Haemoglobin

Introduction

Haemoglobin is an essential protein in the human body that is found in red blood cells (erythrocytes). It plays a central role in the transport of oxygen from the lungs to the tissues and organs and in the return transport of carbon dioxide from the tissues back to the lungs.

Structure and composition

Haemoglobin is a complex protein consisting of four subunits, each containing a chain of amino acids and a haem group. The haem groups contain a central iron molecule that is responsible for binding oxygen. There are several types of haemoglobin, which differ in their amino acid sequence. The most common haemoglobin in the adult human body is haemoglobin A, which consists of two alpha and two beta chains.

Function and mechanism

The main function of haemoglobin is to transport oxygen. In the lungs, oxygen binds to the iron atom in the haem group of haemoglobin, creating an oxygenated haemoglobin complex. This oxygen-rich blood is then transported through the bloodstream to the tissues. In the tissues, the oxygen is released and bound to carbon dioxide, which is then transported back to the lungs, where it is exhaled.

Significance in the body

Haemoglobin is essential for maintaining normal physiological functions in the body. A sufficient supply of oxygen is necessary for energy production in the cells, which in turn is required for all bodily functions. Carbon dioxide, a waste product of cellular metabolism, must be efficiently removed from the body to regulate blood pH and prevent an acidic metabolic load.

Normal values and measurement

The haemoglobin concentration is often measured as part of a blood test (complete blood count). Normal values vary depending on age and gender, but are typically:

• Adult men: 13.8 to 17.2 grams per decilitre (g/dL)
• Adult women: 12.1 to 15.1 g/dL

Deviations from these normal values can indicate various health conditions.

Health-related conditions

• Anaemia: A reduced haemoglobin concentration in the blood, known as anaemia, can be caused by various factors such as iron deficiency, vitamin B12 deficiency, chronic diseases or genetic disorders (e.g. sickle cell anaemia, thalassaemia). Symptoms of anaemia include tiredness, weakness, paleness and shortness of breath.
• Polycythaemia: An increased haemoglobin concentration can be caused by conditions such as polycythaemia vera (a bone marrow disorder) or chronic oxygen deficiency, e.g. due to lung disease or altitude adaptation. Symptoms include headaches, dizziness, increased blood pressure and an increased tendency to blood clots.
• Haemoglobinopathies: These genetic disorders affect the structure and function of haemoglobin. Examples include sickle cell disease and thalassaemia, which can cause serious health problems.

Conclusion

Haemoglobin is a vital protein in the human body that plays a crucial role in the transport of oxygen and carbon dioxide. Its concentration and function are key indicators of health and well-being. Deviations from normal values can indicate a variety of health problems that require thorough diagnosis and treatment. The importance of haemoglobin in medicine can therefore not be overestimated.