Digestive System Overview

Mouth and Epiglottis

• Teeth break down food into small pieces and mix with saliva from the tongue to form a bolus.
• Epiglottis closes the trachea to prevent food from entering and causing choking.

Esophagus

• The esophagus is a 20cm long tube that produces mucus and uses peristalsis to move food from the throat to the stomach.

Stomach

• The stomach stores food and breaks it down into tiny pieces, mixing it with digestive juices that contain pepsins to break down proteins and lipids.
• Hydrochloric acid (HCL) in the stomach kills bacteria.
• The food in the stomach is called chyme.

Small Intestine

• The small intestine is 7m long and composed of the duodenum, jejunum (absorbs the most), and ileum.
• The lining of the small intestine has villi, which are covered in microvilli to increase surface area for absorption.
• The small intestine absorbs 80% of ingested water, vitamins, minerals, carbohydrates, proteins, and lipids.

Large Intestine

• The large intestine is 1.5m long and absorbs whatever the small intestine doesn't absorb.
• The large intestine digests bacteria, ferments carbohydrates, and absorbs more water and concentrates waste.

Accessory Organs

Liver

• The liver produces bile, which helps digest fat and filters out toxins and waste.
• The liver regulates blood sugar levels.

Gallbladder

• The gallbladder stores bile from the liver and releases it into the small intestine through the bile duct.
• Fatty acids can cause gallstones.

Pancreas

• The pancreas produces digestive enzymes to digest fats, carbohydrates, and proteins.
• The pancreas regulates blood sugar levels by producing insulin.