Digestive System of Rat

Anatomy of Earthworm,Cockroach & Frog of Class 11

The digestive system consists of an alimentary canal and the digestive glands. The alimentary canal is a long and coiled tube, extending from mouth to amus and distinguished into four main parts - buccopharyngeal cavity (oral cavity + pharynx), oesophagus, stomach, and intestine.

The mouth opens in the buccal cavity that is surrounded by the vestibule, which is a space between the lips, cheeks, and teeth.

The oral cavity encloses large incisor teeth, molar teeth, the tongue, and the bony roof of the mouth or hard palate. The palate separates the nasal and oral cavities. Unlike carnivorous mammals whose teeth stop growing shortly after they emerge, the teeth of many herbivorous mammals continue to grow throughout life.

Stomach — Sac-like structure that serves as a storage site for ingested foods. The stomach is comprised of three areas that are morphologically similar but histologically different. These are the cardiac portion (entrance from the oesophagus), the fundic portion (large middle area), and the pyloric portion (constricted posterior portion). The stomach opens to the duodenum through the pyloric sphincter.

Small Intestine — Comprised of three regions which can be differentiated histologically.

Duodenum: The anterior portion receives the ducts from the digestive glands, pancreas, and liver. The second portion is the jejunum, most posterior is the ileum.

The small intestine is the site of most chemical digestion and the absorption of nutrients. Digestive enzymes from the pancreas and the intestine itself are secreted into the lumen of the small intestine where the chemical breakdown of food occurs.

Digestive System of Rat

Fig. Rat digestive system diagram

Large Intestine : The ileum opens into the large intestine via the ileocolic valve. The large intestine consists of the four areas; a large caecum or blind sac near the ileocolic valve; an ascending colon on the right side; a short transverse colon; and a descending colon heading posteriorly.

  • The caecum is quite large in herbivores, like the rat, and may contain microbes that further breakdown the plant material not already digested by the enzymes of the small intestine.
  • Major function of the large intestine itself is the reabsorption of the large quantities of water secreted into the gut during digestion. Thus, as undigested material moves along the colon,
  • water is removed from it, resulting in a mass of waste material, the faeces. Faeces are stored in the rectum (the terminal portion of the colon) until eliminated through the anus.

Rectum — The rectum is the continuation of the descending colon through the pelvic region. It terminates with the anus which opens externally.

Digestive Glands

There are four pairs of salivary glands. The first is the parotid gland which lies just beneath the ear and extends over the ventro-lateral surface of the neck to the shoulder. The submaxillary glands are just ventral to the slightly larger parotids and are inseparable from the more anterior overlying sublingual glands.

Fourth pair is of infra-orbital glands. Saliva contains the enzyme ptyalin that helps to digest starch of the food.

  • Liver — It is divided into several lobes. The bile that is produced in the liver passes directly to the duodenum via the bile ducts. The bile is stored in most mammals by the help of gall bladder, Which is not present inside the rat. Bile is needed for digestion of fats. The liver has many functions such as detoxification of certain chemicals and production of glycogen (a carbohydrate storage material).
  • Spleen — This is an elongate flattened organ which is attached to the greater curvature of the stomach. The spleen and the liver remove old red blood cells from circulation and break them down. The products of the breakdown are secreted into the stomach by the spleen and into the duodenum by the liver.
  • Pancreas — The pancreas is a diffuse gland which is embedded in the mesentery proper and greater omentum. It is found along the anterior edge of the duodenum, just after the stomach The pancreas secretes many digestive enzymes into the small intestine as well as hormones (insulin and glucagon) into the blood.

Frequently Asked Questions (FAQs)

Q1. How long does it take for rats to digest food

Ans. The fasted body weight of each animal is determined and the dose is calculated according to the body weight. After the substance has been administered, food can be withheld for a similarly 3-4 hours in rats or 1-2 hours in mice.

Q2. Do rats and humans have the same digestive system?

Ans. The major difference between the human digestive system and rat digestive system is that the human digestive system has a gallbladder in which the bile juice is transferred from the liver. On the other hand, rats don’t have a gallbladder.

Q3. Do rats have two stomachs?

Ans. The rat's stomach has two parts : Forestomach: thin-walled, non-glandular section that receives the esophagus and serves as a holding chamber for food. Its walls are similar to those of the esophagus.

Q4. Where can I get NCERT Solutions for Class 11?

Ans. You can find NCERT Solution for Class 11 on our site. You can also access the NCERT Solutions for every class on our website.

Also Check:

  1. Circulatory System of Rat
  2. Respiratory System of Rat
  3. Reproductive System of Rat
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