Blood Composition and Functions

• Blood is a type of loose connective tissue.
• Blood circulates in the cardiovascular system.

Basic Functions of Blood

• Transports oxygen from the lungs and nutrients from the gastrointestinal tract to tissues.
• Carries carbon dioxide and waste materials to the organs.
• Plays a role in body defense against pathogenic microorganisms.

Key Blood Facts

• Arterial blood is oxygenated and bright red.
• Venous blood is deoxygenated and dark purplish red.
• Average blood volume for males is 5-6 Liters.
• Average blood volume for females is 4-5 Liters.
• Blood makes up 7-8% of total body weight, equivalent to 75-85 mL per kilogram of body weight.
• Blood is composed of 55% fluid portion and 45% formed elements
• The fluid portion is 90% water and 10% proteins, carbohydrates, salts, hormones and other substances.
• Formed elements include red blood cells, white blood cells, and platelets.

Plasma vs. Serum

• Plasma contains anticoagulant, forms 3 layers when centrifuged, and contains all coagulation factors.
• Plasma has a normal yellowish or straw color.
• Serum lacks anticoagulant, forms a clot containing fibrin, and lacks fibrinogen.
• Serum has a normal yellowish or straw color.

Formed Elements of Blood

• Formed elements are red and white blood cells.
• Granulocytes (with granules) include neutrophils, eosinophils, and basophils.
• Agranulocytes (without granules) include monocytes and lymphocytes.
• The three types of lymphocytes are T cells, B cells, and NK cells.

Romanowsky Method

• Romanowsky method involves staining to distinguish formed elements using Giemsa, Jenner, Wright, and Leishman methods.

Hematocrit

• Hematocrit is the percentage of blood volume accounted for by RBCs.
• Normal hematocrit range for females: 37-47%.
• Normal hematocrit range for males: 40-54%.
• WBC differential count refers to the percentage distribution of five types of WBCs in blood.

Shape of Formed Elements

• RBCs are biconcave discs.
• WBCs are spherical.
• Platelets are biconvex discs but appear ovate in transverse view.

Red Blood Cells (RBCs/ Erythrocytes)

• Hemoglobin imparts color, and is the cells' oxygen-carrying pigment.
• Produced in bone marrow.
• Before entering blood, they extrude their nucleus and cytoplasmic organelles.
• Deliver oxygen from the lungs to different tissues of the body.
• Erythrocyte ghost occurs when RBCs undergo hemolysis in hypotonic solutions.

Red Blood Cell Abnormalities

• Anisocytosis is variation in size.
• Normocytes are of normal size.
• Macrocytes are greater than 9um.
• Microcytes are less than 6um.
• Poikilocytosis is variation in shape.
• Rouleaux formation is the stacking of coins, indicating increased fibrinogen and globulins.
• Antigens are proteins on RBC membranes perceived as foreign by the immune system.
• Antibodies are immune responses against antigens.
• ABO system involves naturally occurring antibodies.
• Hemoglobin is a globular protein, comprising about 33% of RBC mass.
• Hemoglobin is composed of globin (protein molecule) and heme (iron-containing).
• Normal hemoglobin range for males: 14-18g per 100mL.
• Normal hemoglobin range for females: 12-16 g per 100 m.

Platelets/ Thromboplastid

• Platelets, also known as thromboplastid, are produced by fragmentation of the cytoplasm of giant cells called megakaryocytes.
• Surface connecting canalicular system serves as entry and exit points of substance.
• Dense tubular system stores calcium ions and cyclooxygenase.
• Platelet adhesion occurs when a platelet adheres to exposed collagen fiber.
• Platelet aggregation occurs when a platelet adheres to another platelet.

Blood is a loose connective tissue in the cardiovascular system. It transports oxygen and nutrients to tissues and removes carbon dioxide and waste. Blood also plays a role in body defense. Blood is composed of plasma and formed elements which include red blood cells, white blood cells, and platelets.