Physiology Body fluids

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What is water balance

What is water balance

Water balance refers to the delicate equilibrium between water intake and water output.

What are the body fluid compartments

Body Fluid Compartments:

• Total Body Water (TBW)

• Intracellular Fluid (ICF)

• Extracellular Fluid (ECF)

  • Interstitial Fluid (ISF): The fluid that surrounds your cells in tissues.

  • Plasma

Explain the dye dilution technique for measurement of body fluid compartments/volumes

In this method, a known quantity of a marker substance (dye) is injected into the bloodstream, and its concentration is measured over time to estimate the volume of the fluid compartment being studied. The principle behind this technique is that the marker substance evenly distributes throughout the fluid compartment, allowing its concentration to be used as an indicator of the compartment's volume.

Pertaining the dye dilution technique for measurement of body fluid compartments, explain properties of the dyes used and give relevant examples.

They should be non-toxic, biologically inert, and not readily metabolized or excreted from the body during the measurement period. The marker should not significantly alter the fluid compartment being studied or its dynamics.

1. Inulin

2. Radioactive isotopes

3. Indocyanine green

What is the expression of solute concentration in body fluids; percent solution, molar solution, equivalent, osmolar concentration

1. Percent Solution: Percent solution expresses the concentration of a solute as a percentage of the total solution

2. Molar Solution: Molar solution expresses the concentration of a solute in terms of moles per liter (mol/L)

3. Equivalent: Equivalent is a unit used to express the concentration of ions or charged particles.

4. Osmolar Concentration: Osmolar concentration expresses the concentration of osmotically active particles (osmoles) in a solution.

Constituents of the intracellular fluids

The ICF is the fluid present inside the cells. It contains high concentrations of potassium (K+), magnesium (Mg2+), phosphate (HPO42-), and proteins. It also contains smaller amounts of sodium (Na+), chloride (Cl-), bicarbonate (HCO3-), and other ions.

Gibbs-Donnan effect

According to the Gibbs-Donnan effect, the permeable ions will distribute themselves in a way that the electrical potential difference across the membrane becomes equal to the concentration difference of the impermeable charged solutes

What is oedema and what causes it.

Edema, also spelled as "oedema," is the medical term used to describe the abnormal accumulation of fluid in the interstitial spaces. It results in swelling or puffiness in the affected area.

1. Increased hydrostatic pressure

2. Decreased oncotic pressure

3. Lymphatic obstruction

4. Inflammation

5. Medications

Starling's Law and factors that influence

Starling's Law of Ultrafiltration, also known as the Starling equation, describes the process of fluid filtration across the capillary walls based on the balance between hydrostatic and oncotic pressures.

factors:

1. Capillary Hydrostatic Pressure (Pc)

2. Interstitial Fluid Hydrostatic Pressure (Pif):

3. Capillary Oncotic Pressure (πc):

4. Interstitial Fluid Oncotic Pressure (πif):

Factors that influence fluid movement into the interstitium

1. Capillary Hydrostatic Pressure

2. Capillary Permeability

3. Oncotic Pressure

4. Interstitial Fluid Hydrostatic Pressure

5. Lymphatic Function

6. Inflammation

7. Gravity

What is blood and what are its general properties

Blood is a connective tissue.

Properties of Blood:

1.Blood is composed of plasma, red blood cells, white blood cells and platelets

2. Typically bright red when oxygenated and darker red when deoxygenated. Its pH ranges from 7.35 to 7.45, making it slightly alkaline.

3. Is more viscous than water due to the presence of cells and proteins.

Functions of blood

1. Oxygen Transport:

2. Carbon Dioxide Transport

3. Nutrient and Waste Transport:

. 4. Hormone Transport

5. Immune Response

6. Blood Clotting

7. Thermoregulation

8. pH and Electrolyte Balance:

9. Buffering:

. 10. Blood Pressure Regulation:

Components of plasma

Water

Plasma Proteins: The three major types of plasma proteins are albumin, globulins, and fibrinogen.

Electrolytes: such as sodium, potassium, calcium, magnesium, chloride, bicarbonate, and phosphate

Nutrients: like glucose, amino acids, lipids, vitamins, and minerals

Waste Products

Gases: Oxygen and carbon dioxide

Functions of plasma proteins

1. Osmotic Regulation

2. Transport of Substances

3. Blood Clotting

4. Immune Response

5. Maintenance of Acid-Base Balance

6. Defense against Edema

7. Hormone Binding

What are the properties of red blood cells.

1. Shape and Size: Red blood cells are small and disk-shaped, with a biconcave morphology.

2. Lack of Nucleus and Organelles: This absence of a nucleus allows for more space to accommodate hemoglobin, the oxygen-carrying protein.

3. Hemoglobin

4. Oxygen Transport

5. Carbon Dioxide Transport

6. Flexibility and Deformability: The biconcave shape of red blood cells gives them flexibility and deformability

7. Lifespan: Red blood cells have a limited lifespan of approximately 120 days.

8. Hematocrit: The hematocrit is a measure of the proportion of red blood cells in the total blood volume. In normal adults, it is typically around 40-45%

9. Production and Regulation: Regulated by the hormone erythropoietin, which is primarily secreted by the kidneys in response to low oxygen levels.

10. Blood Typing: Red blood cells express specific surface antigens, such as the ABO and Rh antigens, which determine an individual's blood type

Development of red blood cells

- Erythropoiesis takes place primarily in the bone marrow, specifically in the spongy bone of the axial skeleton and the proximal ends of long bones.

- The process is regulated by the hormone erythropoietin, which is secreted by the kidneys in response to low oxygen levels in the blood.

- Hematopoietic stem cells in the bone marrow differentiate into erythrocyte progenitor cells called erythroblasts.

- Erythroblasts undergo a series of divisions and differentiations, gradually reducing their size and increasing the concentration of hemoglobin within their cytoplasm.

- During maturation, the nucleus is expelled, and the cell becomes a reticulocyte, which still contains some organelles but lacks a nucleus.

- Reticulocytes are released into the bloodstream and mature into fully functional red blood cells within 1-2 days.

Destruction of red blood cells

- As red blood cells age, they undergo changes that make them more susceptible to removal from circulation.

- Macrophages, primarily in the spleen and liver, phagocytize and break down old or damaged red blood cells.

- Hemoglobin from the degraded red blood cells is recycled, and iron is stored or used for new red blood cell production.

- Bilirubin, a byproduct of hemoglobin breakdown, is released and further processed in the liver before being excreted in bile.

Factors affecting erythropoeisis

1. Erythropoietin (EPO)

2. Oxygen Levels

3. Nutrients

4. Bone Marrow Environment

5. Hormonal Factor

6. Chronic Diseases and Inflammatory C

7. Genetic and Acquired Disorders

8. Medications and Toxin

Importance of water

• Water makes up around 60% of an adult's body weight and plays a critical role in various bodily functions:

  • Regulating body temperature

  • Lubricating joints

  • Transporting nutrients and waste products

  • Maintaining blood volume

  • Supporting digestion and absorption

  • Facilitating cellular processes

How is water regulated

Water is regulated through thirst mechanism and hormonal regulation. The primary organ responsible for regulating water is kidneys

What is total body water and percentage composition with respect to body weight

Total Body Water (TBW): This is all the water in your body, roughly 60% of your weight.

What is intracellular fluid and its composition. What is the percentage composition with respect to total body water

Intracellular Fluid (ICF): This is the fluid inside your cells, making up about 60% of your TBW. It contains water, electrolytes, proteins and organic molecules

What is extracellular fluid and its composition. What is the percentage composition with respect to total body water

• Extracellular Fluid (ECF): This is the fluid outside your cells, making up about 40% of your TBW. It's further divided into:

  • Interstitial Fluid (ISF): The fluid that surrounds your cells in tissues, accounting for about 20% of TBW. It has a similar composition to blood plasma, but with lower protein content.

Constituents of extracellular fluid

Extracellular Fluid (ECF): The ECF is the fluid outside the cells and can be further divided into interstitial fluid (fluid between cells) and plasma (liquid component of blood). The interstitial fluid contains similar constituents to the plasma but at lower protein concentrations. The primary constituents of the ECF include sodium (Na+), chloride (Cl-), bicarbonate (HCO3-), and proteins (in plasma). Other ions, such as calcium (Ca2+), potassium (K+), and magnesium (Mg2+), are present but at lower concentrations compared to the ICF.

The Starling equation

Net Filtration = Kf [(Pc - Pif) - (πc - πif)]

Kf represents the filtration coefficient, which accounts for the permeability of the capillary wall to fluid. It determines the overall filtration capacity of the capillary.

What is Haemoglobin

Haemoglobin is a protein found in red blood cells that is responsible for carrying oxygen throughout the body. It consists of four subunits, each containing a molecule of heme, which binds to oxygen. Abnormalities in the structure or production of haemoglobin can lead to various disorders known as haemoglobinopathies.

What is Anemia

Anemia refers to a condition in which there is a decrease in the number of red blood cells or a decrease in the amount of hemoglobin in the blood. Anemia can result from various causes, including nutritional deficiencies (such as iron, vitamin B12, or folate deficiency), chronic diseases, inherited disorders like thalassemia, and other factors.

What is Thalassemias

Thalassemias are a group of inherited blood disorders characterized by reduced or absent production of one or more of the globin subunits of haemoglobin. There are two main types: alpha thalassemia and beta thalassemia. Alpha thalassemia occurs when there is a deficiency in the production of alpha-globin chains, while beta thalassemia is caused by a deficiency in the production of beta-globin chains.

What is Sickle cell disease

Sickle cell disease is caused by a mutation in the gene that produces the beta-globin subunit of haemoglobin. This mutation leads to the production of an abnormal form of haemoglobin called haemoglobin S. The abnormal haemoglobin causes red blood cells to become rigid and take on a characteristic sickle shape, which can result in blockages in blood vessels and a reduced ability to carry oxygen. Symptoms of sickle cell disease include chronic anemia, pain crises, organ damage, and increased susceptibility to infections.

What is Haemoglobinopathies

Haemoglobinopathies are a group of genetic disorders characterized by abnormal or decreased production of normal haemoglobin. The most well-known haemoglobinopathies are sickle cell disease and thalassemia.

What are white blood cells (WBCs) and their types

white blood cells (WBCs) are a vital part of the immune system and help protect the body against infections and foreign substances. The main types of white blood cells are:

1. Neutrophils: Abundant and mobile cells that engulf and destroy bacteria and foreign particles.

2. Lymphocytes: B cells produce antibodies that recognize and neutralize specific pathogens, while T cells have various functions, including attacking infected cells and regulating immune responses.

3. Monocytes: Circulating cells that transform into macrophages or dendritic cells. Macrophages engulf and digest debris and pathogens, while dendritic cells present antigens to initiate immune responses.

4. Eosinophils: Cells involved in combating parasitic infections and modulating allergic and asthmatic immune responses.

5. Basophils: Less common cells that release histamine and other chemicals involved in allergic reactions and inflammation.

development of WBCs

1. Development:

The development of WBCs begins with hematopoietic stem cells (HSCs) present in the bone marrow. These HSCs have the ability to differentiate into various types of blood cells, including WBCs. The process of differentiation involves a series of steps and is regulated by various growth factors and signaling molecules.

Maturation of white blood cells

2. Maturation:

Once the HSCs commit to the lymphoid lineage, they differentiate into lymphoid progenitor cells. These progenitor cells further differentiate into different types of lymphocytes, such as B cells, T cells, and natural killer (NK) cells. B cells mature in the bone marrow, while T cells complete their maturation in the thymus gland.

Destruction of wbcs

3. Destruction:

White blood cells are not long-lived cells like red blood cells. They have a finite lifespan, and their destruction occurs through various mechanisms. One of the primary mechanisms of destruction involves the phagocytic activity of macrophages. Macrophages engulf and digest aged or damaged white blood cells as part of the body's natural turnover process.

What are lymphocytes

Lymphocytes are a type of white blood cell (WBC) that play a central role in the adaptive immune response. They are responsible for recognizing and targeting specific pathogens or foreign substances in the body. Lymphocytes are divided into three main subtypes: B cells, T cells, and natural killer (NK) cells.

Explain in depth the types of lymphocytes

1. B cells:

B cells are lymphocytes that mature in the bone marrow. They are primarily involved in the production of antibodies, which are proteins that can recognize and bind to specific antigens (foreign substances) present on pathogens. When a B cell encounters its specific antigen, it undergoes activation and differentiation into plasma cells, which are responsible for secreting large quantities of antibodies. Antibodies help neutralize pathogens, mark them for destruction by other immune cells, and facilitate the clearance of antigens from the body.

2. T cells:

T cells are lymphocytes that undergo maturation in the thymus gland. They play a crucial role in cell-mediated immunity, which involves direct cell-to-cell interactions. There are several subtypes of T cells, including:

- Helper T cells (CD4+ T cells): Helper T cells coordinate immune responses by recognizing antigens presented by specialized antigen-presenting cells (APCs) and secreting cytokines that stimulate other immune cells. They are essential for activating B cells, cytotoxic T cells, and other immune responses.

- Cytotoxic T cells (CD8+ T cells): Cytotoxic T cells directly target and destroy infected or cancerous cells. They recognize specific antigens presented on the surface of infected cells or tumor cells and induce their death through the release of cytotoxic molecules.

- Regulatory T cells (Tregs): Regulatory T cells help maintain immune homeostasis and prevent excessive immune responses. They suppress the activity of other immune cells, ensuring that the immune system does not mount an overly aggressive response that could harm healthy tissues.

3. Natural Killer (NK) cells:

NK cells are lymphocytes that are part of the innate immune system. Unlike B cells and T cells, NK cells do not require prior activation or recognition of specific antigens. They are capable of directly recognizing and killing infected or abnormal cells, such as virus-infected cells or tumor cells. NK cells play a critical role in the early defense against pathogens and in immune surveillance against cancer.

What are platelets

Platelets, also known as thrombocytes, are small, irregularly shaped cell fragments that are essential for blood clotting (hemostasis) and wound healing. While they are not considered true cells, platelets are derived from larger cells called megakaryocytes in the bone marrow.

Functions of platelets

1. Hemostasis: Platelets are crucial for the formation of blood clots to prevent excessive bleeding. When a blood vessel is damaged, platelets adhere to the site of injury and aggregate together to form a platelet plug, sealing the damaged blood vessel. They do this by binding to exposed collagen fibers in the damaged vessel wall and to each other, forming a temporary barrier.

2. Coagulation: Platelets participate in the coagulation cascade, a complex process involving a series of biochemical reactions that ultimately leads to the formation of a stable blood clot. Platelets release various substances, such as clotting factors and chemicals, that help initiate and promote the coagulation process.

3. Secretion of Growth Factors: Platelets contain numerous growth factors, such as platelet-derived growth factor (PDGF), transforming growth factor-beta (TGF-β), and vascular endothelial growth factor (VEGF). These growth factors play a vital role in tissue repair and healing by promoting cell proliferation, angiogenesis (formation of new blood vessels), and tissue regeneration.

4. Immune Response: Platelets also participate in immune responses and inflammation. They can interact with immune cells, such as neutrophils and monocytes, and modulate their activity. Platelets can release immune mediators, cytokines, and chemokines that contribute to the inflammatory response and recruit immune cells to the site of injury or infection.

5. Maintenance of Vascular Integrity: Platelets contribute to the maintenance of the integrity of blood vessels. They release substances that promote vasoconstriction, reducing blood flow to the site of injury and minimizing bleeding. Platelets also help repair damaged blood vessels by releasing factors that stimulate the growth and repair of the endothelial lining of blood vessels.

Clot Retraction:

Clot Retraction:

After the formation of a blood clot, a process called clot retraction takes place. Clot retraction involves the contraction of platelets within the clot, which pulls the edges of the damaged blood vessel closer together. This contraction reduces the size of the clot and helps to stabilize the damaged vessel, promoting the healing process.

Fibrinolysis

Fibrinolysis:

Fibrinolysis is the process by which blood clots are broken down and dissolved. The main enzyme involved in fibrinolysis is called plasmin. Plasmin is derived from an inactive precursor called plasminogen, which is present in the blood. Plasminogen is activated to plasmin by various activators, such as tissue plasminogen activator (tPA) or urokinase plasminogen activator (uPA).

Haemophilia

Haemophilia:

Haemophilia is a genetic disorder characterized by a deficiency or dysfunction of certain blood clotting factors, most commonly factor VIII (hemophilia A) or factor IX (hemophilia B). These clotting factors are necessary for the normal clotting process, and their deficiency leads to impaired blood clot formation and an increased tendency to bleed.

Individuals with haemophilia may experience spontaneous bleeding or prolonged bleeding following an injury or surgery. The severity of the condition can vary, with mild cases often only manifesting during surgeries or traumatic injuries, while severe cases may result in spontaneous bleeding into joints or muscles.

Treatment for haemophilia involves replacing the deficient clotting factor. This can be done through regular infusions of clotting factor concentrates, which are derived from human plasma or produced using recombinant DNA technology. These infusions help to restore the missing clotting factor and prevent excessive bleeding.

Anticoagulants:

Anticoagulants are medications that inhibit the formation or activity of blood clots. They are commonly used in the prevention and treatment of various conditions, such as deep vein thrombosis (DVT), pulmonary embolism (PE), atrial fibrillation, and certain types of heart disease.

How do Anticoagulants work by type

Anticoagulants work by interfering with the clotting process at different stages. Some common types of anticoagulants include:

1. Heparin: Heparin is a naturally occurring anticoagulant that works by enhancing the activity of a protein called antithrombin III. Antithrombin III inhibits several clotting factors, including thrombin and factor Xa. Heparin is often used in acute settings, such as during surgeries or in hospitalized patients, and is typically administered by injection or intravenously.

2. Warfarin: Warfarin is an oral anticoagulant that interferes with the synthesis of vitamin K-dependent clotting factors (factors II, VII, IX, and X) in the liver. It takes several days to reach its full effect and requires regular monitoring of the international normalized ratio (INR) to ensure the appropriate dose. Warfarin is commonly used for long-term anticoagulation in conditions such as atrial fibrillation or venous thromboembolism.

3. Direct Oral Anticoagulants (DOACs): DOACs, also known as novel oral anticoagulants, are a newer class of anticoagulants that directly inhibit specific clotting factors. Examples of DOACs include dabigatran (direct thrombin inhibitor), rivaroxaban, apixaban, and edoxaban (direct factor Xa inhibitors). DOACs have a more predictable anticoagulant effect and do not require routine monitoring like warfarin.

It's important to note that anticoagulants carry a risk of bleeding, so their use should be carefully monitored by healthcare professionals. The specific choice of anticoagulant depends on the individual's medical condition, risk factors, and other considerations, and should be made in consultation with a healthcare provider.

The buffering properties of blood

The pH of blood is tightly regulated within a narrow range of approximately 7.35 to 7.45.

1. Bicarbonate buffer system: This is the most important buffering system in blood. It involves the reversible reaction between carbon dioxide (CO2) and water (H2O) to form carbonic acid (H2CO3), which can dissociate into bicarbonate ions (HCO3-) and hydrogen ions (H+). The reaction is catalyzed by an enzyme called carbonic anhydrase. The equation for this reaction is as follows:

CO2 + H2O ⇌ H2CO3 ⇌ HCO3- + H+

When the concentration of H+ ions increases, bicarbonate ions can combine with them, reducing the acidity of the blood. Conversely, when the concentration of H+ ions decreases, carbonic acid can release H+ ions, thereby increasing the acidity of the blood.

2. Protein buffer system: Proteins, particularly hemoglobin in red blood cells, act as buffers by accepting or donating H+ ions. The amino acid residues with ionizable groups in proteins can bind H+ ions when the blood becomes too acidic or release H+ ions when the blood becomes too alkaline. This protein buffer system helps stabilize the pH of the blood.

In addition to these buffering systems, blood also contains other substances, such as phosphate ions and certain organic acids, which contribute to its buffering capacity.

Inflammation

Inflammation is a complex biological response of the immune system to tissue injury, infection, or irritation. It is a protective mechanism that aims to eliminate the cause of injury or infection, remove damaged cells and tissues, and initiate the healing process. Inflammation is a characteristic feature of many diseases, including infections, autoimmune disorders, and chronic inflammatory conditions.

The inflammatory response involves a coordinated series of events mediated by various immune cells, chemical mediators, and signaling molecules. The key components of the inflammatory response include:

1. Vasodilation and increased vascular permeability: In response to injury or infection, blood vessels in the affected area dilate, leading to increased blood flow. This causes redness and warmth at the site of inflammation. Additionally, the blood vessels become more permeable, allowing fluid, proteins, and immune cells to leak into the surrounding tissues. This results in swelling and edema.

2. Recruitment of immune cells: Inflammatory mediators, such as cytokines and chemokines, attract immune cells to the site of inflammation. Neutrophils are among the first immune cells to arrive at the site and play a crucial role in phagocytosing and destroying pathogens. They are followed by monocytes, which differentiate into macrophages. Macrophages help clear debris, stimulate tissue repair, and initiate the adaptive immune response by presenting antigens to T cells.

3. Activation of the complement system: The complement system is a group of proteins that work together to eliminate pathogens and promote inflammation. Activation of the complement system leads to the formation of membrane attack complexes that can directly kill certain microorganisms. Additionally, complement fragments promote chemotaxis, opsonization (marking pathogens for phagocytosis), and enhance the inflammatory response.

4. Release of inflammatory mediators: Various molecules are released during inflammation to amplify and regulate the immune response. These include cytokines (such as tumor necrosis factor-alpha, interleukins), prostaglandins, leukotrienes, and histamine. These mediators contribute to vasodilation, increased vascular permeability, recruitment of immune cells, and activation of other inflammatory pathways.

5. Tissue repair and resolution: Once the cause of inflammation is eliminated, the inflammatory response gradually subsides. Macrophages and other immune cells clear debris, and the process of tissue repair and regeneration begins. Anti-inflammatory mediators help dampen the inflammatory response and restore homeostasis.

Antibodies

Antibodies, also known as immunoglobulins, are proteins produced by the immune system in response to the presence of foreign substances called antigens. They play a crucial role in the immune response by recognizing and neutralizing these antigens.

The mechanism of action of antibodies involves several steps:

1. Recognition: Antibodies are highly specific and can recognize and bind to specific antigens. The variable region of the antibody, known as the antigen-binding site, is responsible for this recognition. It has a unique shape that complements the shape of the antigen.

2. Neutralization: Once antibodies bind to antigens, they can neutralize them in several ways. They can prevent the antigens from entering or damaging host cells by blocking their receptor sites. Antibodies can also bind to toxins produced by bacteria or viruses, rendering them harmless.

3. Opsonization: Antibodies can act as opsonins, molecules that enhance the process of phagocytosis. They coat the surface of antigens, making them more recognizable to immune cells called phagocytes. This facilitates the engulfment and destruction of the antigens by phagocytes.

4. Activation of complement system: Antibodies can activate the complement system, which is a group of proteins that work together to eliminate pathogens. Activation of the complement system leads to the formation of a membrane attack complex, causing cell lysis and destruction of the pathogen.

Allergy

Allergy is an exaggerated immune response to harmless substances known as allergens. When a person with allergies comes into contact with an allergen, their immune system produces an excessive amount of antibodies, specifically immunoglobulin E (IgE). These IgE antibodies bind to mast cells and basophils, which are immune cells involved in allergic reactions.

Humoral Immune Response

1. Humoral Immune Response: The humoral immune response primarily involves the production and activity of antibodies, which are soluble proteins found in the body fluids, such as blood and lymph. This response is mainly mediated by B cells, a type of white blood cell.

When B cells encounter an antigen, they can differentiate into plasma cells, which are specialized cells that produce and secrete large amounts of antibodies. These antibodies circulate in the body fluids and can bind to specific antigens, neutralizing them and marking them for destruction.

The humoral immune response is particularly effective against extracellular pathogens, such as bacteria and toxins, as antibodies can bind to these pathogens and prevent their spread in the body. Additionally, antibodies can also activate the complement system, enhancing the immune response.

Cellular Immune Response:

2. Cellular Immune Response: The cellular immune response involves the activation and activity of various types of white blood cells, particularly T cells. This response is primarily responsible for eliminating intracellular pathogens, such as viruses and certain types of bacteria, as well as abnormal cells, including cancer cells.

T cells can recognize and bind to specific antigens presented on the surface of infected or abnormal cells. There are two main types of T cells involved in the cellular immune response:

- Helper T cells (CD4+ T cells): These cells play a central role in coordinating the immune response. They release chemical signals called cytokines, which activate other immune cells and help regulate the overall immune response. Helper T cells also assist B cells in antibody production.

- Cytotoxic T cells (CD8+ T cells): These cells directly destroy infected or abnormal cells. They recognize and bind to antigens presented on the surface of target cells, leading to the release of cytotoxic molecules that induce cell death.

The cellular immune response is essential for eliminating pathogens that have infected host cells and for surveilling the body for the presence of abnormal cells.

Basic aspect of development of immune system

1. Primary Lymphoid Organs: The immune system develops in specialized organs known as primary lymphoid organs, primarily the bone marrow and the thymus. The bone marrow is responsible for the production of all blood cells, including immune cells. In the bone marrow, stem cells differentiate into various types of immune cells, including B cells, natural killer (NK) cells, and some subsets of T cells. The thymus is involved in the maturation of T cells, where they acquire their antigen-specific receptors and undergo selection processes to ensure their effectiveness and prevent autoimmunity.

2. Differentiation of B and T Cells: B cells and T cells are the two main types of lymphocytes involved in adaptive immunity. B cells mature in the bone marrow, while T cells migrate from the bone marrow to the thymus for maturation. During their development, both B and T cells undergo processes that shape their antigen receptor repertoire and ensure self-tolerance. These processes include gene rearrangement, positive and negative selection, and elimination of self-reactive cells.

3. Maturation and Activation: Once B and T cells have developed and acquired their antigen receptors, they migrate to secondary lymphoid organs such as lymph nodes, spleen, and tonsils. In these organs, they encounter antigens and undergo activation. B cells recognize antigens directly, while T cells require antigen presentation by specialized antigen-presenting cells (APCs) such as dendritic cells. Once activated, B cells differentiate into plasma cells that produce antibodies, and T cells differentiate into various subsets with specific functions, such as helper T cells and cytotoxic T cells.

4. Immunological Memory: Following exposure to antigens, the immune system can develop long-lasting immunological memory. Memory B and T cells are generated during the initial immune response and can quickly recognize and respond to the same antigen upon re-exposure. This memory response results in a faster and more robust immune reaction, providing enhanced protection against previously encountered pathogens.

5. Maturation of Innate Immunity: Alongside the development of the adaptive immune system, the innate immune system, which provides immediate defense against pathogens, also matures. Components of the innate immune system, including phagocytes, natural killer cells, and complement proteins, develop and become fully functional early in life.

Blood volume in an adult

5 litres

Percentage blood constitutions

1. Red Blood Cells (RBCs): Red blood cells make up the majority of blood cells and are responsible for carrying oxygen to the body's tissues. They constitute approximately 40-45% of the total blood volume in males and 37-42% in females.

2. Plasma: Plasma is the liquid component of blood and makes up the remaining percentage after accounting for red blood cells. It contains various substances such as water, electrolytes, proteins, hormones, and waste products. Plasma constitutes about 55% of the total blood volume.

3. White Blood Cells (WBCs): White blood cells are responsible for the immune response and protecting the body against infections. They constitute a small percentage of the total blood volume, typically around 1% or less.

4. Platelets: Platelets are involved in blood clotting to prevent excessive bleeding. They are also present in a small percentage, often less than 1% of the total blood volume.

Plasma proteins

Plasma proteins are a group of proteins present in the liquid component of blood called plasma. These proteins play essential roles in maintaining the body's overall health and performing various functions. The three main types of plasma proteins are:

1. Albumin: Albumin is the most abundant plasma protein, accounting for approximately 55-60% of total plasma proteins. It helps maintain osmotic pressure, which is important for regulating the distribution of fluids between blood vessels and tissues. Albumin also binds and transports various substances such as hormones, fatty acids, and drugs.

2. Globulins: Globulins are a diverse group of proteins that can be further classified into three subtypes:

a. Alpha-globulins: Alpha-globulins include proteins such as alpha-1 antitrypsin, which inhibits enzymes that can damage tissues, and alpha-2 macroglobulin, which is involved in the immune response and blood clotting.

b. Beta-globulins: Beta-globulins consist of proteins like transferrin, which binds and transports iron in the blood, and low-density lipoproteins (LDL) and high-density lipoproteins (HDL), which are involved in lipid transport.

c. Gamma-globulins: Gamma-globulins are a class of proteins known as immunoglobulins or antibodies. They play a crucial role in the immune system by recognizing and neutralizing foreign substances such as bacteria, viruses, and other pathogens.

3. Fibrinogen: Fibrinogen is involved in blood clotting. When there is an injury or damage to blood vessels, fibrinogen is converted into fibrin, forming a network that helps in the formation of blood clots to stop bleeding.

These plasma proteins perform vital functions such as maintaining osmotic balance, transporting substances, regulating immune responses, and facilitating blood clotting. They are synthesized in the liver and released into the bloodstream, where they circulate and carry out their respective roles.

Haematopoiesis

Haematopoiesis, also known as hematopoiesis, is the process by which the body produces new blood cells. It occurs in the bone marrow, which is the soft, spongy tissue found inside certain bones. Haematopoiesis is a continuous and highly regulated process that ensures a constant supply of functional blood cells throughout an individual's lifetime.

The process of haematopoiesis involves the differentiation and maturation of hematopoietic stem cells (HSCs) into various types of blood cells. HSCs are undifferentiated cells that have the ability to self-renew and give rise to different cell lineages. There are two main lineages of blood cells:

1. Myeloid Lineage: Myeloid cells give rise to red blood cells (erythrocytes), platelets (thrombocytes), and various types of white blood cells (leukocytes), including granulocytes (neutrophils, eosinophils, basophils), monocytes, and dendritic cells.

2. Lymphoid Lineage: Lymphoid cells differentiate into lymphocytes, which are a type of white blood cell involved in the immune response. Lymphocytes include B cells, T cells, and natural killer (NK) cells.

The process of haematopoiesis is regulated by various growth factors and cytokines, which are signaling molecules that control the differentiation and proliferation of blood cells. Examples of these regulatory factors include erythropoietin (EPO) for red blood cell production, thrombopoietin (TPO) for platelet production, and various colony-stimulating factors (CSFs) for white blood cell production.

In addition to the bone marrow, some lymphoid organs, such as the thymus, spleen, and lymph nodes, also contribute to the production and maturation of certain blood cells, particularly lymphocytes.

Overall, haematopoiesis is a complex and tightly regulated process that ensures the continuous production of functional blood cells, which are essential for various physiological processes, including oxygen transport, immune response, and blood clotting.

Erythropoiesis

Erythropoiesis is the process of red blood cell (erythrocyte) production. It occurs in the bone marrow, specifically in the spongy or cancellous bone, which contains hematopoietic stem cells (HSCs) capable of differentiating into red blood cells.

The process of erythropoiesis involves several stages:

1. Hematopoietic Stem Cell (HSC) Differentiation: Hematopoietic stem cells in the bone marrow can differentiate into committed progenitor cells called erythroblasts under the influence of various growth factors and cytokines, including erythropoietin (EPO).

2. Proerythroblast Stage: Erythroblasts begin their maturation process by transitioning from HSCs to proerythroblasts. Proerythroblasts are large cells with a high nucleus-to-cytoplasm ratio. They are actively dividing and synthesizing cell components.

3. Erythroblast Stage: Proerythroblasts further differentiate into several subsequent stages of erythroblasts, including basophilic, polychromatic, and orthochromatic erythroblasts. During these stages, the cells undergo changes in their size, shape, and staining properties as they accumulate hemoglobin, the oxygen-carrying protein.

4. Reticulocyte Stage: Orthochromatic erythroblasts develop into reticulocytes, which are immature red blood cells. Reticulocytes still contain remnants of ribosomes and other organelles, giving them a reticular (mesh-like) appearance when stained. They are released into the bloodstream from the bone marrow.

5. Maturation to Mature Red Blood Cells: Reticulocytes spend about one to two days in the bloodstream, during which time they lose their remaining organelles and become mature, fully functional red blood cells. Mature red blood cells have a biconcave disc shape, which allows for increased surface area and flexibility for oxygen transport.

The production and maturation of red blood cells are tightly regulated by various factors, with erythropoietin being a key hormone involved. Erythropoietin is primarily produced in the kidneys in response to low oxygen levels in the body. It stimulates the proliferation and differentiation of erythroblasts and enhances the production of red blood cells.

Erythropoiesis is crucial for maintaining adequate levels of oxygen-carrying capacity in the blood. It is influenced by factors such as oxygen demand, altitude, certain medical conditions (e.g., anemia), and hormonal regulation.

Basophils

Basophils are a type of white blood cell (leukocyte) that plays a role in the immune response and inflammatory reactions. They are the least common type of white blood cell, constituting less than 1% of the total white blood cell population. Basophils are characterized by the presence of large, dark-staining granules in their cytoplasm.

Here are some key features and functions of basophils:

1. Granules: Basophils contain numerous granules in their cytoplasm that store various substances, including histamine, heparin, proteoglycans, and other inflammatory mediators. These granules are responsible for the characteristic dark staining of basophils when viewed under a microscope.

2. Allergic Response: Basophils play a role in allergic reactions. When triggered by an allergen, basophils release histamine and other chemical mediators from their granules. Histamine causes blood vessels to dilate and become more permeable, leading to symptoms such as itching, swelling, and redness.

3. Inflammatory Response: Basophils are involved in the inflammatory response to infection or tissue injury. They release inflammatory mediators that attract other immune cells, such as neutrophils and eosinophils, to the site of inflammation to help fight off pathogens or aid in tissue repair.

4. Immune Regulation: Basophils have been found to interact with other immune cells, such as T cells and dendritic cells, and modulate immune responses. They can release cytokines that influence the activation and differentiation of other immune cells, contributing to the overall immune response.

5. Parasitic Infections: Basophils are thought to play a role in defense against certain parasitic infections. They can release substances that are toxic to parasites and contribute to the recruitment of other immune cells involved in parasite clearance.

It's important to note that basophils are relatively short-lived in the bloodstream and have the ability to migrate into tissues, where they can continue to carry out their functions. Basophil levels can increase in response to certain conditions, such as allergies, asthma, and some types of infections, but they are generally present in low numbers under normal circumstances.

Most abundant cations mansions in Extra cellular fluid

Ca2+ HCO3- Na+ Cl-

Most abundant cations mansions in intra cellular fluid

K+ Po3- Mg2+ Proteins -