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CHAPTER 50 LECTURE SLIDES To run the animations you must be in Slideshow View. Use the buttons on the animation to play, pause, and turn audio/text on or off. Please note: once you have used any of the animation functions (such as Play or Pause), you must first click in the white background before you advance the next slide. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. The Circulatory System Chapter 50 Blood • Type of connective tissue composed – Fluid matrix called plasma – Formed elements • Functions of circulating blood 1. Transportation 2. Regulation 3. Protection 3 4 Blood plasma • 92% water • Contains the following solutes – Nutrients, wastes, and hormones – Ions – Proteins • Albumin, alpha (a) and beta (b) globulins • Fibrinogen – If removed, plasma is called serum 5 Formed elements • Red blood cells (erythrocytes) – About 5 million per microliter of blood – Hematocrit is the fraction of the total blood volume occupied by red blood cells – Mature mammalian erythrocytes lack nuclei – RBCs of vertebrates contain hemoglobin • Pigment that binds and transports oxygen 6 Formed elements • White blood cells (leukocytes) – Less than 1% of blood cells – Larger than erythrocytes and have nuclei – Can migrate out of capillaries into tissue fluid – Types • Granular leukocytes – Neutrophils, eosinophils, and basophils • Agranular leukocytes – Monocytes and lymphocytes 7 Formed elements • Platelets • Cell fragments that pinch off from larger cells in the bone marrow • Function in the formation of blood clots 8 Formed elements • • • • All develop from pluripotent stem cells Hematopoiesis is blood cell production Occurs in the bone marrow Produces 2 types of stem cells – Lymphoid stem cell Lymphocytes – Myeloid stem cell All other blood cells • Erythropoietin stimulates the production of erythrocytes (erythropoiesis) 9 10 Invertebrate Circulatory Systems • Sponges, Cnidarians, and nematodes lack a separate circulatory system • Sponges circulate water using many incurrent pores and one excurrent pore • Hydra circulate water through a gastrovascular cavity (also for digestion) • Nematodes are thin enough that the digestive tract can also be used as a circulatory system 11 Invertebrate Circulatory Systems • Nature of the circulatory system in multicellular invertebrates is directly related to the size, complexity, and lifestyle of the organism • No circulatory system – Sponges and most cnidarians utilize water from the environment as a circulatory fluid • Gastrovascular cavity – Nematodes • Use the fluids of the body cavity for circulation • Small or long and thin 12 Invertebrate Circulatory Systems • Larger animals require a separate circulatory system for nutrient and waste transport • Open circulatory system – No distinction between circulating and extracellular fluid – Fluid called hemolymph • Closed circulatory system – Distinct circulatory fluid enclosed in blood vessels and transported away from and back to the heart 13 14 Vertebrate Circulatory Systems • Fishes – Evolved a true chamber-pump heart – Four structures are arrayed one after the other to form two pumping chambers • First chamber – sinus venosus and atrium • Second chamber – ventricle and conus arteriosus – These contract in the order listed • Blood is pumped through the gills, and then to the rest of the body 15 Vertebrate Circulatory Systems 16 Vertebrate Circulatory Systems • Amphibians – Advent of lungs required a second pumping circuit, or double circulation – Pulmonary circulation moves blood between the heart and lungs – Systemic circulation moves blood between the heart and the rest of the body 17 Vertebrate Circulatory Systems • Amphibian heart – 3-chambered heart • 2 atria and 1 ventricle – Separation of the pulmonary and systemic circulations is incomplete – Amphibians living in water obtain additional oxygen by diffusion through their skin – Reptiles have a septum that partially subdivides the ventricle, thereby further reducing the mixing of blood in the heart 18 19 Vertebrate Circulatory Systems • Mammals, birds, and crocodilians – 4-chambered heart – 2 separate atria and 2 separate ventricles – Right atrium receives deoxygenated blood from the body and delivers it to the right ventricle, which pumps it to the lungs – Left atrium receives oxygenated blood from the lungs and delivers it to the left ventricle, which pumps it to rest of the body 20 21 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Lancelets Fish Amphibians Mammals Squamates Turtles Crocodilians Birds 4-chamber heart 4-chamber heart 3-chamber heart 2-chamber heart 22 The Cardiac Cycle • Heart has two pairs of valves – Atrioventricular (AV) valves • Maintain unidirectional blood flow between atria and ventricles • Tricuspid valve = On the right • Bicuspid, or mitral, valve = On the left – Semilunar valves • Ensure one-way flow out of the ventricles to the arterial systems • Pulmonary valve located at the exit of the right ventricle • Aortic valve located at the exit of the left ventricle 23 The Cardiac Cycle • Valves open and close as the heart goes through the cardiac cycle • Ventricles relaxed and filling (diastole) • Ventricles contracted and pumping (systole) • “Lub-dub” sounds heard with stethoscope – Lub – AV valves closing – Dub – closing of semilunar valves 24 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Pulmonary valve Aortic valve Right atrium Left atrium Left AV valves Right ventricle ventricle 2. “Lub”: The ventricles contract, the atrioventricular (AV) valves close, and pressure in the ventricles builds up until the aortic and pulmonary valves open. 1. The atria contract. 3. Blood is pumped out of ventricles and into the aorta and pulmonary artery. Diastole 4. “Dup”: The ventricles relax, the pressure in the ventricles falls at the end of systole, and since pressure is now greater in the aorta and pulmonary artery, the aortic and pulmonary valves slam shut. Systole 5. The ventricles fill with blood. Diastole Pressure (mm Hg) 125 130 mL 100 75 “Lub” 50 “Dup” 25 65 mL 0 0 0.1 0.2 0.3 0.4 0.5 0.6 Time (seconds) 0.7 0.8 0.9 1.0 25 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Pulmonary valve Aortic valve Right atrium Left atrium Left AV valves Right ventricle ventricle 2. “Lub”: The ventricles contract, the atrioventricular (AV) valves close, and pressure in the ventricles builds up until the aortic and pulmonary valves open. 1. The atria contract. 3. Blood is pumped out of ventricles and into the aorta and pulmonary artery. Diastole 4. “Dup”: The ventricles relax, the pressure in the ventricles falls at the end of systole, and since pressure is now greater in the aorta and pulmonary artery, the aortic and pulmonary valves slam shut. Systole 5. The ventricles fill with blood. Diastole pressure in left ventricle Pressure (mm Hg) 125 130 mL 100 75 “Lub” 50 “Dup” 25 65 mL 0 0 0.1 0.2 0.3 0.4 0.5 0.6 Time (seconds) 0.7 0.8 0.9 1.0 26 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Pulmonary valve Aortic valve Right atrium Left atrium Left AV valves Right ventricle ventricle 2. “Lub”: The ventricles contract, the atrioventricular (AV) valves close, and pressure in the ventricles builds up until the aortic and pulmonary valves open. 1. The atria contract. 3. Blood is pumped out of ventricles and into the aorta and pulmonary artery. Diastole 4. “Dup”: The ventricles relax, the pressure in the ventricles falls at the end of systole, and since pressure is now greater in the aorta and pulmonary artery, the aortic and pulmonary valves slam shut. Systole 5. The ventricles fill with blood. Diastole pressure in left ventricle Pressure (mm Hg) 125 130 mL 100 1. 75 “Lub” 50 “Dup” 25 65 mL 0 0 0.1 0.2 0.3 0.4 0.5 0.6 Time (seconds) 0.7 0.8 0.9 1.0 27 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Pulmonary valve Aortic valve Right atrium Left atrium Left AV valves Right ventricle ventricle 2. “Lub”: The ventricles contract, the atrioventricular (AV) valves close, and pressure in the ventricles builds up until the aortic and pulmonary valves open. 1. The atria contract. 3. Blood is pumped out of ventricles and into the aorta and pulmonary artery. Diastole 4. “Dup”: The ventricles relax, the pressure in the ventricles falls at the end of systole, and since pressure is now greater in the aorta and pulmonary artery, the aortic and pulmonary valves slam shut. Systole 5. The ventricles fill with blood. Diastole pressure in left ventricle Pressure (mm Hg) 125 130 mL 100 1. 2. 75 “Lub” 50 “Dup” 25 65 mL 0 0 0.1 0.2 0.3 0.4 0.5 0.6 Time (seconds) 0.7 0.8 0.9 1.0 28 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Pulmonary valve Aortic valve Right atrium Left atrium Left AV valves Right ventricle ventricle 2. “Lub”: The ventricles contract, the atrioventricular (AV) valves close, and pressure in the ventricles builds up until the aortic and pulmonary valves open. 1. The atria contract. 3. Blood is pumped out of ventricles and into the aorta and pulmonary artery. Diastole 4. “Dup”: The ventricles relax, the pressure in the ventricles falls at the end of systole, and since pressure is now greater in the aorta and pulmonary artery, the aortic and pulmonary valves slam shut. Systole 5. The ventricles fill with blood. Diastole pressure in left ventricle Pressure (mm Hg) 125 130 mL 100 1. 2. 75 3. “Lub” 50 “Dup” 25 65 mL 0 0 0.1 0.2 0.3 0.4 0.5 0.6 Time (seconds) 0.7 0.8 0.9 1.0 29 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Pulmonary valve Aortic valve Right atrium Left atrium Left AV valves Right ventricle ventricle 2. “Lub”: The ventricles contract, the atrioventricular (AV) valves close, and pressure in the ventricles builds up until the aortic and pulmonary valves open. 1. The atria contract. 3. Blood is pumped out of ventricles and into the aorta and pulmonary artery. Diastole 4. “Dup”: The ventricles relax, the pressure in the ventricles falls at the end of systole, and since pressure is now greater in the aorta and pulmonary artery, the aortic and pulmonary valves slam shut. Systole 5. The ventricles fill with blood. Diastole pressure in left ventricle Pressure (mm Hg) 125 130 mL 100 1. 2. 4. 75 3. “Lub” 50 “Dup” 25 65 mL 0 0 0.1 0.2 0.3 0.4 0.5 0.6 Time (seconds) 0.7 0.8 0.9 1.0 30 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Pulmonary valve Aortic valve Right atrium Left atrium Left AV valves Right ventricle ventricle 2. “Lub”: The ventricles contract, the atrioventricular (AV) valves close, and pressure in the ventricles builds up until the aortic and pulmonary valves open. 1. The atria contract. 3. Blood is pumped out of ventricles and into the aorta and pulmonary artery. Diastole 4. “Dup”: The ventricles relax, the pressure in the ventricles falls at the end of systole, and since pressure is now greater in the aorta and pulmonary artery, the aortic and pulmonary valves slam shut. Systole 5. The ventricles fill with blood. Diastole pressure in left ventricle Pressure (mm Hg) 125 130 mL 100 1. 2. 4. 75 5. 3. “Lub” 50 “Dup” 25 65 mL 0 0 0.1 0.2 0.3 0.4 0.5 0.6 Time (seconds) 0.7 0.8 0.9 1.0 31 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Pulmonary valve Aortic valve Right atrium Left atrium Left AV valves Right ventricle ventricle 2. “Lub”: The ventricles contract, the atrioventricular (AV) valves close, and pressure in the ventricles builds up until the aortic and pulmonary valves open. 1. The atria contract. 3. Blood is pumped out of ventricles and into the aorta and pulmonary artery. Diastole 4. “Dup”: The ventricles relax, the pressure in the ventricles falls at the end of systole, and since pressure is now greater in the aorta and pulmonary artery, the aortic and pulmonary valves slam shut. Systole 5. The ventricles fill with blood. Diastole pressure in left ventricle pressure in aorta Pressure (mm Hg) 125 130 mL 100 1. 2. 4. 75 5. 3. “Lub” 50 “Dup” 25 65 mL 0 0 0.1 0.2 0.3 0.4 0.5 0.6 Time (seconds) 0.7 0.8 0.9 1.0 32 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Pulmonary valve Aortic valve Right atrium Left atrium Left AV valves Right ventricle ventricle 2. “Lub”: The ventricles contract, the atrioventricular (AV) valves close, and pressure in the ventricles builds up until the aortic and pulmonary valves open. 1. The atria contract. 3. Blood is pumped out of ventricles and into the aorta and pulmonary artery. Diastole 4. “Dup”: The ventricles relax, the pressure in the ventricles falls at the end of systole, and since pressure is now greater in the aorta and pulmonary artery, the aortic and pulmonary valves slam shut. Systole 5. The ventricles fill with blood. Diastole pressure in left ventricle pressure in aorta Pressure (mm Hg) 125 130 mL 100 1. 2. 4. 75 volume in left ventricle 5. 3. “Lub” 50 “Dup” 25 65 mL 0 0 0.1 0.2 0.3 0.4 0.5 0.6 Time (seconds) 0.7 0.8 0.9 1.0 33 The Cardiac Cycle • Heart contains “self-excitable” autorhythmic fibers • Most important is the sinoatrial (SA) node – Located in wall of right atrium – Acts as pacemaker – Autonomic nervous system can modulate rate 34 The Cardiac Cycle • Each SA depolarization transmitted – To left atrium – To right atrium and atrioventricular (AV) node • AV node is only pathway for conduction to ventricles – Spreads through atrioventricular bundle – Purkinje fibers – Directly stimulate the myocardial cells of both ventricles to contract 35 The Cardiac Cycle • Electrical activity can be recorded on an electrocardiogram (ECG or EKG) – First peak (P) is produced by depolarization of atria (atrial systole) – Second, larger peak (QRS) is produced by ventricular depolarization (ventricular systole) – Last peak (T) is produced by repolarization of ventricles (ventricular diastole) 36 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Right atrium Left atrium SA node (pacemaker) Internodal pathway AV AV node Interventricular septum AV bundle AV bundle Purkinje fibers Purkinje fibers Left and right bundle branches 1. The impulse begins at the SA node and travels to the AV node. 2. The impulse is delayed at the AV node. It then travels to the AV bundle. R Millivotts +1 P wave T wave 0 Q S 1 sec -1 Seconds 37 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. AV bundle Interventricular septum Left and right bundle branches 3. From the AV bundle, the impulse travels down the interventricular septum. 4. The impulse spreads to branches from the interventricular septum. Purkinje fibers 5. Finally reaching the Purkinje fibers, the impulse is distributed throughout the ventricles. R Millivotts +1 P wave T wave 0 Q S 1 sec -1 Seconds 38 The Cardiac Cycle • Right and left pulmonary arteries deliver oxygen-depleted blood from the right ventricle to the right and left lungs • Pulmonary veins return oxygenated blood from the lungs to the left atrium of the heart 39 The Cardiac Cycle • Aorta and all its branches are systemic arteries, carrying oxygen-rich blood from the left ventricle to all parts of the body – Coronary arteries supply oxygenated blood to the heart muscle • Blood from the body drains into the right atrium – Superior vena cava drains upper body – Inferior vena cava drains lower body 40 The Cardiac Cycle • Arterial blood pressure can be measured with a sphygmomanometer • Systolic pressure is the peak pressure at which ventricles are contracting • Diastolic pressure is the minimum pressure between heartbeats at which the ventricles are relaxed • Blood pressure is written as a ratio of systolic over diastolic pressure 41 42 Characteristics of Blood Vessels • Blood leaves heart through the arteries • Arterioles are the finest, microscopic branches of the arterial tree • Blood from arterioles enters capillaries • Blood is collected into venules, which lead to larger vessels, veins • Veins carry blood back to heart 43 Characteristics of Blood Vessels • Arteries and veins are composed of four tissue layers – Endothelium, elastic fibers, smooth muscle, and connective tissue – Walls too thick for exchange of materials across the wall • Capillaries are composed of only a single layer of endothelial cells – Allow rapid exchange of gases and metabolites between blood and body cells 44 Characteristics of Blood Vessels 45 Characteristics of Blood Vessels • Arteries and arterioles – Larger arteries contain more elastic fibers in their walls than other blood vessels • Recoil each time they receive blood from the heart – Contraction of the smooth muscle layer of the arterioles results in vasoconstriction • Greatly increases resistance and decreases flow • Chronic vasoconstriction can result in hypertension – Relaxation of the smooth muscle layer results in vasodilation • Decreasing resistance and increasing blood flow to an organ 46 • Vasoconstriction and vasodilation are important means of regulating body heat in both ectotherms and endotherms 47 Characteristics of Blood Vessels • Capillaries – Every cell in the body is within 100 micrometers (μm) of a capillary – Although each capillary is very narrow, so many of them exist that the capillaries have the greatest total cross-sectional area of any other type of vessel • Slows blood flow to allow for exchange with extracellular fluid 48 Characteristics of Blood Vessels • Veins and venules – Thinner layer of smooth muscles than arteries – Venous pump helps return blood to heart • Skeletal muscle contractions and oneway venous valves 49 The Lymphatic System • Significant amount of water and solutes in the blood plasma filter through the walls of the capillaries to form the interstitial (tissue) fluid • Most fluid leaves at the arteriole end of the capillary and returns at the venule end • Fluid that does not return to capillaries is returned to circulation by the lymphatic system 50 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Arteriole Lymphatic capillary Capillary bed Venule Interstitial fluid a. Lymphatic capillary Excess interstitial fluid becomes lymph Interstitial fluid Blood flow Capillary Filtration Absorption Arteriole Venule Blood pressure Pressure Osmotic pressure Net absorption due to osmotic pressure Net filtration due to blood pressure Arteriole Venule Direction of blood flow b. 51 The Lymphatic System • Consists of lymphatic capillaries, lymphatic vessels, lymph nodes, and lymphatic organs (spleen and thymus) • Excess fluid in the tissues drains into blind-ended lymph capillaries • Lymph passes into progressively larger vessels with one-way valves • Eventually drains into subclavian veins 52 Cardiovascular Diseases • Leading cause of death in the United States • Atherosclerosis – Accumulation of fatty material within arteries – Impedes blood flow • Arteriosclerosis – Arterial hardening due to calcium deposition 53 Cardiovascular Diseases • Heart attacks (myocardial infarctions) – Main cause of cardiovascular deaths in U.S. – Insufficient supply of blood to heart • Angina pectoris (“chest pain”) – Warning sign that the blood supply to the heart is inadequate but is still sufficient to avoid myocardial cell death • Stroke – Interference with blood supply to the brain 54 Blood Flow and Blood Pressure • Autonomic nervous system modulates heart rhythm and force of contraction • Cardiac center of the medulla oblongata modulates heart rate – Norepinephrine, from sympathetic neurons, increases heart rate – Acetylcholine, from parasympathetic neurons, decreases heart rate 55 Blood Flow and Blood Pressure • Cardiac output is the volume of blood pumped by each ventricle per minute – Increases during exertion because of an increase in both heart rate and stroke volume • Arterial blood pressure (BP) depends on the cardiac output (CO) and the resistance (R) to blood flow in the vascular system • BP = CO x R 56 Blood Flow and Blood Pressure • Baroreceptor reflex – Negative feedback loop that responds to blood pressure changes – Baroreceptors detect changes in arterial blood pressure – If blood pressure decreases, the number of impulses to cardiac center is decreased • Ultimately resulting in blood pressure increase – If blood pressure increases, the number of impulses to cardiac center is increased • Ultimately resulting in blood pressure decrease 57 Blood Flow and Blood Pressure 58 Please note that due to differing operating systems, some animations will not appear until the presentation is viewed in Presentation Mode (Slide Show view). You may see blank slides in the “Normal” or “Slide Sorter” views. All animations will appear after viewing in Presentation Mode and playing each animation. Most animations will require the latest version of the Flash Player, which is available at http://get.adobe.com/flashplayer. 59 Blood Flow and Blood Pressure • Blood pressure increases with blood volume • Blood volume is regulated by four hormones – Antidiuretic hormone (ADH) – Aldosterone – Atrial natriuretic hormone – Nitric oxide (NO) 60