Functions of Digestive System and Accessory Glands

Digestive System

• The digestive system is a collective of organs that work together to facilitate digestion.
• It consists of two parts: the Gastrointestinal Tract (GIT) and the accessory glands.

Anatomy of the Digestive System

• The Gastrointestinal Tract (GIT) is divided into the upper and lower gastrointestinal tracts.
• The upper gastrointestinal tract includes:
  • Oral cavity (Mouth)
  • Pharynx
  • Esophagus
  • Stomach
  • Duodenum
• The lower gastrointestinal tract includes:
  • Most of the small intestine (Duodenum, Jejunum, Illium)
  • All of the large intestine
  • Anus (according to some sources)

Accessory Glands

• The accessory glands consist of:
  • Salivary gland
  • Liver
  • Pancreas
  • Gall bladder

Functions of Digestive System

• The digestive system is responsible for consuming and digesting foodstuffs, absorbing nutrients, and expelling waste.
• The gastrointestinal tract is also a significant part of the immune system.
• The low pH of the stomach neutralizes many microorganisms.
• Health-enhancing intestinal bacteria of the gut flora serve to prevent the overgrowth of potentially harmful bacteria in the gut.

Normal Gastrointestinal Microbiota (Normal Flora)

• Bacteria make up most of the flora in the colon and up to 60% of the dry mass of feces.
• There are between 300 and 1000 different species of bacteria living in the gut.
• Fungi and protozoa also make up a part of the gut flora.
• The microorganisms perform functions such as:
  • Fermenting unused energy substrates
  • Preventing growth of harmful, pathogenic bacteria
  • Regulating the gut

Diseases of Digestive System

• Gastroenteritis is an inflammation of the intestines.
• It occurs more frequently than any other disease of the intestines.

Classification of Infection in the Digestive System

• Infections in the digestive system are classified into two groups:
  • Exogenous infections: pathogens that come into the body
  • Endogenous infections: organisms that are part of the normal flora

Diseases

• Cancer: may occur at any point in the gastrointestinal tract, including mouth, tongue, esophageal, stomach, and anal cancer.
• Inflammatory conditions:
  • Ileitis: inflammation of the ileum
  • Colitis: inflammation of the intestine
  • Appendicitis: inflammation of the vermiform appendix
• Peptic ulcer: open sore in the lining of the stomach or duodenum
• Anal fistula: abnormal, tube-like passageway near the anus
• Dysphagia: difficulty in swallowing
• Jaundice: yellow-orange coloration of the skin and whites of the eyes caused by high levels of bilirubin in the blood