Heart

I. Overview

• Blood Transport:

  • Materials entering, between, and leaving the body.

II. Vessels

• Arteries: Carry blood away from the heart.

• Capillaries: Site of exchange.

• Veins: Carry blood toward the heart.

III. The Heart

• Double Pump:

  • Right side: pumps deoxygenated blood to lungs (pulmonary circuit).

  • Left side: pumps oxygenated blood to body (systemic circuit).

IV. Location

• Mediastinum:

  • Medial to lungs, dorsal to sternum, resting on diaphragm.

V. Heart Structure

• Pericardium:

  • Fibrous and serous pericardium (parietal, cavity, visceral).

• Heart Wall:

  • Epicardium, myocardium, endocardium.

VI. Internal Heart Anatomy

• Right Atrium: Receives blood from venae cavae.

• Right Ventricle: Pumps blood to lungs.

• Left Atrium: Receives oxygenated blood from pulmonary veins.

• Left Ventricle: Pumps blood to body.

• Valves:

  • Atrioventricular (tricuspid and mitral) and semilunar valves (pulmonary and aortic).

VII. Blood Flow Through the Heart

• Oxygen-poor blood returns via vena cavae.

• Oxygen-rich blood returns via pulmonary veins.

VIII. Coronary Circulation

• Coronary Arteries: Right and left coronary arteries, circumflex, anterior interventricular.

• Coronary Veins: Great cardiac vein, posterior cardiac vein, middle cardiac vein, coronary sinus.

IX. Heart Muscle Contraction

• Myogenic:

  • Autorhythmic myocardium (pace-maker functions).

• Contractile Myocardium:

  • Connected by intercalated discs for synchronized contraction.

X. Electrical Conduction in the Heart

• SA Node: Initiates action potentials leading to atrial contraction.

• AV Node: Delays impulse to ventricles; leads to ventricular contraction.

• ECG Waves:

  • P wave (atrial depolarization), QRS complex (ventricular depolarization), T wave (ventricular repolarization).

XI. The Cardiac Cycle

• Systole: Contraction phase (both atria and ventricles).

• Diastole: Relaxation phase (blood fills ventricles).

• Heart Sounds: "Lub" from AV valve closure, "Dub" from semilunar valve closure.

XII. Stroke Volume & Cardiac Output

• Stroke Volume: Blood pumped by one ventricle per contraction.

• Cardiac Output: Blood pumped per ventricle in a given time period.

XIII. Heart Rate Modulation

• Chemical Influences: Hormones (epinephrine, thyroxine) and ions.

• Parasympathetic Stimulation: Decreases heart rate via acetylcholine.

• Sympathetic Stimulation: Increases heart rate via catecholamines.

XIV. Cardiac Muscle Tissue

• Involuntary, striated, branched, with intercalated discs.

XV. Disorders of the Heart

• Coronary Artery Disease: Atherosclerosis, myocardial infarctions, symptoms like angina.

• Heart Failure: Congestive heart failure and pulmonary arterial hypertension.

• Conduction Disorders: Atrial and ventricular fibrillation.