Blood Cell

What is Blood?

 Blood is one of the most important components of life. Almost any animal that possesses a circulatory
system has blood.

 Blood is a fluid connective tissue that consists of plasma, blood cells and platelets. It circulates throughout
our body delivering oxygen and nutrients to various cells and tissues.

 It makes up 8% of our body weight. An average adult possesses around 5-6 litres of blood.
Plasma

 Plasma can be defined as an extracellular and liquid portion of blood, which is transparent and pale yellow

 It is mainly composed of clotting factors and other protein molecules. Overall, plasma constitutes 50 to 55
per cent of total blood volume.

 Composition of plasma – Plasma in blood mainly comprises 80 to 90 per cent of water and the other 10 per
cent is composed of salts, lipids, nutrients, enzymes and hormones.

 Names of Plasma Proteins

 Blood plasma protein names and their normal values are as follows:

 Serum globulin (2 – 3.5 g/dL)

 Serum albumin (3.5 – 5.5 g/dL)

 Fibrinogen (0.2 – 0.4 g/dL)

 The serum contains only globulin and albumin. Fibrinogen is absent in serum because it is converted into
fibrin during blood clotting.

 Blood plasma has a density of approximately 1025 kg/m3, or 1.025 g/ml.

 Plasma is the medium of the blood, in which different types of blood cells exist.

 Blood plasma has a long shelf life; therefore, it can be preserved for more than a year and can be used.

 Blood plasma also contains important proteins and other components necessary for overall health. Hence,
blood plasma transfusions are given to patients with liver failure and life-threatening injuries.

Red blood cells (Erythrocytes)

• Erythrocytes or red blood cells (RBC) are the most abundant of all the cells in
blood.
• A healthy adult man has, on an average, 5 million to 5.5 million of RBCs mm-3 of
blood.
• RBCs are biconcave cells without nucleus in humans
• RBCs contain the iron-rich protein called haemoglobin; give blood its red colour.
• RBCs are the most copious blood cells produced in bone marrows.
• Their main function is to transport oxygen from and to various tissues and organs.
• RBCs have an average life span of 120 days after which they are destroyed in the spleen (graveyard of RBCs).
• The cell membrane of red blood cells is composed of lipids and proteins that gives the cells stability and the
ability to deform under stressful conditions without rupturing.
• In the 120 days that the red blood cells are alive it must perform the function of delivering oxygen from lungs
to all the peripheral tissues in the body. It must also assist in the synthesis of ATP molecules
• Standard RBC count ranges from 4.3 to 5.9 million/mm3 in men and from 3.5 to 5.5 million/mm3 in women.
 • Thalassemia, sickle cell disease, anaemia and pernicious anaemia are some of the diseases related with the
dysfunctioning of red blood cells.
• Hemoglobin is a protein in your red blood cells that carries oxygen to
your body's organs and tissues and transports carbon dioxide from your
organs and tissues back to your lungs.
• If a hemoglobin test reveals that your hemoglobin level is lower than
normal, it means you have a low red blood cell count (anemia).
• Male: 13.8 to 17.2 grams per deciliter (g/dL) or 138 to 172 grams per liter
(g/L) Female: 12.1 to 15.1 g/dL or 121 to 151 g/L.

White blood cells (Leucocytes)

 Leucocytes are also known as white blood cells (WBC) as they are colorless due to the lack of haemoglobin.
 They are nucleated and are relatively lesser in number which averages 6000-8000 mm-3 of blood.
 Leucocytes are generally short lived.
 They serve as a defence against all pathogens in the human body. WBC creates a different sort of protein
called antibodies that recognise and counter the foreign agents like fungi, viruses and bacteria that infect the
human body.
 white blood cells are involved in engulfing and breaking down pathogens
 We have two main categories of WBCs – granulocytes and agranulocytes.
 One group, the granulocytes, includes neutrophils, eosinophils, and basophils, all of which have granules in
their cytoplasm
 The other group, the agranulocytes, includes monocytes and lymphocytes, which do not have granules in the
cytoplasm.

Lymphocytes

 Lymphocytes play a significant role in the development of antibodies and body protection, the size of which
varies from 8 to 10 micrometres and is generally referred to as the natural killer cells.

 A human body comprises on average 10 to 12 cells of lymphocytes.

 These cells are quite significant in the immune system. The two main lymphocyte types are

 B lymphocytes

 T lymphocytes

Monocytes

 The nucleus is generally half-moon shaped or kidney-shaped and it occupies 6 to 8 per cent of WBCs.
  They are the garbage trucks of the immune system.
 The most important functions of monocytes are to migrate into tissues and clean up dead cells, protect
against bloodborne pathogens and move very quickly to the sites of infections in the tissues.
 These white blood cells have a single bean-shaped nucleus, hence referred to as Monocytes.

Neutrophils

 They are normally found in the bloodstream.

 Around 60 to 65 per cent of WBCs are neutrophils with a diameter of 10 to 12 micrometres.

 Neutrophil helps in the destruction of bacteria with lysosomes, and it acts as a strong oxidant.

 Neutrophils are also the first cells of the immune system to respond to an invader such as a bacteria or a
virus.

 The lifespan of these WBCs extends for up to eight hours and is produced every day in the bone marrow.

Basophils

 They are the least common of the granulocytes, ranging from 0.5 to 1 per cent of WBCs.

 They contain large cytoplasmic granules, which play a vital role in mounting a non-specific immune response
to pathogens, and allergic reactions by releasing histamine

 There are about 20 to 25 percent of basophils in WBCs.

 These cells are best known for their role in asthma and their result in inflammation and bronchoconstriction
in the airways.

 They secrete serotonin, histamine and heparin.

 Eosinophils (2-3 per cent) resist infections and are also associated with allergic reactions. These cells are
present in high concentrations in the digestive tract.
Platelets

 Platelets also called thrombocytes, are cell fragments produced from megakaryocytes (special cells in the
bone marrow).

 Blood normally contains 1,500,00-3,500,00 platelets mm-3.

 Platelets can release a variety of substances most of which are involved in the coagulation or clotting of
blood.

 Tiny disc-shaped cells that help regulate blood flow when any part of the body is damaged, thereby aiding in
fast recovery through clotting of blood.

Blood Clotting Factor

 Platelets

 Vit K

 Ca ion

 Globin protein

 Potassium