Circulatory System Open circulatory system –Pump blood into an internal cavity called a hemocoel or sinuses Which bathe tissues with an oxygen and nutrient carrying fluid called hemolymph –Insects and mollusks Closed circulatory system –Blood in confined to vessels –Annelida, certain mollusks (octopus & squid), and vertebrates

Closed Circulatory System Blood vessels –Arteries –Arterioles –Capillaries –Venules –Veins (values prevent backflow) –Gas and nutrient exchange occurs by diffusion through capillary walls into interstitial fluids and into the surrounding cells. –Wastes and excess interstitial fluids move in the opposite direction as they diffuse into the capillaries

Heart Right atrium –Superior vena cava (systemic circulation) –Inferior vena cava (systemic circulation) Right ventricle –Pulmonary artery (pulmonary circulation) Left atrium –Pulmonary veins (pulmonary circulation) Left ventricle –Aorta (systemic circulation)

Cardiac cycle SA node (sinoatrial) or pacemaker AV node (atrioventricular) Bundle of His –Purkinje fibers Systole phase (ventricles contract) Diastole phase (ventricles relax)

Lymphatic system Picks up excess interstitial fluid and wastes Returns it to the circulatory system Values in lymph vessels prevent backflow Functions as a filter using lymph nodes –Acts as cleaning filters and as immune response centers that defend against infection

Blood Red blood cells or erythrocytes –Transports oxygen –Contains hemoglobin –Catalyzes the conversion of CO 2 and H 2 O to H 2 CO 3 –No nucleus White blood cells or leukocytes Platelets –Cell fragments that are involved in blood clotting –Converts fibrinogen to fibrin (forms clot) Plasma- liquid portion of the blood