Circulation and Gas Exchange

The Respiratory System GETS oxygen for the body GETS RID of carbon dioxide Characteristics/Requirements of ALL Gas Exchange Mechanisms: MOIST membranes Close spacing of gas and blood for easy diffusion High surface area-to-volume ratio An animal’s respiratory surfaces must be large enough to provide oxygen and expel carbon dioxide for the entire body

Countercurrent Exchange- blood & water flow in opposite directions

Tracheae The respiratory system used by insects Tracheae are air tubes that branch throughout the insect body The finest branches of the tracheae extend to the surface of nearly every cell, where gas is exchanged by diffusion

Human Respiratory System

Open vs. Closed Circulatory Systems In open circulatory systems, hemolymph bathes the internal organs directly Insects, arthropods, mollusks In closed circulatory systems, blood is confined to vessels Blood exchanges materials with the ISF bathing the cells Earthworms, squids, octopuses, vertebrates

Open vs. Closed Circulatory Systems

REPTILES (EXCEPT BIRDS) Pulmocutaneous circuit FISHES AMPHIBIANS REPTILES (EXCEPT BIRDS) MAMMALS AND BIRDS Systemic capillaries Lung capillaries Lung and skin capillaries Gill capillaries Right Left Systemic circuit Pulmocutaneous circuit Pulmonary circuit Systemic circulation Vein Atrium (A) Heart: ventricle (V) Artery Gill circulation A V Systemic aorta Right systemic aorta Figure 42.4 Vertebrate circulatory systems

Double Pump Right side pumps to the lungs and back to left atrium (PULMONARY CIRCUIT) Left side pumps to the entire body and returns blood to right atrium (SYSTEMIC CIRCUIT) Oxygenated & deoxygenated blood never mix!

The mammalian cardiovascular system Pulmonary vein Right atrium Right ventricle Posterior vena cava Capillaries of abdominal organs and hind limbs Aorta Left ventricle Left atrium artery Capillaries of left lung head and forelimbs Anterior of right lung Figure 42.5 1 10 11 5 4 6 2 9 3 7 8