NHA MOD 2

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MODULE 2 NHA CPT Exam 1 Chapter 6 - The Cardiovascular System

Overview

  • Topics Covered:

    • The Circulatory System

    • Blood Components

    • Hemostasis & Complications

    • Career Development: Building a Professional Resume

    • Laboratory: Vein Identification & Mock Blood Draws

Learning Outcomes

  1. Describe circulation and the purpose of the vascular system.

  2. Identify and describe the structures and functions of the different types of blood vessels.

  3. Locate and name the veins most commonly used for phlebotomy procedures.

  4. Identify the major components of blood and describe the major functions of each.

  5. Define hemostasis and describe the basic coagulation process.

  6. Describe how A B O and Rh blood types are determined.

Why Anatomy & Physiology Matters in Phlebotomy

  • Understanding the circulatory system helps in safely drawing blood, minimizing errors, and interpreting patient reactions.

    • Anatomy: Structure of the body.

    • Physiology: Function of those structures.

    • Importance of knowing anatomy to avoid injury (e.g., hitting arteries, nerves).

    • Discussion Prompt: How does knowledge of vein and artery structures affect confidence during venipuncture?

The Circulatory System: The Body’s Transportation Network

  • Connects every organ, tissue, and cell, delivering oxygen, nutrients, hormones, while removing carbon dioxide and waste through 70,000+ miles of vessels.

Main Structures

  • Heart: Muscular pump ensuring unidirectional blood flow.

  • Blood Vessels: Arteries, veins, and capillaries.

  • Blood: Connective tissue carrying essential elements.

Circuits

  • Pulmonary Circuit: Right heart → Lungs → Left heart (gas exchange).

  • Systemic Circuit: Left heart → Body → Right heart (delivery of oxygen/nutrients).

    • Average Blood Volume: The average adult has 8–12 pints of blood, roughly the volume of a gallon of milk.

Clinical Relevance

  • Phlebotomists typically collect systemic venous blood which appears darker due to metabolic by-products.

  • Discussion Prompt: Why is venous blood collected instead of arterial blood?

The Heart: Structure, Function, and Flow

  • Description:

    • The heart is a strong, hollow muscle (the size of a fist) slightly left of midline in the chest.

    • Acts as a double pump:

    • Right side: sends blood to the lungs for oxygen.

    • Left side: pumps oxygen-rich blood to the body.

  • Heart Beat: Each beat pushes approximately 70 mL of blood, which is the reason a pulse can be felt.

Four Chambers of the Heart

  • Right Atrium → Right Ventricle → Left Atrium → Left Ventricle

Septum

  • Wall separating oxygen-poor (right) from oxygen-rich (left) sides.

Valves

  • Tricuspid Valve: Between Right Atrium & Right Ventricle.

  • Pulmonary Valve: Between Right Ventricle & Pulmonary Artery.

  • Mitral/Bicuspid Valve: Between Left Atrium & Left Ventricle.

  • Aortic Valve: Between Left Ventricle & Aorta.

    • Function of Valves: Maintain one-way flow and prevent backflow of blood.

The Heart: Layers and Protective Structures of the Heart

  • Composition:

    • Made of specialized cardiac muscle tissue.

    • Walls: Three layers – Endocardium, Myocardium, Epicardium.

    • Location: In the mediastinum, between lungs.

    • Function: Each layer works together for smooth, continuous blood pumping.

    • Damaging one layer can threaten circulation and life.

Endocardium - The Inner Lining

  • Composition: Smooth, delicate lining contacting blood directly.

  • Function:

    • Friction-free surface for blood movement.

    • Protects against damage or clot formation.

  • Clinical Relevance:

    • Endocarditis (infection of endocardium) can cause clots leading to strokes.

Myocardium - The Muscular Pump

  • Function: Generates pressure to move blood.

  • Concerns: Myocardial infarction (heart attack) can damage the myocardium.

Epicardium - The Protective Outer Layer

  • Function: Acts as protective covering and lubricator reducing friction during contractions.

The Heart: The Pericardium - The Heart’s Protective Sac

  • Description: A two-layered membrane that encloses and anchors the heart, preventing friction.

  • Composition: Fibrous pericardium (outer tough layer) and serous pericardium (inner layer).

  • Clinical Relevance:

    • Pericarditis can cause chest pain and fluid buildup (cardiac tamponade).

The Heart: Function

  • Central pump for the body, maintaining circulation through coordinated contraction.

Circulation Pathways

  1. Pulmonary Circulation: Moves deoxygenated blood from right ventricle to lungs and returns oxygenated blood to the left atrium.

  2. Systemic Circulation: Carries oxygen-rich blood from the left ventricle to body tissues and back.

  3. Coronary Circulation: Supplies the heart muscle itself.

Blood Vessels - Structure, Function, and Clinical Relevance

Structure of Blood Vessels

  1. Arteries: Carries blood away from heart, typically thicker walls to withstand high pressure.

    • Characteristics: Deeply located, strong pulse, bright red blood.

    • Phlebotomy Relevance: Do not puncture intentionally.

  2. Veins: Returns blood to the heart, thinner walls, valves prevent backflow.

    • Phlebotomy Relevance: Primary sites for blood draws.

  3. Capillaries: Connect arteries and veins; site of nutrient and gas exchange.

    • Phlebotomy Relevance: Used for small-volume tests.

Blood Composition - Components, Functions, and Clinical Relevance

  • Blood is a specialized connective tissue composed of cells and plasma essential for transport of oxygen, nutrients, waste, and immune defense.

Major Components of Blood

  1. Plasma (Liquid Portion): Comprises approximately 55% of blood, containing water, proteins, electrolytes, hormones, and waste.

  2. Formed Elements: Approximately 45% of blood consisting of erythrocytes, leukocytes, and thrombocytes.

Hematopoiesis

  • The process of blood cell formation from hematopoietic stem cells in red bone marrow. Each type of cell has specific roles.

Erythrocytes (RBCs)

  • Carry oxygen using hemoglobin.

Leukocytes (WBCs)

  • Essential for immune defense against infection.

Thrombocytes (Platelets)

  • Involved in clotting and hemostasis.

Hemostasis Process

  1. Vascular Spasm

  2. Platelet Plug Formation

  3. Coagulation

  4. Clot Retraction and Repair

Blood Types - ABO and Rh System

  • ABO System: Based on A and B antigens on RBCs and antibodies in plasma impacting transfusion compatibility.

  • Rh System: Based on Rh antigens (presence or absence of D antigen) affecting maternal-fetal blood interactions.

Clinical Relevance in Phlebotomy

  • Understanding each of these systems impacts the quality and safety of blood draws and analyses, which is essential for accurate clinical interpretation.