Summary and Exam Tips for Digestion and Absorption
Digestion and absorption is a subtopic of Human Physiology, which falls under the subject Biology in the IB DP curriculum. The process begins in the oesophagus, a hollow tube that uses peristalsis to move food to the stomach. The stomach acts as a storage tank where food is churned and proteins begin to digest in an acidic environment. The small intestine is a long, folded tube where nutrients are absorbed, consisting of the duodenum, jejunum, and ileum. The large intestine absorbs water and minerals and includes the colon and rectum. Salivary glands release enzymes like amylase to start starch breakdown. The pancreas produces enzymes and hormones like insulin, while the liver processes absorbed materials, producing bile stored in the gallbladder. Peristalsis aids in mixing food with enzymes in the intestines. Pancreatic juice contains enzymes for digesting macromolecules. Villi in the small intestine increase surface area for absorption of nutrients, ions, and vitamins. Nutrients are absorbed through various membrane transport methods, with glucose co-transported with sodium ions. The liver converts excess glucose to glycogen for storage.
Exam Tips
- Understand Key Processes: Focus on the role of each organ in digestion and absorption, such as the stomach's acidic environment and the small intestine's nutrient absorption.
- Memorize Enzyme Functions: Know the specific enzymes involved in digestion, like amylase for starch and lipase for triglycerides.
- Diagram Practice: Practice drawing and labeling the digestive system, emphasizing structures like the villi and their role in absorption.
- Conceptualize Peristalsis: Grasp how peristalsis moves food through the alimentary canal and its importance in digestion.
- Transport Mechanisms: Be clear on how different nutrients are absorbed, including active transport and facilitated diffusion.
