In this article, we will discuss about the fascinating physiology of human digestive system. The human digestive system composed of several tissues and organs. Different organs perform different functions such as digestion of carbohydrates start from mouth. Digestion of protein takes place in stomach and digestion of lipids in small intestines. Several accessory glands play role in digestion, such as hepatic and gastric secretions. We will also provide related references to understand the concept deeply.
INTRODUCTION OF PHYSIOLOGY OF DIGESTIVE SYSTEM:
The human digestive system is a complex network of organs and processes that work together to break down food and absorb nutrients. It plays a crucial role in maintaining our overall health and well-being. Understanding the physiology of the digestive system can help us appreciate the intricate mechanisms involved in this essential bodily function.
PHYSIOLOGY OF HUMAN DIGESTIVE SYSTEM:
The digestive system consists of several organs, including the mouth, esophagus, stomach, small intestine, large intestine, rectum, and anus. Each organ has a specific role in the digestion and absorption of nutrients.
1. DIGESTION IN MOUTH:
The digestive system begins with the mouth, where food is ingested and mechanically broken down by chewing. Saliva, produced by the salivary glands, contains enzymes such as amylase that initiate the chemical breakdown of carbohydrates. The food then travels down the esophagus, a muscular tube that connects the mouth to the stomach.
2. DIGESTION IN STOMACH:
The stomach is a highly muscular organ that further breaks down food through mechanical churning and the secretion of gastric juices. These juices, including hydrochloric acid and pepsin, help to break down proteins into smaller peptides. The stomach also plays a role in the absorption of certain substances, such as alcohol and some medications.
3. DIGESTION IN SMALL INTESTINES:
From the stomach, partially digested food enters the small intestine, where the majority of nutrient absorption takes place. The small intestine is divided into three sections: the duodenum, jejunum, and ileum. The inner lining of the small intestine is covered in finger-like projections called villi, which increase the surface area available for absorption. Nutrients are absorbed into the bloodstream through the villi and transported to various organs and tissues for energy production and other metabolic processes.
4. DIGESTION IN LARGE INTESTINES:
The large intestine, also known as the colon, is responsible for the absorption of water and electrolytes, as well as the formation and elimination of feces. The colon is home to trillions of beneficial bacteria, collectively known as the gut microbiota, which play a crucial role in digestion and overall health. The microbiota help break down certain indigestible carbohydrates, produce vitamins, and protect against harmful pathogens.
5. ROLE OF ACCESSORY GLANDS IN DIGESTION:
Several accessory organs support the digestive process. The liver produces bile, which is stored in the gallbladder and released into the small intestine to aid in the digestion and absorption of fats. The pancreas secretes digestive enzymes into the small intestine to further break down carbohydrates, proteins, and fats.
REGULATION OF PHYSIOLOGY OF HUMAN DIGESTIVE SYSTEM:
The digestive system is regulated by both neural and hormonal mechanisms. The enteric nervous system, a network of nerves within the digestive tract, controls the movement and secretion of the digestive organs. It receives input from the central nervous system and responds to signals from the gut. Hormones also play a vital role in regulating digestion. For example, the hormone gastrin stimulates the secretion of gastric juices in the stomach, while cholecystokinin (CCK) stimulates the release of digestive enzymes from the pancreas and bile from the gallbladder.
The physiology of the human digestive system is a complex and intricate process that involves the coordination of various organs and mechanisms. From the initial breakdown of food in the mouth to the absorption of nutrients in the small intestine, each step is essential for maintaining our overall health. Understanding the physiology of digestion can help us make informed choices about our diet and lifestyle, ultimately leading to better digestive health.
Huynh HT, et al. Salivary amylase: Digestion and metabolic syndrome. Curr Diab Rep. 2017;17(10):92. https://pubmed.ncbi.nlm.nih.gov/27640169/
Sachs G, et al. The gastric biology of the proton pump inhibitor era: Beyond acid inhibition. Gastroenterology. 2017;153(2):320-334. https://pubmed.ncbi.nlm.nih.gov/19006606/
Dressman JB. Comparison of canine and human gastrointestinal physiology. Pharm Res. 1986;3(3):123-131. https://pubmed.ncbi.nlm.nih.gov/24271517/
Chiang JY. Bile acids: Regulation of synthesis. J Lipid Res. 2009;50(10):1955-1966. https://pubmed.ncbi.nlm.nih.gov/19346330/