Nutrition Essentials: Vitamins and Iron

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What role does hepcidin play in iron absorption?

It induces the sloughing off of enterocyte iron stores.

It facilitates the absorption of iron in macrophages.

It binds to ferroportin to inhibit iron release from enterocytes. (correct)

It enhances iron absorption in the intestines.

What would likely occur if hepcidin levels are elevated?

Increased absorption of iron from dietary sources.

Decreased levels of iron in the bloodstream. (correct)

Enhanced release of iron from macrophages.

Absorption of iron in the kidneys.

Which of the following best describes the consequence of iron remaining in enterocytes?

It is sloughed off and lost in feces. (correct)

It will eventually be released into the bloodstream.

It is rapidly utilized for erythropoiesis.

It is excreted through bile.

How does DMT1 influence iron absorption?

It mediates the transport of iron into enterocytes. Signup and view all the answers

What effect does teropolin have on iron metabolism?

It can block iron from being released from enterocytes. Signup and view all the answers

What is the primary function of ferroportin regarding iron?

To facilitate iron exportation from enterocytes and macrophages. Signup and view all the answers

What might occur if the release of iron from macrophages is inhibited?

Anemia may occur due to reduced iron availability. Signup and view all the answers

What is a potential consequence of a mutation in the Ab gene related to HbS?

Occlusion of small vessels leading to severe pain Signup and view all the answers

Which type of anemia is characterized by small red blood cells with decreased hemoglobin content?

Microcytic Hypochromic Anemia Signup and view all the answers

What is a cause of macrocytic (megaloblastic) anemia?

Vitamin B12 deficiency Signup and view all the answers

Anemia due to chronic inflammation is classified as which type?

Normocytic Normochromic Anemia Signup and view all the answers

In iron deficiency anemia, increased iron demand may occur due to which of the following conditions?

Pregnancy and lactation Signup and view all the answers

What percentage of iron in the body is typically found in hemoglobin?

70% Signup and view all the answers

What is the main storage form of iron in the body?

Ferritin Signup and view all the answers

What form of iron has a higher bioavailability?

Heme iron Signup and view all the answers

How much iron does a normal adult male lose daily?

0.5 – 1.0 mg Signup and view all the answers

Which process is primarily responsible for iron absorption in the body?

Pinocytosis Signup and view all the answers

What is the daily iron requirement for an average adult?

30 mg Signup and view all the answers

What is the primary consequence of free iron in the body?

Generation of reactive oxygen species (ROS) Signup and view all the answers

Which type of iron is derived from plant sources?

Non-heme iron Signup and view all the answers

Where is hemosiderin mainly found in the body?

Bone marrow Signup and view all the answers

What percentage of dietary iron is typically absorbed from heme sources?

10% Signup and view all the answers

What is the role of hepcidin in iron metabolism?

It inhibits the release of iron from macrophages. Signup and view all the answers

Which factor is associated with an increase in hepcidin secretion?

Inflammation. Signup and view all the answers

What is a primary treatment method for hereditary hemochromatosis?

Phlebotomy. Signup and view all the answers

In which condition is MCHC typically below normal?

Hypochromic anemia. Signup and view all the answers

How is MCH calculated?

MCH = Hb content x 10 / RBC's count. Signup and view all the answers

What is a common consequence of hemosiderosis, often referred to as 'bronze diabetes'?

Increased hemosiderin in tissues. Signup and view all the answers

What typically results from iron overload due to repeated blood transfusions?

Hemosiderosis. Signup and view all the answers

Which statement about the action of hepcidin is true?

It acts to maintain iron homeostasis through upregulation in iron loading. Signup and view all the answers

What is indicated by a hematocrit value used in MCV calculation?

Volume fraction of red blood cells in the blood. Signup and view all the answers

What is the lifespan of enterocytes?

3-4 days Signup and view all the answers

Which mechanism is involved in exporting iron out of enterocytes?

Ferroportin Signup and view all the answers

Before iron can be transported into the bloodstream, it must be oxidized to which form?

Ferric Signup and view all the answers

What is the role of transferrin in iron metabolism?

To transport iron where needed Signup and view all the answers

Which enzyme is required for the oxidation of iron before its transport?

Ferroxidase Signup and view all the answers

What is the major regulator of iron absorption in the body?

Hepcidin Signup and view all the answers

What happens to iron transport in the presence of high levels of hepcidin?

Decreased absorption Signup and view all the answers

What is the immediate consequence of the oxidation of iron before blood absorption?

It allows iron to bind to transferrin Signup and view all the answers

What condition would be likely if ferroportin function is impaired?

Iron overload Signup and view all the answers

Which statement best describes the relationship between ferritin and hepcidin?

Hepcidin reduces ferritin levels Signup and view all the answers

Study Notes

Vitamin C

Essential vitamin, especially vitamin B12 (cyanocobalamine) and folic acid.
Vitamin B12 source: animal products (liver, meat, chicken).
Folic acid source: vegetables, fruits, liver, meat.
Vitamin B12 function: DNA synthesis, nuclear maturation, synthesis of myelin in nerves.
Vitamin B12 deficiency effects: macrocytic anemia, neurological symptoms.
Daily requirement: 5 micrograms.
Storage: liver (significant amounts).
Absorption issues: often due to absorption problems rather than dietary deficiency (except in vegetarians).
Absorption mechanism:
- Parietal cells in stomach release intrinsic factor.
- Intrinsic factor combines with vitamin B12, protecting it from digestive enzymes.
- Absorption in the terminal ileum (pinocytosis).
- Pancreatic trypsin aids absorption.
- Transcobalamin II transports absorbed B12 to the blood.
- Liver stores excess vitamin B12.

Iron

Body iron content: 3-5 grams.
Forms: hemoglobin (70%), muscle myoglobin (3%), enzymes (2%), ferritin (25%—main storage form).
Hemosiderin: aggregated ferritin molecules (50% iron).
Iron requirements: 30 mg/day.
Iron loss: roughly 1 mg/day for males, more in females due to menstruation.
Primary iron source: breakdown of hemoglobin from the liver and spleen.
Absorption: enterocytes in the duodenum absorb iron.
Dietary iron:
- Heme iron (in meat/meat products): higher bioavailability (10%).
- Non-heme iron (in plant-based foods): lower bioavailability (90%).
Iron absorption mechanism:
- Stomach acid (HCl) converts ferric iron (Fe³⁺) to ferrous iron (Fe²⁺).
- Divalent metal transporter 1 (DMT1) transports Fe²⁺ into enterocytes.
- Inside enterocytes, stored as ferritin if iron levels are high.
- If needed, iron is oxidized to Fe³⁺ and transported to the blood by ferroportin.
- Iron binds to transferrin for transport.
Hepcidin: major regulator of iron absorption.
- High hepcidin levels: inhibit iron absorption.
- Low hepcidin levels: promote iron absorption.
Factors affecting hepcidin secretion:
- Increased: inflammation, hypoxia
- Decreased: erythropoiesis, iron deficiency.

Anemia

Polycythemia: increased red blood cell count (6-8 million/mm³).
Types: Primary (Polycythemia Vera) and Secondary.
Anemia: reduced oxygen-carrying capacity due to low red blood cell count or hemoglobin levels.
- Hereditary spherocytosis
- G6PD deficiency (Favism)
- Thalassemias
- Sickle cell anemia
Types of anemia:
- Microcytic hypochromic: small, pale red blood cells (often iron-deficiency).
- Macrocytic (megaloblastic): large, immature red blood cells (often vitamin B12 or folate deficiency).
- Normocytic normochromic: normal-sized, normal-colored red blood cells (often due to acute blood loss, hemolytic anemia, etc.).
Blood indices: Mean corpuscular hemoglobin (MCH), Mean corpuscular volume (MCV), Mean corpuscular hemoglobin concentration (MCHC).

Iron homeostasis

Excess dietary iron decreases DMT-1, lessening iron absorption.
Hepcidin (25 amino acid hormone secreted by the liver) is a major iron regulator, influencing iron absorption, macrophage release, and liver release.
Factors affecting hepcidin: hypoxia, erythropoietin.
Iron loading: Increases secretion.
Inflammation: Increases secretion, causing anemia.
Hereditary hemochromatosis: mutant gene leading to increased iron absorption.
Repeated blood transfusions, hemosiderosis, pancreatic damage, and liver cirrhosis are all potential complications of iron overload.
Blood removal (phlebotomy) and iron chelating agents are common treatments.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

Test your knowledge on essential vitamins, especially B12 and folic acid, alongside the role and absorption of iron in the body. This quiz covers sources, functions, and deficiency effects of these vital nutrients. Perfect for students in health and nutrition courses!