Most food is solid and in the form of large complex molecules which are insoluble and chemically inert (not readily usable)
The process of digestion therefore performs two key functions:
The process of digestion therefore performs two key functions:
- It breaks down insoluble molecules into smaller subunits which can be readily absorbed into body tissues
- It breaks down inert molecules into usable subunits which can be assimilated by cells and reassembled into new products
- Dialysis tubing contains pores typically ranging from 1 - 10 nm in diameter and is semi-permeable according to molecular size
- Large molecules such as starch cannot pass through the tubing, however smaller molecules (such as maltose) can cross
- Unlike the membranes of living cells, dialysis tubing is not selectively permeable based on charge (ions can freely cross)
Nature of Science:
6.1.NOS: Use models as representations of the real world-dialysis tubing can be used to model absorption in the intestine.
Objectives:
6.1.NOS: Use models as representations of the real world-dialysis tubing can be used to model absorption in the intestine.
Objectives:
- Explain the use of models in physiology research.
- State two examples of model systems used to study digestion.
- State limitations of using model systems in physiology research.
Models are an essential part of the scientific method and have been discussed in our biology syllabus in topics ranging from Neural Development, the human brain, DNA structure and membranes.
Models allow scientists to represent an idea that is difficult, or impossible to experience directly. By their nature they are simplifications of the real world processes they describe, but they are still extremely useful as a means of explaining processes, making predictions, testing hypotheses and analysing data. Think of the importance of models of climate change or fisheries populations – these models have direct impacts on economics, politics and society.
In 6.1 we are discussing the use of models in the digestive system. A classic middle-school demonstration is to use visking, or dialysis, tubing to demonstrate the workings of the digestive system. An example experiment using starch, iodine and Benedict’s solution shows how this might work. The inside of the model gut originally contains both starch and glucose. However, testing over time shows that after 15 minutes, the gut still contains starch, however the liquid outside the “gut” tests positive for glucose. The movement of glucose out of the gut and into the surrounding fluid, while the larger starch molecules stay behind, helps demonstrate the need to reduce the size of polysaccharides before they can be absorbed and used by the body.
Models allow scientists to represent an idea that is difficult, or impossible to experience directly. By their nature they are simplifications of the real world processes they describe, but they are still extremely useful as a means of explaining processes, making predictions, testing hypotheses and analysing data. Think of the importance of models of climate change or fisheries populations – these models have direct impacts on economics, politics and society.
In 6.1 we are discussing the use of models in the digestive system. A classic middle-school demonstration is to use visking, or dialysis, tubing to demonstrate the workings of the digestive system. An example experiment using starch, iodine and Benedict’s solution shows how this might work. The inside of the model gut originally contains both starch and glucose. However, testing over time shows that after 15 minutes, the gut still contains starch, however the liquid outside the “gut” tests positive for glucose. The movement of glucose out of the gut and into the surrounding fluid, while the larger starch molecules stay behind, helps demonstrate the need to reduce the size of polysaccharides before they can be absorbed and used by the body.