gastrovascular cavity water vascular system open circulatory system closed circulatory system hemolymph sinuses ostia cardiovascular system heart blood vessels blood single circulation double circulation atrium ventricle oxygenated blood deoxygenated blood pulmocutaneous circulation pulmonary circulation
systemic circulation cardiac circulation blood pressure systole diastole cardiac output
stroke volume heart/pulse rate pulse heart sounds heart murmur Sinoatrial node (Pacemaker) Atrioventricular node Atrioventricular Bundle (Bundle of His) Bundle Branches EKG or ECG (electrocardiogram) P-wave QRS complex T-wave pre-capillary sphincter lymphatic system