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Aarambh 2024: The Biggest Event for IIT JEE and NEET UG Aspirants
The alimentary canal and digestive glands make up the frog’s digestive system. Because frogs are carnivores, the alimentary canal is small, resulting in a shorter gut. Through the pharynx, the mouth opens into the buccal cavity, which leads to the oesophagus. Due to the lack of a neck, the oesophagus is a narrow tube. The duodenum is formed when the small intestine curls upwards and forms a U with the stomach. The ileum, which is coiled, continues the rest of it. A common hepatopancreatic duct connects the liver and pancreas, bringing pancreatic and bile juice into the duodenum.
Parts of Digestive system:
- Mouth: The alimentary canal begins here. There is a significant gap between the teeth and the mouth. It runs from one side of the nose to the other. The mouth is bounded by two bone jaws that are protected by inflexible lips. The upper jaw is fixed. Because the lower jaw is flexible, it can close and open the mouth by moving up and down.
- Frog buccal cavity: The frog’s mouth opens into the buccal cavity. The buccal cavity is large, shallow, and shallow. It features a ciliated columnar epithelial lining with mucous glands. These mucous glands release mucus, which aids in meal lubrication. Frogs do not have salivary glands.
- Teeth: The lower jaw is devoid of teeth. Teeth, on the other hand, are found in a row on either side of the premaxilla and maxilla bones in the upper jaw. The teeth are angled in the opposite direction.
Frogs have a massive, muscular, sticky, and projecting tongue. It is found on the floor of the oral cavity. The anterior end of the tongue is connected to the inner border of the lower jaw. The back end is bifid and unattached. After capturing the prey, this free end can be rapidly flicked out and retracted. The tongue’s slimy surface aids in the capturing of prey. A shift in pressure in the large sublingual lymph sac causes tongue protrusion.
Pharynx:
There is no discernible separation between the buccal cavity and the short pharynx. As a result, they are occasionally referred to as a single bucco-pharyngeal cavity. Several passageways lead into the pharynx. A middle elevation on the floor carries the glottis. The oesophagus is a muscular tube that is short, wide, and exceedingly distensible. It has a mucous epithelial layer that is longitudinally folded and contains some mucous glands.
Longitudinal foldings aid in the expansion of food as it goes through the digestive system.
The oesophageal glandular lining secretes an alkaline digestion fluid.
The oesophagus expands to connect the stomach in the peritoneal cavity.
Abdomen:
The stomach is placed on the left side of the bodily cavity. A mesentery known as a mesogaster connects it to the dorsal body wall. It’s around 4 cm long and has robust muscular walls as well as a large, somewhat curved bag or tube. The front section is broad and wide. It’s known as a cardiac stomach. The back of the body is slender and short. It’s known as the pyloric stomach. The stomach’s internal surface features several prominent longitudinal folds. When food is consumed, it causes stomach distension. Its mucous epithelium contains multicellular gastric glands. Unicellular oxyntic glands secrete the enzyme pepsinogen as well as hydrochloric acids.
The small intestine is a long, coiled, and microscopic tube that connects the small intestine to the rest of the body. It’s around 30cm long, with mesenteries connecting it to the body wall mid-dorsally. The nucleus is found towards the cell’s base.
Duodenum: The duodenum runs parallel to the stomach and is shaped like a U. It is linked to the liver by a hepatopancreatic duct. The liver and pancreas produce bile and pancreatic juice, respectively. Low transverse folds are formed by the internal mucous lining.
The ileum is the longest portion of the alimentary canal. It grows multiple loops before connecting the rectum posteriorly. The internal mucus lining has several longitudinal folds. There are no true villi, distinct glands, or crypts like in higher animals. The small intestine is where food is processed and digested food is digested.
The large intestine, often known as the rectum, is a short, wide tube about 4cm in length. It opens into the cloaca by running straight behind anus. The orifice is protected by an anal sphincter. The inner lining of the large intestine features several minor longitudinal folds. It is utilised to reabsorb water as well as prepare and store faeces.
Cloaca: The little sac-like component at the tube’s end. When the anus and urogenital openings open, the cloaca forms. The cloaca can open to the outside through the vent or cloacal opening, which is found near the back end of the body.
Food can be kept in the stomach for up to 2-3 hours, which is sufficient. Gastric juice is secreted by the gastric glands on the stomach wall. The gastric juice is composed of hydrochloric acid and the inactive pre-enzyme pepsinogen. Pepsinogen is converted to active pepsin in the presence of hydrochloric acid.
Pepsin now catalyses protein hydrolysis, converting it to peptones and proteases. Acid softens the food while also acting as an acidic medium. It eliminates germs and fungi found in food. The stomach wall’s muscular contractions aid in the breakdown and mixing of digestive enzymes with food. The stomach secretes the hormone gastrin in the presence of meals.
Gastrin stimulates cells that secrete HCl.
Chyme is the name given to the semi-digested liquified acidic food. When the chyme achieves the proper condition, the pyloric sphincter relaxes and the chyme enters the duodenum.
Conclusion:
Frogs are carnivorous, they eat insects, worms, crustaceans, mollusks, small fish, and even small frogs and tadpoles. With a swift flick of the tongue, the victim is seized and swallowed whole. The meal has finally arrived at the stomach. Because frogs lack salivary glands, mucus secreted by the walls of the bucco-pharyngeal cavity and oesophagus lubricates the meal. Peristalsis is a wave of contraction of the esophageal muscle wall that draws food down.
