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Animal Form and Function. Internal Transport (Circulatory system). Why do animals NEED an ITS?. Cells need a constant supply of nutrients and oxygen Cells produce waste to be removed Small organisms can use diffusion for these “tasks” but that is too inefficient for large organisms.
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Animal Form and Function Internal Transport (Circulatory system)
Why do animals NEED an ITS? • Cells need a constant supply of nutrients and oxygen • Cells produce waste to be removed • Small organisms can use diffusion for these “tasks” but that is too inefficient for large organisms.
Functions of an ITS • Supplies nutrients, oxygen, hormones to cells • Remove CO2 and other waste from cells • Maintain fluid balance, temperature and defend against infection
What are the main structures of an ITS? • Fluid – (ex: blood, haemolymph) liquid that contains nutrients and wastes and some dissolved gases. • Pump – Heart that circulates the blood. • Vessels – network of vessels that transports blood.
Types of ITS’s • Open circulatory system – -Mainly found in invertebrates (insects, crustaceans, molluscs) -Blood is free to float through tissues of body cavity -Blood pumped by tubular heart -Blood enters through ostia and pumped toward head through dorsal vessel. -Diagram
Types of ITS’s • Closed circulatory systems -Earthworms and vertebrates -Blood contained within vessels and pumped by a heart -Exchanges between blood and fluid around cells occurs by diffusion across capillaries. -Can be single or double circulation
Single circuit closed system • Fish and earthworms • Blood is returned to heart after every circulation • Diagram:
Double Circuit closed system • Mammals and other vertebrates • Deoxygenated blood pumped to lungs where it is oxygenated then returns to the heart where it is pumped again before returning to body to distribute oxygen/nutrients • Diagram
Efficiency of the systems • Closed – single: -Blood loses pressure at gills and flows at low pressure around the body (overcome by swimming) -One circuit • Closed – double: -High blood pressure maintained -Lungs circuit separated from body circuit
Pumps (Hearts) • Earthworms – 5 “pseudo” hearts with valves for one way flow • Insects – tubular heart running along dorsal surface, blood enters through ostia and pumped to head • Vertebrates – 2, 3, or 4 chambers. ATRIA collect blood and VENTRICLES pump blood
Vertebrate hearts con’t. • Fish – 2 chambered (one A one V) • Amphibians – 3 chambered (2 A one V). Not fully divided, some mixing occurs (overcome by absorption from skin) • Mammals/Birds – 4 chambered (2 A 2 V). Oxygenated and deoxygenated separated.
Pigment (all about O2) • Note: Haemolymph has NO pigment because no O2! • Haemoglobin – Found in closed systems. Oxygen binds to IRON. Red when oxygenated, blueish when not. • Haemocyanin – Found in open systems. Oxygen binds to COPPER. Blue when oxygenated, clear when not.
Structure of blood • Plasma – 90% water, 10% proteins/ions (for pH regulation and membrane permeability)/hormones/dissolved gases/nutrients/wastes • White blood cells and platelets – for defense and immunity (WBCs) and clotting (platelets) • Red blood cells – mainly to transport OXYGEN • Diagram
Vessels • Arteries - carry blood AWAY from the heart • Elastic and stretchy to withstand high pressure • Muscle layer to help push blood through • THICK outer layer • ARTERIOLES are small arteries that deliver blood to capillaries
Vessels • Veins • Return blood to heart (deoxygenated) • Same sort of structure as arteries, but less elastic tissue • Many have one way valves to prevent backflow • Blood is at low pressure (after passing though capillaries • VENULES are small veins that return blood from capillaries
Vessels • Capillaries -VERY SMALL vessels that connect artery and vein systems -allow efficient exchange of gases, nutrients and wastes between tissues -present in the form of “beds” -Fluid leaks out and returned to blood system – some picked up by lymphatic (gland) system.