Food transport systems

Question 1

Travel of food to be digested

Answer 1

Food will enter through the mouth, be partially dissolved by the salivary glands, it travels down the œsophages, into the stomach, in the stomach they are broken down, these materials travel into the large intestine then the small where they are absorbed into the bloodstream and then waste materials are excreted through the rectum.

Question 2

End products of digestion

Answer 2

• Starch is broken down to glucose
• Protein is broken down to amino acids
• Fats are broken down to glycerol and fatty acids

Question 3

Absorption in the small intestine

Answer 3

The main function of the small intestine is to absorb the end products of digestion through its walls and then pass them into the circulatory system.

The small intestine is very efficient at this job because:

• It is long

• Its internal surface is folded and has finger like projections called villi
Together these create a very large surface area to the digested food.

Question 4

Villi

Answer 4

• The villi are covered by a cellular lining that is only one cell thick so the
soluble products of digestion can pass through rapidly

• The villi contain a dense network of blood capillaries into which
glucose and amino acids pass. These end products of digestion are
then transported to the liver in the hepatic portal vein.

• The villi contain a tiny lymphatic vessel called the lacteal that collects the
products of fat digestion and passes them into the lymphatic system