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Circulation and gas exchange Gases are dissolved in aqueous solutions

Circulation and gas exchange Gases are dissolved in aqueous solutions Transport systems deliver gases (and nutrients) to the cells Diffusion can occur only over short distances. Gastrovascular cavity Cnidarians have radial symmetry and a very thin body wall

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Circulation and gas exchange Gases are dissolved in aqueous solutions

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  1. Circulation and gas exchange Gases are dissolved in aqueous solutions Transport systems deliver gases (and nutrients) to the cells Diffusion can occur only over short distances

  2. Gastrovascular cavity Cnidarians have radial symmetry and a very thin body wall Gastrovascular cavity extends into all areas of the body Flatworms: single opening

  3. In more complex animals, too many cell layers tp allow diffusion through a body cavity Circulatory systems blood blood vessels heart Open and closed circulatory systems

  4. Earthworms, squids, Octopi, vertebrates Arthropods, most mollusks

  5. General features of cardiovascular system Heart with atria and ventricles Arteries, veins and capillaries Complexity of system determined by: metabolic rate type of breathing mechanism

  6. Fish- two-chambered heart Amphibians- three-chambered heart (one ventricle) Reptiles- ventricle is partially divided Crocodilians, birds, mammals- four-chambered heart separates oxygen-rich from oxygen-poor blood

  7. “trace a drop of blood…”

  8. Cardiac cycle Flow form atria to ventricles Controlled by valves Systole, diastole (contraction, relaxation) Cardiac output a function of heart rate stroke volume Can be adjusted to body needs

  9. Control of heart rhythmicity

  10. Features of arteries and veins Degree of musculatures Presence of valves Ability of expand Venous flow affected by skeletal muscles, breathing

  11. Factors affecting blood flow fact

  12. Circulatory system spreads out in network of arteries, arterioles and capillaries Overall surface area greatly increases Blood flow slows through capillaries

  13. Peripheral resistance- to blood being pumped from the heart Controlled by contraction and relaxation of smooth muscles; also by cardiac output Arterioles can dilate, and cardiac output can increase, in response to body’s needs In humans, parallel circuits through the body can direct blood where it is most needed

  14. Gravity is a factor for large terrestrial animals Blood must be pushed through blood vessels above the heart Blood pressure must be adjusted as position changes

  15. How does blood deliver substances to cells?

  16. Exocytosis Diffusion Osmotic pressure regulates fluid loss what is osmolarity? what is an osmotically active substance?

  17. What happens to that “lost” fluid? About 4L/day pass from the blood to the tissues Some returns to venules Some is returned via lymphatic system

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