Chapter 16_1 flashcards
(20 cards)
Heart: Location, Base, Apex
Located left of midline in the chest, within the mediastinum. Base: upper part where great vessels enter/leave. Apex: pointed end at the lower left.
Heart Wall Layers: Epicardium, Myocardium, Endocardium
Epicardium: Outer layer, covers heart and great vessels, forms part of pericardium. Myocardium: Heart’s muscular layer that contracts, controlled by ANS. Endocardium: Thin, three-layered membrane lining interior heart and covering valves.
Pericardium & Pericardial Cavity
Pericardium: Double-walled sac surrounding heart (visceral and parietal layers). Pericardial Cavity: Space between pericardial layers, contains 30-50 mL serous fluid for lubrication.
Coronary Circulation: Main Arteries & Branches
Two major: Right Coronary Artery (RCA) and Left Main Coronary Artery (LMCA), arise from aortic arch. LMCA branches to Left Anterior Descending (LAD) artery (supplies LV, common in MI) and Circumflex artery. RCA supplies RA, RV, and posterior heart.
Coronary Collateral Vessels: Stimulation
Exercise stimulates angiogenesis (construction of collateral vessels), providing extra circulatory routes to myocardium, which is cardioprotective.
Heart Chambers: Overview & Blood Flow
Four chambers: Right Atrium (receives deoxygenated blood from body via SVC/IVC), Right Ventricle (pumps deoxygenated blood to lungs via pulmonary artery), Left Atrium (receives oxygenated blood from lungs via pulmonary veins), Left Ventricle (pumps oxygenated blood to body via aorta).
Pulmonary Circulation vs. Systemic Circulation
Pulmonary: Low-pressure system; RV -> pulmonary artery -> lungs (O2 pickup) -> pulmonary veins -> LA. (Pulmonary artery carries deoxygenated blood, pulmonary vein carries oxygenated). Systemic: High-pressure system; LV -> aorta -> body tissues (O2 delivery) -> veins -> SVC/IVC -> RA.
Systole vs. Diastole & Stroke Volume (LVEF)
Systole: Period of ventricular contraction and blood ejection. Diastole: Period of ventricular relaxation and filling. Stroke Volume (SV) / Left Ventricular Ejection Fraction (LVEF): Volume of blood ejected from LV per contraction (healthy adult: 50-70%).
Cardiac Conduction System: Components & Pathway
SA node (pacemaker in RA) -> AV node (between atria/ventricles, delays impulse) -> Bundle of His (in septum) -> Right & Left Bundle Branches -> Purkinje fibers (in ventricular walls).
Cardiac Muscle Action Potential: 5 Phases
Phase 0 (Depolarization): Fast Na+ channels open, Na+ influx (-90mV to +20mV). Phase 1 (Partial Repolarization): Abrupt Na+ channel closure. Phase 2 (Plateau): Slow Na+-Ca++ channels open, Ca++ influx. Phase 3 (Rapid Repolarization): K+ channels open, K+ efflux. Phase 4 (Resting Potential): Na+/K+ pump restores ion balance.
Absolute Refractory Period (Cardiac Action Potential)
Period during phases 0, 1, 2, and part of phase 3 when cardiac cells cannot be re-stimulated to contract. Protects heart by ensuring alternating contraction/relaxation and preventing fatal arrhythmias.
Electrocardiogram (ECG): Definition & Basic Waves
Recording of the heart’s electrical activity. P wave: Atrial depolarization. QRS complex: Ventricular depolarization. T wave: Ventricular repolarization.
12-Lead ECG: Purpose
Provides 12 different views of the heart’s electrical forces from different positions on the body, aiding in diagnosing various cardiac conditions.
Ischemia: Definition
Deprivation of adequate blood flow and oxygen to a tissue or organ.
Acute Coronary Syndrome (ACS): Definition & Types
Ischemic disorders of the heart that occur suddenly and require immediate treatment. Includes: 1. Unstable Angina (UA) 2. Myocardial Infarction (MI).
Myocardial Infarction (MI): Definition
Prolonged ischemia leading to irreversible damage and death of myocardial cells (necrosis).
Angina Pectoris: Definition
Squeezing pain in the chest that occurs when there is a lack of blood flow to the myocardium (myocardial ischemia).
Key Terms: Depolarization vs. Repolarization
Depolarization: Electrical activation of myocardial cells due to influx of positive ions (Na+, Ca++), leading to contraction. Repolarization: Return of myocardial cells to their resting electrical state due to efflux of K+, preparing for next impulse.
Key Terms: Coronary Artery Disease (CAD)
Atherosclerosis of the coronary arteries, leading to narrowing and potential obstruction of blood flow to the myocardium.
Key Terms: Dysrhythmias (Arrhythmias)
Disorders of cardiac rhythm due to disruptions in the heart’s electrical signal generation or conduction.
