? Cardiovascular Study Guide ? Anatomy & Physiology Basics Heart Location : In mediastinum, between lungs, rests on diaphragm. Function : Pumps blood to tissues to supply O? and nutrients. Pericardial Space : Contains ~20 mL fluid to reduce friction during systole. ? Cardiac Cycle Diastole = Relaxation phase ? Ventricular filling. Systole = Contraction phase ? Blood ejected from atria & ventricles. Cycle Events : Diastole ? Atrial systole ? Ventricular systole. Valves : AV valves: Tricuspid (right), Mitral/Bicuspid (left). Semilunar: Pulmonary & Aortic. ?? Heart Chambers & Circulation Right Heart : Deoxygenated blood ? lungs (pulmonary circulation). Left Heart : Oxygenated blood ? body (systemic circulation). ? Conduction System Component Function SA Node Primary pacemaker, 60–100 bpm AV Node Delays impulse, 40–60 bpm Bundle of His Conducts impulses to ventricles Purkinje Fibers Final conduction ? triggers ventricular contraction Electrical Cell Properties : Automaticity : Initiate impulse Excitability : Respond to impulse Conductivity : Transmit impulse ? Cardiac Output & Regulation Cardiac Output (CO) = Stroke Volume (SV) × Heart Rate (HR) Normal: 4–6 L/min Stroke Volume : 60–130 mL/beat Influenced by : Preload : Ventricular filling stretch (? = ? SV) Afterload : Resistance to ejection (? = ? SV) Contractility : Force of contraction ? Frank–Starling Law: The more the heart muscle is stretched (within limits), the stronger the contraction. ? Autonomic Control Nervous System Effect Pathway Sympathetic ? HR & contractility Beta-1 receptors, catecholamines Parasympathetic ? HR Vagus nerve Baroreceptors (in aortic arch/carotids): Sense BP changes and adjust HR accordingly. ? Ejection Fraction (EF) Normal EF : 55–65% Low EF (<40%) : Indicates heart failure (HF) ? Aging & Gender Differences Aging : Slower HR due to conduction system decline. Hypertrophy ? ? chamber volume & contractility. Stiff valves ? Murmurs. Women : Smaller heart & arteries ? harder cath /angioplasty. Estrogen = cardioprotective: ? HDL ? LDL Vasodilation CAD risk increases post-menopause. ? Arterial Disorders Arteriosclerosis : Thickening/hardening of arterial walls. Atherosclerosis : Plaque buildup (lipids, Ca²?, etc.) in intima. CRP : Marker for cardiovascular inflammation. PAD : Obstructions from aorta ? popliteal; more distal in diabetes/elderly. ? Diagnostics Hemodynamic Monitoring : Catheter-based measurement of pressures. Lymphoscintigraphy : Imaging lymph uptake with radiolabeled colloid.