Chapter 02 Biology PDF

ist10_ch02.qxd 7/22/09 3:25 PM Page 52 An organ consists of groups of tissues and 2 works with other organs to form organ systems. 52 UNIT A Tissues, Organs, and Systems of Living Things ist10_c...

ist10_ch02.qxd 7/22/09 3:25 PM Page 52 An organ consists of groups of tissues and 2 works with other organs to form organ systems. 52 UNIT A Tissues, Organs, and Systems of Living Things ist10_ch02.qxd 7/22/09 3:25 PM Page 53 Skills You Will Use In this chapter, you will: Our complex movements require the interaction of investigate, using a microscope, specialized cells in the tissues, organs, and organ systems. human body or in plants, focussing on different types of cells, and draw labelled biological diagrams to show the cells’ structural differences investigate, through laboratory or computer-simulated dissection of a plant, worm, fish, or frog, the interrelationships between organ systems of a plant or an animal use a research process to investigate a disease or abnormality related to tissues, organs, or systems of humans or plants Concepts You Will Learn In this chapter, you will: explain the links between specialized cells, tissues, organs, and systems in plants and animals explain the primary functions of a variety of systems in animals explain the interaction of different systems within an organism and why such interactions are necessary for the organism’s survival Why It Is Important In this chapter, you will learn how the tissues in your body work together as organs and how your organs work together as organ systems. Understanding your body will help keep you as healthy as possible. Before Reading Synthesizing: Putting the Pieces Together Good readers know that often they have to read several paragraphs or pages of text to put together a whole picture of a topic. They know that each subtopic is really a piece of the puzzle. Preview the headings and subheadings in section 2.1, and write the ones that seem to go together in your notebook. Key Terms absorption capillaries homeostasis interdependent organ organ system An organ consists of groups of tissues and works with other organs to form organ systems. 53 ist10_ch02.qxd 7/22/09 3:25 PM Page 54 2.1 Organs in Animals and Plants Here is a summary of what you will learn in this section: In animals, tissues combine in special ways to form organs. In plants, tissues combine in special ways to form leaves, stems, and roots. Figure 2.1 The organs were removed from Egyptian mummies before the body was preserved and wrapped. What Is an Organ? In ancient times, the Egyptians believed that all parts of a body were required in the afterlife. They developed special procedures to preserve the dead body in the form of a mummy so that it would not decay. They would cleanse the body and remove most of its internal organs because they would decay rapidly. Only the heart was left in place. An organ is an organized group of tissues that performs a specific function. The body was preserved with a drying agent and stuffed with linens and sawdust. The body was then wrapped from head to foot in linen (Figure 2.1). Four organs — the stomach, intestines, liver, and lungs — were placed in special canopic jars, which prevented the organs from decaying (Figure 2.2). The lids of the jars were decorated with four protective spirits known as the four sons of Horus, who was one of the most important Egyptian gods. Each spirit protected a specific organ. Because the ancient Egyptians believed that the heart contained the spirit of the dead person, it was left inside the body. The brain was either left inside the skull or removed through the nose and discarded. The mummy was buried with the canopic jars so that the body could be complete in Figure 2.2 Four canopic jars contained human organs. the afterlife. 54 UNIT A Tissues, Organs, and Systems of Living Things ist10_ch02.qxd 7/22/09 3:25 PM Page 55 The ancient Egyptians believed that only four organs were important. However, there are many organs in the human body: the kidneys, the eyes, the pancreas, the brain, and the skin are all organs. Each organ is made of a group of tissues that work together to perform a specific purpose. For example, the stomach, liver, and intestines are all organs that are involved with the digestion of food and the absorption of nutrients. The lungs are the site of gas exchange involving the intake of oxygen and the output of carbon dioxide. The skin, which is the largest organ in the human body, serves as a barrier against disease. Your kidneys filter wastes from your blood. All of our organs play a vital role in maintaining the health of our bodies. It is important to keep our organs healthy and functioning properly. For example, eating a healthy diet and doing about 30 minutes of physical exercise a day strengthens your heart and lungs. Wearing sunscreen protects your skin from damage caused by the Sun. When an organ does not work properly because of disease or injury, it is sometimes possible to transplant a healthy organ or part of an organ from a donor. Organs that are most often transplanted include the kidney, liver, lungs, and heart. A13 Quick Lab Mapping the Organs The human body is made up of many organs that Procedure work together to accomplish all of the tasks required 1. Work with a partner, and obtain a large piece of in a healthy functioning organism. Some of the organs paper from your teacher. are located on the outside of the body, while others are found internally. To understand the function of 2. Have your partner trace an outline of your body organs, you need to know where they are found in the on the large piece of paper. human body. 3. Brainstorm for two minutes with your partner about the location, relative size, and shape of the Purpose following organs of the human body: stomach, To predict the location, relative size, and shape of lungs, intestines, liver, kidneys, and heart. some organs of the human body, and to record your 4. Draw and label the organs on the traced outline prediction in the form of a diagram of your body. Materials & Equipment Questions large piece of paper pen and/or pencil 5. Compare your completed labelled diagram with ruler the answer key provided by your teacher. Which organs were the easiest to locate correctly? Which organs were the hardest to locate correctly? 6. Explain how so many organs in the human body fit in such a relatively compact space. An organ consists of groups of tissues and works with other organs to form organ systems. 55 ist10_ch02.qxd 7/22/09 3:25 PM Page 56 Animal Organs Suggested STSE Activity Recall that there are four types of animal tissues: epithelial, connective, A14 Decision-Making Analysis Case muscle, and nervous tissue. Tissues join together to form organs that Study on page 61 have specialized functions. For example, skin is an organ that covers and protects your body, while the heart transports materials around your body. Most organs are made of several different tissues. For example, the heart is made of muscle tissue, connective tissue, nervous tissue, and epithelial tissue. Skin W O R D S M AT T E R The largest organ in your body is the skin. The skin protects the inner The word “epidermis” comes from cells from damage, acts as a defence against disease organisms, the Greek word epi, which means on insulates, releases heat, and excretes bodily wastes. The skin is made up the outside, and the word derma, which means skin. of two different layers of tissues: the epidermis and the dermis (Figure 2.3). The epidermis is the outer protective layer that is made up of epithelial tissue. The epidermis prevents bacteria and viruses from entering your body. The epidermis is also able to make vitamin D when the skin is exposed to ultraviolet radiation from the Sun. Vitamin D is essential for bone development. The dermis is the inner layer of the skin and is made up of connective tissue, nervous tissue, and muscle tissue. Connective tissues provide structure and support. Blood and blood vessels are types of connective tissue. When you are hot, the blood vessels in your skin dilate, or become bigger, so that they can release excess heat. Pores in the skin secrete sweat produced in sweat glands to cool the body. Layers of fat, another type of connective tissue at the base of the dermis, provide insulation (Figure 2.4). The dermis contains nerves that sense pain, pressure, heat, and cold and send information to the brain. Muscle tissue in the dermis produces “goosebumps.” hair epidermis sweat pore dermis muscle nerve sweat gland blood vessels Figure 2.4 Mammals, like these harp seals, that live in the Arctic have thick layers of fat in the Figure 2.3 A cross section of skin showing the tissues and some of the dermis to provide insulation. accessory structures, such as hair and sweat glands. 56 UNIT A Tissues, Organs, and Systems of Living Things ist10_ch02.qxd 7/22/09 3:25 PM Page 57 Lung The lungs are a pair of organs involved in respiration (Figure 2.5). Your lungs allow you to breathe in oxygen and breathe out carbon dioxide. Cells need oxygen to function. In an adult human, one lung is about 1 kg. The lung is made of connective and epithelial tissue. Humans have two lungs that sit in a cavity in the chest area. The lungs are coated with two sacs of connective tissue separated by a thin layer of fluid. This not only protects the lungs but also reduces the effects of friction when the lungs move. pharynx nose larynx mouth trachea lung bronchiole epiglottis bronchus alveoli bronchioles artery vein Figure 2.5 In the lungs, the air travels capillaries through smaller tubes called bronchioles. The bronchioles end in alveoli. to body aorta When you breathe in air through your nose or mouth, the air passes through the pharynx into your trachea. The trachea is a flexible tube from body that is ringed with cartilage. Air moves down the trachea to the bronchus, into smaller bronchial tubes, and then into tiny air to lung left atrium sacs, called alveoli, which are made of a thin layer of epithelial from lung from lung tissue. Alveoli are surrounded by thin-walled blood vessels called capillaries (Figure 2.5). Each lung contains about 150 million right atrium alveoli. Oxygen travels from the alveoli through the capillaries into the blood. Carbon dioxide travels from the bloodstream left across the alveoli to the air in the alveoli. ventricle from body right Heart ventricle The heart is a muscular pump that supplies blood to all parts of Figure 2.6 The right side of the heart the body. An adult human heart is about 300 g and is the size of (right atria and right ventricle) pumps a fist. In an average lifetime, the heart beats about 3.5 billion times. The blood to the lungs so that the blood heart is divided into four chambers: the left and right atria, and the left can pick up oxygen. The left side of the heart (left atria and left ventricle) and right ventricles. The heart serves as a pump to deliver blood to the pumps the oxygenated blood through lungs, to the heart itself, and to the rest of the body (Figure 2.6). the aorta to the rest of the body. An organ consists of groups of tissues and works with other organs to form organ systems. 57 ist10_ch02.qxd 7/22/09 3:25 PM Page 58 Organs of Digestion When you eat, various organs assist with the digestive functions to break down the food (Figure 2.7). For example, your mouth takes in food and begins digestion. The mouth is lined with epithelial tissue. There are also glands, made of specialized epithelial cells, that secrete mucus, saliva, and enzymes. The tongue is made of epithelial tissues and glands, connective tissues, and muscle tissue. Once the food enters During Reading your body, it travels from the mouth down a tube called the esophagus. The food moves along the esophagus because of the rhythmic Reread to Synthesize constriction and relaxation of the smooth muscles that line the Reread the subtopics about esophagus. This movement is known as peristalsis. The esophagus is animal organs. Think about how lined with a protective layer of epithelial tissue. Further down the these subtopics fit together and canal, food enters the stomach, which is made of epithelial, connective, how one organ connects to nervous, and muscle tissues (Figure 2.8). The stomach churns food and another. Create a mind map of the mixes it with digestive juices and enzymes. Finally, the digested organs, using lines and arrows to nutrients and undigested waste products move into the small and large show which organs connect. intestines, which are areas of chemical digestion and removal of Label the arrows with explanations wastes. Solid wastes are stored in the rectum and exit the body through of the connections. the anus. stomach esophagus mouth tongue esophagus liver stomach gall bladder pancreas large small muscle tissue layers intestine intestine folds of epithelial tissue rectum intestine Figure 2.7 Organs of digestion Figure 2.8 The stomach is made of smooth muscle and epithelial tissue as well as connective tissue and nervous tissue (not shown). 58 UNIT A Tissues, Organs, and Systems of Living Things ist10_ch02.qxd 7/22/09 3:25 PM Page 59 Plant Organs flower A flowering plant is made up of four types of plant tissues: epidermal, ground, vascular, and meristematic. These plant tissues group together to form organs that perform special functions for the plant. The organs in a plant are the roots, the leaves, the stem, and the flower or fruit (Figure 2.9). leaf The Roots stem The roots anchor the plant in the soil, which permits the plant to grow above the soil without toppling over. Roots also collect water from the root surrounding soil and transport it to the stem, and store food that is made in other parts of the plant. Different tissues in the root work together to accomplish these functions. The bottom of the root is covered with protective epidermal tissue known as the root cap. Just below the epidermal tissue is a layer of meristematic tissue, which Figure 2.9 Groups of plant tissues allows the root to grow. There are also layers of ground tissue and form organs that perform specialized vascular tissue that make up the centre of the root. functions in a plant. The Leaf The tissues in a leaf work together to accomplish photosynthesis, a chemical reaction in which carbon dioxide and water are converted into sugar and oxygen. The vascular tissue carries water needed for photosynthesis from the root up the stem to the leaf. The sugar produced is carried by the vascular tissues to the rest of the plant. Carbon dioxide enters, and oxygen and excess water exit through openings in the leaf epidermal tissue called stomata. These openings are controlled by special cells known as guard cells. Most of the leaf is made of a specialized ground tissue called mesophyll. Photosynthesis takes place in the mesophyll. Figure 2.10 shows the tissues in a leaf. cuticle epidermal tissue xylem vascular tissue phloem mesophyll epidermal tissue Figure 2.10 A cross section of stomate a leaf showing the tissues guard cells An organ consists of groups of tissues and works with other organs to form organ systems. 59 ist10_ch02.qxd 7/22/09 3:25 PM Page 60 The Stem The stem performs two major functions: transports water and nutrients throughout the plant supports the leaves and flowers Suggested Activity The tissues that make up the stem reflect these functions. A15 Inquiry Activity on page 62 Epidermal tissue provides a protective covering and allows for the exchange of gases and water vapour. In most plants, the epidermal tissue secretes a waxy substance known as the cuticle that forms a protective coating and reduces water loss. Ground tissue provides the stem with strength and support. Vascular tissue transports substances around the plant. anther stigma The Flower stamen filament style The flower is the reproductive structure of the plant. The main pistil function of the flower is to produce seeds through sexual reproduction. The flower contains male organs, called stamens. ovary Each stamen consists of a filament with an anther at the tip. The anther produces pollen, which are the male sex cells. The flower also contains female organs, called the pistil, which consists of the ovary, style, and stigma. Female sex cells, called eggs, are located in the ovary. Figure 2.11 shows the reproductive organs of a plant. When the pollen and an egg unite, the fertilized egg becomes a seed. Some seeds are surrounded by flesh and are called the fruit. Figure 2.11 A flower’s reproductive organs Other types of seeds have no fleshy covering but are encased in a hard shell. Like other parts of the plant, new cells are made from meristematic tissue. As the flower structures develop, the unspecialized meristematic tissue differentiates to form the other parts of the flower, such as the sepals and the stamen. Learning Checkpoint Take It Further Carnivorous plants have the 1. What are the three functions of the roots? unique ability to capture and 2. Describe the major job of the leaf, and explain how two tissues in the leaf work digest prey. The interactions of the cells, tissues, and organs are together to accomplish this job. intriguing. Select a carnivorous 3. Describe two functions of a stem, and explain how the tissues in the stem work plant to study. Explain how the together to accomplish one of the stem functions. plant captures, digests, and processes the nutrients in the 4. What is the major function of a flower? prey. Report your findings to the 5. Sketch a plant showing the root, stem, leaves, and flower. Use a system of class. Begin your research at colour coding or symbols to indicate the location of epidermal tissue, vascular ScienceSource. tissue, and ground tissue. 60 UNIT A Tissues, Organs, and Systems of Living Things ist10_ch02.qxd 7/22/09 3:25 PM Page 61 CASE STUDY SKILLS YOU WILL USE A14 STSE Decision-Making Analysis Skills Reference 4   Identifying issues to explore Justifying conclusions A Look at Stem Cells Issue Analyze and Evaluate Over 40 years ago, Canadian researchers Dr. James 1. Identify the different types of stem cells (from Till and Dr. Ernest McCulloch discovered the existence Chapter 1), and explain how stem cells can be of stem cells in the blood. Stem cells are used in the treatment of diseases. unspecialized cells (Figure 2.13). They have the ability 2. There are many different viewpoints about the use to become any type of cell and, thus, can form skin, of stem cells. Prepare a graphic organizer that bones, and organs. This ability makes stem cells presents the position from one of the following perfect to repair or replace cells that are damaged or points of view: defective. Scientists believe that stem cells may be used to cure diseases of tissues and organs, such as a research scientist Parkinson’s and Alzheimer’s disease, multiple Michael J. Fox sclerosis, cancer, diabetes, and heart and lung a pharmaceutical company/biotech company disease. However, controversy surrounds the use of owner stem cells because the human embryo is the best a public health official source for stem cells. 3. ScienceSource Research how stem cells are used in the treatment of a specific disease or disorder. Background Information Include both the advantages and the Michael J. Fox is a Canadian actor who is best known disadvantages that are associated with the use of for the Back to the Future series of movies. In 1998, stem cells in the treatment of the disease or Fox revealed that he had Parkinson’s disease, which disorder. affects the nervous system and causes people to lose 4. Web 2.0 Develop your research as a Wiki, a control over their muscles. In 2001, Fox launched the presentation, a video, or a podcast. For support, Michael J. Fox Foundation for Parkinson’s Research to go to ScienceSource. raise funds and awareness about Parkinson’s disease. Fox is hopeful that embryonic stem cells may cure Skill Practice Parkinson’s disease. 5. Explain how the ethical issues associated with the Canada has developed strict guidelines use of adult stem cells are different than those surrounding the use of stem cells. Only embryos that associated with the use of embryonic stem cells. are less than 14 days old and that are no longer wanted for reproduction may be used. This means that, in Canada, creating human embryos for stem cell research is not allowed. So far, stem cell research has been done only on lab animals. Using stem cells has improved stroke recovery in rats, treated a disease similar to Parkinson’s in mice, and caused new brain cells to grow in birds. In 2007, a Canadian research team led by Dr. Freda Miller used skin-derived stem cells to repair spinal cord injuries in rats. Figure 2.13 Stem cells An organ consists of groups of tissues and works with other organs to form organ systems. 61 ist10_ch02.qxd 7/22/09 3:25 PM Page 62 SKILLS YOU WILL USE A15 Inquiry Activity Skills References 2, 6  Using equipment, materials, and technology accurately and safely  Observing, and recording observations Dissecting a Flower Flowers vary greatly in their structure and appearance. Analyzing and Interpreting For centuries, flowers have been prized for their 7. Describe the appearance of the petals. Explain beauty and also used as a source of food and how flower petals are adapted to attract pollinators medicine. The flower is the reproductive organ of a to the plant. flowering plant. 8. The pollen of grasses and trees is usually carried Question by the wind. Explain how the structure of grass How is the flower designed for reproduction? pollen may differ from the pollen of a rose. 9. Describe the appearance of the stigma. Explain Materials & Equipment how the structure and location of the stigma is important to the process of reproduction. flower, such as a lily, tweezers tulip, daffodil, or pen and/or pencil Skill Practice gladiolus 10. Explain how dissecting a flower helps you to understand its function. CAUTION: If you are allergic to plants or pollen, let your teacher know. Forming Conclusions 11. Give evidence from your observations to show how Procedure the flower’s structure is suited to the task of 1. Obtain a single flower, and observe the parts reproduction. carefully. Compare your flower with the labelled diagram (Figure 2.12). Make a sketch of each stamen part of the flower, and include notes about the pistil stigma appearance of each part. anther style filament 2. Locate the sepals. Using the tweezers, gently ovary remove the sepals and place them on a paper. 3. Petals are found directly under the sepals. Gently remove the petals, and place them on the paper next to the sepals. 4. Locate the stamens. They may be attached to the ovary or petals. Identify the anther and any pollen sacs that are visible. Make notes about the appearance of each part. 5. Locate the pistil. Identify the stigma, style, and ovary. Make notes about the appearance of each ovary part. 6. Clean up your work area. Make sure to follow your petal teacher’s directions for safe disposal of materials. sepal Wash your hands thoroughly. ovule Figure 2.12 The parts of a flower 62 UNIT A Tissues, Organs, and Systems of Living Things ist10_ch02.qxd 7/22/09 3:25 PM Page 63 2.1 CHECK and REFLECT Key Concept Review 9. Why are so many organs made of connective tissue and epithelial tissue? 1. What is an organ? Give an example of an animal organ and a plant organ. 10. In what three organs would you expect to find muscle tissue? 2. (a) What tissue in the skin provides a layer of protection? 11. Explain why Canadians may be advised to (b) Explain how the tissues in the dermis take a vitamin D supplement during the work together to permit you to respond to winter months. environmental changes. 12. Why would a serious lung infection make you 3. (a) What tissues are found in the lung? feel tired? (b) What is their function in the lung? 13. Explain why it is beneficial to have the heart and the lungs in close proximity. 4. (a) What is the function of the heart? (b) Explain how the heart performs this 14. Give a reason why plants have only a few function. organs while animals have many organs. 5. What are the functions of the stomach and 15. Use a flowchart to show how gas is exchanged intestines? in a leaf. Be sure to name specific tissues. 6. What is a fruit? 16. You wish to move a plant from one location in your garden to another location. Explain 7. Describe the function of a flower in a what would happen to the plant if the roots flowering plant. were damaged during the move. 17. You may be familiar with the job of a security Connect Your Understanding guard or a bodyguard. Explain why the name 8. The photo below shows an electron “guard cell” is appropriate for these cells in micrograph of lung tissue. In the upper centre the leaf. of the micrograph, you can see a capillary filled with red blood cells. The ducts 18. Explain what would happen if plants were surrounding the capillary are the endings of not covered with epidermal tissue. the bronchioles. Explain how the structure of the lung allows for the exchange of oxygen Reflection and carbon dioxide. 19. State two facts that you learned in this section that will influence your choices and behaviour in the coming year. For more questions, go to ScienceSource. Question 8 An organ consists of groups of tissues and works with other organs to form organ systems. 63 ist10_ch02.qxd 7/22/09 3:25 PM Page 64 2.2 Organ Systems in Animals and Plants Here is a summary of what you will learn in this section: Organs function together to form organ systems. Organ systems perform one or more functions in the human body. Organ systems work together to accomplish movement, support, protection, communication, transport, reproduction, digestion, gas exchange, and waste removal. Plants have two organ systems that function in an interdependent fashion. Figure 2.14 The star-nosed mole is an efficient predator because its organ systems work together. Organs Working Together The star-nosed mole (Figure 2.14) may be one of the strangest-looking creatures on Earth, but it is also one of the most efficient predators. It can find and eat prey — including worms and insects — in less than one second! The mole is built not only to be able to find and obtain food quickly but also to escape from harm and danger quickly. The star-nosed mole can be found in eastern North America. In Canada, the star-nosed mole’s range is from Atlantic Canada to eastern Manitoba. In the U.S., the mole ranges along the Atlantic coast to northern Florida. However, people rarely see the star-nosed mole because it lives only in marshes and wetlands. The body of the mole is elongated and covered in dark fur. This body shape is ideal for moving through the soil and the water. The dark colour of fur traps heat and keeps the mole warm while it is swimming in icy water. The limbs of the mole are strong and enable the mole to dig and swim effectively. The mole finds food by digging tunnels in the soil. While digging, the mole is able to move quickly in complex ways by kicking, brushing, and pushing dirt with its back legs. The unusual star on the nose of this mole is a touch organ, formed from 22 tentacles (Figure 2.15). Each tentacle is covered with sensory receptors, called Eimer’s organs. The Figure 2.15 A star-nosed mole tentacles are used to touch objects near the mole. When a mole touches blowing a bubble from its nose. The mole will then inhale the bubble to something that may be food, it needs less than a quarter of a second to smell underwater. identify it, decide if it is edible, and eat it. 64 UNIT A Tissues, Organs, and Systems of Living Things ist10_ch02.qxd 7/22/09 3:25 PM Page 65 The star-nosed mole is a good example of how different organs work together in an organism to accomplish the many varied tasks needed for survival. Organs that function together form organ systems, such as the nervous system or the muscular system. Each organ system consists of a group of organs that work together to carry out specific duties in the body. For example, for the star-nosed mole to find food quickly, the nervous system, which for the mole includes its star appendage, works with its muscular system and its skeletal system to enable the mole to move quickly and efficiently. In other words, the brain coordinates the movements of the muscles and bones so that the mole can react quickly to messages picked up by its star appendage. A16 Quick Lab Moving Materials Materials & Equipment The process of digestion involves several organs. nylon stocking (open at both ends) Each of the organs plays a special role in the digestive an orange process (Table 2.1). To understand the digestive process and how materials move through the Purpose digestive organs, we can use a model of the digestive To investigate a model of the digestive system to system. understand how materials move through the digestive tube Table 2.1 Digestive Organs and Their Functions Digestive Organ Function Procedure mouth physical digestion through action of 1. Form small groups of three to four students. teeth, tongue, and saliva Obtain the materials from your teacher. chemical digestion of sugars using salivary enzymes 2. Review the function(s) of the digestive organs listed in Table 2.1. esophagus movement of food in rhythmic waves known as peristalsis 3. Place the orange in the stocking, and attempt to stomach physical digestion through churning move the orange through the stocking efficiently. action and mixing with digestive juices (acids and enzymes) 4. Record the strategies that you and your group chemical digestion of protein through used to move the orange from one end of the the action of enzymes stocking to the other. liver secretes bile, which breaks up fat to aid absorption, into the intestine Questions pancreas secretes pancreatic juice, insulin, 5. What problems did you encounter when you were and enzymes into the intestine moving the orange from one end of the stocking intestines completes chemical digestion of food to the other? using enzymes reabsorbs water 6. The orange and the stocking can be used as a absorption of nutrients through large model of how digested food moves through the surface area digestive system. How is this model similar to the rectum and storage of waste material until movement of materials through the digestive anus elimination occurs tube? How is this model different? An organ consists of groups of tissues and works with other organs to form organ systems. 65 ist10_ch02.qxd 7/22/09 3:25 PM Page 66 Animal Organ Systems You may have gone to a potluck dinner where every guest brings something that contributes to the meal. For example, someone may bring the salad, while another person brings the main dish, and someone else brings the dessert. The success of the dinner depends on everyone bringing something to the dinner. We can think of an organ system as being similar to a potluck dinner. Just as each person contributes something to the dinner, each organ performs a function in an organ system. Biologists categorize organ systems according to their main functions. There are 11 main organ systems in the human body (Figure 2.16). Table 2.2 summarizes the basic functions of these organ systems. In this section, we will concentrate on the following five organ systems: integumentary, digestive, respiratory, circulatory, and excretory. Integumentary System Skeletal System Muscular System Digestive System Respiratory System Circulatory System Nervous System Figure 2.16 The 11 organ systems in the human body 66 UNIT A Tissues, Organs, and Systems of Living Things ist10_ch02.qxd 7/22/09 3:25 PM Page 67 Table 2.2 Basic Functions of Organ Systems Organ System Organs Involved Basic Function integumentary system skin, hair, nails, glands covers and protects body glands help control body temperature skeletal system bones, cartilage supports body allows movement protects the body muscular system skeletal muscle, smooth muscle, cardiac muscle, works with skeletal system to provide movement tendons, ligaments moves materials within body digestive system mouth, esophagus, stomach, pancreas, gall ingestion bladder, liver, intestines, rectum digestion absorption of nutrients elimination of solid wastes respiratory system nose, mouth, trachea, lungs, bronchi, bronchioles, exchange of gases alveoli, diaphragm circulatory system heart, blood vessels, blood transportation of materials (such as oxygen, nutrients, hormones, and wastes) within body nervous system brain, nerves, spinal cord controls body functions coordinates responses and activities endocrine system glands (pituitary, hypothalamus, thyroid, adrenals), controls growth and development pancreas, ovaries (in females), testes (in males) controls metabolism excretory system skin, kidney, bladder, ureter, urethra elimination of wastes reproductive system ovaries, fallopian tubes, vagina, uterus (in females); reproduction testes, epididymis, vas deferens, penis, urethra (in males) lymphatic system white blood cells, thymus, spleen, lymph nodes, protects body from disease lymph vessels circulates fluid called lymph absorbs and transports fats Endocrine System Excretory System Reproductive System Lymphatic System An organ consists of groups of tissues and works with other organs to form organ systems. 67 ist10_ch02.qxd 7/22/09 3:25 PM Page 68 The Integumentary System The most visible organ system is the integumentary system. It is made up of skin (epidermis and dermis) and accessory structures. Accessory structures include horns, antlers, hooves, quills, claws, hair, and nails. Various glands, including sweat glands, sebaceous (oil) glands, and scent glands are also part of the integumentary system. Figure 2.17 shows the human integumentary system. Skin glands produce fluids that serve different purposes. For example, sweat glands secrete sweat, a clear fluid made of water and body salts. Evaporation of sweat cools the body when it is overheated. Sebaceous glands produce oil that lubricates, waterproofs, and helps prevent skin infections. When the sebaceous glands become plugged with dirt and excess oil, a blackhead forms. Figure 2.17 The integumentary system The Digestive System In humans, the digestive system is essentially a tube that extends from the mouth to the anus (Figure 2.18). The digestive system transports nutrients through the body. In humans, the food passes from the Suggested Activity A18 Inquiry Activity on page 74 mouth, down the esophagus, into the stomach, through the small and large intestine, to the rectum. The major function of the digestive system is the absorption of nutrients. Absorption is the process by which food that has already been broken down passes through the walls of the intestine into the bloodstream. Absorption takes place mainly in the small intestine. Refer to Table 2.1 on page 65 to review the roles that the various organs play in human digestion. The Digestive System of an Earthworm Not all animals have a digestive system that is similar to humans. For example, earthworms are segmented worms that live in soil (Figure 2.19). As an earthworm moves through the soil, it takes in dirt through its mouth. The food is pushed by muscular contractions through the esophagus to the crop. The food then moves into the muscular gizzard, which grinds the food into smaller pieces. The food is then pushed into the intestines, where digestion and absorption of nutrients occur. Waste material is expelled through the anus. Figure 2.18 The digestive system Figure 2.19 An earthworm 68 UNIT A Tissues, Organs, and Systems of Living Things ist10_ch02.qxd 7/22/09 3:25 PM Page 69 Figure 2.20 Yellow perch Figure 2.21 North American bullfrog The Digestive System of a Fish During Reading Fish have a unique digestive system. For example, the yellow perch eats insects and other small organisms (Figure 2.20). The perch’s mouth has A Venn Diagram Synthesizes small sharp teeth that enable it to grasp its prey. Food passes from the Similarities and Differences mouth down the esophagus into the stomach, where the food is broken Every living creature has a down. Some fish have a special pouch, called the pyloric caecum, which digestive system. Create a triple further breaks down the food and absorbs the nutrients. Digestion is Venn diagram for the earthworm, completed in the intestine. the fish, and the frog. In the overlapping part of the circles, put The Digestive System of a Frog the features or actions of the Adult frogs are carnivores that will eat anything that they can catch digestive systems that are similar. (Figure 2.21). A frog’s tongue is attached to the front of the mouth so In the outer parts of the circles, that it can capture flying insects effectively. It has two sets of teeth that put the features or actions that it uses to hold prey. When the frog swallows, it closes its eyes and are different. pushes its eyes downward. This action causes pressure on the roof of the mouth, which forces the food to move into the gullet. The food travels down the esophagus to the stomach and then to the intestines. Waste materials exit the body through an opening called the cloaca. The Respiratory System Each cell in your body requires oxygen to carry out various life processes including growth, movement, and reproduction. Oxygen is also required to break down food to produce energy: this chemical process is known as cellular respiration. The function of the respiratory system is to obtain oxygen and release carbon dioxide. When you inhale, you take in air through either your nose or mouth. The air passes down the trachea into the bronchus to the bronchioles. The bronchioles empty into the alveoli, which are surrounded by thin-walled blood vessels. The alveoli are the sites of gas exchange. Figure 2.22 shows the organs involved in the human respiratory system. Figure 2.22 The respiratory system An organ consists of groups of tissues and works with other organs to form organ systems. 69 ist10_ch02.qxd 7/22/09 3:25 PM Page 70 Breathing Suggested Activities Your lungs are housed in your chest cavity, which is enclosed by the A19 Quick Lab on page 76 ribs, chest muscles, and the diaphragm. When you inhale, your rib cage A20 Quick Lab on page 76 rises and your diaphragm contracts and moves downward, which increases the size of your chest cavity. An increase in the volume of the cavity causes a decrease in the internal air pressure in the cavity. Because the internal air pressure of the cavity is less than the air pressure in the environment, air rushes into your lungs to equalize the pressure. When you exhale, your rib cage lowers and your diaphragm relaxes and moves upward, decreasing the size of your chest cavity. The decrease in the volume of the cavity causes an increase in the internal air pressure in the cavity. Since the internal air pressure is higher than the pressure in the environment, air moves out of your lungs. Figure 2.23 shows the movement of the diaphragm during breathing. air air inhaled exhaled Figure 2.23 During inhalation, the chest cavity expands as the rib cage rises and the diaphragm contracts. rib cage During exhalation, the rib cage lowers rib cage lowers and the diaphragm relaxes, which rises decreases the size of the chest cavity. diaphragm diaphragm inhalation exhalation The Circulatory System The circulatory system is the blood’s transportation system (Figure 2.24). The circulatory system includes the heart, blood, and blood vessels. The heart acts as a pump to transport and regulate the flow of blood through a series of blood vessels: arteries, veins, and capillaries. Arteries are thick-walled vessels that carry blood away from the heart to the tissues. The thickened muscular walls of the arteries allow them to withstand the force of the blood that is pumped from the heart. Veins carry blood back to the heart. The blood flowing through the veins is at a lower pressure than that in the arteries. Therefore, veins have thinner walls than arteries. Veins also contain valves so that the blood does not flow backward. Arteries do not contain valves because the blood flow is pushed along by the blood pumped by the heart. A Figure 2.24 The circulatory system network of capillaries connects veins and arteries. 70 UNIT A Tissues, Organs, and Systems of Living Things ist10_ch02.qxd 7/22/09 3:25 PM Page 71 Capillaries Capillaries are the smallest blood vessels in your body; they are O2 about one cell thick. Oxygen (O2) and carbon dioxide (CO2) alveolus flow in and out of capillaries by the process of diffusion (Figure 2.25). Diffusion is the movement of a substance from CO2 an area of high concentration to an area of low concentration. If the blood has more oxygen than the tissues, oxygen will diffuse across the capillary walls and enter the tissues. Carbon dioxide and other wastes are also removed from tissues by diffusion. If the tissues have more carbon dioxide than the blood, the carbon dioxide diffuses across the capillary walls capillary and enters the blood. The blood then carries the carbon dioxide to the lungs, where it is released as you exhale. Figure 2.25 Gas exchange between a capillary and the membrane of an alveolus The Excretory System The excretory system consists of the kidneys, ureters, urinary bladder, urethra, and skin (Figure 2.26). This system filters waste products from the blood and maintains the proper levels of water and electrolytes in the body. As blood flows through your kidneys, wastes such as urea, carbon dioxide, and water are removed by filters called nephrons. These wastes form a fluid called urine. The urine moves out of the kidneys down the ureters to the urinary bladder, where it is stored until it can be eliminated. Elimination occurs when urine travels through the urethra and out of the body. The skin is considered to be part of the excretory system because it excretes water, salts, and urea in sweat. Learning Checkpoint Figure 2.26 The excretory system 1. What organs in the digestive system are common to the earthworm, perch, and frog? 2. Name one structure that is unique to the digestive system of the earthworm, perch, and frog. 3. What is the diaphragm, and how is it involved in breathing? 4. Explain the role of diffusion in the process of gas exchange. 5. Explain how the excretory system eliminates waste. An organ consists of groups of tissues and works with other organs to form organ systems. 71 ist10_ch02.qxd 7/22/09 3:25 PM Page 72 Plant Organ Systems A plant has two organ systems: a shoot system and a root system (Figure 2.27). The shoot system is everything that is above ground: the stem, leaves, buds, flowers, and fruits. The root system is everything underground, as well as aerial roots even though they are above ground. To understand the interdependence between the shoot and root system, consider how water is transported through the plant. Both the roots and the shoots play a role in moving water through a plant. shoot A plant’s roots can push water up the stem. However, the roots can only push the water a few metres and many plants are over 100 m tall. Water enters the root hairs and travels to the xylem. Once the water is in the xylem, it is moved against gravity up the stem to the leaves through transpiration. Transpiration is the evaporation of water through the stomata in the leaves. As each water molecule evaporates, it creates a transpiration pull on the adjacent water molecules, which root pulls the water up the xylem to the leaves. Once the water reaches the leaf, the transpiration pull is enough to move the water from the xylem into the ground tissue. The leaves lose a high proportion of the water because of evaporation through the stomata. This evaporation Figure 2.27 A tomato plant’s organ maintains the transpiration pull, and water is continuously drawn up systems the stem. Figure 2.28 shows the direction of water movement. The organs of a plant also work together to ensure that the plant survives changes in the environment. For example, some specialized cells record changes in the exposure to light. When the length of daylight increases, chemical messages are delivered to tissues to stimulate the production of a flower. Sometimes, in times of drought and excessive heat, a plant may decrease its production of leaves. Take It Further The tobacco mosaic virus is responsible for severe damage to many Ontario crops. The virus causes changes to a plant’s shoot system including the formation of a mosaic pattern on the leaves. The damage to the leaves stresses the plant and results in stunted plant growth. The study of this virus has helped scientists to learn about diseases of plant organ systems and viruses. Learn more about which Ontario food crops are affected by this virus and how flow of water this virus affects Ontario food crops. Report back to the class. Begin your research at Figure 2.28 Water in a tree flows from the roots ScienceSource. to the leaves. 72 UNIT A Tissues, Organs, and Systems of Living Things ist10_ch02.qxd 7/22/09 3:25 PM Page 73 A17 Skill Builder Activity Dissection Essentials There are some important terms that are used in 2. The front-facing side of the cucumber is the dissection. You will learn these terms while dissecting ventral side. The back side of the cucumber is a vegetable. called the dorsal side. We can think of the ventral side as the stomach side. Refer to Figure 2.29(b). 3. Locate the anterior end, and use a scalpel to make a shallow cut along the ventral side of the Materials & Equipment cucumber to the posterior end. This is known as a cucumber pen and/or pencil sagittal cut. If you cut the cucumber all the way paper towel scalpel through, you would make a sagittal section. paper 4. Make a shallow cut that is midway on the ventral side. Extend the cut from left to right. This type of cut is known as transverse. If you were to cut all of CAUTION: If you are allergic to plants or pollen, let your teacher know. To avoid injury, use proper techniques the way through the cucumber, you would make a when using the scalpel. transverse section of the cucumber. 5. Make a sketch of your cucumber, and label with Procedure the terms that you have learned. 6. Clean up your work area. Make sure to follow your 1. Obtain a cucumber, and cut out two holes in one teacher’s directions for safe disposal of materials. side. These holes represent the eyes. The top of Wash your hands thoroughly. the cucumber is known as the anterior, or cranial. The other end of the cucumber is the posterior, or caudal. Refer to Figure 2.29(a). anterior (cranial) sagittal section transverse section dorsal ventral Figure 2.29 A view of a cucumber showing (a) the anterior and posterior end and (b) the orientation of the posterior (caudal) transverse and sagittal (a) (b) sections. An organ consists of groups of tissues and works with other organs to form organ systems. 73 ist10_ch02.qxd 7/22/09 3:25 PM Page 74 SKILLS YOU WILL USE DI Key Activity A18 Inquiry Activity Skills References 2, 6  Adapting or extending procedures  Interpreting data/information to identify patterns or relationships The Digestive System of an Animal An animal is able to process and absorb nutrients in Procedure the food using its digestive system. Digestive systems vary in animals. Biologists have found that particular Part 1 — Digestive System of the animals, such as the earthworm, perch, and frog, are Earthworm good representatives of the increasing complexity in 1. Since the organs are small, it is helpful if you are digestive systems. familiar with their position in the earthworm before In this activity, you will study these three digestive you begin your dissection. Complete a diagram of systems through dissection. You may do the dissection the earthworm digestive system based on Figure with preserved specimens of an earthworm and perch 2.30. When you are finished with your diagram, or use a virtual dissection program. You may choose to complete a virtual dissection of an earthworm by do only one dissection, or you may do all three to following the instructions in the program, or obtain compare the systems. a preserved specimen of an earthworm, dissection Question tools, and dissection pan. Rinse your specimen with water, and pat dry. How does the digestive system of the earthworm, the perch, and the frog accomplish the process of 2. Using the hand lens, examine the external digestion? structure of the earthworm so that you can identify the prostomium, clitellum, setae, and anus. The prostomium is in front of the mouth. The clitellum looks like a saddle and is on the dorsal side of the earthworm. The setae are tiny bristles found on Materials & Equipment the ventral side. The anus is found on the ventral paper towels dissecting pins side of the last segment of the worm. preserved specimens of forceps 3. Place the earthworm so that the dorsal side is earthworm and perch virtual dissection facing up. Using your scissors, make a shallow hand lens program for cut on the dorsal side from the clitellum to the scalpel or dissecting earthworm, perch, prostomium. scissors and frog probe pen and/or pencil dissecting tray paper anus setae CAUTION: To avoid injury, use proper techniques when using the scalpel. intestine gizzard crop esophagus clitellum mouth Figure 2.30 The external and internal anatomy of the earthworm 74 UNIT A Tissues, Organs, and Systems of Living Things ist10_ch02.qxd 7/22/09 3:25 PM Page 75 A18 Inquiry Activity (continued) 4. Separate the tissue, and use dissecting pins to pin 10. Create a flap through the muscle wall. Make an the body wall down to the tray. You may need to incision from the bottom of the gill cover along the cut through the tissue that holds the body wall. ventral side to the anal opening. Continue the 5. Locate the mouth, esophagus, crop, gizzard, incision up from the anal opening to the lateral intestine, and anus using Figure 2.30. line and then along that line to the head of the fish. Finish your flap by extending your incision 6. Clean up your work area. Make sure to follow your back to the base of the gill cover. teacher’s directions for safe disposal of materials. Wash your hands thoroughly. 11. Lift the flap of muscle wall to look at the organs of the perch. If you have a female perch, the area Part 2 — Digestive System of the Perch may be filled with eggs. If this is the case, you should remove the mass of eggs before 7. Complete a diagram of the perch digestive system proceeding. If the perch is male, the testes will be based on Figure 2.31. When you are finished with smaller and lighter in colour. Locate the liver (light your diagram, complete a virtual dissection of a brown), gall bladder (olive colour), esophagus, perch or obtain a preserved specimen of a perch, stomach, pyloric caeca, and intestines. dissection tools, and dissection pan. Rinse your specimen with water, and pat dry. 12. Clean up your work area. Make sure to follow your teacher’s directions for safe disposal of materials. 8. Observe the external structure of the perch. Note Wash your hands thoroughly. the position and number of fins. Find the lateral line, and locate the gill cover and anal opening. Part 3 — Digestive System of the Frog 9. Examine the mouth of the perch. 13. Complete a virtual dissection of a frog. Identify the mouth parts, liver, gall bladder, stomach, pancreas, small and large intestine, and cloaca. spiny dorsal fin Analyzing and Interpreting gill cover lateral line 14. How is the mouth specialized? 15. Explain how the structure of the intestines is related to their role in digestion. esophagus heart stomach 16. Why do you think the gall bladder is located so gall bladder intestines swim bladder liver pyloric caeca anus close to the liver? Explain your answer. Skill Practice Figure 2.31 The external and internal anatomy of the perch 17. Describe one problem that you encountered in performing the dissection, and explain how you solved the problem. Forming Conclusions 18. How is the digestive system of the worm, the perch, and the frog each suited to its habitat? An organ consists of groups of tissues and works with other organs to form organ systems. 75 ist10_ch02.qxd 7/22/09 3:25 PM Page 76 A19 Quick Lab A Look at Breathing When you breathe, you move about 500 mL of air in and Procedure out of your lungs. Usually we are not aware of our 1. Work in pairs. One partner sits in a chair and bre