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Transcript
Unit 1 – Cells and Systems Chapter 1 – The cell is the basic unit of life. 1.1 Observing Living Things -living things can survive in almost any kind of environment -have features that help them survive -ex: hummingbirds can beat wings up to eighty times per second, allowing them to hover and change direction rapidly -all living things have needs that must be met if they are to survive *Characteristics of Living Things* -five characteristics of living things: -living things respond to their environment -living things need energy -living things grow -living things reproduce -living things must get rid of wastes *Examining Very Small Living Things* -electron micrographs: images made by electron microscopes -microscope is used by scientists to observe very small unicellular and multicellular living things -early microscopes were built in late 1600’s -Anton van Leeuwenhoek was one of first people to build a microscope -magnify up to 250x; used it to observe microscopic things *Compound Light Microscope* -sets of lenses that magnify an image -magnification power: the number of times larger an image appears under a particular lens -Low power – 4x objective -Medium power – 10x objective -High power – 40x objective -multiply objective by eyepiece for total magnification -ex: High power – 40x10 = 400x *Resolving Power* -resolving power: ability to distinguish between two dots or objects that are very close together -human eye has certain resolving power 1 1.2 Cells -unicellular: one-celled; multicellular: more than one cell -organelles: internal structures in which cell functions are carried out -cellular respiration: the process in which glucose and oxygen produce energy for the cell -glucose +oxygen (produce) carbon dioxide + water + energy (ATP) -metabolism: total of all chemical reactions that take place in our cells -cells must have a balance of life processes to survive -intake and storage of nutrients -growth -response to stimuli -exchange of gases -waste removal -reproduction *Cell Theory* -all living things are made of at least one cell -cells are the functional unit of life -all cells come from pre-existing/other cells *Organelle Functions* -organelles: internal structures; special cell functions are carried out >Cell (plasma) Membrane – thin outer covering that regulates materials going in and out of the cell >Cytoplasm – jelly-like substance made of water that contains the organelles >Nucleus – structure that directs all cellular activities, contains DNA -DNA: deoxyribonucleic acid; carries heredity material that is passed on from generation to generation >Vacuole – in plants mostly, contains water – storage compartments; smaller in animal cells and usually called vesicles >Centrioles – protein fibres that aid cell division in animal cells by helping to move chromosomes >Mitochondrion – converts the chemical energy in glucose into ATP energy that the cell can use; cellular respiration >Ribosome – where proteins are assembled; without membrane >Endoplasmic Reticulum – networks of membranes within the cytoplasm that transports material through the cell; some ribosome attach to it >Golgi Body – sorts proteins and packs them into vesicles (membranewrapped structures) 2 >Lysosome – contains digestive chemicals that break down food particles, cell wastes, and worn-out cell parts >Cell Wall (only in plants) – structure that surrounds the cell membrane; maintains shape and protects plant >Chloroplast (only in plants) – carries out photosynthesis -photosynthesis: chemical reaction that takes place when carbon dioxide and water react in the presence of sunlight to produce glucose and oxygen *Prokaryotic and Eukaryotic Cells* -cells are classified into two groups: -Prokaryotic cells: have no nuclear membrane or organelles -Eukaryotic cells: have organelles that are surrounded by membranes, usually larger than prokaryotic cells (animal and plant cells) *Bacteria* -bacteria: any of various groups of single-celled micro-organisms, some of which can cause disease -can vary from 1 mm~20 nm in length -average range is 1 µm~20 nm in length (mm = millimeter; µm = micrometer; nm = nanometer) *1000 mm = 1 m 1 000 000 µm = 1 m 1 000 000 000 nm = 1 m -bacteria have beneficial effects, such as digestive enzymes that help digest food in our intestines; used to make food such as cheese/yogurt -can also have bad effects on cells by producing toxins, reproducing causing more damage; diseases such as tuberculosis and strip throat -three common shapes: Baccilli (rods) Spirilla (spiral) Cocci (spherical) 3 *Viruses* -virus: tiny non-living particles capable of reproducing only when they are inside a host cell; they have no nucleus or organelles and are usually diseasecausing -ex: HIV, chicken pox, cold sores, flu -carries only the information, in form of DNA, necessary to reproduce itself 1.3 Diffusion, Osmosis, and the Cell Membrane -diffusion: natural movement of particles form areas of higher concentration to areas of lower concentration; ex: smell of fresh baked bread ‘spreading’ throughout the room -concentration: the amount of a substance in a given space -equilibrium: when concentration on both sides of membrane is same -cell membranes act as barriers to diffusion -selectively permeable: allows some things through -osmosis: passive transport or diffusion of water across a selectively permeable membrane -if water concentration inside the cell is higher than it is on the outside, water will flow out of the cell; vice versa *Osmosis and the Cell* -cells contain water and need this water to survive -osmosis = how the cell gains and loses its needed water -equal movement of water in and out of cells: -cell retains its normal shape -more water moving into cells than is moving out: -cell swells; red blood cells may continue to swell and eventually may burst; plant cell swells beyond its normal size -more water moving out of cells than is moving in: -cell shrinks; red blood cells shrivel up as they lose water; plant cell membrane shrinks away from the cell wall –- carrot is limp, lack of water 4 5 Chapter 2 – Human body systems work independently and together. 2.1 Body Systems -all systems have following characteristics: -is made of individual parts that work together as a whole -is usually connected to one or more systems -if one part of a system is missing or damaged, the system will not function well or may not function at all *Eleven Systems of the Human Body* >Circulatory System – transports blood, nutrients, gases, and wastes >Digestive System – takes in food; breaks down food; absorbs nutrients; eliminates solid waste >Respiratory System – controls breathing; exchanges gases in lungs and tissues >Excretory System – removes liquid and gas wastes from the body >Immune System – defends body against infections >Endocrine System – manufactures and releases hormones >Reproductive System – includes reproductive organs for producing offspring >Integumentary System – includes skin, hair, and nails; creates a waterproof barrier around the body >Skeletal System – supports, protects, and works with muscles to move parts of the body >Muscular System – has muscles that work with the bones to move parts of the body >Nervous System – detects changes in the environment and signals these changes to the body, which then carries out a response *Organ Systems* -organ system: system that includes one or more organs that work together to perform specific functions in the body -tissues: a group of cells that have the same structure and function -organ: a group of tissues (such as heart tissues) working together to perform a task (such as pumping blood) -within each organ system are tissues and cells -cells of the same structure and function are grouped into tissues -groups of tissues form organs -heart cell cardiac tissue organ (heart) organ system (circulatory system) organism 6 *Tissues* -word ‘tissue’ comes from Latin word meaning to weave -cells that make up tissues are often ‘woven’, or held together by fibres or sticky materials that form between tissue cells -four types of body tissue: -muscle tissue: assists in body movement (skeletal muscle tissue); helps some organs carry out specific functions (heart pumping blood) -nerve tissue: transfers signals in the body and its organs to tell body how to respond to changes in its internal and external environment (transfers signals to and from brain) -connective tissue: holds together/supports other tissues; connects, protects, insulates organs -epithelial tissue: covers surface of organs and body; lines inside of body parts 2.2 The Digestive and Excretory Systems -to grow, your body needs raw material or nutrients -nutrients: substances the body requires for energy, growth, development, repair, or maintenance -comes from your diet -four food groups: -grain products -vegetables and fruit -milk products -meat and alternatives 7 *Types of Nutrients* -five different types of nutrients you can obtain from food -balanced diet will have correct amount >carbohydrates: the body’s quickest source of energy -two kinds: >>simple carbohydrate: molecules of sugar, most common type of sugar glucose >>complex carbohydrate: chain of simple carbohydrates joined together -body must break down the chain into simple sugars to use the energy; ex: pasta, brown rice, whole grain cereals -proteins: used to build muscles, skin, hair, nails; within cells, are used to build various structures and are required for certain chemical reactions -ex: fish, poultry, meat, nuts, soy, dairy products – rich in proteins -fats: used to build cell membranes and that can be stored by the body for future energy needs -ex: shortening, butter, oil, cream, meant >>unsaturated fats: come from fruits, vegetables, and fish -liquid at room temperature >>saturated fats: usually animal fats, such as butter or lard -solid at room temperature -diets rich in saturated fats can lead to an increase in heart disease; plaque builds up in blood vessels, and flow of blood is reduced -plaque: fatty material that is deposited along the walls of blood vessels -leads to an increased risk of heart attack and stroke -minerals & vitamins: needed in small amounts to perform various body functions -vitamin D helps body absorb calcium; sunlight helps make vitamin D --water: not a nutrient, but is essential for life -transports nutrients and wastes -necessary for many chemical reactions and for cooling the body 8 *The Four Stages of Digestion* -digestion: the process in which food is broken down, its nutrients are absorbed and stored, and the wastes are eliminated -digestive system: the system of organs and body structures that work together during the process of digestions ① ingesting – starting point of the digestion process; mouth ② digesting – mouth: mechanical and chemical digestion begins >-mechanical digestion: the chewing and breaking food down into smaller pieces >-bolus: each small piece of food -saliva lubricates the food, and contains an enzyme called amylase >-chemical digestion: occurs when amylase begins to break down complex carbohydrates -esophagus: as food passes through the pharynx, the epiglottis covers the airway tube -food moves on to the esophagus >-esophagus: tube that connects the pharynx and the stomach ☇ long and muscular >-bolus is pushed through the esophagus in a process called peristalsis -stomach: like a stretchable muscular bag -inside stomach is gastric juice; very acidic >-gastric juice: a mixture of hydrochloric acid, mucus, and enzymes; secreted by the stomach lining and aids in digestion 9 -walls are lined with mucus that protects the tissue >- pepsin: enzyme which breaks down protein, and needs an acidic environment >-bolus breaks down into liquid called chyme -small intestine: once chime leaves stomach, it empties into the small intestine -first metre is called the duodenum ☇ digestion is complete after food leaves -within the first 30 cm are ducts that connect to other organs >-pancreas: produces enzymes -liver produces bile; ☇ bile: break globs of fat into smaller droplets ③ absorbing – nutrients are absorbed by the remaining 5 m of the small intestine -to help increase the rate of absorption of nutrients, small intestine is covered in villi (sing. villus) ☇ villi: folds in the wall of the small intestine; increases the surface area from 0.5 m^2 to 250 m^2 -food takes approx. five to six hours to move through small intestine -large intestine: 5 cm wide, 1.5 m long ☇ takes undigested material from the water and some nutrients -90% of water is absorbed by the time the undigested material leaves the large intestine; -12~24 hours -beneficial bacteria helps breakdown and absorption of food ④ elimination – any undigested materials left are called feces ☇ feces: solid waste products -> stored in the rectum until they are eliminated through the anus -ingestion to elimination takes approximately 20~30hours *Excretion* -the excretory system removes liquid and gas wastes from your body -excretion removes liquid wastes through the urinary tract -main organs: two kidneys, two ureters, the bladder, and the urethra -kidneys filter blood and removes wastes -urine passes into the bladder, and is flushed out through the urethra 10 *Nutritional Disorders/Eating Disorders* -obesity: excess in body fat -anorexia nervosa: occurs when a person severely restricts what he/she eats - resulting medical problems could include damage to internal organs and weakening of bones -bulimia nervosa: occurs when a person eats large amounts of food and then vomits or takes laxatives to get rid of the food before it can be completely digested -health problems include stomach and esophagus irritation and tooth decay from stomach acid in vomit 2.3 The Circulatory and Respiratory Systems -circulatory system consists of the heart, arteries, capillaries, and veins -your heart is a pump; pushes approximately 4 L of blood through body every minute -main purpose of respiratory system is to exchange gases -main organ of respiratory system are the lungs *Taking a Closer Look at the Heart* -heart: muscular organ that pumps blood throughout your body -four chambers: -atria (left/right) – moves the blood from the body into the heat; pumps blood into ventricles -ventricles (left/right) – pumps the blood out of the heart ♦ Left atrium ◘ blood arrives from your lungs ♦ Right atrium ◘ blood arrives from your body ♦ Left ventricle ◘ pumps blood to your body ♦ Right ventricle ◘ pumps blood to your lungs -between the chambers are one=way valves -valves allow blood to flow in only one direction -‘Lub dub’ – opening and closing of the valves 11 *The Circulatory System* -made up of blood vessels -if all blood vessels lined up, approximately 100 000 km -types of blood vessels ☇ arteries: blood vessels that carry blood away from the heart -most carry oxygenated blood -thick-walled and elastic to handle blood flow -largest artery aorta -arteries branch into arterioles, and finally capillaries ☇ capillaries: networks of tiny blood vessels that connect arteries to venules; where gases and nutrients are exchanged with the cells -venules: smallest veins in the body, join veins to capillaries ☇ veins: blood vessels that carry deoxygenated blood back to the heart; have valves that prevent backflow of blood -blood returns to heart through veins, superior vena cava, and inferior vena cava -superior vena cava: large vein that carries deoxygenated blood from the head and arms back to the right atrium of the heart -inferior vena cava: large vein that carries deoxygenated blood from the lower body to the right atrium of the heart 12 13 *The Components of Blood* -blood: the fluid that transports substances to and from all parts of the body; consists of plasma, red blood cells, and white blood cells -transports oxygen, nutrients, and water to cells; carries carbon dioxide and wastes away from you cell -also carries cells that fight infection and heal wounds -55% of 5 L of blood is plasma -plasma: clear, yellowish fluid that contains numerous water, proteins and minerals, dissolved salts -45% of 5 L of blood are red blood cells, white blood cells, and platelets -red blood cells: carry oxygen from lungs to body and carbon dioxide from body to lungs; formed in the bone marrow, liver, and spleen >-within each RBC are protein molecules of haemoglobin; carries oxygen in the capillaries -white blood cells: fight infections; much larger than RBC’s -platelets: help clot blood by thickening blood; forming scabs 14 *The Respiratory System* -when you breathe, you inhale oxygen and exhale carbon dioxide -lungs deliver the oxygen, and excrete carbon dioxide -breathing brings the oxygen in, air is filtered by cilia and mucus -cilia: tiny hairs -air travels down the pharynx and larynx (voice box), and then the trachea -pharynx: tube at the meeting point of the airway passage and the esophagus -larynx: tube-like structure that contains vocal chords; air passes through larynx to produce sounds of voice -trachea: airway passage that leads from larynx to lungs -at the base of the trachea are the bronchi, which branch into smaller tubes called bronchioles -bronchi: two tubes that branch out from trachea into the right and left lungs -bronchioles: in the lungs, small air tubes branching out from bronchi -finally, air reaches tiny sacs – alveoli -alveoli: in the lungs, tiny, thin-walled air sacs at the ends of bronchioles, where gas exchange takes place *Gas Exchange in the Alveoli* -each alveolus is surrounded by capillaries -oxygen diffuses out of alveolus, into blood and binds with red blood cells, and carbon dioxide diffuses into the alveolus -oxygenated blood returns to heart to be pumped to rest of body *Smoking* -causes many respiratory diseases, such as lung cancer and emphysema -emphysema causes alveoli walls to lose elasticity, makes breathing increasingly difficult as disease progresses -over 4000 chemicals in a cigarette 15 Chapter 3 – The immune system protects the human body. 3.1 The Immune System -infectious disease – can be spread by contact with infected people, animals, water, or food -pathogens: disease-causing ‘invaders’/organism or substance -four ways to transmit infectious diseases >-direct contact – shaking hands, sharing drinks or bodily fluids with an infected person >-indirect contact – being near an infected person who sneezes without covering his or her mouth -some pathogens can travel up to 5 m and infect people within that range >-water and food – eating foods infected with certain bacteria (food poisoning) -ex: Salmonella -drinking water infected with E. coli bacteria can result in serious illness >-animal bites – being bitten by an animal carrying rabies *First Line of Defence* -skin and linings of all internal body systems -sweat and oil are acidic -gastric juice is very acidic -can destroy pathogens -mucus and cilia prevent pathogens from entering your respiratory system *Second Line of Defence* -innate immune response -response you are born with -quick and general -usually fight bacteria and some viruses -first action is a flow of fluid, cells, and dissolved substances to the infection site -fever, inflammation, and redness occur ☇ inflammation: swelling and redness -phagocytes will increase in number ☇ phagocytes: a type of white blood cell that fights infection by swallowing up/engulfing pathogens 16 -acquired immune response -highly specific attack on pathogens or antigens ☇antigens: any substance the body cannot recognize, it is a non-living particle or substance -your body uses white blood cells called B cells and T cells to respond -B cell: type of white blood cell that recognizes antigens present in body and produces specific antibodies to fight them -T cell: specialized white blood cells that fight disease either by activating B cells (helper T cells)/by attacking antigens directly (killer T cells) -process can take up to a week (first process) -B cells recognize antigens and produce antibodies to fight them ☇antigens: specific particles created by the immune system to destroy specific disease-causing invaders -antibodies attach & destroy antigens and pathogens carrying antigens -T cells: helper T cells recognizes an antigen or pathogen and activates B cells (second process) -killer T cells: work independently, destroy antigens pathogens -all acquired immune responses help give you active immunity -your body remembers which antibodies should be used to attack a pathogen that it has seen before -memory B cells store the new antibodies >Recognition: white blood cell surrounds pathogen and signals T cells; more T cells produced; helper T cells signal B cells >Mobilization: B cells produce antibodies >Disposal: antibodies destroy pathogens >Immunity: some antibodies remain for future use 3.2 Factors Affecting the Immune System *Montagu’s Observations* -Mary Montagu traveled to Turkey in 1717, discovered a vaccine for smallpox -women performing procedure, seemed to protect children getting smallpox -women made small scratch on child’s arm, then put drop of pus from a patient who had mild case of smallpox on scratch -soon pus-filled blisters broke out on the child’s body; healed easily -children treated this way quickly recovered from this mild version of smallpox without ever developing serious form of disease 17 *Jenner’s Famous Experiment* -Jenner gave eight-year-old boy cowpox by placing him near infected cows -after boy recovered, Jenner infected him with smallpox -did not develop an of symptoms of smallpox *Vaccines* -vaccine: a special version of an antigen that gives you immunity against a disease; weakened forms of a disease -stimulates your immune system to create antibodies against the disease -these antibodies are reactivated to fight the antigen if it enters body -some vaccines require booster shots -all grade nine students receive booster shots for tetanus, diphtheria, and pertussis *Disorders of the Immune System* -allergy: an unusually high sensitivity to some substance -allergen: something that causes an allergic reaction -acts as an antigen, and your immune system kicks in -symptoms of an allergy are caused by histamine -histamine: a chemical released by the body in response to an injury or allergen; can cause symptoms such as a runny nose and watery eyes -anaphylactic shock: severe allergic reaction that can result in swelling, breathing difficulty, and sometimes death -adrenaline auto-injectors are one-time-use needles that inject adrenaline into body to counter allergic reaction -Acquired Immunodeficiency Syndrome (AIDS): an infection of the immune system -caused by Human Immunodeficiency Virus (HIV) -HIV attacks immune system itself, and destroys it by affecting helper T cells; immune system unable to activate killer T cells or B cells *Taking Care of Your Immune System* -eat a well-balanced diet -maintain person hygiene – brush teeth, shower/bathe, wash hands often -keep home clean -avoid tobacco and other non-prescription drugs -get plenty of rest and exercise -keep vaccinations up to date -do not engage in activities that involve sharing body fluids with others 18