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Splash. Chapter Introduction Transport Systems in Plants 7.1 Adaptations for Life on Land 7.2 Water Transport 7.3 Nutrient Transport Transport Systems in Animals 7.4 Circulatory Systems 7.5 Circulation in Vertebrates 7.6 The Human Heart 7.7 Molecular Basis of Muscle Contraction

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  1. Splash

  2. Chapter Introduction Transport Systems in Plants 7.1 Adaptations for Life on Land 7.2 Water Transport 7.3 Nutrient Transport Transport Systems in Animals 7.4 Circulatory Systems 7.5 Circulation in Vertebrates 7.6 The Human Heart 7.7 Molecular Basis of Muscle Contraction Regulation and Transport 7.8 Blood Pressure 7.9 Composition of Blood 7.10 The Circulatory System and Homeostasis Chapter Highlights Chapter Animations Chapter Menu Contents

  3. Learning Outcomes By the end of this chapter you will be able to: A Summarize the adaptations made by plants to life on land. B Compare the structure and function of xylem and phloem tissues. C Describe the advantages offered by a closed circulatory system. D Explain what blood pressure is and describe factors that affect it. E Name the constituents of blood and describe the function of each. F Explain how the circulatory system functions in homeostasis. Learning Outcomes

  4. An arteriogram of a human hand showing the arterial structure (enhanced). Transport Systems • What system is responsible for the movement of blood throughout the body in humans? • How do transport systems contribute to the survival of multicellular organisms? Chapter Introduction 1

  5. An arteriogram of a human hand showing the arterial structure (enhanced). Transport Systems • Complex multicellular organisms, such as most land plants and animals, cannot eliminate wastes by diffusion and active transport through their surfaces. • Transport systems play a key role in maintaining the internal balance necessary for life. Chapter Introduction 2

  6. End of the Introduction

  7. Transport Systems in Plants 7.1 Adaptations for Life on Land • The first land plants probably evolved from green algae about 430 million years ago. • Challenges posed by life out of water include: • loss of moisture to the air • soil contains water and minerals, but the light and carbon dioxide needed for photosynthesis must be obtained above ground 7.1 Adaptations for Life on Land 1

  8. Transport Systems in Plants 7.1 Adaptations for Life on Land (cont.) • Two groups of plants emerged during this period: • Vascular plants with specialized tissue, called vascular tissue, that consists of cells joined into tubes that transport water and nutrients throughout the body of the plant • Nonvascular plants in which complex transport tissues did not evolve • Vascular land plants differentiated into an underground root system that absorbs water and minerals and an aerial system of stems and leaves that makes food. 7.1 Adaptations for Life on Land 2

  9. Different parts of a plant have different activities, all of which require materials that must be transported where needed. Water is the material needed in greatest amounts. It also serves as the transport fluid, carrying minerals through one type of transport tissue and the products of photosynthesis through another. 7.1 Adaptations for Life on Land 3

  10. Transport Systems in Plants 7.1 Adaptations for Life on Land (cont.) • Specialization in vascular plants required additional adaptations: • The sections of roots that absorb water generally lack a cuticle and have increased surface area. • Lignin, a hard material embedded in the cellulose matrix of the cell walls, supports trees and other large vascular plants. • Hollow tube-shaped cells called xylem carry water and minerals up from the roots. • The phloem, which distributes organic nutrients throughout the plant, consists of elongated cells arranged into tubes filled with streaming cytoplasm. 7.1 Adaptations for Life on Land 4

  11. The arrows identify the path of water through this tree. Trace the path of the water from the root hairs through the xylem tissues to the leaves. 7.1 Adaptations for Life on Land 5

  12. Transport Systems in Plants 7.2 Water Transport • The xylem of flowering plants consists of two types of water-conducting cells, tracheids and vessel elements, plus strong weight-bearing fibers. • Columns of vessel elements form the xylem vessels through which water moves throughout the plant. 7.2 Water Transport 1

  13. Transport Systems in Plants 7.2 Water Transport (cont.) • Scientists have developed the cohesion-tension hypothesis—based on the molecular properties of water and transpiration—as the likely mechanism for water transport through the xylem. • The root system also exerts pressure that causes water and other materials to ooze out of a cut plant stem. 7.2 Water Transport 2

  14. Transport Systems in Plants 7.2 Water Transport (cont.) • Hydrogen bonds form between water molecules causing cohesion—the tendency of water to stick together. • The positive and negative charges of water molecules form weak bonds to other charged molecules—the property called adhesion. • Capillary action causes water to rise inside a tube because the water molecules develop adhesion to charged groups on the walls, pulling them upward; additional water molecules are then drawn up by cohesion. 7.2 Water Transport 3

  15. Transport Systems in Plants 7.2 Water Transport (cont.) • Due to cohesion, each water molecule that leaves the plant during transpiration tugs on the one behind it. • The result is that a long chain of water molecules is continually pulled through the xylem from root to leaf. 7.2 Water Transport 4

  16. Transport Systems in Plants 7.3 Nutrient Transport • In vascular plants, nutrients travel through living phloem cells joined end to end. • Tiny pores in the walls at the ends of the phloem cells allow the contents of the cells to mix. • Phloem channels are often called sieve tubes. 7.3 Nutrient Transport 1

  17. Transport Systems in Plants 7.3 Nutrient Transport (cont.) • Sugars and amino acids move through the phloem cells from the leaves to other parts of the plant. • The pressure-flow hypothesis is the best explanation for the movement of sugars through the phloem. • According to this hypothesis, water and dissolved sugars move through the phloem from sources (areas of higher pressure) to sinks (areas of lower pressure). 7.3 Nutrient Transport 2

  18. Sources and sinks in phloem transport Click the image to view an animated version. 7.3 Nutrient Transport 3

  19. End of Section 1

  20. Numbers indicate the pathway from endocytosis of food to exocytosis of indigestible wastes. Transport Systems in Animals 7.4 Circulatory Systems • In unicellular and other simple organisms, substances pass across the plasma membrane between each cell and a watery environment. 7.4 Circulatory Systems 1

  21. Transport Systems in Animals 7.4 Circulatory Systems (cont.) • Most larger animals have digestive and excretory organs and typically carry out transport with a pump (heart) and other organs and tissues, such as blood vessels and blood. • Both the size of an organism and its level of activity play a role in how complex and efficient this system has to be. 7.4 Circulatory Systems 2

  22. Transport Systems in Animals 7.4 Circulatory Systems (cont.) • Insects, crabs, and other arthropods have an open circulatory system, in which there is no separation between blood and other intercellular fluid. 7.4 Circulatory Systems 3

  23. Transport Systems in Animals 7.4 Circulatory Systems (cont.) • An earthworm has a closed circulatory system, which means that the blood is confined to vessels. • Blood travels through a closed circulatory system more rapidly than it flows through an open system. 7.4 Circulatory Systems 4

  24. Blood with a high concentration of oxygen is shown in red. Blood with a low concentration of oxygen is shown in blue. Transport Systems in Animals 7.5 Circulation in Vertebrates • Humans and other vertebrates have a closed circulatory system, also called the cardiovascular system. • The components of the cardiovascular system are the heart, blood vessels, and blood. 7.5 Circulation in Vertebrates 1

  25. Transport Systems in Animals 7.5 Circulation in Vertebrates (cont.) • The vertebrate heart consists of one or more atria, chambers that receive blood returning to the heart, and one or more ventricles, chambers that pump blood out of the heart. 7.5 Circulation in Vertebrates 2

  26. Transport Systems in Animals 7.5 Circulation in Vertebrates (cont.) • There are three types of blood vessels: • Arteries carry blood away from the heart to organs throughout the body. • Capillaries are the network of microscopic vessels that infiltrate every tissue. • Veins return blood to the heart. 7.5 Circulation in Vertebrates 3

  27. This scanning electron micrograph, x100, of human capillaries lines the wall of the gall bladder. Arteries and veins connect with capillaries by way of smaller vessels or connecting channels. Blood can pass from arteries to connecting channels to capillaries or directly through the connecting channels to veins. 7.5 Circulation in Vertebrates 4

  28. Transport Systems in Animals 7.5 Circulation in Vertebrates (cont.) • Fish have a two-chambered heart with one atrium and one ventricle. 7.5 Circulation in Vertebrates 5

  29. Transport Systems in Animals 7.5 Circulation in Vertebrates (cont.) • Amphibians and most reptiles have a three-chambered heart with two atria and one ventricle. • Oxygenated and deoxygenated blood continually mix in the single ventricle, lowering the level of oxygen reaching the organs of the body. 7.5 Circulation in Vertebrates 6

  30. Transport Systems in Animals 7.5 Circulation in Vertebrates (cont.) • The four-chambered heart found in mammals, birds, and crocodilians has two atria and two completely divided ventricles. • This double circulation system keeps oxygenated blood completely separate from deoxygenated blood which delivers high levels of oxygen. 7.5 Circulation in Vertebrates 7

  31. Transport Systems in Animals 7.6 The Human Heart • Each heartbeat is a sequence of muscle contraction and relaxation called the cardiac cycle. • In each cycle, the four chambers of the human heart go through phases of contraction, or systole, and relaxation, or diastole. 7.6 The Human Heart 1

  32. Blood enters the atria, which contract, forcing blood into the ventricles. The atria relax and fill. The ventricles contract, forcing blood into the pulmonary artery and the aorta. Then, the ventricles relax and the atria contract, repeating the cycle. Transport Systems in Animals 7.6 The Human Heart (cont.) 7.6 The Human Heart 2

  33. Blood flow through the human heart Click the image to view an animated version. 7.6 The Human Heart 3

  34. Transport Systems in Animals 7.7 Molecular Basis of Muscle Contraction • Muscle contractions are produced by a molecular motor largely composed of two proteins called actin and myosin. • Actin filaments are anchored to a structure called a Z-line at each end of the unit. • Myosin filaments contact the actin with rows of globular crossbridges, which bind to the actin. 7.7 Molecular Basis of Muscle Contraction 1

  35. An enzyme uses the energy of ATP to form cross bridges between myosin and actin filaments, causing the muscle to contract. Transport Systems in Animals 7.7 Molecular Basis of Muscle Contraction (cont.) • During contraction, these crossbridges “ratchet” along the actin filaments toward the Z-lines by continually releasing their attachment at one point, changing position, and reattaching at a point farther along. 7.7 Molecular Basis of Muscle Contraction 2

  36. End of Section 2

  37. Regulation and Transport 7.8 Blood Pressure • Blood vessels differ in the amounts of muscle and elastic tissue in their walls: • The largest arteries, which are under high pressure, have walls made up largely of muscle and other elastic tissue. • The walls of smaller arteries are made of muscle and elastic tissue that contract and expand to regulate blood pressure and the flow of blood into different parts of the body. • Veins, which are under lower pressure, have thinner walls with less muscle and elastic tissues than arteries. 7.8 Blood Pressure 1

  38. The structure of blood vessels Click the image to view an animated version. 7.8 Blood Pressure 2

  39. The valves regulate the flow of blood toward the heart. Note that back pressure on the valve tends to keep it closed until the pressure of blood on the other side opens it. Regulation and Transport 7.8 Blood Pressure (cont.) • Valves in the veins prevent blood under lower pressure from flowing backward. 7.8 Blood Pressure 3

  40. Movement of blood in veins is brought about by pressure from adjacent muscles. Compression forces blood in both directions, but valves prevent blood from flowing backward and away from the heart. Regulation and Transport 7.8 Blood Pressure (cont.) • Contraction of the skeletal muscles around the veins and gravity help to push the blood along. 7.8 Blood Pressure 4

  41. Note the change in the distribution of blood supply during rest and exercise. Regulation and Transport 7.8 Blood Pressure (cont.) • A healthy blood pressure is maintained through complex interactions involving hormones and the nervous, excretory, and circulatory systems. • Various organs and tissues of the body respond differently to circulatory signals. 7.8 Blood Pressure 5

  42. Regulation and Transport 7.8 Blood Pressure (cont.) • About 20% of the adult population in the United States has blood pressure constantly higher than the normal range. This is a condition called hypertension. • Hypertension can be controlled by medication prescribed by a physician, regular physical examinations, proper diet, and exercise. 7.8 Blood Pressure 6

  43. Regulation and Transport 7.9 Composition of Blood • Vertebrate blood contains several types of cells suspended in a fluid. • Specialized cells called red blood cells, or erythrocytes, transport oxygen. • Erythrocytes contain an oxygen-carrying red protein called hemoglobin. • Hemoglobin consists of four subunits, each of which carries an iron atom suspended in an organic molecule called a heme group. 7.9 Composition of Blood 1

  44. (a) Erythrocytes moving single file through a human capillary, x2000. (b) Each red erythrocyte contains many molecules of hemoglobin, x6000. (c) Hemoglobin is a large molecule composed of four protein subunits. (d) Each subunit includes an iron-containing heme molecule. 7.9 Composition of Blood 2

  45. Regulation and Transport 7.9 Composition of Blood (cont.) • The iron of heme forms a temporary chemical bond with oxygen, which the erythrocyte transports to body cells. • Human erythrocytes live only about 120 days. Replacement cells are manufactured in the marrow, the soft tissue in the long center of the bones of the body. 7.9 Composition of Blood 3

  46. Cells visible here include erythrocytes, x400, three types of leukocytes (left, center, and right), and platelets (the small particle, upper left). Regulation and Transport 7.9 Composition of Blood (cont.) • Specialized white blood cells, or leukocytes, circulate in the blood and form a line of defense against invading organisms such as bacteria and viruses. • Some types of leukocytes, called macrophages, surround bacteria and absorb them. 7.9 Composition of Blood 4

  47. Regulation and Transport 7.9 Composition of Blood (cont.) • The fluid portion of the blood, called plasma, consists of water, proteins, dissolved ions, amino acids, sugars, and other substances. • Plasma transports: • most of the carbon dioxide generated as a waste product during cell respiration. • digested food from the intestine. • hormones that are secreted by glands. 7.9 Composition of Blood 5

  48. Regulation and Transport 7.9 Composition of Blood (cont.) • Dissolved ions in the plasma help maintain the osmotic balance between the blood and the intercellular fluid. They also help maintain the normal pH of the blood. • The kidneys maintain these plasma ions (also called electrolytes) at precise concentrations. 7.9 Composition of Blood 6

  49. Regulation and Transport 7.9 Composition of Blood (cont.) • Some intercellular fluid is recycled into the circulatory system indirectly by the lymphatic system. • The fluid in the lymphatic system, which contains certain specialized cells, water, large protein molecules, salts, and other substances, is called lymph. 7.9 Composition of Blood 7

  50. Regulation and Transport 7.9 Composition of Blood (cont.) • A vital characteristic of blood is its ability to clot, or coagulate. • Coagulation begins when small cell fragments in the blood, calledplatelets, interact with a protein found in connective tissue that has been exposed at a wound site. 7.9 Composition of Blood 8

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