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Blood

Blood is a body fluid that contains plasma, cells and other nutrients that circulate through the body.

Blood is transported through the body by the circulatory system. The average person's blood volume is about 5 liters.

Blood is made up of plasma, white blood cells, red blood cells and platelets.

 

Plasma

Proteins found in plasma carry out a variety of tasks, including assisting in blood clotting and chemical transport. Along with other dissolved nutrients, blood plasma includes glucose. Plasma is made up of arround 55% of blood fluid, and is 92% water. The remaining 8% contains:

  • proteins
  • hormones
  • glucose
  • fats mineral salts
  • vitamins.

Red and white blood cells and platelets mainly consist of the remaining 45%.

 

Red blood cells

They are the most common component of blood cells. Erythropoietin, a hormone produced primarily by the kidneys, regulates the production of red blood cells. Red blood cells begin as immature cells in the bone marrow and are released into the bloodstream after about seven days of maturation. Red blood cells, unlike many other cells, lack a nucleus and can easily change shape, allowing them to pass through the various blood vessels in your body. While the absence of a nucleus makes a red blood cell more flexible, it also shortens the cell's life as it travels through the smallest blood vessels, damaging the cell's membranes and depleting its energy supplies. The average lifespan of a red blood cell is 120 days. 

Red blood cells contain a special protein called hemoglobin, which aids in the transport of oxygen from the lungs to the rest of the body and then returns carbon dioxide from the body to the lungs for exhalation. Blood appears red due to the large number of red blood cells, which are colored by hemoglobin. The hematocrit is a common measure of red blood cell levels that is defined as the percentage of whole blood volume that is made up of red blood cells.

 

White blood cells (leukocytes)

The body is shielded from infection by white blood cells. They make up roughly 1% of your blood, which is a far smaller percentage than red blood cells.

The "immediate response" neutrophil, which makes up 55 to 70% of the overall white blood cell count, is the most prevalent form of white blood cell. Your bone marrow must continually produce new neutrophils in order to maintain immunity to infection because each neutrophil has a lifespan of less than a day. Since neutrophils do not stay in the body for very long, transfusion is typically ineffective.

Lymphocytes are the other main type of white blood cells. These cells are divided into two primary groups. T lymphocytes directly attack various infection cells and tumors while also assisting in the regulation of the activity of other immune cells. Antibodies, which are proteins that selectively target bacteria, viruses, and other foreign substances, are produced by B lymphocytes.


Platelets(thrombocytes)

In contrast to red and white blood cells, platelets are actually minute pieces of cells. By assembling at the site of an injury, adhering to the blood vessel's lining, and creating a platform for blood coagulation to take place , platelets aid in the process of blood clotting (or coagulation). As a result, a fibrin clot forms over the wound, closing it off and stopping the flow of blood. Fibrin also creates the first framework on which new tissue develops, aiding in the healing process.

Increased platelet counts can result in unneeded clotting, which can cause heart attacks and strokes. Fortunately, antiplatelet medicines have advanced, and there are now medications available to help avoid these potentially catastrophic occurrences. On the other hand, abnormally low counts might cause significant bleeding.

A normal platelet count is 150,000 to 450,000 platelets per microliter of blood.

 

Where are blood cells made?

Blood cells are formed in the bone marrow through the highly regulated process of hematopoiesis from hematopoietic stem cells. Hematopoietic stem cells can differentiate into red blood cells, white blood cells, and platelets. These stem cells can be found in the blood and bone marrow of people of all ages, as well as in newborn babies umbilical cords. Stem cells from all three sources have the potential to be used to treat a wide range of diseases, including leukemia, lymphoma, and immune disorders.


Functions of blood

Blood performs various functions that are central to our survival

  • Suppling oxygen to vital cells and tissues
  • Protecting the body against diseases and infections
  • Removing waste from the body such as urea, carbon dioxide, and lactic acid
  • Supply of nutrients such as amino acids, glucose, and fatty acids
  •  Immunological functions such as white blood cell circulation and antibody detection of foreign material
  • Regulating body temperature 

 

Blood group

There are 4 main types of blood group (A, B, AB and O)

The antibodies and antigens in the blood determined your blood group.

  • Blood group A - contains A antigens on the red blood cells with anti-B antibodies in the plasma
  • Blood group B -contains B antigens with anti-A antibodies in the plasma
  • Blood group O -has no antigens, but contains both anti-A and anti-B antibodies in the plasma
  • Blood group AB - contains both A and B antigens, but no antibodies

 

The Rh System

A protein known as the RhD antigens can sometimes be present in the red blood cells. RhD positive means your red blood cells have the RhD antigen and Rhd negative means the the RhD antigen is absent in your red blood cells.

 The Rh blood group system 

A person can belong to 1 of  the 8  blood groups according to the presence or absence of the Rh antigen.(Rh factor)

  • A Rhd positive (A+)
  • A RhD negative (A-)
  • B RhD positive (B+)
  • B RhD negative (B-)
  • O RhD positive (O+)
  •  O RhD negative (O-)
  • AB RhD positive (AB+)
  • AB RhD negative (AB-)

 

Blood Disorders

Disorders and diseases of the blood can affect your total health.

some  common blood disorders include:

  • Anaemia:
  • Hemorrhage
  • Hemophilia
  • Sickle cell disease
  • Thalassemia 
  • Hematoma
  • Leukemia
  • Hemolytic anemia
  • Lymphoma
  • Hemochromatosis
  • Bacteremia
  • Malaria
  • Polycythemia 
  • Myocardial infarction
  • Disseminated intravascular coagulation
  • Myocardial infarction 
  • Multiple myeloma

 

Problems caused by illness or blood loss can be fatal, but effective treatment for many blood-related disorders is available.

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