221 Human Body Parts Encyclopedia

The peritoneum is a dual layered membrane. One is the parietal peritoneum that covers the abdominal wall and the other is the visceral peritoneum that covers the abdominal organs. The space between these two layers is called the peritoneal space. The layer creates a smooth lining over the organs and helps them to slide upon […]

Large Intestine The large intestine is also known as colon. It is a long continuous tube-like tract through which food residue passes before defecation. The colon begins as a dilated pouch, the caecum, to which appendix is attached. The large intestine does not take part in the digestion or the absorption of the food. The

The absorption of the digested food takes place entirely in the small intestine through two channels, the capillary blood vessels and the lymphatics of the villi. A villus looks like a small, finger that lies above the intestinal wall surface. Villi are found in a large number in the beginning of the small intestine. But

Duodenum The duodenum is the upper (first) part of the small intestine. Its length ranges from about 23 to 28 cm. It resembles a horse shoe in shape. The bile and the pancreatic ducts open in the duodenum. It is divided into four segments: the superior, descending, horizontal and ascending duodenum. The food spends a

The small intestine completes the process of digestion. The food before reaching the duodenum undergoes acid treatment and chemical digestion. The form of food that reaches the duodenum is called the chyme. Here, the digestion and absorption process of the nutrients in the chyme gets completed. Pancreatic and intestinal enzymes play an important role in

The oesophagus is a hollow muscular tube, also known as the food pipe or gullet. It is a connecting tube between the mouth and the stomach. It is located behind the trachea. The oesophagus consists of four coats of tissues. The movement of the tissue layers is responsible to move the food towards the stomach

The pharynx is a cone-shaped passageway that lies behind the nose, mouth and larynx. The pharynx chamber plays both respiratory and digestive functions. The pharynx chamber consists of the naso pharynx, oral pharynx and laryngeal pharynx. The chief muscles of the pharynx are constrictor muscles which contract, when food is received into the pharynx, and

Teeth play an important role in the digestive process. The mouth contains teeth which masticate the food. Mastication means biting and grinding of food into smaller pieces between the upper and the lower teeth. This allows the enzymes (present in saliva) to mix well with food and hence swallowed more easily. If the food is

Food begins its journey from the mouth. The main parts of the mouth are: teeth, tongue and salivary glands. In the mouth, food particles are broken down physically with the help of teeth. It is known as mechanical digestion. Saliva, the watery secretion of the salivary glands, moistens and lubricates the food. Saliva starts the

Food is needed for growth. It acts as a fuel for the production of heat and energy. The digestive system receives the food and breaks it down into simpler components so that it may be used in the body. The entire process of the reception of food and its breaking down into simpler components is

Spleen Spleen is the largest organ of adult lymphatic system, located behind the stomach, in the abdominal cavity. It resembles a lymph node, but it is larger than lymph nodes. It is made up of two types of tissues. (1) Red pulp that removes bacteria and lymphocytes (white blood cells) and macrophages. (2) White pulp

A lymph duct collects lymph from various tissues and then moves it to the blood vessels. There are two lymph ducts in the body: thoracic (left lymphatic duct) and right lymphatic duct. The thoracic duct moves along the abdomen to the neck. It collects lymph from the digestive tract. The right lymphatic duct (a smaller

Lymph vessels are similar in structure to the veins but they bear several valves on its surface. These valves impart a beaded appearance to the lymph vessels. They move corresponding to veins and arteries. The valves present on the lymph vessels prevent the back flow of the lymph, once the lymph has entered the main

Tonsils are the part of the immune system of the body. They constitute the first line of defence of the body. Tonsils are located at the top of the pharynx, on each side of the back of the throat. There are three pairs of tonsils: the pharyngeal, the palatine tonsils, and the lingual tonsils. The

The lymphatic system is simply referred as the drainage system of the body. It collects the excess fluid from the tissues in the body and returns it to the blood system or the central circulatory system. The lymphatic system is well equipped with vessels. It supports the immune system. The major parts of this system