Chap19 PPT

Chapter Overview

• Title: The Circulatory System: Heart Anatomy & Physiology

• Edition: Tenth Edition, Kenneth S. Saladin

• Publisher: McGraw Hill LLC

• Theme: Learning changes everything

Cardiovascular System Overview

• Expected Learning Outcomes:

  • Define and distinguish between pulmonary circuit and systemic circuit

  • Describe general location, size, and shape of the heart

  • Describe pericardium enclosing the heart

Key Definitions

• Cardiology: Study of the heart and its disorders

• Cardiovascular System: Heart and blood vessels

  • Heart: Pump maintaining blood flow through vessels

  • Vessels: Deliver blood to body tissues and return it to the heart

    • Arteries: Carry blood away from the heart

    • Veins: Carry blood toward the heart

    • Capillaries: Microscopic vessels connecting smallest arteries and veins

  • Circulatory System: Refers to heart, vessels, and blood

Pulmonary and Systemic Circuits

• Cardiovascular Division:

  • Pulmonary Circuit: Carries blood to lungs for gas exchange and back to heart

  • Systemic Circuit: Supplies oxygenated blood to all body tissues and returns to the heart

Heart Functions in Circuits

• Right Side of Heart: Supplies pulmonary circuit

  • Receives oxygen-poor blood from body tissues via superior/inferior vena cavae

  • Sends blood to alveoli of lungs via pulmonary trunk and arteries

  • Oxygen is picked up and returns to heart via pulmonary veins

• Left Side of Heart: Supplies systemic circuit

  • Sends fully oxygenated blood to body tissues via aorta, branching to smaller vessels

  • Deoxygenated blood returns to heart via superior/inferior vena cavae

  • Great Vessels: Major arteries and veins entering/leaving the heart

Position, Size, and Shape of the Heart

• Location: Mediastinum (space between lungs)

• Shape:

  • Base: Wide, superior part; large vessels attach here

  • Apex: Tapered, inferior end tilting left

• Size:

  • Adult heart weighs about 10 ounces, measures 3.5 inches wide and 5 inches from base to apex, roughly the size of a fist

Pericardium

• Enclosure:

  • Double-walled sac allows heart to beat without friction, provides room to expand, resists excessive expansion

  • Anchored to diaphragm inferiorly and sternum anteriorly

• Structure:

  • Fibrous Pericardium: Tough outer layer

  • Serous Pericardium: Consists of:

    • Parietal layer: lines fibrous pericardium

    • Visceral layer (epicardium): adheres to heart surface

  • Pericardial Cavity: Space containing 5 to 30 mL of fluid, reducing friction

  • Pericarditis: Inflammation resulting in friction rub

Gross Anatomy of the Heart

• Three Heart Wall Layers:

  • Epicardium: Outer membrane, may have adipose

  • Myocardium: Cardiac muscle layer; thickness varies with workload

  • Endocardium: Smooth inner lining of heart and blood vessels

• Chambers:

  • Four Chambers:

    • Right & left atria (upper)

    • Right & left ventricles (lower); thickness varies

  • Internal features: septa separate chambers, an unique arrangement provides structural support

Blood Flow Through the Heart

Blood Pathway Overview

• Pathway:

  1. Right atrium receives oxygen-poor blood from body

  2. Flows through right AV valve into right ventricle

  3. Right ventricle contracts, forcing pulmonary valve open

  4. Blood flows into pulmonary trunk and to lungs for oxygenation

  5. Oxygen-rich blood returns to left atrium via pulmonary veins

  6. Flows through left AV valve into left ventricle

  7. Left ventricle contracts, forcing aortic valve open

  8. Blood flows into ascending aorta and distributed to the body

  9. Returns oxygen-poor blood to heart via venae cavae

Heart Valves

• Function: Ensure one-way blood flow

• Types of Valves:

  • Atrioventricular (AV) Valves: Control blood flow between atria and ventricles

    • Right AV (Tricuspid) valve: Typically has 3 cusps

    • Left AV (Mitral) valve: Typically has 2 cusps

  • Semilunar Valves: Control flow from ventricles into major arteries

    • Pulmonary valve: Between right ventricle and pulmonary trunk

    • Aortic valve: Between left ventricle and aorta

Blood Flow Control Through Valves

• Mechanisms: During ventricular contraction and relaxation, blood pressure changes open/close valves

• Pathology:

  • Valvular Insufficiency: Failure of valve to prevent regurgitation

  • Valvular Stenosis: Stiffened cusps causing restricted flow

• Heart Sounds: Produced by closure of valves, detected during auscultation

Coronary Circulation

• Function: Supplies blood to myocardium

• Coronary Arteries:

  • Left Coronary Artery (LCA)**: Supplies left ventricle and anterior interventricular septum

  • Right Coronary Artery (RCA)**: Supplies right ventricle and posterior walls

• Variability: Flow through coronary arteries varies with cardiac cycle, peaking during heart relaxation

Cardiac Muscle and Conduction System

• Cardiac Muscle: Striated, branched cells with intercalated discs for efficient contractions

• Conduction System: Regulates heartbeat, originating from SA node

  • Pacemaker: SA node initiates heartbeats.

  • Signal Pathway:

    • Atria to AV node

    • AV bundle and branches reach ventricles

    • Purkinje fibers stimulate ventricular contraction

Electrical Activity of the Heart

• Heartbeat Control: Myogenic, independent of nervous input

• Action Potentials:

  • Unique shape allows for coordinated contraction

  • Long refractory periods prevent tetanus

• Cardiac Cycle: Follows regular rhythm associated with systole (contraction) and diastole (relaxation)

Cardiac Output Regulation

• Definition: Amount of blood pumped by each ventricle per minute

• Determinants: Heart rate, stroke volume

• Cardiac output=heartrate × stroke volume, which indicates that an increase in either heart rate or stroke volume will result in a higher cardiac output.

• stroke volume= end-diastolic volume (EDV) - end-systolic volume (ESV) amount of blood exiting the left ventricle

• Control:

  • Autonomic Nervous System influences heart rhythm and strength

  • Chronotropic Effects: Factors increasing/decreasing heart rate

• Influence of Exercise: Increases cardiac output by enhancing stroke volume and heart rate

Coronary Artery Disease

• Definition: Degenerative disease resulting from atherosclerosis

• Risk Factors: Hypertension, diabetes, unhealthy diet contribute to disease progression

• Treatments: Lifestyle changes, angioplasty, and by-pass grafting for blood flow restoration

Summary Effects on Cardiac Output

• Balance: Essential for maintaining circulation and preventing fluid accumulation in tissues

• Monitoring: Understand ECG patterns for detecting abnormalities in heart function.