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CardioVascular System CardioVascular System Presentation Transcript

  • Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Chapter 29 Circulation and Cardiovascular Systems
  • A Circulatory System Helps Maintain Homeostasis 29-
  • 29.1 A circulatory system serves the needs of cells
    • The circulatory system transports oxygen and nutrients, such as glucose and amino acids, to the cells
      • It picks up wastes, which are later excreted from the body by the lungs or kidneys
    • Both gas exchange and nutrient-for-waste exchange occur across the walls of the smallest blood vessels, capillaries
      • No cell in the body of an animal is far from a capillary
    29-
  • Figure 29.1 Exchanges of gases, nutrients, and wastes takes place across capillary walls 29-
  • 29.2 Some invertebrates do not have a circulatory system
    • Cnidarians, such as hydras, and flatworms, such as planarians, do not have a circulatory system
    • In a hydra
      • The cells are either part of an external layer, or they line the gastrovascular cavity
      • In either case, each cell is exposed to water and can independently exchange gases and get rid of wastes
    • In a planarian
      • Trilobed gastrovascular cavity branches throughout the small, flattened body
      • No cell is very far from one of the three digestive branches, so nutrient molecules can diffuse from cell to cell
    29-
  • Figure 29.2 Invertebrates with a gastrovascular cavity 29-
  • 29.3 Other invertebrates have an open or a closed circulatory system
    • There are two types of circulatory fluid:
      • Blood - always contained within blood vessels
      • Hemolymph - a mixture of blood and tissue fluid that flows into a body cavity
    • Open circulatory system - found in arthropods and molluscs
      • Heart pumps hemolymph via vessels into tissue spaces and eventually hemolymph drains back to the heart
      • Slow delivery of oxygen and nutrients is sufficient for a sluggish animal (clam)
      • A grasshopper has colorless blood and doesn’t depend on its open circulatory system to deliver oxygen to its muscles
      • Tracheae open to outside and take oxygen directly to flight muscles
    • Closed circulatory system - found in annelids (earthworms)
      • Heart pumps blood, which usually consists of cells and plasma, into a system of blood vessels and valves prevent the backward flow of blood
      • Blood moves into capillaries, for exchanges with tissue fluid
      • Blood then moves from small veins into the dorsal blood vessel (a vein)
      • This dorsal blood vessel returns blood to the heart for repumping
    29-
  • Figure 29.3A Open circulatory system in a grasshopper 29-
  • Figure 29.3B Closed circulatory system in an earthworm 29-
  • 29.4 All vertebrates have a closed circulatory system
    • Two different circulatory pathways in vertebrates
      • Single-loop: heart only pumps blood to gills
      • Two-circuit: systemic circuit - heart pumps blood to all parts of the body except for the lungs; the pulmonary circuit - heart pumps blood to the lungs
    • Fishes - heart has a single atrium and a single ventricle
      • Blood is fully enriched with oxygen when it leaves gills , the respiratory organ for aquatic organisms
    • Amphibians and Reptiles - single ventricle pumps blood in the pulmonary circuit to the lungs
      • Also pumps blood in the systemic circuit to the rest of the body
      • Although both O 2 -rich and O 2 -poor blood enter the single ventricle, it is kept separate
        • O 2 -poor blood is pumped out of the ventricle to the lungs before O 2 -rich blood enters and is pumped to the systemic circuit
    • Birds and Mammals
      • Two atria and two ventricles in the heart and the complete separation of the pulmonary and systemic circuits
      • Right ventricle pumps blood under pressure to the lungs, and the larger left ventricle pumps blood under pressure to the rest of the body
    29-
  • Figure 29.4A Single-loop circulatory pathway in fishes 29-
  • Figure 29.4B Two-circuit pathway in amphibians and most reptiles 29-
  • Figure 29.4C Complete separation of pulmonary and systemic circuits in birds, mammals, and some reptiles 29-
  • The Mammalian Cardiovascular System Consists of the Heart and Blood Vessels 29-
  • 29.5 The mammalian heart has four chambers
    • All vertebrates have a closed circulatory system, called a cardiovascular system because it consists of a heart ( cardio ) and a system of blood vessels ( vascular )
      • Septum divides the heart into left and right sides
        • Right side of heart pumps O 2 -poor blood to lungs, and the left side pumps O 2 -rich blood to tissues
    • Each side has two chambers
      • Upper, thin-walled chambers are atria (sing., atrium )
      • Lower chambers are thick-walled ventricles
        • Atria receive blood; ventricles pump blood away from heart
    29-
  • Heart Valves
    • Atrioventricular valves - between the atria and ventricles
    • Semilunar valves - between the ventricles and their attached vessels
    • After the blood passes through the right atrioventricular valve, the right ventricle pumps it through the pulmonary semilunar valve into the pulmonary trunk and pulmonary arteries that take it to the lungs
      • Pulmonary veins bring O 2 -rich blood back to the left atrium
    • After the blood passes through the left atrioventricular valve, the left ventricle pumps it through the aortic semilunar valve into the aorta , which takes it to the tissues
      • Heart murmur is often due to leaky atrioventricular valves, which allow blood to pass back into the atria after they have closed
    29-
  • Figure 29.5 Structure of the heart 29-
  • 29.6 The heartbeat is rhythmic
    • The average human heart contracts, or beats, about 70 times a minute, or 2.5 billion times in a lifetime
      • Each heartbeat, called the cardiac cycle , can be divided into three phases
        • The atria contract (while the ventricles relax)
        • The ventricles contract (while the atria relax)
        • All chambers rest
    • Systole refers to contraction of the heart chambers, and the word diastole refers to relaxation of these chambers
    • When the heart beats, the familiar “ lub-dub ” sound is heard as the valves of the heart close
      • Pulse - wave effect that passes down walls of arterial blood vessels following ventricular systole
    • Rhythmic contraction of heart is due to cardiac conduction system
      • The SA (sinoatrial) node initiates the heartbeat every 0.85 seconds and is called the cardiac pacemaker
      • An electrocardiogram (ECG) is a recording of the electrical changes that occur in the heart during a cardiac cycle
    29-
  • Figure 29.6A The phases of a heartbeat 29-
  • Figure 29.6B Conduction system of the heart 29-
  • 29.7 Blood vessel structure is suited to its function
    • Arteries (and arterioles) - carry blood away from the heart to the capillaries
      • Arteries have a much thick wall with elastic tissue that allows arteries to expand and accommodate the sudden increase in blood volume that results after each heartbeat
      • Smaller arteries branch into a number of arterioles
    • C apillaries - permit exchange of material with tissues
      • Extremely narrow (8–10 mm wide) and have thin walls composed of single layer of epithelium with basement membrane
      • The thin walls of a capillary facilitate capillary exchange
    • Veins (and venules) - return blood from the capillaries to the heart
      • Venules (small veins) - drain blood from the capillaries; then join to form a vein
      • Veins often have valves that allow blood to flow only toward the heart when open and prevent the backward flow of blood when closed
    29-
  • Figure 29.7A Types of blood vessels 29-
  • Figure 29.7B Anatomy of a capillary bed 29-
  • 29.8 Blood vessels form two circuits in mammals
    • The Pulmonary Circuit
      • O 2 -poor blood from all regions of body collects in right atrium and then passes into right ventricle, which pumps it into the pulmonary trunk
      • Pulmonary trunk divides into the right and left pulmonary arteries, which carry blood to the lungs
      • As blood passes through pulmonary capillaries, carbon dioxide is given off and oxygen is picked up
      • O 2 -rich blood returns to left atrium of through pulmonary veins
    • The Systemic Circuit
      • Aorta and the venae cavae (sing., vena cava ) are the major blood vessels
      • To trace the path of blood to any organ in the body, start with the left ventricle, then go the aorta, then the proper branch of the aorta, the organ, and the vein returning blood to the vena cava, which enters the right atrium
      • Portal systems begin and end in capillaries
        • Hepatic portal system takes blood from the intestines to the liver
    29-
  • Figure 29.8 Path of blood in the body 29-
  • 29.9 Blood pressure is essential to the flow of blood in each circuit
    • Blood pressure is normally measured on the brachial artery of the upper arm
      • A blood pressure reading consists of two numbers that represent systolic and diastolic pressures, respectively
        • Systolic pressure results from blood being forced into the arteries during ventricular systole
        • Diastolic pressure is the pressure in the arteries during ventricular diastole
    • Blood pressure accounts for the flow of blood from the heart to the capillaries
      • As blood flows from the aorta into the various arteries and arterioles, blood pressure falls
      • Blood pressure in the veins is low and cannot move blood back to the heart, especially from the limbs
      • Venous return depends upon three factors:
        • Skeletal muscle contraction, presence of valves in veins, and respiratory movements
    29-
  • Figure 29.9A Velocity and blood pressure are related to the cross-sectional area of the blood vessels 29-
  • Figure 29.9B How a valve affects the movement of blood in a vein 29-
  • APPLYING THE CONCEPTS—HOW BIOLOGY IMPACTS OUR LIVES 29.10 Blood vessel deterioration results in cardiovascular disease
    • In U.S., about 20% of population suffers from hypertension, high blood pressure
      • Heredity and lifestyle contribute to hypertension
        • Hypertension is often seen in individuals who have atherosclerosis, which occurs when plaque protrudes into the lumen of a vessel and interferes with the flow of blood
    • Plaque can cause a clot to form on the irregular arterial wall
      • As long as the clot remains stationary, it is called a thrombus , but when and if it dislodges and moves along with the blood, it is called an embolus
    • A stroke often occurs when a small cranial arteriole bursts or is blocked by an embolus
    • Heart attack - when a coronary artery is completely blocked, a portion of the heart muscle dies due to lack of oxygen
    29-
  • APPLYING THE CONCEPTS—HOW BIOLOGY IMPACTS OUR LIVES 29.11 Cardiovascular disease can often be prevented
    • The Don’ts
      • Smoking - When a person smokes, nicotine enters the bloodstream and causes the arterioles to constrict and the blood pressure to rise
      • Drug Abuse - Stimulants, such as cocaine and amphetamines, can cause an irregular heartbeat and lead to heart attacks and strokes
      • Weight Gain - in persons who are more than 20% above the recommended weight more tissues require servicing, and the heart sends the extra blood out under greater pressure
    • The Dos
      • Healthy Diet - Physicians advise people to replace harmful saturated fats and trans fats with healthier ones, such as monounsaturated fats (olive and canola oils) and polyunsaturated fats (corn, safflower, and soybean oils)
      • Cholesterol Profile - Starting at age 20, all adults are advised to have their cholesterol levels tested at least every five years
      • Exercise - People who exercise are less apt to have cardiovascular disease
    29-
  • Figure 29.11 Plaque buildup in a coronary artery 29-
  • Blood Has Vital Functions 29-
  • 29.12 Blood is a liquid tissue
    • Blood’s numerous functions include the following:
      • Transports substances to and from the capillaries, where exchanges with tissue fluid take place
      • Helps defend the body against invasion by pathogens (e.g., disease-causing viruses and bacteria)
      • Helps regulate body temperature
      • Forms clots, preventing a potentially life-threatening loss of blood
    • Blood has two main portions
      • Plasma - composed mostly of water (90–92%) and proteins (7–8%)
        • Also contains smaller quantities of many types of molecules, including nutrients, wastes, and salts
      • Formed elements - red blood cells, white blood cells, and platelets
    29-
  • Types of Blood Cells
    • Red blood cells (erythrocytes) - transport oxygen using h emoglobin, which contains iron, and combines loosely with oxygen
    • White blood cells (leukocytes) - help fight infections
      • Neutrophils , which are amoeboid, squeeze through the capillary wall and enter the tissue fluid, where they engulf foreign material
      • Monocytes appear and are transformed into macrophages, large phagocytizing cells that release white blood cell growth factors
      • Lymphocytes play important role in fighting infection
        • T cells attack infected cells that contain viruses
        • B cells - produce antibodies
          • Each B cell produces just one type of antibody, which is specific for one type of antigen
          • An antigen, which is most often a protein but sometimes a polysaccharide, causes the body to produce an antibody to combine with the antigen
    29-
  • Figure 29.12 Composition of blood 29-
  • 29.13 Blood clotting involves platelets
    • Platelets result from fragmentation of large cells in the bone marrow called megakaryocytes
      • Blood contains 150,000–300,000 platelets per mm 3
    • When a blood vessel in the body is damaged platelets clump at the site of the puncture and partially seal the leak
      • Platelets and the injured tissues release a clotting factor called prothrombin activator that converts prothrombin to thrombin
      • Thrombin acts as an enzyme that severs two short amino acid chains from each fibrinogen molecule
      • These activated fragments then join forming long threads of fibrin that wind around the platelet plug in the damaged area of the blood vessel and provide the framework for the clot
    • If blood is allowed to clot in a test tube, a yellowish fluid develops above the clotted material, called serum
      • Contains all the components of plasma, except fibrinogen
    • Hemophilia is a well-known, inherited clotting disorder
      • Due to the absence of a particular clotting factor, the slightest bump can cause internal bleeding
    29-
  • Figure 29.13 Blood clotting 29-
  • APPLYING THE CONCEPTS—HOW SCIENCE PROGRESSES 29.14 Adult stem cells include blood stem cells
    • A stem cell is a cell that is capable of becoming different types of cells
      • While embryonic stem cells possess the ability to become virtually any cell type, adult stem cells are not quite as versatile because they can become only certain other types of cell
    • Adult stem cells have been identified in many tissues, including the liver, skin, muscle, and even within the brain, but the richest source is in the red bone marrow
      • Adult stem cells from bone marrow are used to treat many white blood cell and immune system disorders, including leukemia, certain blood cancers, and anemia
      • Like any organ transplant, a bone marrow transplant poses the risk of rejection
    29-
  • Figure 29.14 Hematopoietic cells (adult stem cells in red bone marrow) produce cells that become the various types of blood cells. 29-
  • 29.15 Capillary exchange is vital to cells
    • Capillary exchange occurs between a systemic capillary and tissue fluid , the fluid between the body’s cells
      • Two forces control movement of fluid through capillary wall
        • Blood pressure, which tends to cause water to move out of a capillary into the tissue fluid
        • Osmotic pressure, which tends to cause water to move from the tissue fluid into a capillary
    • Red blood cells and almost all plasma proteins remain in the capillaries
      • Fluid and other substances that leave a capillary contribute to the tissue fluid
    • At the venous end of a capillary, blood pressure has fallen so osmotic pressure is greater than blood pressure, and water tends to move into the capillary
      • Some excess tissue fluid is always collected by the lymphatic capillaries
      • Tissue fluid contained within lymphatic vessels is called lymph
        • Lymph is returned to the systemic venous blood when the major lymphatic vessels enter the subclavian veins in the shoulder region
    29-
  • Figure 29.15A Capillary exchange 29-
  • Figure 29.15B A lymphatic capillary bed lies near a blood capillary bed 29-
  • 29.16 Blood types must be matched for transfusions
    • ABO System
      • Presence or absence of type A and type B antigens on red blood cells determines a person’s blood type
        • In the ABO system, there are four types of blood: A, B, AB, and O
          • Type O blood has no antigens on the red blood cells and is sometimes called the universal donor
    29-
  • 29-
  • Rh System and Erythroblastosis Fetalis
    • Rh System
      • Another important antigen in matching blood types is the Rh factor
      • 85% of the U.S. population have this particular antigen on red blood cells and are called Rh-positive
    • Erythroblastosis Fetalis
      • During pregnancy, if the mother is Rh-negative and the father is Rh-positive, the child may be Rh-positive
      • Rh-positive red blood cells may begin leaking across the placenta into the mother’s cardiovascular system, since placental tissues normally break down before and at birth
      • The mother produces anti-Rh antibodies, which may cross the placenta and destroy the child’s red blood cells during a subsequent pregnancy
    29-
  • Figure 29.16A No agglutination occurs when the donor and recipient have the same type blood 29-
  • Figure 29.16B Agglutination occurs because blood type B has anti-A antibodies in the plasma 29-
  • Connecting the Concepts: Chapter 29
    • It is possible to relate the type of cardiovascular system to the lifestyle of an animal
      • Some small, aquatic animals have no cardiovascular system—external water passing in and out of a gastrovascular cavity is sufficient to meet the needs of their cells
      • Grasshoppers have an open circulatory system, but they utilize tracheae to deliver oxygen directly to their muscles
    • We traced the evolution of the two-circuit circulatory pathway in vertebrates and saw that a two-circuit pathway allows blood to pass to the lungs and to the tissues under pressure
      • This is particularly useful in birds and mammals, which maintain a warm body and an active way of life
      • Body fluids make ideal culture media for the growth of infectious parasites, and these fluids often have ways to ward off an invasion. You already know that white blood cells are involved in these endeavors
    29-