HardBiologyHigh School (9–10)GeneralLife Processes › NutritionHuman Body › Digestive SystemNumerical
Treat one villus as a small cylinder of radius 0.05 mm and height 0.8 mm.
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
Treat one villus as a small cylinder of radius and height . Count only its curved side, .
- Find the area of the side of one villus.
- of the wall carries villi. Find the total lining on that square millimetre: the flat plus the sides of the villi.
Need a reminder? The key ideaShow
Saliva (salivary amylase): starch to sugar. Stomach: hydrochloric acid, pepsin for proteins, mucus. Small intestine: bile emulsifies fats and makes the food alkaline; pancreatic juice has trypsin and lipase; intestinal juice gives amino acids, glucose, and fatty acids with glycerol. Villi absorb the food; the large intestine takes back water.
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. One villus. .
Step 2. All the villi. (with more decimals, ).
Step 3. The lining. .
Answer: for one villus, and about of lining on each mm² of wall: more than seven times the flat area.
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