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Chapter 36 Circulation Sections 1-7 Albia Dugger • Miami Dade College 36.1 A Shocking Save • Each heartbeat starts with an electrical signal; in sudden cardiac arrest, a defibrillator is needed to restart the heart • An inborn heart defect causes most cardiac arrests in people under age 36; in older people, heart disease usually causes the heart to stop functioning • High school student Matt Nader experienced sudden cardiac arrest during a football game – his life was saved by CPR and an automated external defibrillator (AED) Surviving Sudden Cardiac Arrest 36.2 The Nature of Blood Circulation • A circulatory system distributes materials throughout the vertebrate body (and some invertebrates) • It includes one or more hearts (muscular pumps) that propel fluid through vessels extending through the body Open and Closed Circulatory Systems • Open circulatory system (arthropods, mollusks) • A heart pumps hemolymph into open-ended vessels • Hemolymph leaves the vessels and mixes with interstitial fluid • Closed circulatory system (annelids, vertebrates) • A heart pumps blood through a continuous series of vessels • Materials diffuse across the walls of the smallest-diameter blood vessels aorta pump heart spaces or cavities in body tissues dorsal blood vessel pump large-diameter blood vessels (rapid flow) large-diameter blood vessels (rapid flow) gut cavity capillary bed (many small vessels that serve as a diffusion zone) ventral blood vessels two of five hearts Figure 36-2a p628 ANIMATED FIGURE: Types of circulatory systems To play movie you must be in Slide Show Mode PC Users: Please wait for content to load, then click to play Mac Users: CLICK HERE ANIMATED FIGURE: Circulatory systems To play movie you must be in Slide Show Mode PC Users: Please wait for content to load, then click to play Mac Users: CLICK HERE Evolution of Vertebrate Circulation • Fishes • Heart with two chambers • Single circuit of circulation • Amphibians • Heart with three chambers • Two partially separated circuits • Birds and mammals • Heart with four chambers • Two fully separate circuits gill capillaries heart: ventricle atrium capillaries of body Figure 36-3a p629 Systemic Circuit Pulmonary Circuit lungs left atrium right atrium ventricle rest of body Figure 36-3b p629 Systemic Circuit Pulmonary Circuit lungs left atrium right atrium right ventricle left ventricle rest of body Figure 36-3c p629 ANIMATED FIGURE: Major human blood vessels To play movie you must be in Slide Show Mode PC Users: Please wait for content to load, then click to play Mac Users: CLICK HERE ANIMATED FIGURE: Human blood circulation To play movie you must be in Slide Show Mode PC Users: Please wait for content to load, then click to play Mac Users: CLICK HERE Circulation in Birds and Mammals • The four-chambered heart has two separate halves, each with an atrium and a ventricle • Each half pumps blood in a separate circuit • Pulmonary circuit: Blood flows from right half of heart, to lungs (gains oxygen), to left half of heart • Systemic circuit: Blood flows from left half of heart, to body (loses oxygen), to right half of heart Take-Home Message: How do animals distribute substances to body cells? • Most animals have a circulatory system that speeds the distribution of substances through the body. • Some invertebrates have an open circulatory system, other invertebrates and all vertebrates have a closed circulatory system, in which blood always remains enclosed within the heart or blood vessels. Take-Home Message: (cont.) • Fish have a one-circuit circulatory system. All other vertebrates have a short pulmonary circuit that carries blood to and from the lungs, and a longer systemic circuit that moves blood to and from the body’s other tissues. • A four-chambered heart evolved independently in birds and mammals. Such a heart allows strong contraction of one ventricle to speed blood through the systemic circuit, while a weaker contraction of the other ventricle 36.3 Human Cardiovascular System • The term “cardiovascular” comes from the Greek kardia (for heart) and Latin vasculum (vessel) • Each circuit includes a network of blood vessels that carries blood from the heart to small vessels where exchanges occur and then back to the heart Blood Vessels • The ventricles force blood through a series of vessels: • Arteries carry blood from ventricles to arterioles • Arterioles control blood distribution to capillaries • Capillaries exchange substances • Venules collect blood from capillaries • Veins deliver blood back to heart Jugular Veins Carotid Arteries Ascending Aorta Superior Vena Cava Pulmonary Arteries Pulmonary Veins Coronary Arteries Hepatic Veins Brachial Arteries Renal Veins Renal Arteries Inferior Vena Cava Abdominal Aorta Iliac Veins Iliac Arteries Femoral Veins Femoral Arteries Figure 36-4 p630 The Pulmonary Circuit • The pulmonary circuit carries blood to and from the lungs • Oxygen-poor blood is pumped from the right ventricle into pulmonary arteries • As blood flows through pulmonary capillaries, it picks up oxygen and gives up carbon dioxide. • Oxygen-rich blood returns through pulmonary veins to the left atrium The Pulmonary Circuit right pulmonary artery capillaries of right lung capillary bed of right lung pulmonary trunk from systemic circuit heart a Pulmonary Circuit left pulmonary artery capillary bed of left lung to systemic circuit pulmonary veins capillaries of left lung The Systemic Circuit • The systemic circuit carries blood to and from the body • The left ventricle pumps blood into the aorta • Arteries and arterioles carry blood to various body parts • Blood gives up oxygen and picks up carbon dioxide as it flows through capillaries • Oxygen-poor blood returns through venules and veins to the right atrium Hepatic Blood Flow • Most blood moving through the systemic circuit flows through only one capillary bed • Blood that passes through capillaries in the small intestine flows through the hepatic portal vein to capillaries in the liver • The liver stores some absorbed glucose as glycogen, and breaks down some absorbed toxins, including alcohol capillaries of head, neck, upper trunk, arms aorta to pulmonary circuit from pulmonary circuit heart capillaries of organs in the thoracic cavity capillaries of the liver capillaries of the intestines B Systemic Circuit capillaries of other abdominal organs, lower trunk, legs Figure 36-5b p631 ANIMATED FIGURE: Rh factor and pregnancy To play movie you must be in Slide Show Mode PC Users: Please wait for content to load, then click to play Mac Users: CLICK HERE ANIMATED FIGURE: Hemostasis To play movie you must be in Slide Show Mode PC Users: Please wait for content to load, then click to play Mac Users: CLICK HERE Take-Home Message: What are the two circuits of the human cardiovascular system? • The pulmonary circuit carries oxygen-poor blood from the heart through the pulmonary arteries to arterioles and then capillaries in the lungs. Pulmonary veins return oxygenated blood to the heart. • The systemic circuit carries oxygenated blood from the heart out the aorta, through branching arteries and to capillaries throughout the body. It returns oxygen-poor blood to the heart by way of venules and veins. • Most blood in the systemic circuit passes through one capillary bed, but blood that flows through capillaries in the intestines also flows through capillaries in the liver. 36.4 Components and Functions of Blood • Vertebrate blood carries oxygen, nutrients, and other solutes to cells, and carries away their metabolic wastes and secretions, including hormones • Blood also carries cells and proteins that protect and repair tissues • In birds and mammals, shifts in the distribution of blood flow help maintain a constant body temperature Blood Volume and Composition • An average adult human has about 5 liters (10 pints) of blood • Blood’s fluid portion is plasma • Blood cells and platelets form in bone marrow and are transported in plasma Plasma • Plasma is mostly water with hundreds of different plasma proteins dissolved in it • Some plasma proteins transport lipids and fat-soluble vitamins; others have a role in blood clotting or immunity • Some gases and nutrients such as sugars, amino acids, and vitamins are dissolved in plasma Blood Cells • Red blood cells (erythrocytes) • Contain hemoglobin that carries oxygen from lungs to tissues • Quantified in a cell count • White blood cells (leukocytes) • Defend the body from pathogens • Neutrophils, basophils, eosinophils, monocytes, and lymphocytes (B and T cells) Platelets • Platelets are fragments of megakaryocytes • After a platelet forms, it lasts five to nine days • When activated, it releases substances needed for blood clotting Components of Human Blood Cellular Components of Mammalian Blood hematopoietic stem cells in red bone marrow myeloid stem cell red blood cell precursor granulocyte precursor lymphoid stem cell monocyte precursor megakaryocytes platelets red blood cells neutrophils eosinophils basophils (erythrocytes) monocytes B lymphocytes T lymphocytes (immature (mature in (mature in phagocytes) bone marrow) thymus) ANIMATED FIGURE: The human heart To play movie you must be in Slide Show Mode PC Users: Please wait for content to load, then click to play Mac Users: CLICK HERE ANIMATED FIGURE: Cardiac cycle To play movie you must be in Slide Show Mode PC Users: Please wait for content to load, then click to play Mac Users: CLICK HERE Take-Home Message: What are the components and functions of human blood? • Blood consists mainly of plasma, a protein-rich fluid that carries wastes, gases, and nutrients. • Blood cells and platelets form in bone marrow and are transported in plasma. Red blood cells contain hemoglobin that carries oxygen from lungs to tissues. White cells help defend the body from pathogens. Platelets are cell fragments involved in clotting. 36.5 Hemostasis • Hemostasis is a three-phase process that stops blood loss, constructs a framework for repairs: • Damaged vessel constricts • Platelets accumulate • Cascading enzyme reactions involving plasma proteins cause clot formation Three-Phase Process of Hemostasis Take-Home Message: How does the body halt bleeding? • The vessel constricts, platelets accumulate, and cascading enzyme reactions involving protein components of plasma cause clot formation. 36.6 Blood Typing • Blood type • Genetically determined differences in molecules on the surface of red blood cells • Agglutination • Clumping of foreign cells by plasma proteins • When blood of incompatible types mixes, the immune system attacks the unfamiliar molecules ABO Blood Typing • ABO blood typing analyzes variations in one type of glycolipid on the surface of red blood cells • Blood type O has neither A nor B – the immune system treats both type A and type B cells as foreign • Blood type O is a universal donor • Blood type AB can receive blood from any donor ABO Blood Types Mixing ABO Blood Types Rh Blood Typing • Rh blood typing is based on the presence or absence of the Rh protein • An Rh- mother may develop Rh+ antibodies if blood from an Rh+ child enters her bloodstream during childbirth • These antibodies may attack the red blood cells of the next Rh+ fetus Rh– Rh+ Rh+ markers on the red blood cells of a fetus fetus Figure 36-10a p635 anti-Rh+ antibody molecules any subsequent Rh+ fetus Figure 36-10b p635 Take-Home Message: What is a blood type? • Blood type refers to the kind of surface molecules on red blood cells. Genes determine which form of these molecules an individual has. • When blood of incompatible types mixes, the immune system attacks the unfamiliar molecules, with results that can be fatal. 36.7 The Human Heart • The heart is a durable, muscular pump that contracts in response to its own spontaneous action potentials • A sac of connective tissue (pericardium) surrounds the heart muscle (myocardium) • Endothelium lines heart chambers and blood vessels The Human Heart • Each side of the human heart contains two chambers: • An atrium that receives blood from veins • A ventricle that pumps blood into arteries • Heart valves keep blood moving in one direction: • AV valves separate atria and ventricles • Semilunar valves separate ventricles and arteries Major Blood Vessels • Two veins deliver deoxygenated blood to the right atrium: • The superior vena cava from upper regions • The inferior vena cava from lower regions • The right ventricle pumps blood into two pulmonary arteries, each leading to one lung • Oxygenated blood returns to the left atrium via pulmonary veins, and is pumped out of the left ventricle into the aorta right lung left lung superior vena cava (flow from head, arms) aorta (to body) trunk of pulmonary arteries (to lungs) pulmonary valve (closed) pericardium diaphragm aortic valve (closed) right pulmonary veins (from lungs) left pulmonary veins (from lungs) Right Atrium Left Atrium right AV valve (open) left AV valve (open) Left Ventricle Right Ventricle cardiac muscle inferior vena cava (from trunk, legs) septum Figure 36-11 p636 superior vena cava (flow from head, arms) aorta (to body) trunk of pulmonary arteries (to lungs) pulmonary valve (closed) aortic valve (closed) right pulmonary veins (from lungs) left pulmonary veins (from lungs) Right Atrium Left Atrium right AV valve (open) left AV valve (open) Right Ventricle Left Ventricle inferior vena cava (from trunk, legs) cardiac muscle septum C Cutaway view, showing the heart’s internal organization. Arrows indicate the path taken by oxygenated (red) and oxygen-poor (blue) blood. Stepped Art Figure 36-11 p636 The Cardiac Cycle • In the cardiac cycle, heart muscle alternates between diastole (relaxation) and systole (contraction) • Blood collects in atria • AV valves open, blood flows into ventricles • Contraction of ventricles drives blood circulation • Ventricles contract with a wringing motion from bottom to top 1 Relaxed atria fill. Fluid pressure opens AV valves and blood flows into the relaxed ventricles. As blood flows into the arteries, pressure in the ventricles declines and the aortic and pulmonary valves close. 4 Contracting atrial squeeze more blood into the still-relaxed ventricles. 2 Ventricles start contracting and rising pressure pushes AV valves shut. A further rise in pressure opens aortic and pulmonary valves. 3 Stepped Art Figure 36-12a p637 ANIMATED FIGURE: Examples of ECGs To play movie you must be in Slide Show Mode PC Users: Please wait for content to load, then click to play Mac Users: CLICK HERE Setting the Pace for Contraction • The sinoatrial (SA) node in the wall of the right atrium, is the cardiac pacemaker – it generates about 70 action potentials per minute • Gap junctions between adjacent cells allow action potentials generated by the SA node to spread across the atria • The signal spreads from the SA node to the atrioventricular (AV) node, then to junctional fibers in the septum, so the heart contracts from the bottom up SA node (cardiac pacemaker) AV node conducting fibers Figure 36-13 p637 ANIMATED FIGURE: Lymphoid organs To play movie you must be in Slide Show Mode PC Users: Please wait for content to load, then click to play Mac Users: CLICK HERE ANIMATION: Human lymphatic system To play movie you must be in Slide Show Mode PC Users: Please wait for content to load, then click to play Mac Users: CLICK HERE 3D ANIMATION: Electrical and Mechanical Events of the Heart Take-Home Message: How does heart structure relate to its function? • The four-chambered heart is a muscular pump partitioned into two halves, each with an atrium and a ventricle. Forceful contraction of the ventricles provides the driving force for blood circulation. • The SA node is the cardiac pacemaker. Its spontaneous, rhythmic signals make cardiac muscle cells of the heart wall contract in a coordinated fashion.