In which organ does the absorption of iron takes place?

AIIMS Patna NO - 2020

Applied Physiology

Easy

Appeared in: AIIMS Patna NO - 2020

Explanation

The duodenum is the primary site for the absorption of dietary iron.
The acidic pH of the duodenum and the presence of specific transporters on its epithelial cells are optimized for iron uptake.
Both heme iron (from animal products) and non-heme iron (from plants) are absorbed in the duodenum, although through different mechanisms.
The body regulates iron balance mainly by controlling the amount of iron absorbed in the duodenum, a process influenced by the hormone hepcidin.

Option A: The colon's main function is the absorption of water and electrolytes from indigestible food matter and the storage of feces. It lacks the specific transporters and acidic environment needed for efficient iron absorption.
Option C: The liver is the main storage site for iron (in the form of ferritin and hemosiderin) and plays a central role in regulating iron homeostasis in the body. However, it does not absorb iron directly from the digested food.
Option D: The stomach plays a crucial preparatory role but is not the site of absorption. It secretes acid that helps to release iron from food and converts it to the more soluble ferrous (Fe²⁺) form, which is then absorbed in the duodenum.

Clinical Relevance

Nursing practice connection: Knowing Physiology of iron absorption in the gastrointestinal tract helps nurses interpret findings accurately and avoid errors in routine assessment, medication administration, and patient teaching.
Understanding the site of iron absorption is critical for diagnosing and managing iron deficiency anemia. Conditions affecting the duodenum, such as celiac disease, Crohn's disease, or surgical resection, directly impair iron uptake.
Nurses must educate patients on factors that affect iron absorption. For example, taking iron supplements with vitamin C (ascorbic acid) enhances absorption, while taking them with milk, tea, or antacids can inhibit it.
What if a patient has had a gastrectomy (surgical removal of the stomach)? The loss of stomach acid would significantly reduce the conversion of ferric iron to the absorbable ferrous form, leading to poor iron absorption in the duodenum and a high risk of iron deficiency anemia, even with adequate dietary intake.

How to Approach the Question

First, identify the key physiological process asked in the question, which is the 'absorption of iron'.
Next, recall the primary functions of each organ listed in the options concerning digestion and absorption.
Stomach: Its main roles are food storage, mixing, and secreting acid and enzymes for initial digestion.
Duodenum (Small Intestine): This is the primary site for the chemical digestion and absorption of most nutrients.
Liver: This organ has many metabolic functions, including producing bile, detoxifying blood, and storing nutrients like glycogen and iron.
Colon (Large Intestine): Its main function is to absorb water and electrolytes and form feces.

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