Circulatory System

1. Circulatory System Transport systems in animals

2. Overview • Functions of a transport/circulatory system • Cellular transport • Invertebrate circulation • Gastrovascular cavity • Water vascular system • Open circulatory system • Closed circulatory system • Vertebrate circulation • Fishes • Amphibians • Reptiles • Birds • Mammals

3. Functions of the circulatory system • Transports materials • Nutrients from digested food • Respiratory gases: CO2 and O2 • Waste materials: toxins and nitrogenous wastes • Antibodies • Hormones • Enzymes • Immune functions • Maintains homeostasis • Blood pH • Heat transport

4. Transport at the cellular level • Cell membrane • Passive transport (diffusion, facilitated diffusion, osmosis) • high concentration of solutes to low concentration of solutes • no need to expend energy • Active transport • spending energy • moving materials from low concentration to high concentration of solutes • Transport of large molecules • endocytosis vesicles  exocytosis • Cyclosis (cytoplasmic streaming) • occurs in eukaryotes, e.g. Paramecium • facilitated by microfilaments • requires energy

5. Transport at the cellular level (con’t) • Endoplasmic reticulum • manufacturing and transport facility • proteins produced in rough ER are packaged in vesicles • Golgi apparatus • modification and storage facility • receiving end and shipping end • Vacuole • large membrane bound sacs • usually stores undigested nutrients

6. How are materials transported in multicellular organisms? Gastrovascular cavity in simple invertebrates • No system is required • Single opening: exchange of materials with the environment • Central cavity for digestion and distribution of substances throughout the body • Body walls are two cell layers thick  materials undergo diffusion • Cnidarians (e.g. Hydra) and flatworms (e.g. planarians)

7. How are materials transported in multicellular organisms? Water vascular system in echinoderms • multi-purpose: locomotion, food and waste transport, respiration • closed system of canals connecting tube feet • madreporite  ring canal  radial and lateral canal  tube feet  ampullae

8. How are materials transported in multicellular organisms? Open circulatory system • Phylum Arthropoda, Phylum Mollusca (with one exception) • hemolymph (colorless) • heart(s)  sinuses ostia heart(s) • diffusion from sinuses to organs • insects: well-developed respiratory systems, O2 not transported through the blood

9. How are materials transported in multicellular organisms? Closed circulatory system or cardiovascular system • cephalopods, annelids, vertebrates • presence of blood vessels • advantages • rapid flow • may direct blood to specific tissues • blood cells and large molecules remain within vessels • can support higher levels of metabolic activity

10. General plan of the cardiovascular system • Heart • Atrium • Ventricle • Blood vessels • Arteries • Arterioles • Capillaries and capillary beds • Venules • Veins • Blood

11. Different adaptations of the cardiovascular systems in vertebrates: fishes • Single-circulation • Fish heart • 2 chambered hearts • atrium and ventricle • vessel • African lungfish heart • 3-chambered • 2 atria • left side of atrium receives oxygenated blood (to tissues) • right side receives deoxygenated blood (to lung or gills) • spiral fold • partially divided ventricle

12. Different adaptations of the cardiovascular systems in vertebrates: amphibians • Pulmocutaneous and systemic circulation are partly separated • Amphibian heart • 1 ventricle pumps blood to lungs, skin, and tissues • 2 atria: • rt. atrium receives deoxygenated blood • lt. atrium receives oxygenated blood • advantage: oxygen-rich blood reaches the body’s organs faster • some mixing of O2-rich and poor blood occurs

13. Different adaptations of the cardiovascular systems in vertebrates: reptiles • Reptilian heart • 3-chambers (except for crocodilians with 4) • 2 atria • 1 ventricle (2 ventricles in crocodiles and alligators) • partially divided, decreases mixing • may stop sending blood to lungs when not breathing

14. Different adaptations of the cardiovascular systems in vertebrates: birds and mammals • 4 chambered heart: • 2 atria • 2 ventricles • full separation of pulmonary and systemic circuits • Advantages • no mixing of oxygenated and deoxygenated blood • gas exchange is maximized • separation allows for pulmonary and systemic circuits to operate at different pressures • Importance • Endothermic  high nutrient and O2 demands in tissues • Numerous vessels  great deal of resistance, so requires high pressure

15. Blood flow in mammals • R side of heart: • pulmonary circuit • L side of heart: • systemic circuit • one way valves: • atrioventricular valves • semilunar valves

16. Blood flow in mammals • right atrium receives O2-poor blood from superior and inferior venae cavae • from right atrium into the right ventricle through the tricuspid valve • pumped into the pulmonary artery through the pulmonary semilunar valve to lungs • O2-rich blood from lungs is returned to the left atrium via the pulmonary veins • enters the left ventricle via the mitral or bicuspid valve • exits the left ventricle into the aorta via the aortic semilunar valve • circulated to body tissues