Blood Function Chemistry PDF

# Blood Function Chemistry ## Introduction to the Physiology of Blood Cells - **Hematology** is the branch of medicine concerned with the study of the cause, prognosis, treatment, and prevention of diseases related to blood. - It involves treating diseases that affect the production of blood and...

# Blood Function Chemistry ## Introduction to the Physiology of Blood Cells - **Hematology** is the branch of medicine concerned with the study of the cause, prognosis, treatment, and prevention of diseases related to blood. - It involves treating diseases that affect the production of blood and its components, such as blood cells, hemoglobin, blood proteins, bone marrow, platelets, blood vessels, spleen, and the mechanism of coagulation. - Blood chemistry tests measure the level of several substances in the blood. - Blood chemistry analysis can provide important information about the function of blood and other organs. ### **Benefits of functional blood chemistry analysis:** 1. **Evaluates metabolic status**. 2. **Identifies early health risks** in blood sugar, cardiovascular health, thyroid function, autoimmune disorders, hormonal imbalances, immune challenges, adrenal dysfunction. 3. **Identifies unique nutritional deficiencies or excesses**. 4. **Provides personalized nutritional protocols to address nutritional imbalances instead of wasting money on "the supplement of the month."**. 5. **Provides early detection signs of life-threatening health conditions**. 6. **Helps to identify root cause of many chronic health challenges.** 7. **Calls attention to lab values that are out of Functional Range as opposed to Lab Ranges, which could be addressed with life style changes, supplements, diet modifications.** 8. **Monitor records and effectiveness of nutritional program with precise modifications when necessary.** Maintaining desired blood markers within functional (optimal) ranges will allow your immune, endocrine and neurological systems to function at their best and helping your live healthier life. ## Blood Physiology: - Blood is a body fluid in the circulatory system of humans and other vertebrates that delivers necessary substances such as nutrients and oxygen to the cells and transports metabolic waste products away from those same cells. - Blood in the circulatory system is also known as peripheral blood, and the blood cells it carries, peripheral blood cells. ## Blood Circulation: - Blood is circulated around the body through blood vessels by the pumping action of the heart. - Arterial blood carries oxygen from inhaled air to all of the cells of the body, and venous blood carries carbon dioxide, a waste product of metabolism by cells, to the lungs to be exhaled. - One exception includes pulmonary arteries, which contain the most deoxygenated blood in the body, while the pulmonary veins contain oxygenated blood. - Additional return flow may be generated by the movement of skeletal muscles, which can compress veins and push blood through the valves in veins toward the right atrium. | Blood Flow | Direction | | | ------------------------------ | -------- | --------------------------------------- | | **Blood from the heart** | Away | Carries oxygen and nutrients | | **Blood to the heart** | To | Carries carbon dioxide and waste products | | **Blood from body’s cells** | To | | | **Blood to body's cells** | Away | | ## Whole Blood Characteristics - Blood is a fluid that is technically considered a connective tissue. - It is an extracellular matrix in which blood cells are suspended in plasma. - It normally has a pH of about 7.4 and is slightly denser and more viscous than water. - Blood contains red blood cells (RBCs), white blood cells (WBCs), platelets, and other cell fragments, molecules, and debris. ## Blood Function Chemistry - **Albumin** is the main protein found in plasma, and it functions to regulate the colloidal osmotic pressure of blood. - **Blood appears red** because of the high amount of hemoglobin. - **Blood Volume:** Blood generally accounts for 8% of the human body weight. The average adult has a blood volume of roughly five liters. ### Characteristics of whole blood: 1. pH: 7.35-7.45 (slightly alkaline) 2. Viscosity: about 5 times as viscous as water. 3. Temperature: about 38°C. 4. Volume: approximately 8% of body weight (i.e. approximately 5 liters of blood in an average-sized, 60 kilogram person). ## Functions of Blood: - **Blood is responsible for the following body functions:** 1. **Transportation Functions** - **Provides oxygen to the cells:** Blood absorbs oxygen from the lungs and transports it to different cells of the body. The waste carbon dioxide moves from the blood to the lungs and is exhaled. - **Transports Hormones and Nutrients:** The digested nutrients such as glucose, vitamins, minerals, and proteins are absorbed into the blood through the capillaries in the villi lining the small intestine. The hormones secreted by the endocrine glands are also transported by the blood to different organs and tissues. - **Transport of waste to the Kidney and Liver:** Blood enters the kidney where it is filtered to remove nitrogenous waste out of the blood plasma. The toxins from the blood are also removed by the liver. 2. **Defense Functions** - **The White Blood Cells** fight against infections. They multiply rapidly during infections. Many types of WBCs protect the body from external threats. Other WBCs seek out and destroy internal threats. 3. **Maintenance of Homeostasis:** - **Thermoregulation:** Blood helps to maintain the internal body temperature by absorbing or releasing heat. Increasing blood flow to the surface (e.g., during warm weather or strenuous exercise) causes warmer skin, resulting in faster heat loss. In contrast, when the external temperature is low, blood flow to the extremities and surface of the skin is reduced and to prevent heat loss and is circulated to the important organs of the body, preferentially. - **Blood also helps to maintain the chemical balance of the body.** Proteins and other compounds in blood act as buffers, which help to regulate the pH of body tissues. - **Blood also helps to regulate the water content of body cells** because it has large proteins that exert osmotic pressure, which resist excessive fluid loss from the blood.. 4. **Hydraulic functions:** The components of the circulatory system are run on hydraulic power. The body uses two adjacent "lines" to transfer the "hydraulic fluid". - **Example of a hydraulic function** is the jumping spider, in which blood forced into the legs under pressure causes them to straighten for a powerful jump, without the need for bulky muscular legs. ## Components of blood: - Blood accounts for 7% of the human body weight. - There are different amounts of the four components in the blood. - The average adult has a blood volume of roughly 5-6 liters, composed of **plasma and formed elements of the blood** which are **erythrocytes (red blood cells, RBCs), leukocytes (white blood cells), and thrombocytes (platelets).** | Component | Function | | -------------- | ---------------------------------------------------------------------------------- | | Red blood cell | To carry oxygen from the lungs to every cell in the rest of the body | | White blood cell | To fight infection by pathogens and stop disease | | Plasma | Carries the blood cells and platelets around the body | | Platelet | Broken down parts of cells that form scabs | ## Composition of Blood - About 55% of blood is blood plasma. - The blood plasma volume totals of 2.7-3.0 liters. - It is mainly made of water and is pale yellow so is often called **straw-colored**. - It is essentially an aqueous solution containing **92% water, 8% blood plasma proteins, and trace amounts of other materials**. - It carries all the platelets and red and white blood cells around the human body. - It also carries hormones, dissolved glucose for respiration, dissolved salts and enzymes around the body. - Waste products like carbon dioxide are also transported in the plasma. ### **Plasma proteins:** - They are proteins present in blood plasma. - They serve many different functions, including transport of lipids, hormones, vitamins, and minerals in activity and functioning of the immune system. - Other blood proteins act as enzymes, complement components. - The three significant plasma protein fractions are **albumin, globulin, and fibrinogen.** | Blood protein | Normal level | % | Function | | ------------- | ------------- | --- | ----------------------------------------------------------------------------------------------------- | | Albumins | 3.5-5.0 g/dl | 55% | Create and maintain osmotic pressure; Transport insoluble molecules; Participate in immune system | | Globulins | 2.0-2.5 g/dl | 38% | Blood coagulation | | Fibrinogen | 0.2-0.45 g/dl | 7% | | | Regulatory proteins | <1% | <1% | Conversion of fibrinogen into fibrin | | Clotting factors | <1% | <1% | Regulation of gene expression | ### Clinical significance: - Separating serum proteins by electrophoresis is a valuable diagnostic tool, as well as a way to monitor clinical progress. - Current research regarding blood plasma proteins is centered on performing proteomics analyses of serum/plasma in the search for biomarkers. ## **1) Albumin:** - It is the most abundant class of plasma protein (2.8 to 4.5 gm/100 ml) with the highest electrophoretic mobility. - It is soluble in water. - Albumin is synthesized in the liver. - The serum albumin consists of essential amino acids such as lysine, leucine, valine, phenylalanine, threonine, arginine, and histidine. - Albumin normally accounts for approximately 54% of the total plasma protein content, or 3.5-5.0 g/dL of blood. ### Functions of albumin: 1. Albumin acts as a transport carrier for various biomolecules such as fatty acids, trace elements, and drugs (albumin molecules serve as binding proteins-transport vehicles for fatty acids and steroid hormones.) 2. It has a nutritive role. 3. Albumin is also the most significant contributor to the osmotic pressure of blood; that is, its presence holds water inside the blood vessels and draws water from the tissues, across blood vessel walls, and into the bloodstream. This in turn helps to maintain both blood volume and blood pressure. ### Abnormalities: 1. **Hypoalbuminemia:** most common causes of hypoalbuminemia are liver diseases, Kidney disease, Severe burns. - **Generalized edema:** As the albumin level drops in liver disease, there is insufficient oncotic pressure to hold fluids within cells. Fluid moves into the interstitial spaces, causing generalized edema. - **Hyperalbuminemia:** this condition is a sign of severe or chronic dehydration. ## **2) Globulins:** - The second most common plasma proteins. - Globulins are a family of globular proteins that have higher molecular weights than albumins and are insoluble in pure water but dissolve in dilute salt solutions. - Some globulins are produced in the liver, while others are made by the immune system. - Globulins make up approximately 38% of the total plasma protein volume, or 1.0-1.5 g/dL of blood. - A heterogeneous group, there are three main subgroups known as alpha, beta, and gamma globulins. ### Types of globulins: a) **al-Globulin:** This fraction includes several complex proteins containing carbohydrates and lipids. These are al-glycoprotein, and a-lipoproteins. b) **a2-Globulins:** this fraction also contains complex proteins such as 02-glycoproteins, plasminogen, prothrombin, haptoglobin, ceruloplasmin (transports Cu). - **Plasminogen and prothrombin** are the inactive precursors important role in blood clotting. c) **B-Globulins:** This fraction of plasma protein contains these different ẞ-lipoproteins. It also has transferrin, which transports non-heme iron in plasma. - **Transferrin** is an iron transport protein. d) **¥-Globulins:** These are also called **immunoglobulin's** and have antibody activity. Based on their electrophoretic mobility, they are classified as IgG, IgA, and IgM. Immunoglobulin's are clinically significant components of globulins and are concerned with "immunological reactions." - **The alpha and beta globulins** transport iron, lipids, and the **fat-soluble vitamins A, D, E, and K** to the cells. - **The gamma globulins** are proteins involved in immunity. ### Globulin level: - **Total protein** is routinely done as part of the liver function tests. - **Subtracting albumin from serum protein** leaves the total globulin level **Globulin ratio** may also be used, which is the ratio of albumin to globulin, and is usually between 1.7-2.2, i.e there is normally around twice as much albumin as globulin. ### Decreased total globulin level: 1. Malnutrition (due to decreased synthesis). 2. Congenital immune deficiency (due to decreased synthesis). 3. Nephrotic syndrome (due to protein loss through the kidneys). 4. Increased albumin level - eg, acute dehydration. ### Increased total globulin level: 1. Chronic inflammatory disease. 2. Hyperimmunisation. 3. Low albumin level causing increased globulin fraction - cirrhosis, nephrotic syndrome. ## **4) Fibrinogen:** - Fibrinogen is the least abundant plasma protein. - It is a fibrous protein. - It has six polypeptide chains which are held together by disulfide linkages. - It is essential for blood clotting. - Fibrinogen accounts for about 7% of the total plasma protein volume, or 0.2-0.45 g/dL of blood. ### Functions of Plasma Proteins: 1. **Blood Coagulation:** Prothrombin is present in the a2-globulin fraction, and fibrinogen participates in blood clotting. - **Prothrombin -> Thrombin (Presence-Thromboplastin)** - **Fibrinogen -> Fibrin (Clot) (Presence-Thrombin)** 2. **Osmotic pressure and water balance:** plays an essential role in maintaining a proper water balance between the tissues and blood. - **Plasma albumin** is mainly responsible for this function due to its low molecular weight and quantitative dominance over other proteins. - During protein loss from the body, as in kidney diseases, an excessive amount of water moves into the tissues, producing edema. 3. **Buffering action:** Plasma proteins help maintain the body's pH by acting as ampholytes. ## **(II) Peripheral blood cells: Formed Elements of the Blood-45%:** 1. **Erythrocytes (red blood cells)** 2. **Leukocytes (white blood cells)** 3. **Platelets (thrombocytes)** ## **1) Red Blood Cells (or erythrocytes): RBCS** - Red blood cells are the most numerous cell in the blood. - In one drop of blood there are around 3-5 million red blood cells. - They are made in bone marrow. - They are specialized cells that circulate through the body and deliver oxygen to tissues. - Oxygen moves by diffusion into red blood cells in the lungs. - They have a pigment protein inside them called hemoglobin, a red pigment which binds with the oxygen to carry oxygen to where it is needed for respiration. - This reaction is reversed near the cells. - In humans, red blood cells are small and biconcave, and do not contain mitochondria or a nucleus when mature. - They Lack of mitochondria keeps red blood cells from using any of the oxygen they're carrying, maximizing the amount delivered to tissues of the body. - They cannot reproduce (average lifespan = about 120 days). - Old or damaged red blood cells are broken down in the liver and spleen, and new ones are produced in the bone marrow. - They contain carbonic anhydrase (critical for transport of carbon dioxide). ### Erythropoiesis = formation of erythrocytes - The body must produce about 2.5 million new RBCs every second. - **4.7 to 6.1 million (male), 4.2 to 5.4 million (female) Erythrocytes**. ## Hemoglobin: - Hemoglobin is the principal determinant of the color of blood in vertebrates. - Hemoglobin is **not a blood protein,** as it is carried within red blood cells, rather than in the blood serum. - **Hb is the iron-containing oxygen-transport protein present in red blood cells.** - Red cells contain hemoglobin which allows them to carry oxygen (O₂) and carbon dioxide (CO₂). ## Structure of Hemoglobin: - Hemoglobin has a quaternary structure characteristic of many **multi-subunit globular proteins.** - Hemoglobin is composed of **four polypeptide globin chains** each with an iron containing haem molecule. - Each of the four subunits consists of a polypeptide chain attached to a haem group, which can **reversibly bind with one O₂ molecule.** ## Types of hemoglobin: ### Normal hemoglobin: 1. **Hemoglobin A:** - It is the major hemoglobin in adults (97%). - Its globin comprises **4 polypeptide chains; two α chains (141 amino acids), two - chains (146 amino acids).** - This globin is abbreviated 2α2β. - Three types of hemoglobin occur in normal adult blood: hemoglobin A, A2 and F. - The iron of each heme group is bounded by coordination bounds to nitrogen atoms of imidazole rings of histidine amino acids: **number (58) and (87) in αchain, number (63) and (92) in β chains**. - Each polypeptide chain has a helical structure and folded into 8 stretches labeled A to II creating a pocket inside it for heme binding. 2. **Hemoglobin A2:** - It accounts about 2% of adult human hemoglobin. - Its globin consists of **2α chains and 2β chains (α2 82)**. - HbA2 elevated up to 8%. - Decreased level may be found in: iron deficiency anemia, Hb H disease, hereditary persistence of Hb F, fibroblastic anemia, carriers of a Thalassemia. 3. **Fetal Hemoglobin:** - This hemoglobin presents in the **fetus during intrauterine fetal life.** - It consists of **2α chains and 2γ chains (α2γ2)**. - **Hemoglobin F** is the major Hb of the fetus and the newborn infant. - HbF levels reach the adult levels of 1% of the total Hb from about 24 months of age and its replaced by adult Hb (HbA). - **HbF** is able to bind oxygen with greater affinity than HbA. - The two α-chains composed of 142 and two y-chains, composed of 144-amino-acid residues. 4. **Glycated Hemoglobin (HbA1c):** - The concentration of HbA1c is very low (5-8%) but in **diabetes mellitus** where blood sugar levels are **high** the concentration of HbA1c may reach 120 or more of the total hemoglobin concentration. - Provides an estimate of the level of **glycemia** over lifetime of an RBC, or approximately 90 days. | Condition | HbA1c | Fasting plasma glucose | | --------------- | ------------------------------ | ---------------------- | | Non-diabetic | HbA1c < 6.0 | < 100 | | Pre-diabetes | HbAlc 6.0-6.4 | 100-125 | | Diabetes | HbA1c ≥ 6.5 | > 126 | ### Abnormal hemoglobin: 1. **Met-hemoglobin: (Met-Hb)** - It is **oxidized hemoglobin** in which the **ferrous ions (Fe+2)** of hemoglobin is **oxidized to ferric state (Fe+3)**. - Some drugs, endogenous oxidants, H.Os and No. of free radicals cause formation of met hemoglobin. - If met hemoglobin is present in high concentration it will lead to **Hypoxia and cyanosis (Blue color).** 2. **Carboxy-hemoglobin:** - It is hemoglobin combining with **carbon mono oxide (CO).** - Carbon monoxide combines at the same position in the Hb. molecules as O₂ with the affinity about 200 times greater than O₂. - Concentration of (CO-Hb) above 40% usually results in **unconsciousness and may be fatal.** 3. **Sulf Hemoglobin: (S-Hb);** - It is hemoglobin combining with sulfur. - It results from exposure of hemoglobin to the toxic effects of certain drugs as sulfonamides. - S-Hb produces **Anosia and Cyanosis** because it cannot acts as oxygen carrier. ## **Hemoglobin Function:** 1. Hb, serve as the main vehicle for the **transportation of oxygen and carbon dioxide**. - It carries oxygen from the lung to tissues. - CO₂ from the tissue to the lung. ### Oxygen transport: - About **98.5%** of the oxygen in a sample of arterial blood in a healthy human breathing air at sea-level pressure is **chemically combined** with the hemoglobin (oxy-hemoglobin). - About **1.5%** is **physically dissolved** in the other blood liquids and not connected to hemoglobin. - The oxy-hemoglobin reaches the tissues, breaks up releasing **most of its oxygen,** and regains its normal purple color as **hemoglobin**, there by the blood acts as an efficient oxygen carrier. ### Carbon Dioxide transport: - CO₂ is carried in blood in **three different ways** as following: 1. Most of it (about **70%**) is **converted to bicarbonate ions HCO3** by the enzyme carbonic anhydrase in the red blood cells by the reaction - H2O + CO2 -> H2CO3 -> HCO3 + H+ 2. about **7%** is **dissolved in the plasma** - HCO3 + H+ 3. and about **23%** is **bound to hemoglobin** as carbamino compounds - Hb-CO₂ ## **Diagram of blood flow, including how CO₂ is transported:** | Location | Blood Flow | Description | | ---------- | ---------- | ----------- | | Tissues | Hb-CO₂ | Oxygen, CO₂ and other nutrients are released from the blood and waste products like CO₂ move into the blood. | | Blood | Hb+CO₂ | CO₂ combines with Hb to be transported to the lungs. | | Lungs | | CO₂ diffuses into the alveoli of the lungs and is exhaled. | ## Hemoglobin Function: 1. **Iron** combines with oxygen and gives it a red color: - The oxygen combining capacity is directly related to Hb concentration, not the number of RBCs. - The iron of heme is in **Fe++ form,** and it can combine irreversibly with oxygen and has a major role as an oxygen carrier. 2. Hb acts as a **buffer in the extracellular fluid (acid-base buffer system):** - In tissues, the oxygen concentration is lower, and **CO₂ and H+ ions** concentration is higher. - When the **pH is lower**, then oxygen dissociates from Hb. - Now deoxygenated Hb will bind to **H ions** and then raise the pH. - CO₂ diffuses into RBCs and forms carbonic anhydrase, converting CO₂ to **HCO3¯ and protons**. - Protons are bound to Hb **HCO3¯ ions** and leave the cell. - Every **HCO3¯ ion** leaving the cell will lead to the entry of a chloride ion. - This buffer system depends on **the lungs and kidneys** to eliminate CO₂ and IIC03. ## The oxygen dissociation curve: (Oxygen Saturation) - Hemoglobin, the main **oxygen-carrying molecule** in red blood cells, carries both oxygen and carbon dioxide. - However, the CO₂ bound to hemoglobin does not bind to the same site as oxygen. - Instead, it combines with the **N-terminal groups** on the four globin chains. - However, because of allosteric effects on the hemoglobin molecule, the **binding of CO₂ decreases the amount of oxygen that is bound** for a given partial pressure of oxygen. ## **Hemoglobin-O₂ dissociation curve:** - The ability of hemoglobin to bind O₂ is measured as the **hemoglobin-O₂ dissociation curve.** - The **rapid reversible combination** of O₂ with Hb to form **Oxyhaemoglobin (HbO₂)** is written as: - Depending on the number of binding sites occupied by O₂, Hb can be considered as either **saturated (carrying all four molecules of O₂) or partially saturated (carrying less than four molecules of O₂).** - The **actual O₂-carrying capacity** will depend on the amount of Hb in the blood, with the pressure of O₂ (PO₂) driving the O₂ into the blood. - O₂ saturation of Hb refers to the proportion of Hb bound to O2. ## Other oxygen-binding proteins: 1. **Myoglobin:** - Found in the muscle tissue. - It is a **monomer** that lacks cooperative binding. - It is used to store oxygen rather than transport it. - **Higher affinity for O₂ than normal adult Hb (HbA):** the O₂ dissociation curve is relatively to the left. - Therefore, myoglobin takes up O₂ from Hb in the capillaries. - **Acts to transport and temporarily store O₂** in skeletal muscle and has limited availability during anaerobic conditions, lasting only a few seconds. - **Binds O₂ at PO₂ values greater** than those in venous blood PO₂. Hence it would be unsuitable as a blood carrier for O₂ (because it would not surrender O₂ to the tissues). ## Red blood cell disorders - RBC disorders are conditions that **affect RBCs**, which are responsible for carrying oxygen from the lungs to the rest of the body. - There are many types of RBC disorders, which health experts can categorize by the kind of structure they affect. Some examples include: - **Hemoglobinopathies;** are disorders that involve the hemoglobin protein within RBCs such as **(sickle cell anemia, thalassemia, etc..)** - **Cytoskeletal abnormalities** in RBCs include conditions that change the structure or permeability of the RBC or its membranes such as (hereditary spherocytosis, etc..) - **Enzymopathies** are genetic conditions that affect the production of enzymes in RBCs and cell metabolism. Examples of RBC disorders that involve enzyme deficiencies include **glucose-6-phosphate dehydrogenase**. - **Anemia** occurs when a person has a **low number of healthy RBCs**. This may happen due to changes in the cell itself or components of the cell, such as hemoglobin. There are different types of anemia, each with its own causes. ## **2) White Blood Cells (WBCs) or Leukocytes** - White blood cells, also called leukocytes, are much **less common than red blood cells and make up less than %1** , percent of the cells in blood. - They are primarily involved in **immune responses**, recognizing and neutralizing **invaders such as bacteria and viruses**. - Although leukocytes are **far less numerous** than red blood cells, they are important to body defense against disease. - **White blood cells (WBCs)** are a part of the **immune system**, They help fight infection and defend the body against other foreign materials. - On average, there are **4000 to 11.000 WBCs/mm³**. - White blood cells are larger than red blood cells, and unlike red blood cells, they have a **normal nucleus and mitochondria**. - White blood cells come in **five major types, and these are divided into two different groups,** named for their appearance under a microscope. ### **One group,** the **granulocytes,** includes neutrophils, eosinophils, and basophils, all of which have **granules in their cytoplasm** when stained and viewed on a microscope. ### **The other group,** the **agranulocytes,** includes monocytes and lymphocytes, which do not have granules in the cytoplasm. ## **1. Neutrophils:** - Neutrophils are the **most common type of white blood cell in the body** with levels of between 2000 to 7500 cells per mm³ in the bloodstream. - They have a **short lifespan of approximately 10 hours** in the circulation. - Neutrophils are **medium-sized white blood cells** with irregular nuclei and many granules that perform various functions within the cell. - They have a **multi-lobed nucleus (3-5lobes)** and very fine granules that respond to both acid and basic stains. - Consequently, the **cytoplasm as a whole stains pink**. - Neutrophils are **avid phagocytes at sites of acute infection.** ## Function: 1. They kill germs by means of a process known as **phagocytosis or "cell-eating".** 2. Besides eating bacteria one-by-one, they also release a burst of **super oxides** that have the ability to kill many bacteria at the same time. ## **2. Lymphocytes;** - Lymphocytes are **much more common in the lymphatic system than in blood.** - Lymphocytes are **small, round cells** that have a large nucleus within a small amount of cytoplasm. - They have a **large dark purple nucleus** that occupies most of the cell volume. - They have an **important function** in the **immune system**, being major players in the humoral immune system, which is the part of the **immune system** that relates to **antibody production**. - Lymphocytes tend to **take up residence** in lymphatic tissues, including the spleen, tonsils, and lymph nodes. - There are **about 1300 to 4000 lymphocytes per mm³ of blood**. ### Lymphocytes include: 1. **B cells make antibodies** that can bind to pathogens, block pathogen invasion, and enhance pathogen destruction. 2. **T cells help coordinate the immune response**. ## Function: 1. B lymphocytes make **antibodies**, which is one of the **final steps in disease resistance**. 2. When B lymphocytes make antibodies, they prime pathogens for destruction and then make **memory cells ready** that can go into action at any time, remembering a previous infection with a specific pathogen. 3. **T lymphocytes are another type of lymphocyte, differentiated in the thymus and important in cell-mediated immunity.** ## **3. Monocytes:** - They are the **largest type of white blood cell, share the "vacuum cleaner". ** - Monocytes are agranulocytes, meaning they have **few granules in the cytoplasm** when seen under the microscope. - They **circulate for 20-40 hours** and then **enter tissues**, become macrophages, mature and carry out their principal functions. - Except for their **more abundant cytoplasm and indented (kidney like) nucleus** , they resemble large lymphocytes. - Monocytes **turn into macrophages when they exit the bloodstream.** ## Function: 1. As macrophages, monocytes do the job of **phagocytosis (cell-eating)** of any type of **dead cell in the body**, whether it is a **somatic cell or a dead neutrophil**. ## **4. Eosinophils:** - Eosinophil compose **about 2-4%** of white blood cells in **circulating blood**. - They have a **bi-lobed blue-red nucleus** and **red-orange staining granules (containing histamine).** - They have **large granules** that help in cellular functions. - Eosinophils are especially important when it comes to **allergies and worm infestations**. - Their number increases rapidly during **allergies and infections by parasitic worms (flat-worms, tapeworms, etc.)**. ## Function: 1. Eosinophils work by releasing **toxins from their granules to kill pathogens**. 2. The main pathogens eosinophil's act against are **parasites and worms.** 3. High eosinophil counts are associated with allergic reactions. ## **5. Basophils:** - Basophils are **closely related to mast cells**. - Basophils are the **least frequent type** of white blood cell, with only 0-100 cells per mm³ of blood. - They are the **rarest of the WBCs**, have **S shaped nucleus** contain **large histamine-containing granules** that stain dark blue. - They are the **least numerous** of peripheral blood leucocytes and have large dark purple granules which may obscure the nucleus. ## Function: 1. The granule contents include **histamine and heparin** and are released following binding of **IgE** to surface receptors. 2. They play an important part in **immediate hypersensitivity reactions**. 3. Mast cells also have an **important role in defense against allergens and parasitic pathogens**. 4. They **secrete two chemicals that aid in the body's defenses:** histamine and heparin. 5. **Histamine** is responsible for widening blood vessels and increasing the flow of blood to injured tissue. 6. It also makes blood vessels **more permeable** so neutrophils and clotting proteins can get into connective tissue more casily. 7. **Heparin** is an anticoagulant that inhibits blood clotting and promotes the movement of white blood cells into an area. ## **Concentrations of the Different White Blood Cells in the Blood:** - The adult human being has **approximately ranged from (4,000 to 11,000 cells per microliter of blood (cells/mL)**. - The normal percentages of the different types of white blood cells are approximately the following: **Neutrophils 62.0%, Eosinophils 2.3%, Basophils 0.4%, Monocytes 5.3%, and Lymphocytes 30.3%.** ## **White Blood Cell** | Cell Type | Description | | :---------- | :---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | **Granulocytes** | | | Neutrophil | Phagocyting bacteria and other pathogens. | | Eosinophil | Control mechanisms associated with allergy. | | Basophil | Contain histamine and heparin; histamine is released from the basophils. | | **Agranulocytes** | | | Monocyte | Phagocytosis. | | Lymphocyte | Secretion of antibodies. | ## **Life Span of the White Blood Cells:** - The life span of WBC ranges from 13 - 20 days, depending on the type, after which they are destroyed in the lymphatic system. - When immature WBCs are first released from the bone marrow into the blood, they are called bands or stabs. - Lymphocytes can live for as long as a month. - Lymphocytes include B cells that produce antibodies and T cells that protect the body on a cellular level.. - The life span of B cells ranges from three or four days to up to five weeks. ## **White Blood Cell Disorders:** - White blood cell disorders fall into two categories: ### **a) Leukopenia:** - A decrease in white blood cells - This type of white blood cell decreased is usually the neutrophil. - Some of the white blood cell disorders associated with leukopenia includes: 1. Autoimmune neutropenia: A condition in which your immune system mistakenly attacks and destroys neutrophils. 2. Congenital neutropenia: A genetic disorder in which the body doesn't make enough neutrophils. ### **b) Leukocytosis:** - An increase in white blood cells - It can be a normal response of the immune system but also caused by certain cancerous or non-cancerous diseases. - Leukocytosis is usually healthy (e.g., fighting an infection), but it also may be dysfunctionally proliferative. - Some of the white blood cell disorders associated with includes: 1. **Lymphoma:** A group of cancers that start in cells of the lymphatic system. 2. **Leukemia:** In leukemia, the bone marrow becomes cancerous, and huge numbers of WBCs are turned out rapidly. Although this might not appear to present a problem, the "newborn" WBCs or leukemic cells, especially the