Body size and shape to keep cells in contact with their enviroment Circulatory System moves fluid between each cell s surroundings and the environment Exchange gases Absorb nutrients Dispose of waste Figure 42 2 Circular canal Mouth Gastrovascular cavity Mouth Pharynx Radial canals 5 cm a The moon jelly Aurelia a cnidarian 2 mm b The planarian Dugesia a flatworm Circulatory fluid Interconnecting vessles Muscular pump Figure 42 3 a An open circulatory system b A closed circulatory system Heart Heart Interstitial fluid Hemolymph in sinuses surrounding organs Pores Blood Small branch vessels in each organ Dorsal Auxiliary vessel hearts main heart Tubular heart Ventral vessels Receives Blood Pumps blood In a house Atrium entry way to a house vents pump out air a Single circulation b Double circulation Pulmonary circuit Gill capillaries Lung capillaries Artery Heart A Atrium A A V Right Ventricle V V Left Vein Systemic capillaries Body capillaries Systemic circuit Key Oxygen rich blood Oxygen poor blood Amphibians Pulmocutaneous circuit Figure 42 4 Atrium A Right Lung capillaries Lung capillaries Right systemic aorta A V Right Left Pulmonary circuit Pulmonary circuit Lung and skin capillaries Atrium A Mammals and Birds Reptiles Except Birds A V Left Left systemic aorta Incomplete septum A V Right A V Left Ventricle V Systemic circuit Systemic circuit Key Oxygen rich blood Oxygen poor blood Systemic capillaries Systemic capillaries Systemic capillaries Figure 42 5 Systemic circuit 3 chambered heart no septum pulmocutaneous circuit skin and lung life cycle partially in H2O Figure 42 6 Superior vena cava Capillaries of head and forelimbs Pulmonary artery Capillaries of right lung Pulmonary vein Right atrium Right ventricle Inferior vena cava 4 chambered heart septum pulmonary circuit just lungs Pulmonary artery Aorta Capillaries of left lung Pulmonary vein Left atrium Left ventricle Aorta Capillaries of abdominal organs and hind limbs Gills Trachea Lungs Gills Figure 42 22 Coelom Gills Parapodium functions as gill a Marine worm Gills Tube foot b Crayfish c Sea star O2 poor blood Gill arch O2 rich blood Lamella Blood vessels Gill arch Operculum Water flow Blood flow Countercurrent exchange PO2 mm Hg in water 150 120 90 60 30 Gill filaments Net diffusion of O2 140 110 80 50 20 PO 2 mm Hg in blood Figure 42 23 Tracheoles Mitochondria Muscle fiber Figure 42 24 2 5 m Water flow Tracheae Air sacs Body cell Air sac Tracheole Trachea External opening Air Figure 42 25 Branch of pulmonary vein oxygen rich blood Terminal bronchiole Branch of pulmonary artery oxygen poor blood Nasal cavity Pharynx Left lung Larynx Esophagus Alveoli 50 m Trachea Right lung Capillaries Bronchus Bronchiole Diaphragm Heart Dense capillary bed enveloping alveoli SEM