AP Biology Presentation Chapter 42 Circulation and Gas Exchange By: Joe D’Ambrosia

42.1 Circulatory Systems Reflect Phylogeny Invertebrate Circulation Hydras & other cnidarians Have gastrovascular cavities, Serves both digestion and distribution of substances Open and Closed Circulatory Systems Overcome the limitations of diffusion 3 basic components – blood blood vessels heart Open system bathes organs directly in blood Closed system blood confined to vessels separate from interstitial fluid

42.1 Circulatory Systems Reflect Phylogeny Survey of Vertebrate Circulation Vertebrates Closed circulatory systems Called cardiovascular systems Fishes Gill circulation Systemic circulation Amphibians Pulmocutaneous circuit Systemic circuit Reptiles (minus birds) Pulmonary & systemic circuit Ventricle divided by a septum Mammals & Birds Heart divided into right and left chambers

Vertebrate Circulatory Systems Fish Circulation Amphibian Circulation Reptile Circulation Mammal Circulation Diagrams of Vertebrate Circulatory Systems

42.2 Double Circulation in Mammals depend on the heart Mammalian Circulation: the pathway Right ventricle pumps blood to lungs Blood picks up O2 and rids CO2, the O2 blood goes to left atrium Left ventricle pumps blood to body tissues through systemic circuits Blood leaves left ventricle via aorta to supply blood to heart, head arms, abdomen and legs O2 poor blood leaves upper body through anterior vein posterior vein drains blood from lower body Both veins dump blood in right atrium

42.2 cont.. The Mammalian Heart Cardiac Cycle – complete sequence Systole – contraction phase Diastole – relaxation phase Atrioventricular valve (AV) Between atrium and ventricle Keeps blood from flowing back into the atria Semilunar valves Located at heart exits; where aorta leaves left ventricle and pulmonary artery leaves right ventricle

42.2 cont.. HEART DIAGRAM Maintaining Heart’s Rhythmic Beat Sinoatrial (SA) node (aka pacemaker) sets rate and timing of cardiac muscles SA impulses ensure the atria empty completely before the ventricles contract Impulses produce electrical currents Conducted through bodily fluids Recorded as electrocardiogram SA node sets the tempo for the entire heart Influenced by nerves hormones & body temperature HEART DIAGRAM

42.3 Physical Principles Govern Blood Circulation Blood Vessel Structure & Function Circulatory system consists of network of blood vessels Outside layer of vessels are elastic Middle layer contains smooth muscle & elastic fibers Endothelium lines all blood vessels to minimize resistance of blood flow Blood Flow Velocity Blood travels like fluid through a pipe following the law of continuity Blood flow is faster in arteries than capillaries – why? blood travels through one artery faster than an entire cross-section of capillaries

42.3 Physical Principles Govern Blood Circulation Blood Pressure Force Hydrostatic pressure drives fluids thru pipes Pushes fluid from high to low pressure areas Blood pressure is greater in arteries than veins Ventricular systole Heart contracts Blood pressure is highest in the arteries Peripheral resistance Walls of arteries snap back during diastole Heart contracts before pressure of arteries is relieved

42.3 Physical Principles Govern Blood Circulation Capillary Function 5-10% of body’s capillaries have blood flowing through them at one time Each tissue has many capillaries so blood is supplied at all times Two mechanisms to regulate capillary bed blood distribution Contraction of the smooth muscle layer decreases blood flow to capillary bed Precapillary sphincters control the flow of blood between arterioles and venules

Fluid Return by Lymphatic System Lymphatic system – system that returns lost fluid and proteins to the blood Fluid inside the lymphatic system is called lymph (composition same as interstitial fluid) Lymph nodes along lymph vessel and filter the lymph and attack viruses & bacteria Lymphatic system helps defend against infection & maintains volume & protein concentration of blood

42.4 Blood is Connective Tissue with Cells Suspended in Plasma Blood Composition and Function Plasma – cells suspended in a liquid matrix About 90% water, rest are solutes Blood electrolytes maintain osmotic balance Plasma proteins – buffers for pH changes, maintain osmotic balance, contribute to bloods thickness Also contains nutrients, metabolic wastes, respiratory gases, and hormones

42.4 Blood is Connective Tissue with Cells Suspended in Plasma Cellular Elements Red blood cells transport O2 White blood cells defense Platelets involved in clotting process Red blood cells = most numerous Hemoglobin – iron-containing protein transports O2 5 major white blood cells: Monocytes Neutrophils Basophils Eosinophils Lymphocytes Platelets = fragments of large cells in bone marrow & contribute to process of blood clotting

42.4 Blood is Connective Tissue with Cells Suspended in Plasma Stem Cells and Replacement of Cellular Elements Stem cells Located in red marrow of bones Develop red and white blood cells and platelets Erythropoietin Hormone from the kidney that simulates the production of erythrocytes if tissues not receiving enough O2 Blood Clotting Fibrinogen = sealant in its inactive form Fibrin Assembles into threads that help form the clot Active form Platelets release factors that transforms fibrinogen to fibrin

42.4 Blood is Connective Tissue with Cells Suspended in Plasma Cardiovascular Disease Disorders of the heart and blood vessels develop genetically or non-genetically Bad cholesterol (low-density lipoproteins) can clog the arteries, Good cholesterol (high-density lipoproteins) Help reduce bad cholesterol Heart attack Death of cardiac muscle tissue due to blockage of arteries Stroke Death of nervous tissue in the brain from blockage of arteries in the head

42.5 Gas Exchange across Respiratory Surfaces Uptake of O2 from environment Discharge of CO2 to environment Respiratory medium The source of O2 Air for land animals Water for aquatic animals Respiratory surface Part of an animals body where gases are exchanged with the surrounding environment

42.5 Gas Exchange across Respiratory Surfaces Gills in Aquatic Animals Outfoldings of the body surface that are suspended in the water Ventilation increases the flow of the respiratory medium over the respiratory surface Tracheal Systems in Insects Made up of air tubes that branch throughout the body The tracheae open outside and fine branches exchange gas to nearly every cell Lungs Restricted to one location, connected to body by circulatory system Size & complexity are correlated with animal’s metabolic rate

42.6 Breathing Ventilates the Lungs Alternate inhalation and exhalation of air How an Amphibian breathes Ventilate lungs by using positive pressure breathing How a Mammal breathes Ventilate lungs by using negative pressure breathing How a Bird breathes Birds have both lungs & air sacs Birds have Para bronchi instead of alveoli, allows air to flow in one direction and renews it Control of Breathing in Humans Breathing control centers located in brain, the medulla oblongata and the pons Aided by the pons, the medulla sets basic breathing rhythm

42.7 Respiratory Pigments Bind/Transport Gases The Role of Partial Pressure Gradients Gases diffuse down pressure gradients in the lungs & other organs Gas always diffuses from high partial pressure region to lower on Respiratory Pigments Respiratory pigments – certain proteins that circulate in the blood bind to O2 THANK YOU - ANY QUESTIONS??