Free medical quiz
Iron Metabolism Quiz
Focused SBA-style practice, followed by the answer and explanation for every question.
- Free now
- 5 questions
- Full bank
- 30 questions
- Answers
- Explained
Free question
Try one with the answer
A question from this quiz. Answer it to see the explanation students get.
Which is the main physiological compartment for reserve iron storage in the body?
- A Enterocytes of the duodenum storing iron as ferritin during absorption You picked ✕
- B Skeletal muscle fibres storing iron as myoglobin for oxygen transport You picked ✕
- C Free iron circulating unbound in plasma You picked ✕
- D Hepatocytes and macrophages containing ferritin and haemosiderin You picked ✓
- E Renal tubular cells storing excess iron for excretion You picked ✕
Correct!
Incorrect
The answer is D: Hepatocytes and macrophages containing ferritin and haemosiderin
Explanation
Why D is correct
See Iron Storage. Option D is correct. Iron is toxic when free, so the body keeps it locked inside proteins. The main store is ferritin, a soluble iron-protein complex that holds iron in a hollow shell and releases it in a controlled way. Where ferritin molecules clump together, they form insoluble haemosiderin, which builds up in macrophages (scavenger cells) of the liver, bone marrow and spleen. Hepatocytes (liver cells) also hold a large store, and the liver and the macrophages of the reticuloendothelial system (the network of scavenger cells in the liver, spleen and marrow) hold most of the body's reserve. Most iron in the body comes from recycling old red cells, which macrophages engulf: they either send the iron back into the blood on transferrin or keep it as ferritin. That is why the diet only needs to replace a small amount each day. Because the body cannot excrete iron, storage is tightly controlled, and over-loading, as in haemochromatosis or repeated transfusion, damages the organs that store it.
- Ferritin: the main iron store, a soluble iron-protein complex that releases iron in a controlled way.
- Haemosiderin: insoluble clumped ferritin that builds up in macrophages of the liver, bone marrow and spleen.
- Main sites: hepatocytes and the macrophages of the reticuloendothelial system hold most of the reserve.
Why the other options are incorrect
- A. Enterocytes of the duodenum storing iron as ferritin during absorption: Enterocytes can hold iron as ferritin while they regulate absorption, but this is a temporary transit pool and the cells are shed within days, so they are not the main reserve store. Your answer
- B. Skeletal muscle fibres storing iron as myoglobin for oxygen transport: Myoglobin holds iron for oxygen transport in muscle and is not a reserve store that the body can draw on, so it accounts for only a small share of body iron. Your answer
- C. Free iron circulating unbound in plasma: Free iron is toxic, so it is not allowed to circulate unbound. In plasma it is carried bound to transferrin, and the plasma holds only a tiny amount. Your answer
- E. Renal tubular cells storing excess iron for excretion: The kidneys are not used to store iron, and the body has no active way of excreting it. Iron that is not needed is held in ferritin elsewhere. Your answer
With Premium, questions you miss become Revision Coach flashcards, scheduled for review.
Question preview
What you will practise
More questions from this set. Start the quiz to answer them and see each explanation.
-
1
Which blood film appearance is most characteristic of iron deficiency anaemia?
-
2
Which statement best explains why haem iron from meat is absorbed more efficiently than non‑haem iron from plant sources?
Revise before you test
Review SimpleMed's doctor-written article, then return here to check recall.
Read the topic articleNeed wider coverage?
Explore every Haematology topic set, or build a tailored mixed session.
Browse subject quizzes