Blood Composition and Function Overview

Blood is made up of plasma (55%), red blood cells (41%), and white blood cells/platelets (4%).

Plasma transports nutrients, wastes, hormones, and gases; maintains blood pressure and pH.

Albumin, a protein made in the liver, helps maintain blood pressure.

Blood smears are stained with dyes like Giemsa's to see different blood cell types clearly under a microscope.

Red blood cells (RBCs) appear yellow/pale red with a darker rim in stained blood smears.

Methylene blue in Giemsa's stain, stains DNA and RNA, appearing blue-grey/violet.

Blood transports essential substances, removes waste, regulates temperature and pH.

Blood can be classified into various types based on specific antigens present on the surface of the red blood cells.

The disc-like shape of red blood cells with a depressed center on both sides, maximizing surface area for efficient gas exchange.

The outer membrane of red blood cells is thin, allowing easy diffusion of oxygen and carbon dioxide.

The internal framework of red blood cells, giving them flexibility to squeeze through narrow blood vessels.

Red blood cells lack a nucleus and organelles to maximize space for hemoglobin, which carries oxygen.

Red blood cells allow oxygen and carbon dioxide to pass through their membrane easily while restricting other substances.

Red blood cells also carry nitric oxide (NO), a molecule that dilates blood vessels.

Complete Blood Count (CBC) is a blood test that measures various components like red blood cells, white blood cells, hemoglobin, and hematocrit.

Anemia is a condition characterized by a deficiency in red blood cells and/or hemoglobin, leading to reduced oxygen carrying capacity.

A type of white blood cell with granules in their cytoplasm. They are involved in immune responses, primarily against bacteria and parasites.

Neutrophils, a type of granulocyte, have a multilobed nucleus, small specific granules, and few mitochondria. They are the most abundant white blood cell.

Eosinophils are granulocytes with bilobed nuclei and specific granules that stain red due to acidic dyes.

Basophils are granulocytes with an S-shaped nucleus and specific granules that stain dark blue or purple due to basic dyes.

Neutrophils have two types of granules: specific granules (smaller, pale, contain enzymes for killing bacteria) and azurophilic granules (larger, dense, contain lysosomal enzymes).

Neutrophils are the first responders to infection. They phagocytose bacteria and secrete enzymes to kill them. They can also survive in low-oxygen environments.

Neutrophils are inactive and spherical in circulation, but become amoeboid and active when adhering to collagen in connective tissue.

Neutrophils store glycogen, which they break down to glucose for energy, allowing them to function in low-oxygen environments.

A condition where there are too few neutrophils in the blood, making the body vulnerable to bacterial infections.

A collection of dead neutrophils, bacteria, and inflammatory debris found at the site of infection.

Eosinophils contain two types of granules: Specific granules with major basic protein for killing parasites, and Azurophilic granules with lysosomal enzymes.

Eosinophils release histaminase and sulphatase to neutralize histamine and other chemicals released during allergic reactions.

Eosinophils attack parasitic worms by forming pores on their surface and releasing toxic molecules.

Macrophage chemotactic factor attracts macrophages to the site of inflammation.

Monocytes are attracted to the site of infection, where they mature into macrophages.

Basophils contain two types of granules: specific granules (large, irregular, contain heparin, histamine, etc.) and azurophilic granules (lysosomes with hydrolytic enzymes).

Basophils release histamine (allergic reaction), heparin (anticoagulant), and eosinophil chemotactic factor (attracts eosinophils). They also have limited phagocytic ability.

High basophil counts in blood suggest an allergic reaction or other hypersensitivity. IgE antibodies bind to basophils and mast cells, triggering these responses.

Agranulocytes lack specific granules but contain azurophilic granules (lysosomes). Includes lymphocytes and monocytes.

Monocytes are large agranulocytes with a large, indented nucleus (horseshoe or kidney-shaped). Their cytoplasm is basophilic and contains fine azurophilic granules.

Monocytes are phagocytic cells that engulf pathogens and cellular debris. They differentiate into macrophages in tissues.

Lymphocytes have a round or slightly indented nucleus and a small amount of cytoplasm, often with a few azurophilic granules.

Lymphocytes are responsible for specific immune responses, recognizing and targeting specific pathogens. They differentiate into T cells and B cells.

Alpha granules are a type of granule found in platelets. They contain fibrinogen and platelet-derived growth factor.

Delta granules, also known as dense bodies, are another type of granule found in platelets. They store calcium ions, ADP, ATP, and serotonin.

Lambda granules, also referred to as small vesicles, are the third type of granule found in platelets, containing only lysosomal enzymes.

Primary aggregation is the initial response of platelets to an injury where they adhere to exposed collagen via a collagen-binding protein on their membrane, forming a platelet plug.

Secondary aggregation follows primary aggregation, involving adhesive glycoproteins and ADP released from platelets in the plug to further enhance platelet adhesion and enlarge the plug.

A blood clot forms through a complex cascade of reactions involving proteins from the blood plasma, damaged blood vessels, and platelets. This process results in fibrin formation, which traps red blood cells, white blood cells, and platelets to form a blood clot.

Clot retraction is the process where the blood clot contracts due to the interaction of platelet actin, myosin, and ATP, essentially tightening the clot.

A blood clot can be removed through the action of a proteolytic enzyme called plasmin. Plasmin is activated by plasminogen activators released from the endothelium, and also by enzymes from alpha granules.

Eosin, also known as esinophilic, is a dye that stains hemoglobin, giving it an orange-red color. This helps visualize red blood cells clearly.

Azurophilic staining uses dyes to highlight lysosomal enzymes. These enzymes are important for breaking down cellular waste within cells.

Red blood cells (RBCs) are biconcave disks, meaning they are disc-shaped with a depression on both sides. This shape increases their surface area, maximizing oxygen transport.

The majority of the RBC's cytoplasm is filled with hemoglobin. Hemoglobin is the protein responsible for carrying oxygen throughout the body.

In small blood vessels, red blood cells often stack up in coin-like formations, like a stack of paper. This is called rouleaux formation.

The RBC membrane is a lipid bilayer, formed by proteins, lipids, and carbohydrates. This membrane acts as a barrier that controls what enters and exits the cell.

Hemoglobin is a protein, containing four polypeptide chains (two alpha and two beta for adults, or two alpha and two gamma for fetuses) and a heme group.

Hemoglobin is a metalloprotein mainly responsible for carrying oxygen and some carbon dioxide in the blood.

Abundant granulocytes with a multilobed nucleus, possessing small specific granules and a few mitochondria. They are the first responders to infections, phagocytizing bacteria and releasing enzymes to kill them.

Granulocytes with bilobed nuclei and specific granules that stain red due to acidic dyes. Primarily involved in anti-allergic and anti-parasitic responses.

Neutrophils store glycogen, which they break down into glucose for energy, enabling them to effectively fight infections even in poorly oxygenated regions.

Mature monocytes that engulf pathogens, cellular debris, and fight infections. They are known as 'big eaters' for their phagocytic abilities.

Red blood cells (RBCs) have a biconcave shape, resembling a flattened disc with a depressed center on both sides. This shape increases surface area for efficient gas exchange.

RBCs have a thin outer membrane, allowing for easy diffusion of oxygen and carbon dioxide across the membrane.

The RBC cytoskeleton and flexible membrane allow RBCs to squeeze through narrow blood capillaries, reaching even the smallest blood vessels.

RBCs lack a nucleus and other organelles, maximizing space for hemoglobin, the protein responsible for oxygen transport.

RBCs are selectively permeable, allowing oxygen and carbon dioxide to pass through easily while preventing other substances from entering.

RBCs also carry nitric oxide (NO), a neurotransmitter that causes blood vessel dilation. This contributes to blood flow regulation.

A blood test used for diagnosing and managing various conditions, measuring components like RBCs, WBCs, hemoglobin, and hematocrit.

A condition characterized by a deficiency in RBCs and/or hemoglobin, resulting in reduced oxygen-carrying capacity in the blood.

Macrophages are cells that protect against infections by engulfing harmful microbes and cellular debris.

Macrophages develop from monocytes, which are produced in the bone marrow.

Macrophages are activated by signals like growth factors and cytokines.

These cells form when macrophages fuse together, usually in response to disease or injury.

Lymphocytes are categorized by surface molecules and function, with distinct roles in immune responses.

B-lymphocytes are responsible for humoral immunity, producing antibodies to fight infections.

Plasma cells are specialized B-lymphocytes that produce and release antibodies.

T-lymphocytes are involved in cell-mediated immunity, directly attacking infected cells and regulating immune responses.

Platelets contain three types of granules: alpha granules, delta granules (dense bodies), and lambda granules. Each type stores different substances essential for platelet function.

Primary aggregation is the initial sticking of platelets to exposed collagen at the site of injury. This forms a temporary plug to stop bleeding, forming a 'platelet plug.'

Secondary aggregation expands the platelet plug. Platelets in the plug release adhesive substances like glycoproteins and ADP, attracting more platelets to the site.

Blood coagulation involves a complex series of reactions involving plasma factors, damaged blood vessels and platelets. Ultimately, it leads to the formation of fibrin, which forms a network trapping blood cells to form a strong clot.

Clot retraction is the squeezing and tightening of a blood clot. This happens due to the interaction of platelet actin, myosin, and ATP, making the clot more compact.

Megakaryocytes are giant cells found in bone marrow with a large, lobulated nucleus containing multiple copies of DNA. Their cytoplasm is basophilic and contains many granules (alpha, delta, and lambda).

Megakaryocytes are responsible for producing platelets. They extend their processes into the bloodstream, releasing platelets into circulation.

Thrombocytopenia is a condition characterized by a lower than normal platelet count in the blood. This leads to spontaneous bleeding, often seen as small red dots on the skin (petechiae), especially in the gut.

Basophils are granulocytes with an S-shaped nucleus and large, dark blue granules containing heparin, histamine, and eosinophil chemotactic factor. These granules stain red with toluidine blue due to their heparin content, a phenomenon called metachromasia.

Basophils release histamine to trigger allergic reactions, heparin to prevent blood clotting, and eosinophil chemotactic factor to attract eosinophils to fight parasites. They also have limited phagocytic ability.

Agranulocytes are white blood cells that lack specific granules but contain azurophilic granules (lysosomes). This group includes lymphocytes and monocytes, which play important roles in specific immune responses.

Monocytes are large agranulocytes with a large, indented nucleus often shaped like a horseshoe or kidney. Their cytoplasm is basophilic and contains fine azurophilic granules.

Monocytes are phagocytic cells that engulf pathogens and cellular debris in the blood. They differentiate into macrophages in tissues, becoming powerful 'big eaters' of foreign invaders.

Lymphocytes are agranulocytes with a round or slightly indented nucleus and a small amount of cytoplasm, often containing a few azurophilic granules. There are two main types: T cells and B cells.

T lymphocytes (T cells) are responsible for cell-mediated immunity. They directly attack infected cells and regulate immune responses, playing a key role in controlling intracellular pathogens.

B lymphocytes (B cells) are responsible for humoral immunity. They produce antibodies to fight infections in the body fluids. They mature into plasma cells, which are antibody factories.