Storage

Question 1

Name sources of iron.

Answer 1

Meat, egg yolk, beans, nuts, shell fish

Question 2

Where does the homeostatic control of iron balance primarily reside?

Answer 2

In the intestinal epithelium of the duodenum. Here, ion is actively absorbed. 10% of ingested iron is absorbed into the blood each day.

Question 3

Name the complex that acts as an intracellular store for iron.

Answer 3

Ferritin

Question 4

How does the body’s iron contents affect iron absorption?

Answer 4

If stores are enough, the increased conc of free iron leads to increased transcription of the gene encoding ferritin so more ferritin is synthesised. More iron binds to ferritin and less is in the blood.

If stores are low, ferritin production decreases.

Question 5

How does absorbed iron not bound to ferritin travel?

Answer 5

It is released into the blood, bound to the plasma protein Transferrin. Transferrin also transports iron to bone marrow to be incorporated into new erythrocytes.

Question 6

Where is most of the iron stored within the liver?

Answer 6

Within ferritin in Kupffer cells

Question 7

In the post-absorptive state of glucose, what are the 3 main sources of glucose?

Answer 7

1. Glycogenolysis: hydrolysis of glycogen to glucose-6-phosphate. Occurs in liver.
2. Lipolysis: triglycerides are hydrolysed to produce glycerol and fatty acids. In the liver, glycerol is converted to glucose. (gluconeogenesis)
3. Protein: Protein is broken down to amino acids and converted to glucose in the liver via the alpha-keto acid pathway.
   (gluconeogenesis)

In all instances, 6 molecules of ATP are consumed for every 1 molecule of glucose formed.