Chapter 13 Use This Edition 8

Liquid Fraction of Blood

• Plasma: The liquid (extracellular) fraction of whole blood.

Blood Composition & Characteristics

• Body Weight Contribution: Blood accounts for approximately 7% to 9% of total body weight in an average adult.

• Normal Blood pH: Generally ranges from 7.35 to 7.45, slightly alkaline.

Learning Objectives (Lesson 13.1)

• Comprehend the primary functions and composition of blood including:

  • Characteristics of blood tissue and plasma.

  • Identification of key functions for each formed element of blood.

  • Structure and function of red blood cells (RBCs).

  • Explanation of RBC count and the role of hemoglobin.

  • Understanding ABO and Rh systems for blood typing.

Blood Composition Overview

• Blood as Connective Tissue: Essential for life and serves as the primary fluid for transportation.

• Components:

  • Composed of millions of cells and various dissolved chemicals.

  • Plasma: Contains many dissolved substances necessary for cellular functions (nutrients, oxygen, CO2, hormones).

  • Formed Elements: Cellular components suspended in plasma.

Blood Volume

• Average Volume:

  • Normal blood volume in adult: 4 to 6 liters (7% to 9% body weight).

  • Plasma: Approx. 2.6 liters (over half).

  • Formed elements: Approx. 2.4 liters.

Blood pH

• Characteristics: Blood is slightly alkaline (pH 7.35 to 7.45).

• Acidosis: Condition when blood pH approaches neutral; symptoms include shortness of breath (SOB), confusion, muscle aches, fatigue, seizures.

Blood Donations

• Statistics: About 14 million units donated annually.

• Storage Limitation: Donated blood is typically stored for up to 6 weeks.

Blood Plasma

• Function: Transportation of dissolved substances.

• Composition: Comprises about 55% of blood volume.

  • Contains water and many key substances essential for life.

  • Carries nutrients, oxygen, CO2, salts, plasma proteins, hormones.

  • 1.5% of O2 and 10% of CO2 is dissolved in plasma.

Plasma Proteins Composition

• Plasma Proteins make up about 7% of plasma by weight:

  • Albumins: Retain water in blood (osmotic pressure).

  • Globulins: Antibodies for immune defense.

  • Fibrinogen & Prothrombin: Essential for blood clotting.

• Serum: Plasma minus clotting factors.

Formed Elements of Blood: Overview

• Three Main Types:

  1. Red Blood Cells (RBCs): Erythrocytes; lifespan of about 4 months.

  2. White Blood Cells (WBCs): Leukocytes; various types with differing lifespans.

  3. Platelets: Thrombocytes; tiny fragments crucial for clotting.

Red Blood Cell Characteristics

• Structure: Biconcave shape provides a larger surface area for gas exchange.

  • High surface area facilitates transport of oxygen and carbon dioxide.

• Lifespan: Limited to 80-120 days; lack of organelles impedes repair.

Red Blood Cells Function

• Transport of Gases:

  • Oxyhemoglobin: O2 transport (98.5% via hemoglobin).

  • Carbaminohemoglobin: CO2 transport; also plays a role in acid-base balance.

Red Blood Cell Count (CBC)

• Hematocrit: Measure of the percentage of RBCs in blood; normal levels around 45%.

  • Important for diagnosing conditions like anemia and dehydration.

Blood Types & Systems

• ABO System: Blood types based on antigens.

  • Type A: A antigens, anti-B antibodies.

  • Type B: B antigens, anti-A antibodies.

  • Type AB: Universal recipient; no anti-A or anti-B antibodies.

  • Type O: Universal donor; both anti-A and anti-B antibodies.

  • No Rhfactor: Negative Rh factor means the absence of the Rh antigen; individuals with this type can only receive Rh-negative blood.

  • Rh-positive: Presence of the Rh antigen; individuals with this type can receive both Rh-positive and Rh-negative blood.

• Rh System: Rh factor antigen present present in RBC’s (Rh+). Rh- No Rh factor antigen present in RBC’s; individuals can develop anti-Rh antibodies if exposed to Rh+ blood.

Clinical Applications of Blood Typing

• Erythroblastosis fetalis: Rh incompatibility can cause issues in pregnancies.

• Importance of RhoGAM: Administration prevents mother from forming anti-Rh antibodies during subsequent pregnancies.

Disorders Related to Blood Cells

• Anemia: Low RBC counts or hemoglobin levels.

  • Symptoms: Fatigue, pallor(paleness), weakness, increased heart and respiratory rates.

• Polycythemia: Overproduction of RBCs leading to complications like thickened blood.(viscosity)

White Blood Cells (WBCs)

• Structure: No hemoglobin; categorized into granular (neutrophils, eosinophils, basophils) and agranular (lymphocytes, monocytes).

• Functions: Immune defense, phagocytosis, antibody production.

• WBC count: Normal WBC count is between 5-10 thousand of blood - cubic mm

• Neutrophils: The most abundant type of white blood cells, accounting for 50-70% of the total WBC count, primarily responsible for engulfing and digesting bacteria and fungi.

• Eosinophils: Eosinophils: A type of white blood cell that makes up about 1-4% of the total WBC count, primarily involved in combating parasitic infections and playing a role in allergic reactions.

• Basophils: Comprising about 0.5-1% of the total WBC count, basophils are involved in inflammatory responses and release histamine during allergic reactions.

• Agranular

• Monocytes: Large white blood cells that account for about 2-8% of the total WBC count, monocytes are crucial for phagocytosis and differentiate into macrophages and dendritic cells to help in immune defense.

• Lymphocytes: Comprising approximately 20-40% of the total WBC count, lymphocytes are essential for adaptive immunity and include T cells, B cells, and natural killer cells, each playing a unique role in recognizing and responding to pathogens.

• B lymphocytes: These cells are responsible for the production of antibodies, which bind to specific antigens on pathogens, facilitating their neutralization and destruction.

• T lymphocytes: Also known as T cells, these lymphocytes are vital for cell-mediated immunity, recognizing infected cells and coordinating the immune response by directly killing infected cells or helping other immune cells.

• Disorders

• Leukopenia: A condition characterized by a lower than normal number of white blood cells, which can lead to increased susceptibility to infections and other immune-related disorders.

• Leukocytosis: A condition marked by an elevated number of white blood cells, often in response to infection, inflammation, or other stressors on the body. Leukemia high wbc count

Clotting Mechanism Overview

• Platelets contribute to the formation of blood clots in response to injuries by forming a platelet plug and releasing clotting factors.

• Steps in Clotting Mechanism: Activation of prothrombin leading to thrombin, which converts fibrinogen into fibrin, creating a clot.

Disorders Related to Clotting

• Thrombocytopenia: Low platelet count leading to bleeding issues.

• Hemophilia: Genetic disorder affecting clotting factor production.

• Vitamin K Deficiency: Essential for the production of several clotting factors, leading to increased bleeding risks.