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1 The organization of the human body FIND OUT ABOUT • Levels of organization. • The chemical composition of living things. • Cells: the basic unit of living things. An implant in the inner ear stimulates nerve fibres that convert acoustic signals into electrical signals. • Prokaryotic cells. • Eukaryotic cells. • Cell organelles and structures. • Human tissue. • Organs and organ systems. KNOW HOW TO • Observe animal cells under the microscope. • Identify cells and cell structures in micrographs. Artificial blood runs through tubes. The blood is made with nanoparticles. Like real blood, nanoparticles bind to oxygen and carry it throughout the body. WORK WITH THE IMAGE • Ask a classmate about parts of this prototype: What is ... like? What does ... do? • Describe a feature of the bionic man: It is like ... It converts/enables/sends ... Your classmate names the part. • Why doesn't Rex have organs and organ systems? • Compare the bionic man’s face with the human face that served as a model. 4 HOW DO WE KNOW? Who is Rex, the bionic man? Rex, a robotic exoskeleton, is a prototype designed by a team of robotics experts. All Rex's organs were created in a laboratory. They show the advances being made in medical technology to replace certain body parts. GIVE YOUR OPINION Do you think it will be possible to build a bionic person exclusively with artificial organs? Why? / Why not? A camera in Rex’s glasses sends images to microchips located in an artificial retina. This retina is the same as those implanted in patients. The artificial trachea is like those implanted in cancer patients. Internal organs, such as the pancreas, spleen and kidneys, are not yet fully developed technically. The first fully artificial kidney could become available for human trial in 2017. This could eliminate dialysis in patients with kidney disease. The heart is an artificial valve that pumps blood throughout the body. It was designed for use in patients waiting for heart transplants. Robotic fingers can bend at the joints and hold objects. The force they can exert varies. STARTING POINTS • What basic units are living things made up of? • What types of cells are bacteria made up of? • How are organ tissues different from organs? Prosthetic legs respond to electrical impulses and enable movement. • What are life functions? Name an organ and a system that are involved in each life function. 5 LEARNING OBJECTIVES 1 Levels of organization • Describe the levels of organization in living things. • Define bioelement and biomolecule. All living things have a structural and functional organization. Each level of organization helps to build the next level. The lower levels are very simple while the upper levels become more complex. Going from the least complex to the most complex, the levels of organization in humans are: Atom. The smallest component of the chemical elements that make up living things (bioelements), primarily carbon (C), oxygen (O), hydrogen (H), nitrogen (N), phosphorus (P), sulfur (S), calcium (Ca), magnesium (Mg) and sodium (Na). Molecule. A group of two or more atoms joined together chemically. The molecules that make up living things are called biomolecules. Organelle. A group of biomolecules that work together to form cell structures, such as membranes, ribosomes and mitochondria. Cell. A group of organelles and structures. A cell is the simplest level of life. Organ. A group of different tissues that work together to carry out a specific function. Examples include the bones, kidneys and heart. Organ system. A group of similar or different organs that work together to carry out life functions. Examples include the skeletal system and the musculoskeletal system. Organism. An independent living thing made up of organ systems that can carry out all the life functions.. 6 Tissue. A group of specialized cells that work together to perform a specific function. Examples include bone tissue, muscle tissue and nervous tissue. The organization of the human body 2 1 The chemical composition of living things WORK WITH THE IMAGE Bioelements join together to form biomolecules. These can be classified into two types: inorganic or organic. 1 Describe a level of organization: It's a group of biomolecules. Your classmate identifies it: It's an organelle. Inorganic biomolecules They are found in living and non-living things. • Water. The most abundant substance found in living things. It makes up about 65% of the human body, but the exact amount varies from one organ to another; for example, the brain contains more water than bone. Water is also the main component of cells and body fluids like blood. ACTIVITIES 2 Match each of these with a level of organization: erythrocytes, blood, pancreas, lipids. • Mineral salts. Substances that can be found in living things in the form of dissolved ions, such as a sodium ion (Na +) and potassium ion (K +), or precipitated as crystals, such as phosphate and calcium carbonate. 3 Make a table to show the four major types of organic biomolecules and the macromolecules created when they join together. Organic biomolecules They are unique to living things and contain significant amounts of the chemical element carbon. Fatty acids Monosaccharide Glycerol Disaccharide Polysaccharide Fat Carbohydrates. Monosaccharides are composed of one molecule, for example, glucose. Disaccharides, such as sucrose or maltose, are formed when two monosaccharides are joined. Polysaccharides, such as cellulose or glycogen, are formed when many monosaccharides are joined. Lipids. These molecules vary widely in chemical structure. Lipids include fats, phospholipids and cholesterol. Fats are the simplest lipid and can be broken down into fatty acids and glycerol (a sugar alcohol). Protein DNA Amino acids Proteins. These large biomolecules (macromolecules) are composed of many smaller molecules called amino acids. Some important human proteins are collagen, haemoglobin and antibodies. Nucleotide Nucleic acids. These macromolecules are composed of smaller ones called nucleotides. There are two types: DNA (deoxyribonucleic acid) and RNA (ribonucleic acid). 7 LEARNING OBJECTIVES 3 Cells: the basic unit of living things • Define cell and describe its function. All living things, from the simplest to the most complex, are made up of cells. The cell is the simplest living unit that can carry out the life functions of nutrition, interaction and reproduction. It is the basic unit of all living things: • It is the structural unit because it forms all structures. • It is the functional unit because it carries out life functions internally. • It is the biological unit because it contains the genetic material of the individual. • It is the basic unit because all cells come from a pre-existing cell through the process of cell division. Living things can be made of one cell or many cells: DID YOU KNOW? A micrometre or micron is one millionth of a metre: 1 μm = 0.000 001 m A nanometre is one billionth of a metre: 1 nm = 0.000 000 001 m • Unicellular organisms. Microscopic living things are made up of one cell. Examples can be found in the Monera kingdom (bacteria), in the Protista kingdom (protozoa and unicellular algae) and in the Fungi kingdom. • Multicellular organisms. Generally, macroscopic living things are made up of many cells. Their organization is complex. Examples can be found in the Protista kingdom (algae) and in the Fungi, Plant and Animal kingdoms. The human body contains billions of cells. Adults have over 200 different types of cells. Each cell type has a specific shape, size and function. There are many beneficial bacteria in the human body. They are involved in processes like digestion, immunity and growth. For these reasons, the human body is called a complex ecosystem. Sperm: the head is about 3 µm in diameter. Enterocyte: about 10 µm in diameter. Muscle cell: between 10 and 100 µm in length. WORK WITH THE IMAGE 1 Describe the size of a cell: It is about ... It is between ... Your classmate names the cell. 2 Ask about the cells: Which is the largest/smallest/longest? What relationship do you see between its size or mobility and its function? 8 Erythrocyte: 8 µm in diameter. Fibroblast: between 20-30 µm in diameter. Neuron: up to several centimetres long. The organization of the human body Life functions in cells 1 WORK WITH THE IMAGE Cells perform three life functions: nutrition, interaction and reproduction. 3 Work with a classmate to • Cellular nutrition consists of all the processes in which cells obtain the matter and energy necessary to perform life functions. To do this, cells take in substances, called nutrients, from the outside. Nutrients are used for energy and to obtain the substances necessary for growth and building or repairing structures. Once inside the cell, the nutrients undergo a series of chemical processes. These chemical processes are called cellular metabolism. There are two types of metabolic reactions: catabolism and anabolism. describe the two types of cellular metabolism. Use these words: In this process, simple/complex substances are broken down/ synthesized to produce energy/complex substances. This process produces/ requires energy. • Cell interaction enables cells to get information from their environment and communicate with other cells. Catabolism Complex organic substances Simple substances Anabolism Simple substances Energy Energy Complex organic substances • The destructive phase of metabolism. • The constructive phase of metabolism. • The energy produced is used to synthesize new molecules for reproduction and for cell function. • The complex molecules produced are used in growth and structural repairs. ellular reproduction is the process by which a parent cell • C divides into two or more new cells, called daughter cells. In unicellular organisms, cell division reproduces an entire organism. The new individual is identical to the parent. As a result, there is an increase in population. In multicellular organisms, cell division results in an increase in the number of cells that make up an organism. This increase is reflected in the growth of the organism or the repair of damaged or lost parts. ACTIVITIES 4 Explain the difference between unicellular and multicellular organisms. 5 Draw four different types of cells. Label the main differences. 6 Draw a cell. Your classmate guesses the type. Take turns. 7 If you had to design a cell that could have a lining, what shape would you choose? 9 LEARNING OBJECTIVES 4 Prokaryotic cells • Compare prokaryotic cells and eukaryotic cells. • Describe the main differences between the two types of cell organization. Prokaryotic cells have a simple structure and are generally much smaller than eukaryotic cells. Prokaryotes have three main characteristics: • No nucleus. Genetic material is dispersed in the cytoplasm. • Ribosomes are the only organelles. • The cell membrane is usually covered by a cell wall. Bacteria are prokaryotes and consist of a single cell. They belong to the Monera kingdom. Evidence of bacterial life on the Earth has been found in rocks 3.8 billion years old. Cell membrane. It surrounds the cytoplasm. The exchange of substances takes place here. Bacterial chromosome. A circular DNA molecule that contains genetic material. Cell wall. The thick, rigid layer around the cell membrane. It protects the bacteria and gives it its shape. Ribosomes. Organelles that carry out protein synthesis. Appendices. Structures like flagella and fimbriae. Flagella are involved in movement. Fimbriae are shorter and more numerous. They enable bacteria to adhere to a surface. Bacterial capsule. A thick outer covering on some bacterial cells. It promotes adhesion and protects the cell. WORK WITH THE IMAGE 1 Ask questions about the parts of prokaryotic and Optical microscope eukaryotic cells: Which part of the cell ...? Your classmates identifies the part and the type of cell. Eyepiece Objectives Electron microscope Electron gun (electron source) 2 The development of microscopes has enabled direct observation of biological structures. Find out about these two types of microscopes. Which is the oldest type? Which enlarges an image more? How does each work? It uses ... to ... Specimen Magnetic lenses Specimen 10 Light source Optical binocular The organization of the human body 5 1 Eukaryotic cells Eukaryotic cells are more complex and generally larger than prokaryotic cells. Their size can range from 10–100 μm to several centimetres. Eukaryotic cells are found in human beings, animals and plants. All eukaryotes have three structures: Structure of a cell membrane Carbohydrate • Cell membrane. This membrane surrounds the cell and enables the exchange of substances with the outside environment. The membrane consists of two layers of phospholipids, with cholesterol and diverse protein molecules distributed throughout. This type of membrane is called a fluid mosaic structure because the elements move and change position. • Cytoplasm. This substance fills the space between the cell membrane and the nucleus. The cytoplasm contains: Protein Phospholipids – Hyaloplasm. The fluid component of the cytoplasm. – Organelles. Cellular structures that carry out different functions. – Cytoskeleton. Protein fibres involved in movement, internal organization and cell division. • Nucleus. This spherical structure contains the genetic material that controls cellular function. It is surrounded by a double membrane called the nuclear envelope. The membrane has tiny holes called nuclear pores. They regulate the exchange of substances with the rest of the cell. The nucleus contains the nucleoplasm, chromatin and nucleolus. Nuclear pores Nuclear envelope ACTIVITIES 3 Draw this animal cell as seen under the electron microscope. Label the membrane, cytoplasm and the nucleus. Nucleolus. A round, dense structure made up of RNA and proteins. It is only visible when a cell is not dividing. Cells may have one or several nucleoli. 4 Compare prokaryotic and Nucleoplasm. The fluid found in the nucleus. Chromatin. A combination of DNA and protein makes up the genetic material in the nucleus of a cell. In cell division, chromatin condenses into chromosomes. eukaryotic cells. Describe two structures that they have in common and three structures that are different. Make a Venn diagram. 5 Debate. What are the major advantages of each type of cell? Form two teams: prokaryotes and eukaryotes. 11 LEARNING OBJECTIVES • Describe the structure and functions of organelles and other structures of eukaryotic animal cells. 6 Cell organelles and structures Organelles are tiny structures in the cytoplasm. Some are surrounded by membranes; others have no membranes. Mitochondria. Oval-shaped organelles with two membranes. The outer one is smooth while the inner one folds towards the centre, forming the mitochondrial cristae. Through cellular respiration, mitochondria produce most of the energy of a cell. Vesicles. Small, rounded organelles that store, transport or digest cellular substances. Vesicle Lysosomes. Rounded vesicles produced by the Golgi body. They contain hydrolytic enzymes involved in intracellular digestion. Endoplasmic reticulum (ER). A network of interconnected membranous sacs and channels. There are two types: • Rough ER. This type is connected with the nuclear envelope. Many ribosomes are attached to it. It is involved in the synthesis and transport of proteins to the Golgi body. • Smooth ER. This type has no attached ribosomes. Lipids (fats) are synthesized here. WORK WITH THE IMAGE 1 Ask questions about the organelles: Which are surrounded by membranes/ involved in ...? 2 Describe the function of an organelle: It produces/stores/ transports ... Your classmate identifies the organelle. 12 Golgi body or apparatus. Flat, membranous sacs arranged in layers. This organelle stores, processes and packages substances received from the endoplasmic recticulum. Then, secretory vesicles transport the substances out of the cell. The organization of the human body Ribosomes. Non-membranous organelles made up of RNA and proteins. They are found free in the cytoplasm or attached to the rough ER. They are involved in protein synthesis. 1 Centrosome. This organelle consists of two centrioles: cylindrical structures composed of protein microtubules. The centrioles are perpendicular to each other and surrounded by other microtubules. During cell division, the microtubles form star-shaped asters that help to manipulate chromosomes. Centrosomes participate in mitotic spindle formation when a cell divides. Ribosomes Cilia and flagella. Cilia are short and abundant. Flagella are long; usually only one or two are present. These cytoplasmic projections are involved in cell movement. Cytoskeleton. A network made up of different types of protein filaments. It maintains the shape of the cell and facilitates the movement of the cell, organelles and internal vesicles. It is also involved in chromosome organization during cell division. KNOW HOW TO Observe animal cells under the microscope The lining of the mouth provides a good source of buccal epithelial cells for observation. 1. Obtain a sample. Scrape the inside of your cheek with a toothpick or cotton swab. 2. Fix the slide. Smear the toothpick or cotton swab across a glass slide. Add a drop of water and pass the slide over a flame a few times to fix the cells to the slide. 3. Stain the sample. Add a few drops of methylene blue and wait three minutes. Cover with a cover slip. Remove excess stain from the sides with a paper towel. 4. Place the slide under the microscope and observe. ACTIVITIES 3 Draw and label the cells and their structures. 13 LEARNING OBJECTIVES 7 • List the characteristics and functions of tissues. • Identify the cells that form tissue. Human tissue A tissue is a group of specialized cells that work together to perform a specific function. The branch of biology that studies the tissues of organisms is called histology. Tissue can be grouped into four types: epithelial, connective, muscle and nervous. WORK WITH THE IMAGE Epithelial tissue 1 What type of tissue is being Epithelial cells are generally polyhedral in shape. They are closely packed together and arranged in layers. There are two main groups: covering epithelia and glandular epithelia: described? 2 This is epithelial tissue from the uterus. What type is it? Discuss with a classmate. • Covering epithelia. This tissue covers internal and external body surfaces. It protects these surfaces and regulates the exchange of substances. The type varies depending on location: – Epidermis. This type forms the outer layer of human skin. It consists of many layers of cells. – Mucous membrane. This tissue protects internal cavities such as the digestive and respiratory tracts. 3 Why are epithelial tissues arranged in layers? 4 Name a gland. Your classmate describes its function. Exocrine glands They secrete substances into a body cavity or outside the body through ducts. – Endothelia. This tissue lines the interior surfaces of the body, such as the blood vessels and the heart. It consists of a single layer of cells. • Glandular epithelia. This tissue makes up the glands. It produces and secretes substances. There are three types of glands: Endocrine glands They secrete hormones directly into the bloodstream without ducts. Glandular epithelial cells Mixed glands They produce other substances and secrete hormones into the blood. Pancreas Duct Glandular epithelial cells Sweat glands secrete sweat. The liver secretes bile through a duct into the gall bladder. 14 Blood vessel The thyroid gland secretes hormones such as thyroxine, which controls the body's metabolic rate and growth. Hormoneproducing cells Pancreatic juice-producing cells The pancreas secretes hormones like insulin into the bloodstream and digestive enzymes into the small intestine. The organization of the human body 1 Connective tissue This tissue connects other tissues. It has three components: cells, fibres (that may or may not be made of collagen) and an intercellular substance or matrix. There are several types: Osseous or bone tissue. The cells responsible for bone formation, osteoblasts, produce a strong, solid matrix. Star-shaped bone cells found in mature bone are called osteocytes. Osteocyte Dense connective tissue. It is found between tissues and organs holding them together. Tendons and ligaments are typical examples. Adipose tissue. It is made up of adipocytes or fat cells. They store lipids and protect some organs. Cartilage tissue. Its cells, chondrocytes, contain elastic fibres and produce a solid, flexible matrix like the cartilage found at joints. Adipocyte Chondrocyte Blood tissue. This special tissue is made up of red and white blood cells. Its matrix, plasma, is liquid with no fibres. Blood tissue transports substances. Muscle tissue This contractile tissue has elongated cells called myocytes or muscle fibres. It contains protein filaments of actin and myosin which contract and relax muscles. There are three types of muscle tissue: • Smooth muscle tissue. The myocytes have a single nucleus. Contraction is involuntary. This type of muscle tissue is found in the walls of internal organs. • Skeletal muscle tissue. Skeletal myocytes have many nuclei. Skeletal muscles are striated with dark and light bands. Contraction is voluntary. Skeletal muscle tissue forms skeletal muscles. Striated muscle tissue • Cardiac muscle tissue. Cardiac myocytes are joined in a network. They have a single nucleus and the cytoplasm looks striated. Contraction is involuntary. This tissue forms most of the heart wall. ACTIVITIES Nervous tissue Nervous tissue cells transmit and receive information throughout the body. There are two types of cells: • Neurons. They are star-shaped with branching projections. They transmit nerve impulses. • Glial cells. They nourish and support the neurons. They do not transmit nerve impulses. 5 Make a table of the different types of connective tissue. Use these headings: Tissue type, Cell name, Function. 6 What special characteristics do cells that form muscle tissue have? And nerve cells? 15 LEARNING OBJECTIVES 8 Organs and organ systems • Identify the organ systems of the human body. • Relate organ systems to the life functions they are involved in. The human body is made up of many organs organized by function into organ systems. These systems work together to enable the body to function. The science that studies how living systems function is called physiology. • Organ. A group of tissues that work together to perform a specific function or action. The heart, skin and muscles are examples of organs. WORK WITH THE IMAGE 1 Work with a classmate: describe the difference between an organ and an organ system. 2 Play a matching game in pairs. One person says an organ system; the other person names the organs in that system. How many organs can you match to systems in one minute? • Organ system. A group of organs that work together to perform one or more functions. For example, the circulatory system consists of various organs (the heart, veins and arteries) that work together to transport nutrients throughout the body. The skeletal system is made up of bones that perform different functions. For example, the humerus and vertebrae are involved in movement; the ribs and sternum protect organs. Organ systems can be grouped by function: nutrition, interaction and reproduction. Organ systems involved in nutrition These organ systems obtain nutrients, transport them throughout the body and eliminate harmful substances produced in the body. Digestive system. It consists of the digestive tube and accessory glands (salivary glands, the liver and pancreas). It obtains nutrients from food. Circulatory system. It consists of the heart, blood and blood vessels. It distributes blood, which delivers nutrients to all the cells and collects harmful substances. 16 Respiratory system. It consists of the respiratory tract and the lungs, where gas exchange with the blood takes place. This exchange provides oxygen to the body and eliminates carbon dioxide produced by the cells. Excretory system. It consists of the kidneys, the urinary tract (ureters, the bladder and urethra) and other organs, such as the sweat glands. Excretion is the process of eliminating waste substances. These waste substances are produced by the chemical reactions that occur in cellular metabolism. The organization of the human body 1 Organ systems involved in interaction These organ systems enable the body to communicate and interact with the environment. Nervous system. The main organs are the brain, spinal cord and nerves. The nervous system receives information from the internal and external environment. It then sends nerve impulses (messages) to organs in response to this information. Endocrine system. The organs in this system are the endocrine glands, which are made of glandular epithelial tissue. These glands produce chemical substances called hormones, which are excreted into the bloodstream. Hormones act on specific cells and organs. Musculoskeletal system. It consists of muscles and bones that work together to produce locomotion. Skeletal system. It is the passive part of the musculoskeletal system. It consists of bones of different types and shapes. The mineral matrix of bone tissue provides strength and stiffness. The skeletal system is involved in locomotion. It also protects organs and structures. Muscular system. It is the active part of the musculoskeletal system. It consists of skeletal muscle made of skeletal muscle tissue. It enables locomotion and movements and helps to maintain posture. Organ systems involved in reproduction Reproductive systems. Male and female systems, each consisting of internal and external organs. This system produces reproductive cells or gametes. The male reproductive system produces sperm and male sex hormones. The female reproductive system produces ovules (eggs) and female sex hormones. After fertilization, it hosts the developing foetus until birth. ACTIVITIES 3 Summarize the information on these three organ systems and their organs in a mind map. 4 What organs are involved in two different life functions? Name the organ systems they are related to. 17 ACTIVITY ROUND-UP 1 Copy and complete the diagram of the levels of 6 A white blood cell ingests a bacterium by phagocytosis organization in human beings. and digests it intracellularly. What organelles are directly involved in this process: the mitochondria, the Golgi body, lysosomes or the vesicles? Explain why. 7 Look at the pictures and answer the questions. A B Cell a) What organelles or cellular structures are visible in each picture? What are their functions in the cell? b) Are these pictures of a prokaryotic or eukaryotic cell? Explain how you know. 8 Why do cells need a cell membrane? 9 What is the relationship between DNA, chromatin and 2 Make a table to classify inorganic biomolecules and describe their components. chromosomes? 10 How are endoplasmic reticulum, the Golgi body and 3 What type of metabolic reaction produces energy? What type requires energy? Draw diagrams to explain what occurs in each case. 4 Copy the drawing in your notebook. Add a title and label parts A–E. Which living things have this type of cell? vesicles related? 11 Identify each type of tissue, the name of the cells it is made of and the function of the tissue. Explain how you recognized the tissues. A B A B COOPERATIVE PROJECT A poster on cellular structures C E D 5 Choose four organelles present in eukaryotic cells. Make a fact sheet to compare them. Use these headings: • Name of the organelle. • Main characteristics. • Function or functions. • Drawing of the organelle. 18 Posters are a form of visual communication. Good posters combine text and graphic elements in an attractive design. Texts, photos and illustrations should be large, clear and concise. • Form groups to design the poster for lab photos that will be used in an exposition. • Organize the work so each group member has a different task. • Select the photos; write the texts using fact sheets. Use Activity 15 as a model. • Assemble the poster using the contributions from each group member. KNOW HOW TO The organization of the human body Scientific competence 1 Identify cells and cell structures in micrographs The images below were taken using optical and electron microscopes. A B C They correspond to different types of tissue, cell structures and organelles. MICROGRAPHS • Mitochondria. D E F • Ciliated epithelium. • Pores in the nuclear envelope. • Ovule (egg). • Blood tissue. • Centrosome. • Cardiac muscle. • Neuron. • Adipose tissue. • Buccal epithelial cells. • Cartilage tissue. • Rough ER. • Golgi body. • Cell nucleus. • Flagellum. • Glandular tissue. PRACTICAL MANUAL OF MICROSCOPY Optical microscope (OM) • Maximum magnification: 1 000 X. • Samples are stained to colour them. • Living material can be viewed. Scanning electron microscope (SEM) • Maximum magnification: 500 000 X. Sperm (OM). Cell movement can be observed. Sperm (SEM). The surface is visible in 3D. • Black and white images can be stained. • Surface images are in 3D. • Living material cannot be viewed. Transmission electron microscope (TEM) • Maximum magnification: about 1 000 000 X. • Black and white images can be stained. • Internal structures are in 2D. • Living material cannot be viewed. ACTIVITIES 12 Design a fact sheet for photos A–F. Identify the cell and include information about: cell structure, the organelle or tissue, the type of microscope used. 13 Make simple drawings of photos C–F. Label the parts of each cell and explain: • The type of cell it is found in. • Its main function in the cell. Sperm (TEM). The orderly arrangement of the mitochondria can be observed in the tail. The nucleus is visible in the head. 14 If you had to use assisted reproduction techniques, would you donate spare embryos for research? 15 Which microscope would you use to view: • The wing of a fly. • The inside of a mitochondrion. • The surface of a nuclear envelope. • The shape of a chromosome. • The cilia of a paramecium. 19