B6A7Circulate - Circulatory Systems Circulatory Systems...

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: Circulatory Systems Circulatory Systems Circulatory Systems Functions: • Transporatation – Water & electrolytes (salts) – Dissolved gases— O2 & CO2 – Nutrients – Wastes – Chemical messengers (hormones) – Defense (immune) systems – Repair (clotting) factors • Thermoregulation • Hydraulics Circulatory Systems • Ciliated Body Cavity • Open Circulatory System • Closed Circulatory System Cardiovascular System Lymphatic System Size & System Development • Diffusion is sufficient for small organisms w/ low volumes & metabolic demands (e.g. protozoans and micrometazoans). Hemocoel Ciliated Body Cavity Heyer Cnidarians & Platyhelmintheans • gastrovascular system – ciliated digestive cavity w/ branching extensions. Circulatory Systems Echinoderms • water vascular system – ciliated coelom w/ extensions (dermal branchae & tube feet) for respiration. – Important hydraulic functions Vascular System Components • Four components are –1) circulatory fluids –2) vessels –3) pump –4) valves • Vasculature (vessels) may form open or closed circulatory system Open Circulatory Systems Open Circulatory Systems • In arthropods, onychophorans, & most molluscs. • 4-part system - what are those parts? • circulatory fluids mix w/ interstial fluids of body cavity. • Hence, “blood” is called hemolymph. • Dorsal heart pumps hemolymph out vessels into body cavity (= hemocoel) • Hemocoel partially compartmentalized into sinuses • Hemolymph returns to heart via ostia or veins. Open Circulatory Systems Dorsal Vessel as Pump • Whole dorsal vessel may act as a tubular heart – Insects & Onycophorans • Specific region specialized into a heart – Crustaceans & Molluscs Heyer Limitations of Open Systems • Difficult to regulate different perfusion of different tissues. • Great for small body plans; not so great for big bodies with variable metabolic activities. • How can it be improved? Circulatory Systems Closed Circulatory Systems • Complete circuit between heart, arteries & veins with capillaries. • Better circulation + better regional control fi higher activity levels. • Problem: if circulatory fluid is confined to vessels, how does exchange occur??? Closed Circulatory Systems in Vertebrates Pre-pump Main pump Closed Circulatory Systems • Cephalopod molluscs have 3 hearts — one to each gill and one for the body. • Annelid worms use dorsal vessel plus anterior lateral branches as heart. Closed Circulatory Systems in Vertebrates • Heart is from ventral vessel, not dorsal vessel. • Fish – 2-chambered heart – Single circuit : blood flows from heart to gills, and then to systemic vessels – Blood pressure drops when flowing through the gill capillary beds. – Muscle contraction during swimming accelerates blood flow in the vessels. [Efferent] [Afferent] • Cardiovascular system Closed Circulatory Systems in Vertebrates Closed Circulatory Systems in Vertebrates • Amphibians & (Most) Reptiles • Amphibians & (Most) Reptiles – 3-chambered heart • 2 atria/1 ventricle – Double circuit : • 1a. (amphibians) Pulmocutaneous circuit: blood flows from heart to lungs & skin • 1b. (reptiles) Pulmonary circuit: blood flows from heart to lungs only • 2. Systemic circuit: repressurized blood flows from heart to systemic vessels – ~10% mixing of deoxygenated + oxygenated blood in single ventricle Heyer – 3-chambered heart • 2 atria/1 ventricle – Double circuit : • Pulmocutaneous circuit: blood flows from heart to lungs & skin • Cutaneous exchange may include skin, throat, and/or gills (in larvae & neotenes ) • Pulmonary flow may be diverted to cutaneous while underwater Circulatory Systems Closed Circulatory Systems in Vertebrates Closed Circulatory Systems in Vertebrates • Crocodilians, Birds & Mammals • Crocodilians – 4-chambered heart – 4-chambered heart • 2 atria/2 ventricles • 2 atria/2 ventricles – Double circuit : – Double circuit : • 1. Pulmonary circuit: blood flows from heart to lungs only • 2. Systemic circuit: repressurized blood flows from heart to systemic vessels – No mixing of deoxygenated + oxygenated blood – Pulmonary & systemic circuits are pressurized differently – >10x more efficient systemic oxygenation • 1. Pulmonary circuit: blood flows from heart to lungs only • 2. Systemic circuit: repressurized blood flows from heart to systemic vessels – Shunt to divert pulmonary to systemic flow when underwater Review of Designs Mammalian Cardiovascular System • Two circuits, each with its own 2-chamber pump – Different pressure – Same flow rate Mammalian Cardiovascular System Mammalian Cardiovascular System • Pulmonary circuit: • Systemic circuit: • Right pump ÆlungsÆleft pump • Left pump Æbody Æright pump q Deoxygenated systemic blood fills right A&V q Right A&V contract pushing deoxygenated blood through pulmonary artery to lungs q q Release CO 2 Take up O 2 q Oxygenated blood from lungs flows through pulmonary veins to left atrium Heyer q Oxygenated pulmonary blood fills left A&V q Left A&V contract pushing oxygenated blood through aorta to branching major arteries to all other body organs q q Release O 2 Take up CO 2 q Deoxygenated blood from body tissues flows through branches of veins converging on vena cava to right atrium Circulatory Systems Human Heart Anatomy The Pump • For any pump to function, it needs two components: 1. Constriction (stroke) chamber Øchamber volume fi ↑pressure fi move fluid • Diagrams show heart from front – Viewer’s “right” is heart’s “left” • Enclosed in fluidfilled sac behind sternum 2. Valves fi direct fluid flow direction Human heart in chest cavity The Vessels Cardiac Contractions • • • • • 1. Sinus node (pacemaker) fires 2. Signal spreads across atria 3. Cardiac muscle in atria contract 4. Signal reaches AV node; travels down Bundle of HIS to apex of heart 5. Signal spreads across venticles 6. Cardiac muscle in venticles contract Vessel Structure & Function • Arteries: blood away from heart Artery Vein – Thick-walled and elastic to withstand higher pressure • Capillaries: thin-walled and highly branched – Only vessels exchanging with tissue fluids! – Walls only 1 cell thick to maximize diffusion rates – Not permeable to blood cells & proteins; permeable to water and other solutes Heyer Valve 100 µm Basal lamina Endothelium Endothelium Smooth muscle Connective tissue Smooth muscle Capillary Connective tissue Artery Vein Arteriole Red blood cell Venule 15 µm – Thin, compliant walls – Internal valves prevent backflow SEM Capillary LM • – Smooth muscle in arteriole walls regulate selective blood flow Veins: blood toward heart Fig. 42.10 Arteries – carry blood away from the heart Arterioles – smaller branches of arteries Capillaries – thin, microscopic, with porous walls Venules – smaller branches that converge into veins Veins – carry blood back to heart Circulatory Systems Circulatory Changes During Exercise Capillary beds — the sites for exchange • In addition to regulation by vasodilation/vasoconstriction of arterioles, localized perfusion regulated by precapillary sphincters • Only 5 –10% of capillaries open at a given time Selective flow regulated by dilating & constricting specific arterioles Capillary beds — the sites for exchange • In addition to regulation by vasodilation/vasoconstriction of arterioles, localized perfusion regulated by precapillary sphincters • Only 5 –10% of capillaries open at a given time Capillary beds — the sites for exchange Capillary filtration • • • Capillary beds — the sites for exchange INTERSTITIAL FLUID Capillary • Blood pressure (P B) pushes fluid out Net fluid movement out Net fluid movement in • Osmotic pressure (POsm ) pulls fluid in • At venule end of capillary: ( POsm ) > (PB) Direction of blood flow Blood pressure Pressure • At arteriole end of capillary: (P B) > (P Osm ) Inward flow Outward flow Osmotic pressure Arterial end of capillary Heyer Capillary exchange • Fluids not returned to capillaries goes to lymphatics Body tissue Capillary filtration Walls only 1 cell thick to maximize diffusion rates Not permeable to blood cells & proteins Permeable to water and other solutes Venous end – 85-90% fluid returned to blood circulation – 10-15% taken up by lymphatic capillaries Circulatory Systems Lymph node Lymphatic System Fluid Flow in Veins — both Cardiovascular & Lymphatic Systems • Fluids pumped by “skeletal muscle pumps” • Valves prevent backflow • Recaptures lost fluids & proteins • Interstitial fluids filtered through lymphoid tissues and monitored by immune system • Fluids return to CV system in vena cava Blood: Liquid Tissue Cells Suspended in Plasma Blood Structure and Function “Formed Elements” — cells and cell-derivatives Since erythrocytes and thrombocytes lose their nuclei, they are no longer truly cells. • Erythrocytes (red blood cells) – Carry oxygen • Leukocytes (white blood cells) – Defense/clean up • Thrombocytes (platelets) – Blood clotting Plasma • 90% H2O • 7–9% protein The composition of blood Clotting Plateletes Clotting Factors Prothrombin Thrombin Fibrinogen Fibrin • Leukemia victims lack platelets • Hemophiliacs lack clotting factors. Heyer Human blood smear ...
View Full Document

This note was uploaded on 09/02/2011 for the course BIOL 6a taught by Professor Staff during the Fall '10 term at DeAnza College.

Ask a homework question - tutors are online