Digestive System Overview

Digestion

• Digestion is the process of breaking down food into small particles and molecules that the body can absorb and use.
• Mechanical digestion physically breaks down food into smaller pieces.
• Chemical digestion involves chemical reactions that break down food into small molecules.
• Peristalsis is the wave-like muscle contractions that move food through the digestive tract.
• Villi are finger-like projections that cover the small intestine and increase its surface area for nutrient absorption.
• The excretory system collects and eliminates waste from the body and regulates fluid levels.

Digestive System

• The digestive system breaks down food so the body can absorb nutrients.
• The mouth begins the digestive process, where food is chewed and mixed with saliva.
• The esophagus is a muscular tube that transports food from the mouth to the stomach.
• The stomach stores food and mixes it with gastric juice, which contains acids and enzymes that aid in chemical digestion.
• The liver produces bile, which helps digest fats, and processes blood containing nutrients from the small intestine.
• The gallbladder stores and concentrates bile, releasing it into the biliary tract to aid in fat digestion.
• The pancreas produces enzymes that break down fats, proteins, starches, and acids, as well as hormones like insulin and glucagon that regulate blood sugar.
• The small intestine absorbs most nutrients from digested food.
• The large intestine absorbs water and electrolytes, eliminates waste, and forms solid stool.
• The rectum stores stool and controls its release through the anus.

The Food You Eat

• Food in a biological sense is anything that provides energy for the body.
• This energy is obtained through nutrients.
• Anything that provides nutrients but does not provide energy is not considered food.

Saliva & Digestion

• Saliva starts the chemical digestion process in the mouth, breaking down food into smaller particles.
• Saliva also makes it easier to swallow food.

Villus & Absorption

• Villi are finger-like projections in the small intestine that contain blood vessels.
• These blood vessels collect nutrients from the small intestine and transport them to the bloodstream.