Martini_FAP7_ch19_ag_2

Fundamentals of Anatomy & Physiology

• Author: Frederic H. Martini

• Unit 4: Fluids and Transport

• Copyright © 2005 Pearson Education, Inc.

• PowerPoint® Lecture Slides prepared by Professor Albia Dugger, Miami–Dade College, and Professor Robert R. Speed, Ph.D., Wallace Community College.

Chapter 19: Blood

Components of the Cardiovascular System

• Main Components:

  • Pump: Heart

  • Conducting System: Blood vessels

  • Fluid Medium: Blood

Functions of the Cardiovascular System

• Transport Functions:

  • Oxygen and Carbon Dioxide

  • Nutrients

  • Hormones

  • Immune system components

  • Waste products

Important Components and Functions of Blood

Blood Overview

• Blood is a specialized fluid connective tissue.

• Contains cells suspended in a fluid matrix.

5 Functions of Blood

1. Transports dissolved substances

2. Regulation of pH and ions

3. Restriction of fluid losses at injury sites

4. Defense against toxins and pathogens

5. Stabilization of body temperature

Composition of Blood

• Plasma: Fluid component

• Whole Blood: Formed elements consisting of all cells and solids.

Plasma Composition

• Water: >90% of plasma volume

• Dissolved Plasma Proteins

• Other Solutes

Formed Elements

1. Red Blood Cells (RBCs) or erythrocytes: Transport oxygen

2. White Blood Cells (WBCs) or leukocytes: Part of the immune system

3. Platelets: Cell fragments involved in clotting

Hemopoiesis

• The process of producing formed elements from myeloid and lymphoid stem cells.

General Characteristics of Blood

• Normal temperature: 38°C (100.4°F)

• High viscosity

• Slightly alkaline pH (7.35–7.45)

Composition and Function of Plasma

• Plasma Volume: 50-60% of blood volume

• Water Content: More than 90% of plasma

Classes of Plasma Proteins

1. Albumins (60%): Transport substances (fatty acids, thyroid hormones, steroid hormones)

2. Globulins (35%): Antibodies (immunoglobulins)

3. Fibrinogen (4%): Forms clots and produces long, insoluble fibrin strands.

Structure and Function of Red Blood Cells (RBCs)

• RBCs make up 99.9% of blood’s formed elements.

• Normal Blood Counts:

  • Male: 4.5-6.3 million cells/microliter

  • Female: 4.0-5.5 million cells/microliter

Structure of RBC

• Shape: Small and highly specialized disc

• Structure: Thin in the middle and thicker at the edge.

Importance of RBC Shape and Size

1. High Surface-to-Volume Ratio: Quickly absorbs/releases oxygen

2. Discs Form Stacks: Smoothes flow through narrow blood vessels

3. Bend and Flex: Navigate small capillaries

Lifespan of RBCs

• Lack of nuclei, mitochondria, and ribosomes; live about 120 days.

Structure and Function of Hemoglobin

• Protein molecule responsible for transporting oxygen and carbon dioxide.

• Normal hemoglobin concentration:

  • Adult male: 14–18 g/dl whole blood.

Anemia

• Defined as below normal hematocrit or hemoglobin levels.

• Causes include:

  • Iron deficiency

  • Sickle-cell disease

  • Pernicious anemia

Erythropoiesis

• The formation of red blood cells occurring exclusively in red bone marrow (myeloid tissue).

• Stem cells mature to become RBCs.

Stimulating Hormones for Erythropoiesis

• Erythropoietin (EPO): Secreted during hypoxia (low oxygen levels).

Blood Typing

• Surface Antigens: Identify cells to the immune system.

• Normal cells are ignored while foreign cells are attacked.

Blood Types Characteristics

• Genetically determined by RBC surface antigens A, B, Rh.

4 Basic Blood Types

• Type A: Surface antigen A, anti-B antibodies.

• Type B: Surface antigen B, anti-A antibodies.

• Type AB: Surface antigens A and B, no antibodies.

• Type O: No surface antigens, anti-A and anti-B antibodies.

Agglutinogens

• Antigens on surface of RBCs; screened by the immune system, causing agglutination upon attack by plasma antibodies.

Cross-Reaction

• Occurs when surface antigens interact with opposing antibodies, leading to agglutination (clumping) and hemolysis.

Universal Donors and Recipients

• Type O: Universal donor

• Type AB: Universal receiver

White Blood Cells (WBCs)

• Also called leukocytes, WBCs do not contain hemoglobin and have nuclei/other organelles.

Functions of WBCs

• Defend against pathogens

• Remove toxins and waste

• Attack abnormal cells

WBC Distribution

• Most WBCs found in connective tissue proper and lymphatic system organs; 6000 to 9000 WBCs/microliter in blood.

Types of WBCs

1. Neutrophils

2. Eosinophils

3. Basophils

4. Monocytes

5. Lymphocytes

Classes of Lymphocytes

1. T cells

2. B cells

3. Natural killer (NK) cells

WBC Disorders

• Leukopenia: Abnormally low WBC count.

• Leukocytosis: Abnormally high WBC count.

• Leukemia: Extremely high WBC count.

Key Concept

• RBCs outnumber WBCs by 1000:1.

• WBCs are essential for defending against infection and cleaning up damaged tissues.

Structure and Function of Platelets

• Platelets are cell fragments involved in the human clotting system.

Platelet Circulation

• Circulate for 9–12 days; removed by spleen, with 2/3 reserved for emergencies.

Platelet Counts

• Normal range: 150,000 to 500,000 per microliter.

• Thrombocytopenia: Abnormally low platelet count.

• Thrombocytosis: Abnormally high platelet count.

Hemostasis

• The cessation of bleeding involves three phases:

  • Vascular Phase

  • Platelet Phase

  • Coagulation Phase

The Vascular Phase

• Triggered by a cut, causing vascular spasms (30-minute contraction).

Steps of the Vascular Phase

1. Endothelial cells contract, exposing the basal lamina to the bloodstream.

2. Release chemical factors (ADP, tissue factor, prostacyclin) stimulating smooth muscle contraction and cell division.

3. Endothelial membranes become sticky, sealing off blood flow.

The Platelet Phase

• Begins within 15 seconds after injury:

  • Platelet adhesion: To sticky endothelial surfaces and exposed collagen fibers.

  • Platelet aggregation: Forms a platelet plug, closing small breaks.

Platelet Plug Restriction

• Prostacyclin: Released by endothelial cells to inhibit platelet aggregation to normal surrounding tissues.

The Coagulation Phase

• Blood clotting involves a series of steps converting circulating fibrinogen into insoluble fibrin.

Fibrinolysis

• The slow process of dissolving a clot involving plasminogen converting to plasmin, which digests fibrin strands.