The chapter one deals with digestion in the mouth by salivary glands secretion namely the saliva. After a brief general introduction of digestive system the structure of the salivary glands, innervation composition of saliva and its role digestive function in the mouth are described. Control of salivary secretion is discussed in detail. Deglutition or swallowing is described. Disorders of esophageal motility are outlined. In this section chapter two deals with digestion in the stomach by the gastric juice. The gastric glands structure, types and the composition of gastric secretion is described. Innervation of the gastric glands and the control of secretion of gastric juice described stressing the importance of vagus nerve and its influence on gastric acid secretion. Hydrochloric acid secretion is discussed in details. Three phases of gastric juice secretion, volume secreted in each phase and their regulation by nervous mechanisms and hormones and gastrin are discussed. Tests for gastric function, gastric motility and gastric emptying are mentioned in brief. The clinical aspects related to stomach namely peptic under, cardiospasm, pylorospasm and vomiting are discussed. In this section, chapter three deals with digestion in the small intestines by the pancreatic juice and intestinal juice. The structure of exocrine part of pancreas its secretion the pancreatic juice its composition, its volume, the control of secretion are narrated. The digestion by the pancreatic enzymes trypsin and chymotrypsin are discussed. The nervous and hormonal influences on pancreatic secretion are discussed in detail. The structure of the intestinal glands and intestinal villi are described. Since the digestion of foot materials completed and made into absorbable materials summary of digestion of each kind of food namely, carbohydrates proteins and fats are given in detail. Digestive enzymes actions are given in a tabular statement in order to have a comprehensive idea about enzymes actions and their end products. Chapter 4 deals with digestive functions of the liver. After enumerating the general metabolic functions briefly the author describe structure of the liver, composition of bile and emphasizes the role of bile salts in the digestive process of fats. Bile pigments formation, their circulation are described. The clinical condition, jaundice its types are discussed. The features of different types of jaundice are given in a tabular statement for easy reading and understanding. After describing gall bladder, its duct systems, its functions are described. A brief account of gall bladder stones is given along with other clinical conditions namely cirrhosis, viral hepatitis amoebiasis and ascitis. In this section, chapter five deals with the gastrointestinal hormones. At present the hormones of gastrointestinal tract do not limit to a few hormones, more than 100 active peptides are identified which make the gut the largest endocrine organ of the body. Their function does not confine to the gastrointestinal tract only but also expand their activity as multi-functional intracellular regulators, neurotransmitter, cytokines, and fertility factors. These are viewed as highly concerned intracellular messengers. These facts are emphasized. In this chapter the gastrointestinal hormones are grouped into several families and discussed for their functions Being a recently advanced subjects they are discussed with their historical background and high-lighted. In fact the gastrointestinal hormone, the secretin was the first substance to be called as hormone (Bayliss and Starling 1902). The important hormones and their functions are clearly displayed in two tables. In this section chapter six deals with intestinal movements. The structure of the gastrointestinal wall is described in detail. The fact that the nerves in the intestinal wall constitute complex nervous systems, “the enteric nervous systems” with enormous number of neurotransmitters is highly focused. The various neurotransmitters in the enteric nervous systems are given in a tabular statement. Movements of small intestine and villi are described. Clinical conditions related to intestinal movements are discussed. Large intestine and its movements are discussed. About Intestinal gases, intestinal bacteria, immune bodies formation there is an interesting description. Composition of faces and defaecation and its reflex regulation is discussed in detail. Chapter seven dealt with intestinal absorption. After describing the structure of intestinal villi, the methods of study of intestinal absorptions discussed. Absorption of carbohydrates proteins and fats are discussed. More care taken to make the subject of fat absorption easy. Absorptions of cholesterol, water, electrolytes and vitamins are described. Clinical aspects: Starvation, malabsorption, intestinal obstruction, peritonitis are given in brief. Chapter 8 deals with energy balance and regulation of food intake. After introduction of the subject, how the maintenance of energy balance is affected by adjustments of four important variables namely food intake, store energy, work, and heat protection are discussed. Balanced diet is discussed in detail. Hunger, appetite and satiety are described followed by a detailed discussion on Regulation of food intake. Clinical aspects namely: Anorexia nervosa and obesity are given to a required extent. A recently discovered hormone Ghrelin is explained to a large extent. The role of leptin in negative energy balance and positive energy balance is given in the form of a flow chart which makes understanding very easy.
