Circulation- Deliver O2 and food, remove metabolic waste, complexity varies in different groups or organisms (limits organismal size)- Quiz: Hemostasis maintains blood volume- Quiz: Blood flow is slowest at what point in the circulatory system: capillaries- Homeostasis-circulatory system maintains volume, composition, and temp of extracellular fluids, also tied to lymphatic system- Respiratory pigmentso Hemoglobin (iron-what binds to oxygen)-vertebrates, in cellso Hemocyanin (copper)-molluscs, arthropods, dissolved in blood (dissolved in blood is helpful in areas of higher pressure b/c the temperature is cooler and blood flows slower, and being dissolved in blood allows for the Hemocyanin to bind to more oxygen and fit more of these molecules in blood since they take up less space)o Hemerythrin (iron)-sipuncilids, priapulids, brachiopods, in cells, Myohemirythrin found in marine invertebrate muscle cellso Chlorocruorin (iron)-annelids, dissolved in blood- Marine organisms with gastrovascular cavities have no specialized circulatory systemo Cnidarians (jellyfish, corals, sea anemones, hydrozoanso Flatworms (integumentary exchange-tapeworms, leeches)- Circulatory systemso Open system-heart contracts and blood pumped to spaces or cavities in body tissues (hemocyl) from the ostea and heart, after heart relaxesit causes a negative pressure gradient so the blood is pushed back through the hemocyl to the heart again (very slow)o Arthropods Blood=hemolymph=interstitial fluid Blood flow by heart pump and muscle contraction No blood pressure in hemocoel so blood flows slowly Pigment in hemocyanin Movement of tail can help create pressure gradients so blood flowso Decapod crustacean circulatory system: a case that is neither open norclosed (more closed than open) Blood pools in sinuses and then drains back into heart, but theyhave arteries, veins, and capillaries o Why don’t crabs bleed to death when they lose a limb? Blood contains amebocytes for phagocytosis and clotting- Explosive cells disintegrate, releasing substance that converts fibrinogen to fibrin causing clotting (thickening of blood)- Very fasto Platelets Membrane-bound cell fragments Derived from megakaryocytes which arise from stem cells Release substance that initiate blood clotting- Horseshoe crab blood protects public healtho Endotoxin-main bacterial toxino Primitive immune system causes blood clotting in response to bacteriao Is used by pharmaceutical companies to test for Rx to medications Indicates presence of bacteriao Blood in crab surrounds toxin and begins clotting, if this happens that means there’s an endotoxin in the medication and it cannot be used- Open circulatory system: molluscs (bivalves and snails)o Advantages: less susceptible to pressure, greater control over body temperatureo Disadvantages: less control over oxygen delivery, less efficient filtration of blood and lymph- The exception to the rule: cephalopods have closed circulatory systemo Systemic heart and two branchial heartso Blood pumped through both the systemic tissues and through gills Similar to mammalso Advantage: not relying on a single pump through one heart to pump blood, you have three hearts to pump through separately (swim very fast, need more oxygen=increase speed of pumping, more oxygen)- Closed circulatory system of annelidso Feather duster wormso 5 hearts encircle esophaguso Dorsal vessel-posterior flowo Ventral vessel-anterior flowo Oxygen exchange in Parapodia (main area of gas diffusion, deliver oxygen, remove CO2)o Same process, just added two more hearts- Quiz: what is the evolutionary link between the following aspects of marine organismal biology (body size, gas exchange, the gradient in circulatory systems from none to open to closed systems)o If body size is small you can diffuse across the surface for gas exchange, large body size means you have to have a really good, defined circulatory system in order to move things throughout the body- Comparison of circulatory systems in fish- Standard fish plan (heart to gills to systemic tissues, closed plan of ordinary fish)o 2 problems heart must push blood through entire circuit heart is oxygenated using “spent”-containing CO2 instead of oxygen, bloodo Variations Standard fish have gills and systemic tissues in series Others have gills and systemic tissues in parallel- O2 picked up in mouth, gut, or swim bladder- Originally considered poor adaptation (inefficient mixing)- Now considered potential adaption to provide oxygen tothe heart- ALL VERTEBRATES HAVE CLOSED CIRCULATORY SYSTEM- Reptiles are intermediate o Some have partial separation of ventricleso Others have complete separation as we saw in mammalso Some mixing of blood, only getting half of O2 you need- Circulatory systems in marine reptileso Temperature main problem for diving reptiles  Cold water strips heat from organism Max dive=5 hours- Mammal circulatory system (blood, vessels, heart)- Functions of mammal bloodo Transports oxygen and nutrients to the cello Carries CO2 and wastes away from cellso Helps stabilize internal pHo Carries infection-fighting cellso Helps equalize temperature (hemostasis and homeostasis in one system)- Components of mammal bloodo Plasma portion-liquid, water, proteins, ionso Cellular portion-white blood, red blood cells, platelets- Erythrocytes (red cells)o Most numerous cells in bloodo Transport oxygen and CO2o Colored red (in mammals) by oxygen-binding pigment (hemoglobin)o Form from stem cells in bone marrowo Have no nucleus when matureo Continually replaced (120 days)- Transition from artery to veinso Heart to arteries to arterioles to capillaries to venules to veins to hearto At the capillaries Blood flow slows down because of large ross-sectional area Diffusion zones between blood and interstitial fluid Large total area, so pressure very low Movement across wall by diffusion Need it to slow down b/c you need to exchange CO2 and O2 (for gas diffusion)- Diving Physiology of marine mammals- Duration of dives in diving mammalso Can be very longo Most relatively shorto Can be very deepo Most relatively shallow- Respiratory diving adaptations of whales to minimize the bendso Lungs and rib cage modified for collapse (b/c lack sternum, so are “free floating” anteriorly-no rigidity, can compress these) at 25-100 m depending on specieso Remaining air