Enzymes and their role in digestion II
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- Created on: 18-05-15 18:32
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- Enzymes and their role in digestion
- 5. The Ileum (small intestine)
- It is adapted for the absorption of food in a number of ways (ensures diffusion of food into the blood takes place rapidly):
- process of absorption is aided by a good blood supply and thin permeable membranes of the cells that line the ileum
- folded which greatly increases the surface area
- over 6m in length
- Soluble food is mainly absorbed by diffusion.
- Soluble sugars, amino acids and other products of digestion will be in high concentration in the lumen of the small intestine.
- They will be in low concentration in the blood.
- Therefore, these molecules will diffuse into the blood from the lumen.
- The process of diffusion takes place more rapidly when:
- large surface area
- steep concentrationgradient
- short diffusion pathway
- The villi help absorption by:
- the villus has a thin and permeable surface lining - there is a single layer of epithelial cells between the lumen of the gut and the capillaries and lacteals
- their finger-like shape and microvilli on the surface epithelial cells provide a large surface area for absorption
- they have an excellent blood supply - each villus has an extensive capillary network, which means the whole small intestine is well supplied with blood to transport the absorbed products of digestion (helps maintain a steep concentrationgradient)
- The lacteal absorbs the break down products of fates before returning them to the blood.
- It is adapted for the absorption of food in a number of ways (ensures diffusion of food into the blood takes place rapidly):
- Following digestion the absorbed food molecules travel in the blood to the liver.
- In the liver excess amino acids will be broken down to produce urea, a soluble waste product removed from the blood by the kidneys.
- Excess glucose, under the influence of insulin secreted from the pancreas, will be converted to glycogen in the liver for storage.
- In the liver excess amino acids will be broken down to produce urea, a soluble waste product removed from the blood by the kidneys.
- 5. The Ileum (small intestine)
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