Anatomy and physiology of the digestive system
Every cell in the human body needs carbohydrates, fats, proteins, vitamins, water, and minerals to perform the daily metabolic processes involved in maintaining a living system. Most of these substances are extracted from the food we eat as it passes through the alimentary tract, i.e., the tube that begins with the mouth and ends at the anus. The main function of the alimentary tract is to transfer these materials from the external environment to the internal environment and elimination of food.
Food items are not absorbed in their ingested state. They must be broken down into smaller molecular components before this transfer can occur. This process is called Digestion, and may be through mechanical or chemical means. Absorption refers to the movement of small molecules from the alimentary tract, into the blood and lymphatic vessels.
The anatomy and physiology of the alimentary tract will be discussed in the order that food passes through it. Accessory organs and glands will be discussed when appropriate.