Human Blood Functions and Composition

Blood Functions

• Transports vital substances to cells: water, oxygen, nutrients, hormones, enzymes, medications
• Removes waste products: carbon dioxide and other waste
• Regulates fluid volume, electrolyte balance, pH, body temperature
• Provides clotting factors for hemostasis

Blood Composition

• Formed elements (45%): erythrocytes (red blood cells), platelets, leukocytes (white blood cells)
  • Leukocytes: neutrophils (54-62%), lymphocytes (25-33%), monocytes (3-7%), eosinophils (1-3%), basophils (0-1%)
• Plasma (55%):
  • Proteins (7%): albumin (54%), globulins (38%), fibrinogen (4%), prothrombin (1%)
  • Water (91%)
  • Other solutes (2%): ions, nutrients, waste products, gases, regulatory substances

Plasma Protein Functions

• Albumin: maintains osmotic pressure, preventing fluid leakage into tissues
• Alpha and beta globulins: transport drugs and lipids
• Gamma globulins: act as antibodies
• Fibrinogen: essential for blood clot formation

Blood Cell Production

• Stem cells in bone marrow produce blood cells through erythropoiesis
• Kidney produces erythropoietin, stimulating red blood cell production by bone marrow
• Erythropoiesis requires iron, vitamins B12, C, E, folic acid, and amino acids (obtained from proteins)

Red Blood Cell Functions

• Erythrocytes contain hemoglobin: carries oxygen to cells, removes CO2
• Blood types: A, B, AB, O
• Normal RBC count: 4.2 to 6.2 million/mm3 (varies by gender)
• Normal hemoglobin level: 12 to 18 g/dL (varies by gender)
• Reduced RBCs or hemoglobin levels decrease oxygen transport
• RBC lifespan: approximately 120 days
• Spleen and liver remove old and damaged RBCs

White Blood Cell Functions

• First line of defense against microbial agents
• Normal WBC count: 4500 to 11,000/mm3
• WBC lifespan: 13 to 20 days
• Migrate from bone marrow to tissues through bloodstream
• Divided into granulocytes (with granules) and agranulocytes (without granules)
• Granulocytes: neutrophils, eosinophils, basophils
  • Neutrophils: engulf and destroy bacteria (phagocytosis)
  • Eosinophils: detoxify foreign proteins, increase during allergic reactions and parasitic infections
  • Basophils: release histamine, prevent clotting in small blood vessels
• Agranulocytes: lymphocytes and monocytes
  • Lymphocytes: produced in bone marrow and lymphatic tissue, B cells and T cells
    • B cells: differentiate into plasma cells, produce immunoglobulins (humoral immune response)
    • T cells: killer cells, fight antigens (cell-mediated immune response)
  • Monocytes: differentiate into macrophages (phagocytes) in tissues, fight infection and remove foreign substances

Platelets and Their Function

• Prevent bleeding by promoting clotting
• Fibrin strands attach to aggregated platelets to form clots
• Adhere to damaged surfaces, clump together
• Platelet lifespan: approximately 10 days

Lymphatic System Interaction

• Spleen: filters blood, removes pathogens, old blood cells, and debris, produces lymphocytes
• Spleen acts as a blood reservoir, releasing stored blood during hemorrhage
• Lymph vessels collect fluid and proteins from tissues, return them to bloodstream
• Lymph nodes filter leukocytes and cell debris before lymph returns to bloodstream

Hematologic Changes with Aging

• Decreased plasma volume after age 60
• Reduced bone marrow activity, slower cellular production
• Increased coagulation: higher risk of thrombosis in coronary and cerebral arteries

Causes of Hematologic Disorders

• Genetic disorders: hemophilia, sickle cell disease, agranulocytosis
• Hemorrhage (anemia): surgical blood loss, childbirth, spontaneous abortion, trauma, gastrointestinal bleed
• Anemia: iron deficiency, folic acid deficiency, megaloblastic anemia, chronic blood loss, aplastic anemia
• Hemolysis: blood transfusion reaction, genetic types of anemia
• Bone marrow suppression: antineoplastic agents, radiation treatment, exposure to ionizing radiation, toxic chemicals, bone marrow suppressing drugs
• Bone marrow proliferation or abnormality: leukemia

Nutrients for Red Blood Cell Production (Erythropoiesis)

• Vitamin B12: red meat, especially liver
• Folic acid: green leafy vegetables, liver, meat, fish, legumes, whole grains
• Iron: liver and muscle meats, eggs, dried fruits, legumes, dark green leafy vegetables, whole-grain bread and cereals, potatoes
• Vitamin C: citrus fruits, green leafy vegetables, strawberries, cantaloupe

Cultural Cues for Genetic Hematologic Tendencies

• African Americans: highest incidence of sickle cell disease
• Scandinavian and African Americans: higher prevalence of pernicious anemia
• Middle Eastern: genetic predisposition to thalassemia
• Whites: higher incidence of leukemia, followed by Hispanics

Physical Assessment

• Head and Neck: conjunctiva and sclera color, gums, oral mucous membranes, tongue, enlarged cervical lymph nodes
• Skin: color (pallor), fingernails (brittle, spoon-shaped), ecchymosis, petechiae, jaundice, hair (dry, brittle, thinning)
• Chest and Abdomen: rapid respirations, shortness of breath, swollen lymph nodes, rapid pulse, widened pulse pressure, epigastric tenderness, abdominal distention
• Extremities: swollen or painful joints (hemarthrosis), pulse quality, skin color
• Urine and Stool: signs of blood

Common Problems Related to Hematologic Disorders

• Excessive bleeding
• Excessive clotting
• Fatigue
• Anorexia
• Pain
• Infection
• Bone marrow failure

Anemia

• Insufficient functional red blood cells or hemoglobin to meet tissue oxygen demands
• Classifications: blood loss, failure in blood cell production, destruction of red blood cells
• Mild anemia (Hb 11 to 13 g/dL): mild headache, palpitations, dyspnea on exertion
• Moderate anemia (Hb 8 to 10 g/dL): brittle nails, sore tongue, pallor, chronic fatigue, headache, dizziness
• Severe anemia (Hb less than 8 g/dL): severe symptoms, requiring blood transfusions

Explore the vital roles of blood in the human body with this quiz focusing on its functions, composition, and the significance of different blood proteins. Test your understanding of how blood transports substances, regulates bodily functions, and assists in clotting. Perfect for biology students or anyone interested in human physiology.