Cardiovascular

Cardiovascular System Functions

• Main Functions

  • Delivery of Oxygen

  • Provides oxygen to tissues to support aerobic metabolism.

  • Removal of Waste Products

  • Transports carbon dioxide from tissues to lungs for exhalation.

  • Transports renal waste to kidneys for elimination.

  • Nutrient Transport

  • Delivers nutrients absorbed from the gastrointestinal tract to tissues.

  • Body Temperature Regulation

  • Achieved through vasoconstriction (reducing heat loss in cold) and vasodilation (enhancing heat loss in heat).

  • Transport of Hormones and Neurotransmitters

  • Carries hormones and neurotransmitters to regulate cellular function.

  • Endocrine Role of the Heart

  • The heart secretes hormones such as natriuretic peptides (ANP and BNP).

Heart Location and Membranes

• Located in the Mediastinum

  • Posterior to the sternum, anterior to the vertebral column, between lungs.

• Views of the Heart

  • Anterior view highlights the right atrium, right ventricle, left atrium, and left ventricle.

  • Key vessels include ascending aorta, pulmonary trunk, superior & inferior vena cavae.

  • The apex rests on the diaphragm.

• Pericardial Membranes

  • Visceral Pericardium (Epicardium):

  • Inner layer directly covering the heart.

  • Parietal Pericardium:

  • Outer layer surrounding the heart, inside the fibrous pericardium.

  • Pericardial Cavity:

  • Contains approximately 20 ml of serous fluid, allows the hearts' movements.

External Anatomy of the Heart

• Right Atrium and Ventricles

  • Right atrium receives deoxygenated blood from superior/inferior vena cavae.

  • Right ventricle pumps blood through pulmonary trunk to the lungs.

• Left Atrium and Ventricle

  • Left atrium receives oxygenated blood from the pulmonary veins.

  • Left ventricle ejects blood through the aorta.

• Coronary Arteries

  • Right Coronary Artery

  • Emerges from aorta and descends along the right ventricle.

  • Left Anterior Descending Artery:

  • Supplies the anterior left ventricle and interventricular septum.

  • Left Circumflex Artery:

  • Supplies lateral aspects of the left ventricle.

Internal Anatomy and Blood Flow

• Heart Chambers and Blood Flow

  • Blood collection without directional valves between vena cavae and right atrium.

  • Tricuspid and mitral valves prevent retrograde flow during ventricular contraction.

  • Systolic and Diastolic Phases:

  • Systole: ventricles contract and eject blood.

  • Diastole: chambers fill with blood.

Structural Layers of Heart Wall

• Epicardium:

  • Outermost layer, protective layer.

• Myocardium:

  • Thick layer of cardiac muscle responsible for contraction.

  • Thickness varies: thickest in left ventricle, thinnest in right atrium.

• Endocardium:

  • Innermost layer lining chambers and valves.

  • Contains trabeculae carneae to promote turbulence and prevent clotting.

Pericarditis and Cardiac Tamponade

• Pericarditis:

  • Inflammation of pericardial membranes can lead to friction rub and chest pain.

• Cardiac Tamponade:

  • Accumulation of fluid in the pericardial cavity causing hemodynamic compromise.

  • Anesthetic management includes maintaining volume (full), heart rate (fast), and forward flow.

Cardiac Action Potential

• Pacemaker Cells:

  • SA node primary pacemaker, generates impulses 60-100 times/min.

  • AV node backup pacemaker, 40-60 times/min.

  • Purkinje fibers can become pacemakers if necessary, 15-40 times/min.

• Phases of Action Potential:

  • Resting phase influenced by Na/K pump and ion permeability.

  • Depolarization (Phase 0): rapid influx of Na.

  • Plateau Phase (Phase 2): prolonged influx of calcium and sodium; potassium begins to exit.

  • Repolarization (Phase 3): potassium efflux leads to return to resting membrane potential.

Heart Sounds and EKG Waves

• Heart Sounds:

  • First sound (S1): closure of mitral/tricuspid valves.

  • Second sound (S2): closure of aortic/pulmonic valves.

• EKG Waves:

  • P wave: atrial depolarization.

  • QRS complex: ventricular depolarization.

  • T wave: ventricular repolarization.

Hemodynamic Concepts

• Cardiac Output:

  • Directly related to heart rate (beats/min) and stroke volume (volume/beat).

• Mean Arterial Pressure (MAP):

  • Influenced by cardiac output and total peripheral resistance.

• Regulation:

  • Sympathetic increases heart rate and contractility; parasympathetic decreases.

Pressure-Volume Loop Dynamics

• Ventricular Cycles:

  • Diastolic filling, isovolumetric contraction, ejection, isovolumetric relaxation.

• Effects of Preload and Afterload:

  • Increased preload enhances stroke volume via Frank-Starling mechanism.

  • Increased afterload may decrease stroke volume and increase left ventricular end-systolic volume.

Coronary Circulation

• Coronary Arteries:

  • Right and left coronary arteries branch off the aorta supplying oxygenated blood directly to the heart.

• Myocardial Oxygen Demand:

  • Increased by contractility, heart rate, and afterload.

Summary

• Understanding these components is crucial for comprehending cardiac physiology, hemodynamics, and potential pathologies efficiently.

Cardiovascular System Functions - Main Functions - Delivery of Oxygen - Provides oxygen to tissues to support aerobic metabolism through capillary networks. - Removal of Waste Products - Transports carbon dioxide from tissues to lungs for exhalation via venous return. - Transports metabolic waste, such as urea and creatinine, to kidneys for elimination. - Nutrient Transport - Delivers nutrients (e.g., glucose, amino acids, fatty acids) absorbed from the gastrointestinal tract to tissues for energy and growth. - Body Temperature Regulation - Achieved through vasoconstriction (reducing heat loss in cold by shunting blood away from the skin) and vasodilation (enhancing heat loss in heat by increasing blood flow to the skin surface). - Transport of Hormones and Neurotransmitters - Carries hormones from endocrine glands and neurotransmitters to target cells to regulate cellular function and maintain homeostasis. - Endocrine Role of the Heart - The heart secretes hormones such as natriuretic peptides (ANP and BNP), which help regulate blood pressure and fluid balance.### Heart Location and Membranes - Located in the Mediastinum - Posterior to the sternum, anterior to the vertebral column, between lungs in the thoracic cavity. - Views of the Heart - Anterior view highlights the right atrium, right ventricle, left atrium, and left ventricle. - Key vessels include ascending aorta, pulmonary trunk, superior & inferior vena cavae. - The apex, formed by the left ventricle, rests on the diaphragm, while the base is superior and posterior. - Pericardial Membranes - Visceral Pericardium (Epicardium): - Inner layer directly covering the heart's surface, part of the heart wall. - Parietal Pericardium: - Outer layer surrounding the heart, inside the fibrous pericardium, lining the pericardial cavity. - Pericardial Cavity: - Contains approximately $20 ext{ ml}$ of serous fluid, which acts as a lubricant to reduce friction during the heart's rhythmic contractions.### External Anatomy of the Heart - Right Atrium and Ventricles - Right atrium receives deoxygenated blood from superior/inferior vena cavae and the coronary sinus. - Right ventricle pumps deoxygenated blood through the pulmonary trunk to the lungs for oxygenation. - Left Atrium and Ventricle - Left atrium receives oxygenated blood from the pulmonary veins. - Left ventricle, the strongest chamber, ejects oxygenated blood through the aorta to the systemic circulation. - Coronary Arteries - Right Coronary Artery: - Emerges from the aorta and descends along the right ventricle, supplying the right atrium, most of the right ventricle, and parts of the interventricular septum and SA/AV nodes. - Left Main Coronary Artery: - Divides into two major branches: - Left Anterior Descending Artery (LAD): Often called the