[Unit 4.5] | Co-transport And The Absorption Of Glucose In The Ileum

Question 1

What cells line the Ileum?

Answer 1

Epithelial Cells.

Question 2

What is the structure and function of microvilli?

Answer 2

• They are long finger-like projections of the cell membrane of an epithelial cell.

• They increase the surface area of the membrane which means more protein carriers and channels can be inserted into it, allowing for more facilitated diffusion and active transport.
• Short diffusion pathway

Question 3

What is the ileum commonly called?

Answer 3

The small intestine.

Question 4

How are amino acids and glucose absorbed into the blood?

Answer 4

• Facilitated Diffusion is used; there is a higher concentration of amino acids and glucose in the ileum than in the blood.

• Concentration in the ileum is higher due to the frequent digestion of carbohydrated and proteins.

• Concentration in the blood is lower due to the constant demand for amino acids and glucose during respiration.

Question 5

Why is Active Transport used for the absorption of glucose and amino acids?

Answer 5

Diffusion only allows an equilibrium to be reached, meaning not all glucose and amino acids can be absorbed.

Question 6

What mechanism is used to absorb amino acids and glucose into the blood?

Answer 6

Co-Transport (in the epithelial cells)

Question 7

Explain the process of co-transport.

Answer 7

• Glucose or an amino acid is drawn to a sodium ion which enters the epithelial cell via the lumen.

• The glucose or amino acid can then leave the cell and enter the blood via facilitated diffusion.
• Sodium enters the blood via a Sodium-Potassium pump (Active Transport), where the potassium is supplied by the blood.

Question 8

How does the absorption of glucose use indirect active transport?

Answer 8

• Glucose’s active transport is powered by the sodium ions that follow a high -> low concentration gradient (instead of ATP).