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Chapter 44 (Sections 44.1-44.4) Internal Transport

Chapter 44 (Sections 44.1-44.4) Internal Transport. Moving Materials. Cells require a continuous supply of nutrients and oxygen and removal of waste products

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Chapter 44 (Sections 44.1-44.4) Internal Transport

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  1. Chapter 44(Sections 44.1-44.4)Internal Transport

  2. Moving Materials • Cells require a continuous supply of nutrients and oxygen and removal of waste products • In very small animals, materials are exchanged by diffusion, the net movement of particles from a region of higher concentration to a region of lower concentration • Fluid between the cells (interstitial fluid) provides a medium for diffusion of oxygen, nutrients, and wastes

  3. Circulatory Systems • Evolution of specialized circulatory systems allowed animals to increase in size – it transports oxygen, nutrients, hormones, and other materials to the interstitial fluid surrounding all the cells and removes metabolic wastes • The human circulatory system (cardiovascular system) includes the heart, blood vessels, and blood • Cardiovascular disease is the leading cause of death in the United States and throughout the world

  4. 44.1 TYPES OF CIRCULATORY SYSTEMS LEARNING OBJECTIVE: • Compare and contrast internal transport in animals with no circulatory system, those with an open circulatory system, and those with a closed circulatory system

  5. Animals With No Circulatory System • No specialized circulatory structures are present in sponges, cnidarians (hydras, jellyfish), ctenophores (comb jellies), flatworms, or nematodes (roundworms) • In cnidarians, the central gastrovascular cavity serves as a circulatory organ as well as a digestive organ • The flattened body of the flatworm permits effective gas exchange by diffusion • Fluid in the body cavity of nematodes circulates materials

  6. Circulatory Systems • Larger animals require a circulatory system to efficiently distribute materials • A circulatory system typically consist of three parts: • Blood, a connective tissue consisting of cells and cell fragments dispersed in fluid, usually called plasma • A pumping organ, generally a heart • Blood vessels through which blood circulates • Two main types of circulatory systems are open and closed systems

  7. Open Circulatory Systems • Arthropods and most mollusks have an open circulatory system,in which the heart pumps blood into vessels that have open ends • Blood and interstitial fluid make up hemolymph, which fills large sinuses (the hemocoel or blood cavity) • Hemolymph bathes the body cells, then re-enters the circulatory system through openings in the heart (arthropods) or through open-ended vessels that lead to gills (mollusks)

  8. Open Circulatory Systems (cont.) • Most mollusks have a heart with three chambers: two atria receive hemolymph from gills; a single ventricle pumps oxygen-rich hemolymph into blood vessels • In arthropods, a tubular heart pumps hemolymph into arteries that deliver it to the sinuses of the hemocoel • Some mollusks and arthropods have a copper-containing hemolymph pigment (hemocyanin) that transports oxygen

  9. Invertebrates With Closed Circulatory Systems • Annelids, cephalopod mollusks, and echinoderms have a closed circulatory systemin which blood flows through a continuous circuit of blood vessels • Gases, nutrients, and wastes diffuse between blood in the vessels and interstitial fluid that bathes the cells through the thin walls of capillaries

  10. Invertebrates With Closed Circulatory Systems (cont.) • Proboscis worms (phylum Nemertea) have a complete network of blood vessels but no heart • Annelids (earthworms) have two main blood vessels, five pairs of contractile blood vessels that act as hearts, and a red pigment (hemoglobin) that transports oxygen • Cephalopod mollusks (squids and octopods) have accessory “hearts” at the base of the gills, which speed passage of blood through the gills

  11. The Vertebrate Circulatory System • Vertebrates have a ventral, muscular heart that pumps blood into a closed system of blood vessels • Capillaries, the smallest blood vessels, have very thin walls that permit exchange of materials between blood and interstitial fluid • The vertebrate circulatory system consists of heart, blood vessels, blood, lymph, lymph vessels, and associated organs such as the thymus, spleen, and liver

  12. Functions of the Vertebrate Circulatory System • Transports nutrients from digestive system or storage to cells • Transports oxygen from respiratory structures to cells • Transports metabolic wastes from cells to excretory organs • Transports hormones from endocrine glands to target tissues • Helps maintain fluid balance • Helps distribute metabolic heat and maintain body temperature • Helps maintain appropriate pH • Defends the body against invading microorganisms

  13. KEY CONCEPTS 44.1 • Arthropods and most mollusks have an open circulatory system in which blood bathes the tissues directly • Some invertebrates and all vertebrates have a closed circulatory system in which a heart pumps blood that flows through a continuous circuit of blood vessels

  14. 44.2 VERTEBRATE BLOOD LEARNING OBJECTIVES: • Compare the structure and function of plasma, red blood cells, white blood cells, and platelets • Summarize the sequence of events involved in blood clotting

  15. Blood • In vertebrates, blood consists of a fluid plasma in which red blood cells, white blood cells, and platelets are suspended • In humans, blood volume is approximately 5 L (5.3 qt) in an adult female and about 5.5 L (5.8 qt) in an adult male • About 55% of the blood volume is plasma and 45% is blood cells and platelets

  16. Plasma • Plasma consists of water (about 92%), proteins (about 7%), salts, and transported materials such as dissolved gases, nutrients, wastes, and hormones • Plasma contains several kinds of plasma proteins: • Fibrinogen is involved in clotting • Globulins: Alpha globulins (hormones and proteins that transport hormones); beta globulins (transport fats, cholesterol, vitamins and minerals); gamma globulin (contains many types of antibodies) • Albumins help control blood’s osmotic pressure

  17. Red Blood Cells • Erythrocytes or red blood cells (RBCs), are highly specialized for transporting oxygen • In mammals, the RBC nucleus is ejected – each RBC is a flexible, biconcave disc with an elastic internal framework • Erythrocytes are produced in red bone marrow of vertebrae, ribs, breastbone, skull bones, and long bones • As an RBC develops, it produces large quantities of the oxygen-transporting pigment hemoglobin

  18. Red Blood Cells (cont.) • A human RBC lives about 120 days; old RBCs are removed from circulation by phagocytic cells in the liver and spleen • New RBCs are produced in bone marrow, regulated by a hormone released by the kidneys (erythropoietin) • Anemia, a deficiency in hemoglobin, may be caused by: • Loss of blood from hemorrhage or internal bleeding • Decreased production of hemoglobin or red blood cells (iron-deficiency anemia or pernicious anemia) • Increased rate of RBC destruction (hemolytic anemias)

  19. White Blood Cells • Leukocytes or white blood cells (WBCs) defend the body against harmful bacteria and other microorganisms • Leukocytes are amoeba-like cells capable of independent movement – some slip through the walls of blood vessels and enter the tissues • Human blood contains three kinds of granular leukocytes and two types of agranular leukocytes – all manufactured in the red bone marrow

  20. Granular Leukocytes • Granular leukocytes have large, lobed nuclei and distinctive granules in their cytoplasm • Neutrophils are phagocytic cells that ingest bacteria and dead cells – granules contain digestive enzymes • Eosinophils contain lysosomes with enzymes that degrade cell membranes of parasitic worms and protozoa • Basophils release histamine in injured tissues and in allergic responses; and heparin, an anticoagulant

  21. Agranular Leukocytes • Agranular leukocyteslack granules; their nuclei are rounded or kidney-shaped • Lymphocytesfight infections; some produce antibodies, others directly attack invaders such as bacteria or viruses • Monocytes are phagocytes that migrate from blood into tissues during an infection; they differentiate into: • Macrophagesthat engulf bacteria, dead cells, and debris • Dendritic cells, important in the immune system

  22. Leukemia • Leukemia is a form of cancer in which WBCs multiply rapidly within the bone marrow, crowding out developing RBCs and platelets, leading to anemia and impaired clotting • Death is often caused by internal hemorrhaging, especially in the brain; or infection • Leukemia is treated with chemotherapy, and sometimes with radiation therapy or bone marrow transplant

  23. Platelets • Most vertebrates other than mammals have small, oval, nucleated cells (thrombocytes) that function in blood clotting • Mammals have platelets, tiny spherical or disc-shaped fragments of cytoplasm pinched off from large cells in the bone marrow (lacking nuclei) • When a blood vessel is cut, platelets stick to the rough, cut edges and release substances that attract other platelets

  24. Blood Clotting • Platelets become sticky and adhere to collagen fibers in the blood vessel wall, forming a platelet plug or temporary clot • Using clotting factors, calcium ions, and compounds released from platelets, prothrombin is converted to thrombin • Thrombin catalyzes conversion of the soluble plasma protein fibrinogento an insoluble protein, fibrin • Fibrin polymerizes, producing long threads that form the webbing of the clot, trapping more blood cells and platelets

  25. KEY CONCEPTS 44.2 • Vertebrate blood consists of plasma, which transports nutrients, wastes, gases, and hormones; red blood cells, which are specialized to transport oxygen; white blood cells, which defend the body against disease; and platelets, which function in blood clotting

  26. 44.3 VERTEBRATE BLOOD VESSELS LEARNING OBJECTIVE: • Compare the structure and function of different types of blood vessels, including arteries, arterioles, capillaries, and veins

  27. Blood Vessels • Vertebrates have three main types of blood vessels • Arteries carry blood away from the heart; they divide into many smaller branches (arterioles)which lead to capillaries • Capillariesare microscopic vessels that form networks which exchange materials between blood and tissues • Veinscarry blood back toward the heart

  28. Blood Vessels (cont.) • Walls of arteries or veins have three layers: • Inner lining: endothelium • Middle layer: connective tissue and smooth muscle cells • Outer layer: connective tissue rich in elastic and collagen fibers • Materials are exchanged between blood and interstitial fluid through capillary walls, which are only one cell thick

  29. Blood Vessels (cont.) • Smooth muscle in arteriole walls can constrict (vasoconstriction) or relax (vasodilation), changing the radius of the arteriole • Regulated by the nervous system, arterioles help maintain appropriate blood pressure and control the volume of blood passing to a particular tissue • Small vessels (metarterioles)directly link arterioles with venules (small veins)

  30. Blood Vessels (cont.) • Capillaries branch off from metarterioles and rejoin them, and also interconnect with one another • Where a capillary branches from a metarteriole, a smooth muscle cell serves as a precapillary sphincter that directs blood first to one and then to another section of tissue • Precapillary sphincters (along with the smooth muscle in the walls of arteries and arterioles) regulate the blood supply to each organ and its subdivisions

  31. KEY CONCEPTS 44.3 • Three main types of vertebrate blood vessels are arteries, which carry blood away from the heart; capillaries, which are exchange vessels; and veins, which carry blood back toward the heart

  32. 44.4 EVOLUTION OF THE CARDIOVASCULAR SYSTEM LEARNING OBJECTIVE: • Trace the evolution of the vertebrate cardiovascular system from fish to mammal

  33. Evolution of the Vertebrate Cardiovascular System • The vertebrate cardiovascular system became modified as the site of gas exchange shifted from gills to lungs, and as metabolic rates increased • The vertebrate heart has one or two chambers (atria) that receive blood returning from the tissues and one or two ventriclesthat pump blood into arteries • The fish heart has one atrium and one ventricle; there is a single circuit of blood vessels; blood is oxygenated at capillaries in the gills

  34. Evolution of the Vertebrate Cardiovascular System (cont.) • Amphibians have a double circuit of blood vessels: pulmonary circulation and systemic circulation • The heart has two atria and one ventricle – a sinus venosuscollects oxygen-poor blood returning from the veins and pumps it into the right atrium; blood is oxygenated in lungs and passes directly into the left atrium • Oxygen-poor blood is pumped out of the ventricle before oxygen-rich blood enters; the conusarteriosushelps separate the two

  35. Evolution of the Vertebrate Cardiovascular System (cont.) • Most nonavian reptiles have a double circuit of blood flow – a wall partly divides the ventricles • In crocodilians, the wall between the ventricles is complete –the heart consists of two atria and two separate ventricles • Nonavian reptiles (and amphibians) do not ventilate their lungs constantly – shunts between the two sides of the heart allow blood to be distributed to the lungs as needed

  36. Evolution of the Vertebrate Cardiovascular System (cont.) • In birds, mammals, and crocodilians, the septum (wall) between the ventricles is complete • Biologists hypothesize that the completely divided heart evolved twice during the course of vertebrate evolution; first in the crocodilian-bird clade, then independently in mammals • The conus arteriosus split and became the base of the aorta and the pulmonary artery; a vestige of the sinus venosus remains as the sinoatrial node (pacemaker)

  37. Evolution of the Vertebrate Cardiovascular System (cont.) • A complete double circuit allows birds and mammals to maintain relatively high blood pressures in the systemic circulation and lower pressures in the pulmonary circulation • The pattern of blood circulation in birds and mammals can be summarized as follows: veins (from organs) → right atrium → right ventricle → pulmonary arteries → capillaries in the lungs → pulmonary veins → left atrium → left ventricle → aorta → arteries (to organs) → arterioles → capillaries → veins

  38. KEY CONCEPTS 44.4 • During the evolution of terrestrial vertebrates, adaptations in circulatory system structures separated oxygen-rich from oxygen-poor blood • The four-chambered hearts and double circuits of endothermic birds and mammals completely separate oxygen-rich blood from oxygen-poor blood

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