Transport in animals Why we need a transport system? 3 week old larval anchovy How big can you be and still meet O2 demand of tissue simply by diffusion? The larval anchovy (average body radius = 0.6 mm) can meet all of its metabolic demand by uptake of O2 by diffusion. The respiratory and circulatory systems will take over to supply O2 to the tissues. Any animal larger than 1 mm cannot rely on diffusion alone. Gases diffuse far more readily through gas than aqueous solutions Radius (distance to the geometric body center) increases proportionally to body size. Again, any animal with a body (made of water) radius > 1 mm cannot obtain (or release) gases simply by diffusion, so you need a circulatory system and a medium in that system, i.e. blood. Length = 2 Radius = 0.5 Length = 4 Radius = 1 Why have blood? Transport of nutrients from digestive tract to tissues, to and from storage organs Transport of metabolites (e.g., lactic acid from muscle to liver) Transport of excretory products from tissues to excretory organs Transport of gases respiratory organs to/from tissues Transport of hormones Transport of cells including cells of nonrespiratory function (e.g., leukocytes in verts, numerous cell types in inverts) Transport of heat Transmission of force e.g., locomotion (earthworms, spiders), erection of penis Coagulation Open vs Closed Circulation Closed circulatory system: is found in all vertebrates and some inverts (e.g., cephalopods). Blood remains in vessels; capillaries allow close contact between blood and tissues Arterial system: high pressure, takes blood away from heart Low volume (5-10% of body mass) “Open” circulatory system: is characteristic of many inverts. Blood (hemolymph) empties into hemocoel and bathes tissues and organs directly Low pressure, high volume (up to 40% of body mass) Animal typically has hard shell or exoskeleton. Insects have an open circulatory system, but do not use it for oxygen transport. Mass flow transport Needed for a constant supply of: Oxygen Nutrients Also needed to get rid of waste products such as: Carbon 3 Major Parts of the Circulatory system Blood Vessels - routes blood travels Heart – pumps or pushes blood through Blood – carries important “ *stuff ” through body body head, neck superior vena cava and arms lungs pulmonary artery aorta right inferior vena cava hepatic vein pulmonary vein atrium right ventricle left atrium left ventricle hepatic artery liver hepatic portal vein mesenteric artery gut renal vein kidneys body and legs renal artery The Heart The heart is mainly made of cardiac muscle, each muscle cell is joined to the next by an intercalary disc. These cells are ‘myogenic’, this means they can contract and relax of their own accord throughout a human life superior vena cava aorta right pulmonary artery left pulmonary artery pulmonary veins pulmonary veins right atrium left atrium bicuspid valve left ventricle tricuspid valve right ventricle septum inferior vena cava semi-lunar valves Your Blood is made of Plasma Plasma- water, ions, proteins Plasma proteins albumin- provides osmotic pressure globulinsalpha and beta- transport gamma- antibodies (produced by lymphocytes; other proteins by liver) fibrinogen- clotting Plasma volume regulated by hormones like ADH Formed Cells Erythrocytes- (red blood cells) no nuclei or mitochondria circulate for about 120 days 280 million hemoglobin molecules per cell Leukocytes (white blood cells) granular and agranular granular: neutrophils, eosinophils, basophils agranular: lymphocytes, monocytes capable of amoeboid movement Platelets- involved in clotting The Cardiac Cycle ATRIAL SYSTOLE - Heart END OF PRESENTATION!