Nutrient Digestion and Absorption 2

Question 1

What is triacylglycerol broken into?

What is it broken down by?

Answer 1

triacylglycerol is broken into a momoglyceride and 2 fatty acids by lipase.

Question 2

Where is fat digested and what by?

Answer 2

In the small intestine by water-soluble pancreatic lipase

Question 3

What is emulsification?

Answer 3

dividing large lipid droplets into smaller droplets increased surface area and accessibility to lipase action.

Question 4

Which emulsifying agents are required?

Answer 4

Bile salts and phospholipids prevent large fat droplets reforming.

Question 5

What is a micelle?

Answer 5

Micelle = bile salt + monoglycerides + fatty acids + phospholipids
extracellular and too big to be absorbed

Question 6

What is the function of a micelle?

Answer 6

Enhances absorption of fats and transports fats to membranes without water contact(water is fatal to fat)

Question 7

Why is emulsification neccessary?

Answer 7

Lipase only does surface digestion so large droplets have to be made smaller by emulsification.

Question 8

What happens to fatty acids and monoglycerols when they enter the epithelial cells?

Answer 8

Enzymes in the smooth endoplasmic reticulum convert them into triacylglycerols.

Question 9

What happens to extracellular fat droplets?

Answer 9

Converted into chylomicrons which pass into lacteals(part of the lymphatic system)

Question 10

Which are the fat soluble proteins?

Answer 10

A,D,E and K

Question 11

Which are the water soluble proteins?

Answer 11

B,C and Folic acid

Question 12

How is vitamin B12 absorbed?

Answer 12

It is a large charged molecule which binds to an intrinsic factor in stomach to form complex. Then absorbed via specific transport mechanism in the distal ilium.

Question 13

What is pernicious anaemia?

Answer 13

B12 deficiency that results in the failure of red blood cell maturation.

Question 14

How much B12 does the liver store?

Answer 14

3 years worth.

Question 15

How does iron transport across the brush border membrane?

Answer 15

Via DMT1(hydrogen ion coupled transporter)

Question 16

How is iron stored and why?

Answer 16

In ferritin which is a protein iron complex because iron alone is toxic.

Question 17

How does unbound iron transport into the blood?

Answer 17

Across the serosal membrane.

Question 18

What does unbound iron bind to in the blood?

Answer 18

Transferrin

Question 19

Iron is the only nutrient regulated by the gut.

Answer 19

everything else(carbs,proteins,fats etc) are continually absorbed as you eat, iron is the exception.

Question 20

Define hyperaemia

Answer 20

Increased ferritin levels,therefore more iron bound on the enterocytes.

Question 21

Define anaemia

Answer 21

Decreased ferritin levels, therefore more iron released into blood.