Mechanisms for the absorption of the products of digestion by cells lining the ileum: co-transport mechanisms for absorption of amino acids and monosaccharides; the role of micelles in the absorption of lipids
After digestion, the small intestine absorbs nutrients using two main methods. Sugars and amino acids hitch a ride with sodium ions into cells. Fats use tiny droplets called micelles to reach the intestinal lining.
Real World
Oral rehydration salts (ORS), used worldwide to treat cholera patients, exploit co-transport: the solution contains both glucose and sodium so that glucose drives sodium absorption, and water follows by osmosis, rehydrating the patient rapidly.
Exam Focus
For co-transport questions, always state the sodium gradient is maintained by sodium-potassium ATPase — omitting this mechanism commonly loses marks.
Evaluation Scaffold
A four-step framework for high-quality evaluation. Use this for 'assess', 'evaluate', and 'to what extent' questions.
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