Digestive System Overview
The digestive system GCSE Biology notes provide a comprehensive overview of the digestive process. The system begins with the mouth, where food is mechanically broken down and mixed with saliva containing amylase enzyme is produced in the salivary glands. The food then travels through the esophagus to the stomach, where it is further broken down by stomach acid.
Highlight: The stomach produces acids to kill bacteria and break down food.
The liver produces bile, which contains lipase and is stored in the gallbladder. The small intestine continues the breakdown process and absorbs nutrients, while the large intestine absorbs water. The pancreas plays a crucial role by producing enzymes like amylase and protease.
Definition: Digestion is the process of turning large insoluble molecules into smaller soluble ones.
The digestive process includes several key steps:
- Ingestion
- Peristalsis in the esophagus
- Stomach acid production
- Bile production by the liver
- Nutrient absorption in the small intestine
- Water absorption in the large intestine
- Feces storage in the rectum
- Egestion through the anus
Vocabulary: Peristalsis refers to the wave-like muscle contractions that move food through the digestive tract.
The "Lock and Key Model" explains how enzymes work in digestion. Enzymes are biological catalysts that speed up chemical reactions in organisms. They break down specific substrates during digestion:
- Amylase breaks down carbohydrates into glucose
- Protease breaks down proteins into amino acids
- Lipase breaks down fats into fatty acids
Example: Amylase enzyme is produced in the salivary glands, the small intestine and which other organ? The pancreas also produces amylase.
These enzymes are produced in various parts of the digestive system:
- Amylase: salivary glands, pancreas, small intestine
- Protease: stomach, pancreas, small intestine
- Lipase: pancreas, small intestine
After digestion, nutrients are absorbed from the small intestine into the blood and then diffuse into cells.
