What is Blood?
Blood is the thick fluid that circulates through the arteries and veins of living beings. The heart pumps it throughout the body, reaching every cell. Blood functions as the fuel for life—without it, life cannot continue. In a healthy human, there are approximately five litres of blood. If two liters of blood are lost, the heart cannot maintain the circulatory system, leading to death.
Blood is primarily composed of three types of cells:
Red Blood Cells (RBCs)
The most important component of blood is the red blood cells, also known as haemoglobin. These cells make up about 90% of the blood’s volume. They are produced in the bone marrow with the help of iron. A single red blood cell lives for about 120 days. If the red blood cell count drops, the body’s supply of oxygen and nutrients is disrupted, leading to death. These cells also transport hydrogen gas from the body to the lungs and bring fresh oxygen from the lungs to the rest of the body. In a healthy body, the haemoglobin level is typically around 11-12. A deficiency in red blood cells is known as anaemia.
White Blood Cells (WBCs)
White blood cells act like warriors in the body, fighting off germs and infections. In the process of this battle, white blood cells often die, and their remnants are expelled from the body in the form of pus.
Platelets (Thrombocytes)
Platelets help stop blood flow by forming a thin membrane, or clot, when there is an injury. These cells circulate in the blood, ready to spring into action when needed. If there is an injury, platelets quickly form a clot over the wound to prevent excessive bleeding. A normal platelet count ranges between 150,000 and 450,000. If this count drops below 50,000, bleeding may not stop during an injury. If it falls below 20,000, the skin becomes so delicate that even simple activities like shaving can cause problems.
Causes of Red Blood Cell Deficiency
A deficiency in iron can affect both men and women at any age. This can result from a lack of folate, vitamin B12, minerals, or the inadequate intake of foods like meat, eggs, or leafy green vegetables. Other factors include pregnancy, poor stomach health, or digestive issues. A diet that relies only on vegetables can also lead to a reduction in red blood cells.
Signs of Red Blood Cell Deficiency
- Physical weakness and fatigue
- Pale skin
- Shortness of breath
- Dizziness
- Tingling in hands and feet
- Pain or swelling in the tongue
- Cold hands and feet
- Brittle nails
- Frequent headaches
- Cravings for non-food items like dirt, ice, or raw grains
How to Address Iron Deficiency
The human body requires 150-200 mg of iron daily. To boost iron levels, consume iron- and vitamin C-rich foods such as beans, pumpkin seeds, raisins, eggs, fish, oatmeal, lamb, chicken, beef, oranges, grapes, strawberries, kiwis, guavas, pineapples, melons, bananas, papayas, mangoes, broccoli, bell peppers, cauliflower, tomatoes, and leafy green vegetables.
Additionally, include iron-rich foods like tomatoes, raisins, dried apricots, mulberries, dates, pomegranates, watermelon, prunes, liver, chickpeas, lentils, and spinach.
Where Does Blood Form?
Blood is produced in the bone marrow, the spongy tissue inside bones that many of us enjoy eating in dishes like nihari or biryani. Bone marrow is a structured mixture of cells, and it functions as a factory for blood cell production in animals and birds. A typical adult human’s bone marrow is mostly located in the spine, chest bones, and lower body bones, accounting for about 5% of the total body weight. The bone marrow produces approximately 500 billion cells daily.
There are two types of bone marrow: red and yellow. Red bone marrow produces red blood cells, white blood cells, and platelets, while yellow bone marrow generates fat cells (adipocytes), bone cells, and cartilage. The yellow marrow becomes active when the body requires additional blood cell production.
Blood Types and Blood Transfusion
There are 30 different blood group systems used to classify human blood. However, the most commonly used systems in daily life are the ABO and Rh (Rhesus) systems. The ABO system divides blood into four groups: A, B, AB, and O. The Rh system further classifies these groups as either positive or negative, resulting in eight possible blood types.
- People with A blood type have A antigens on their red blood cells and anti-B antibodies in their plasma.
- People with B blood type have B antigens on their red blood cells and anti-A antibodies in their plasma.
- People with AB blood type have both A and B antigens on their red blood cells but no anti-A or anti-B antibodies in their plasma.
- People with O blood type have neither A nor B antigens on their red blood cells, but they have both anti-A and anti-B antibodies in their plasma.
Rh System:
- If a person has the Rh antigen on their red blood cells, they are Rh-positive; otherwise, they are Rh-negative. This difference can be significant in blood transfusions and pregnancy.
Blood Transfusion
When blood is transfused, it’s critical to ensure compatibility between the donor and recipient’s blood types. While most patients receive blood of the same type, sometimes another type may be used with caution, following specific rules.
- A person with O-negative blood can donate to anyone but can only receive O-negative blood.
- A person with AB-positive blood can receive blood from any group but can only donate to other AB-positive individuals.
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