatic ducts.
  • The pancreatic ducts expand to the bile duct after it crosses the pancreas.
  • The pancreatic cells are large nuclei as well as cytoplasm that is non-granular.
  • The pancreas is the source of pancreatic juice that contains a variety of enzymes that digest carbohydrate, proteins and fats of food items.

b. Endocrine Part

  • Within the acini within connective tissue, there are tiny groups of cells. They are called pancreatic islets, also known as islets of Langerhans.
  • They are somewhat spherical and placed in groups of compact size and absorb very light staining.
  • There are three types of cells within an islet, separated by capillaries.

(i) Alpha Cells

  • The cells are achromatic, with anachromatic nuclei, as well as huge acidophilic granules.
  • The cells produce the hormone glucagon, which raises the blood sugar levels.
  • The deficiency causes hypoglycemia.

(ii) Beta Cells

  • They have small, rounded with deeply stained nuclei, as well as orange-brown granules. They produce insulin hormone.

(iii) D Cells

  • These cells have the vesicular nuclei as well as basophilic granules.

Insulin is necessary for the metabolic processes of carbohydrates, controlling glycogen storage in the muscles and liver as well as the level of sugar in blood and to increase the capacity of tissues to oxidize glucose to provide an energy source. Insufficient insulin can cause the condition known as diabetic (hyperglycemia).

Physiology of digestion in frog

1. Food of Frogs

  • Frogs are carnivores. 
  • They are primarily eating earthworms, spiders and snails. 
  • They also eat fishes, snails, tiny frogs, and tiny insects that eat completely into the stomach by using the tongue that is protractible.

2. Food Ingestion in Frogs

  • Frogs have a place that is frequented by insects while they are pursuing their prey.
  • If an insect is in close proximity, they can expand their mouths and then release their sticky tongues and strike their prey.
  • When the prey comes near the tongue clings to it instantly. The tongue then is pulled to the mouth cavity.
  • Once the prey has been sucked within the buccal cavity it won’t be able to escape due to the hook-like maxillary inwardly directed and vomerine teeth.
  • After that, through within the buccal cavity it’s pulled into the oesophagus via the contraction of the pharyngeal walls.
  • After that, it was caused by the dilation and contraction of the muscle walls of the oesophagus. It is pulled into the stomach.

3. Food Digestion In Frogs

  • When a frog is fed, the food consumed contains complicated organic particles that cannot be utilized immediately because of their insoluble nature and unable to pass throughout the mucous membrane that lines the canal of digestion.
  • Therefore, it has to be treated using physical and chemical modifications of digestion in order to transform into soluble forms that are ready for immediate usage in the human body.
  • Peristaltic movements in the alimentary canal result in physical changes, while the enzymes that act as organic catalysts cause chemical changes that just accelerate the chemical reactions, without producing any change on their own.
  • These are complex proteins , and specific in their action. They are made by the glands that produce exocrine hormones since they operate at the optimal temperature for the body.
  • They are also able to reverse reactions which means that the substances modified may be modified.
  • They come in a variety of forms based on the kind of food upon which they work. Thus proteins are digested through proteolytic enzymes and fats by lipolytic enzymes, and carbohydrates by diastatic enzymes.

a. Buccal Digestion

  • The buccal epithelium is devoid of any digestive glands and the prey caught by Frogs is not subjected to any kind of mastication or chemical activity within the buccal cavities.
  • Prey that is caught in the buccal cavity is then pushed directly into the stomach where physical changes are felt due to the constant peristaltic movements in the walls.
  • Other than mucus, the glands of the oesophagus also release pepsin, but digestion is not a factor since they do not function until they get to the stomach.
  • The mucus makes the active food be inactive and soft, and thus makes its passage much easier.

b. Gastric Digestion

  • The stomach gets food through contractions and relaxations of the oesophageal muscles.
  • The stomach is responsible for performing three major functions –
    • Chemical changes
    • Mechanical mixing
    • Storage
  • As food passes through the stomach, so-called peristaltic motions allow foods to push downwards and then break down into smaller pieces, and is mixed thoroughly thanks to gastric juices released from the glands of gastric digestion located inside the stomach’s lining.
  • The glands secrete their secretions when stimulated by the gastrin hormone created by the stomach’s walls when food is absorbed into the stomach.
  • Gastric glands release gastric juice that is composed of huge amounts of water, inactive enzyme pepsinogen and the unrestricted hydrochloric acids. Pepsinogen that is inactive, when combined with hydrochloric acid transforms to active pepsin.
  • The acid can be used in stopping bacterial degradation and in dissolving organic salts, making food soft.
  • The stomach’s pepsin as well as the oesophagus interact with the protein content of food and convert into proteins and peptones.
  • Food that has been inside the stomach for about 2-3 hours is thoroughly churned, and mixed by contractions of the muscles in the stomach wall. This creates a thick , creamy acid fluid called the chyme.
  • The muscular contractions of the stomach wall force the chyme into passing in tiny quantities through the pylorus and into the duodenum.

c. Intestinal Digestion

  • When the acidic chyme enters the duodenum, a variety of intestinal hormones are created that perform their own roles.
  • Enterogastrone enters the stomach through bloodstream and blocks in the creation of gastric juices with HCl.
  • Cholecystokinin makes gall bladder expand, releasing bile into the duodenum via the hepatopancreatic duct.
  • Secretin and Pancreozymin both work in tandem to stimulate pancreas and pancreas to secrete pancreatic juices into the duodenum.
  • Enterocrinin triggers the release of intestinal juice, also known as the succus entericus.
  • Three important substances interact with food that is absorbed by the intestine to ensure complete digestion.
  • They come from three sources: pancreatic juice, and digestive juice.


  • Bile is an alkaline green fluid that is secreted by the liver.
  • It is deficient in digestive enzymes.
  • It is a source of bile salts, such as sodium bicarbonate and sodium glycocholate. It also contains sodium perchlorate, and so on.
  • Bile, which is alkaline in nature, helps neutralize the acidity in chyme. disperses fats, and triggers the digestive peristaltic function and also activates pancreatic lipase.

Pancreatic juice

  • The alkaline, watery pancreatic juice has a variety of enzymes that perform on the 3 categories of food.
  • Intestinal enterokinase converts trypsinogen into the active pro-proteolytic enzyme, trypsin. Trypsin converts peptones, proteoses and polypeptides into amino acids.
  • Amylase, also known as amylopsin, reduces the amount of starch (polysaccharides) into maltose (disaccharides).
  • Lipase, previously referred to as Steapsin, converts emulsified fats into glycerol and fatty acids.

Succus entericus

  • Succus entericus , also known as the juice of the intestine, is a source of several enzymes, including enterokinase.
  • These enzymes are active on the entire range of food items.
  • Erepsin is the common term used to describe the proteolytic enzymes and peptidases.
  • It converts polypeptides into amino acids.
  • Maltase converts maltose into glucose.
  • Sucrase or Invertase converts sucrose into glucose and fructose
  • Lactase converts lactose into galactose and glucose.
  • Lipase breaks down oils into fatty acids as well as Glycerol.

4. Food Absorption In Frogs

  • The products that are absorbed in those walls in the small intestinal tract are absorbed.
  • The absorptive surface visible internally is progressively increased in folds due to an increase in villi-like process.
  • Each villus is filled with blood capillaries , as well as lymph vessels, or lacteal.
  • The mineral salts and water, and various other nutrients get absorbed directly by the mucosa.
  • The amino acids, glucose and fructose are absorbed through the mucosa to the blood capillaries in the intestine, which then reach the liver via the portal vein to the liver.
  • The liver is able to maintain a constant supply of amino acids as well as sugars in the blood.
  • Glycogen, the sugar that is excreted from glycogen, is stored, however the excess amino acids can’t be stored and are instead converted into urea in the liver cells, which are then eliminated in urine that is pumped out of the kidneys.
  • In the event of a decrease in sugar from that of the normal blood sugar level the glycogen reserves are converted into glucose by liver cells before being transferred to the bloodstream.
  • In blood, cells pick amino acids that are required to make proteins. making protoplasm.
  • Glycerol and fatty acids are absorbed into lymph vessels, also known as lacteals. Glycerol is quickly absorbed because they are water-soluble. However the fatty acids are not absorbed since they are not water-soluble.
  • Thus when fatty acids are absorbed by the body, they are mixed into the bile salts, making them soluble and so are absorption.
  • After absorption is completed in lacteals, the Glycerol and fatty acids are transformed into fat globules that are smaller molecules. This is why the fats are absorbed in the form of glycerol and acidic fatty acids enter the lymph vessels.

5. Food Assimilation In Frogs

  • The food absorbed by the body can serve two main nutritional purposes:
  • The release of energy through breathing.
  • Assimilation is an integral part of the nature that the animals have.
  • Extra glucose is stored as glycogen in the liver and skeletal muscles. It can also be converted into fats. These are stored in the adipose tissue.
  • Proteins can be formed by amino acids to promote development and for repair.
  • Then, it undergoes deamination , which results in the creation of urea, which can be excreted from kidneys by urine.

6. Egestion of Undigested Food In Frogs

  • It is within the small intestine that digestion and absorption are complete.
  • The food that is consumed gets into the rectum through the peristalsis to form and store feces.
  • Leukocytes, old epithelial cells and bile pigments as well as a large number of bacteria make up the feces that are then disposed of promptly through the cloacal opening.


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  • https://staff.4j.lane.edu/~ruzicka/Cal_Young/lifescience/Human%20Body/Frogs/Frog%20Digestive%20System.pdf
  • https://gkscientist.com/digestive-system-of-frog/
  • https://www.brainkart.com/article/Anatomy-of-Frog—Digestive,-Respiratory,-Circulatory,-Nervous,-Excretory,-Reproductive-system_33183/
  • https://www.onlinebiologynotes.com/digestive-system-of-frog-anatomy-and-physiology-of-digestion/
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