Transcript 2672aLec10
Biology 2672a: Comparative Animal Physiology Circulation Why have a circulatory system? Diffusion sucks! Moves oxygen and nutrients to cells Removes CO2 and waste products from cells How do I know it’s a circulatory system? Pump Fluid Vessels or spaces Primitive circulatory systems Open systems have all the characteristics of a circulatory system The vessels in open systems can be quite elaborate… Fig 24.24 Open Circulatory Systems Low pressure Relatively inefficient Can’t keep interstitial fluids and blood separate Don’t allow impressive athletic feats But what about insects? Insect flight muscle has the highest work output in living organisms Oxygen delivery (via the tracheal system) is decoupled from the fluid circulatory system Box 23.3 Closed Circulatory System From Heart To Heart Fig 24.11 Flow Rate through a system Flow rate Q = ΔP R P2 Equation 24.3 Difference in pressure between the entry and exit to the system Resistance in the system P1 ΔP=P1-P2 Flow Rate Flow Q = ΔP R rate can be determined by Pressure at the start of the system Pressure loss in the system Resistance in the system Pressure is proportional to both flow rate and resistance Resistance in a system length resistance R=8Lη 4 πr r L viscosity radius R = 8 L η Resistance 4 π r Longer systems have more resistance More viscosity = higher resistance Resistance is proportional to the 4th power of the radius of the tube A small change in tube diameter = a huge change in resistance A teleost heart Fig. 24.14b Fish circulatory system Head Body Gills Heart Fig. 24.14a What does this mean physiologically? 3 kPa Head Body Gills Heart Counter this with relatively large variation in heart size and performance 5 kPa Heart oxygen demand may be a limiting factor in teleosts Head Body Gills Heart High performance fish hearts Deoxygenated blood perfusing spongy myocardium is a limiting factor for fish Salmonids, Tuna, Sharks have a ‘hybrid heart’. Fig. 24.3c (Most) Fishes Breathing Air Plecostomus - Gut Electric Eel - Mouth Bowfin – Swim bladder Fig. 23.15 (Most) Fishes breathing air No change to heart design Air breathing organs usually in parallel with body tissues Direct mixing of oxygenated and deoxygenated blood Ensures adequate O2 for the heart(?) Frog heart Moyes & Schulte Fig. 9.15b Frog circulation Selective distribution of oxygenated and deoxygenated blood Moyes & Schulte Fig. 9.11c Cephalopod Molluscs Radiated 200 Mya Have a closed, divided circulatory system Fig. 24.20a Oxygenated blood in heart Oxygen delivery to octopus heart muscle Fig. 23.3d Octopus circulation Two branchial hearts, one systemic Gills are in series with the tissues Allows oxygenated blood to be pumped at higher rate through systemic tissues. Circulation in mammals and birds Fig. 24.10a An untwisted mammalian circulatory system Fig. 24.10b End of material for mid-term exam Reading for Thursday Regulation of Circulation Pp 611-641 (continued)