Jejunum and ileum

Question 1

Function of ileum (3m)

Answer 1

• Mainly to absorb vitamin B12 and bile salts

- Absorbs whatever products of digestion were not absorbed by the jejunum.

Question 2

Characteristics of the ileum that help absorption

most absorption occurs in the ileum

Answer 2

• Walls of ileum- villi and microvilli maximise surface area which increases absorption
• Coiled section
  Digested molecules are absorbed across the walls of ileum into blood capillaries
• Total surface area- for absorption of nutrients by human villi

Question 3

Where is the ileum?

Answer 3

Ileum is the third and final part of the small intestine.

Question 4

What important features does villi have to help absorption in the ileum?

Answer 4

• One cell thick wall - ensures that there is only a short distance for absorption to happen by diffusion and active transport
• Network of blood capillaries - transports glucose and amino acids away from the small intestine in the blood
• Internal structure called a lacteal - transports fatty acids and glycerol away from the small intestine in the lymph

Question 5

Where is the jejunum?

Answer 5

The middle section and is the primary site of nutrient absorption.

Question 6

Function of jejunum (2.5m)

Answer 6

• Absorbs nutrients present in foods into the bloodstream.
• Before being passed on to the ileum for further absorption
• Able to absorb these nutrients because it is lined with finger-like projections that are called villi.
• The villi increase the surface area of the jejunum-
  allows much more absorption of nutrients