Respiratory System The respiratory system is a set of organs that help a human being to breathe. Breathing is the process of inhaling oxygen and exhaling carbon dioxide. The respiratory passage consists of the nose, nasal cavity, pharynx, trachea, bronchi, lungs and diaphragm. Human beings can involuntarily control the process of breathing but overall the […]
Food is composed of carbohydrates, proteins, fats, vitamins, minerals and water. The digestive enzymes secreted by the digestive system helps break down the complex nutrients into simpler form. The various enzymes secreted by the human body are: Major Digestive Enzymes Enzyme Produced In Carbohydrate Digestion : Salivary amylase Salivary glands Pancreatic amylase Pancreas Maltase Small
The bile is a liquid secreted by the liver. It plays an important role in the digestion of food. The bile is composed of bile pigments, bile salts, cholesterol and phospholipids. The bile helps break down fats and in the activation of enzymes required for the digestion of fat. The human body secretes approximately 1
The liver vessels help in the transport of substances to and from the liver. Four vessels of the liver are as follows: (1) the hepatic artery that arises from the aorta and supplies oxygenated blood to the liver; (2) the portal vein supplies oxygenated blood to the liver; (3) the hepatic vein returns the blood
Liver The liver is the largest gland in the body, divided into two main lobes, the right and the left. It secretes bile into the small intestine. It is the largest chemical factory that carries out most of the intermediate metabolic functions. For example: (1) it breaks down and builds up new biological molecules, stores
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