What is Haematology?
- The word haematology comes from two words, the Greek haima (means blood) and logos(means discourse); therefore, haematology is the science of studying blood cell components and coagulation.
- Haematology is the branch of medical science dedicated to the study of blood, blood-forming organs, and blood disorders. It focuses on understanding the structure, function, and diseases related to blood cells, including red blood cells, white blood cells, platelets, and plasma. By analyzing and interpreting blood samples, haematologists can diagnose and manage a wide array of conditions that affect the blood and its components, ensuring optimal health and well-being. From common blood disorders like anaemia to more complex conditions like leukaemia, haematology plays a crucial role in the field of medicine.
Comprehensive studies involved in haematology include:-
- Analysis of concentrations of blood components.
- Structure and function of cells in blood.
- precursors of blood cells.
- Determine the chemical and physical characteristics of blood.
- Platelets and proteins that are important in blood clotting.
- Major diseases of the blood.
Importance of Haematology
- Haematology holds immense importance in the field of healthcare. By analyzing blood samples and monitoring blood counts, doctors and haematologists can detect, diagnose, and manage a range of diseases and disorders.
- Haematology helps in identifying abnormalities in blood cells, assessing their functionality, and understanding their impact on an individual’s overall health. Through early detection and treatment, many life-threatening conditions can be effectively managed, ensuring improved quality of life for patients.
- Additionally, haematology plays a crucial role in the success of various medical procedures, such as surgeries and organ transplants, by ensuring optimal blood clotting and function.
Blood
- It is a specialized connective tissue that circulates through the cardiovascular system, transporting oxygen, nutrients, hormones, and waste products throughout the body.
- It plays an important role in maintaining homeostasis, which is the internal balance of the body.
- In medical terms, blood is referred to as haemo (hemo) or haemato (hemato).
Blood: Physical characteristics
- Average amount: 8% body weight (70 kg man‐ 5.6L) (Infants have a higher blood volume in proportion to body weight than adults).
- Specific gravity: 1055‐1065 (viscosity is 5-6 times more than water)
- pH: 7.35‐7.4
- Colour: Bright red to deep red, because contains haemoglobin on the RBC surface.
- Osmolarity: 300 mOs
- Salinity: 0.9%
Components of blood
Blood, the lifeline of our bodies, consists of several vital components that work together to support various physiological functions. Understanding the roles and characteristics of these components is crucial to comprehending haematology fully. Let’s explore the components of blood:
1. Plasma
- Blood plasma is the yellow, liquid component of blood that makes up about 55% of its total volume.
- It is an important part of the circulatory system and performs various functions within the body.
- Plasma without blood clotting proteins is called serum.
Components of plasma:
A. Water: 90%
B. Organic materials: Plasma Proteins (6‐8 gm/dL), (Albumin 3‐4 gm/dL), Globulin (2.5‐4 gm/ dL), Fibrinogen (0.3 gm/ dl).
Non-protein materials include secretary materials (such as creatinine and uric acid) and nutrition (such as glucose and lipid).
C. Non-organic materials: includes ions such as (Fe++, K, Na, Ca, Mg, Cl- and HCO3).
2. Erythrocyte (Red blood cells RBC)
- RBCs are red-colored biconcave cells that do not have a nucleus.
- They are the most abundant cells covering about 99% of the total blood cells.
- They have an average life span of 120 days. RBCs carry carbon dioxide away from the tissues and back to the lungs.
The normal value of RBC: (number of cells per million in one milliliter of blood sample).
Male: 4.7 – 6.1 million/mil.
Female: 4.2 – 5.4 million/mil
3. Leucocyte (White blood cells WBC)
- WBCs are an important part of the immune system and play a vital role in protecting the body from infection, foreign substances, and abnormal cells. Unlike red blood cells, which are primarily involved in oxygen transport, white blood cells are involved in immune responses to pathogens.
- White blood cells are responsible primarily for defending the body against infection.
The normal value of WBC: 4000-11000 cell/mm3
Types of WBC: There are five main types of white blood cells and are classified mainly based on the presence and absence of granules.
Granulocytes
Agranulocytes
1. Granulocytes: The granulated cells include- eosinophils, basophils, and neutrophils.
A. Eosinophils
- They are the cells of leukocytes, which are present in the immune system.
- kill parasites, destroy cancer cells, and are involved in allergic responses.
- They are present in low numbers covering only 1-6% of total WBCs in blood.
B. Basophil
- Basophils are spherical granulocytes with bilobed nuclei (of markedly different shapes) that stain blue or blue-violet due to the absorption of basic methylene blue dye.
- They are the least abundant WBCs covering less than 1% of total WBCs.
- Also, participate in allergic responses.
C. Neutrophil
- They are most abundant covering about 40 – 75% of total WBCs.
- They are normally found in the bloodstream.
- Help protect the body against infections by killing and ingesting bacteria and fungi and by ingesting foreign debris.
2. Agranulocytes: Agranulocytes are further classified into monocytes and lymphocytes.
A.Monocyte:
- Monocytes are the largest type of WBC with a round and very large nucleus that is purple or blue.
- They cover approximately 2 – 10% of total WBC.
- There are two types of monocytes; (i) motile monocytes in the circulation known as phagocytes, and (ii) mostly non-motile monocytes in the tissue known as macrophages.
- They are very important for defence against microbial infection, regulation of inflammation and activation of T-lymphocytes.
B. Lymphocytes:
- Lymphocytes are the second most abundant type of WBC characterized by a large kidney-shaped nucleus.
- They occupy approximately 20 – 50% of the total WBC.
- They are further of two types; (i) T-lymphocytes, and (ii) B-lymphocytes.
- Lymphocytes keep the memory of infection and antigens and produce specific antibodies to fight aga
Functions of Blood
- Respiratory: Transport of O2 from lung tissue to all cells of the body by artery, also CO2 from body cells to lungs.
- Nutritive: Blood delivers nutrition from the digestive system to cells and transports metabolic wastes to excretory organs.
- Regulation of body temperature: Heat energy is distributed throughout the body by movement in all blood vessels.
- Regulation of metabolism: By the transport of hormones from the production site to all cells of the body which controls catabolism and anabolism.
- Defense: This function is specific to WBCs, which can engulf germs, and also contain important antibodies against antigens in the blood.
- Water balance: Transport and excretion of high amounts of water from the kidneys and urinary tract.
- Buffering: Control the concentration of hydrogen ions by adding components specific to the process.