Question

11. In a lactose intolerant individual which of the following answers correctly describes the direction of water movement across the intestinal epithelia?

a. From the lumen of the intestine to the blood supply

b. From the blood supply to the lumen of the intestine

c. From the epithelia of the small intestine to the epithelia of the large intestine

d. From the epithelia of the large intestine to the epithelia of the rectum

Answer 1

Lactose Intolerance:

Lactose intolerance may be caused due to various reasons like:

1. Inherited lactose intolerance- genes of lactase deficiency is inherited. It may be further subdivided as:

a) Primary lactase deficiency- In this case, lactase deficiency occurs gradually or declines after a certain age. This is the most common type of lactose intolerance and is also called lactose on persistence. This may occur at any age, but usually observed above the age of six years.

b) Congenital lactase deficiency- In this case lactose intolerance is observed from birth.

2) Lactase deficiency may also be formed due to external reasons, like:

a) Developmental lactase deficiency- This is a transient form and is observed in premature babies. The condition usually does not last when baby becomes older.

b) Secondary lactase deficiency- Due to injuries, infections, or other diseases, the intestinal may be damage, resulting in lactase deficiency.

• Lactose intolerance leads to accumulation of lactose.
• The increased lactose concentration in intestinal lumen leads to osmotic gradient.
• This results in uptake of water by intestinal tissues from blood and decrease in absorption of water back to blood.
• This causes abdominal cramps and diarrhea.

Answer: b