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GAS EXCHANGE GAS EXCHANGE As you recall, all the cells of organisms carry out aerobic cellular respiration in order to release energy from food. Remember? C6H12O6 + O2 (glucose) (oxygen) CO2 + H2O + ATP (carbon dioxide) (water) (energy) C6H12O6 + O2 (glucose) (oxygen) CO2 + H2O + ATP (carbon dioxide) (water) (energy) • Oxygen is needed for this process. • Carbon dioxide is released from this system. • To survive, organisms must take in oxygen and expel carbon dioxide from their bodies. • This is accomplished through a process called GAS EXCHANGE Review of the eight life processes: 1. 2. 3. 4. 5. 6. 7. 8. Respiration Reproduction Regulation Growth Excretion Nutrition Transport Synthesis VOCABULARY • Respiration: the process of releasing chemical energy stored in foods • Gas exchange: the physical methods that organisms have for obtaining oxygen from their surroundings and removing excess carbon dioxide • Respiratory surface: surface through which gas exchange occurs between an organism and its environment Characteristics of a Respiratory Surface 1. Thin walled for diffusion 2. Must be moist (oxygen and carbon dioxide are dissolved in solution) 3. Must be in contact with the source of oxygen 4. Must be in contact with the transport system so gases can get to all cells Gas exchange occurs by diffusion • As cells use up the oxygen from cellular respiration, the concentration of oxygen in the cell is low • The capillaries carry oxygen rich blood from the respiratory surface so the concentration of oxygen in the blood is high. Therefore oxygen diffuses from the blood to the cells (high to low concentration) Therefore oxygen diffuses from the blood to the cells (high to low concentration) O2 O2 O2 O2 Gas exchange occurs by diffusion • The cells build up carbon dioxide as a waste product of cellular respiration • The blood has a low concentration of carbon dioxide Therefore the carbon dioxide diffused from the cells to the blood (high to low concentration) Therefore the carbon dioxide diffused from the cells to the blood (high to low concentration) CO2 CO2 CO2 CO2 The greater the surface area of the respiratory surface, the greater the rate of gas exchange. Protists have direct exchange between the cell and the environment Multicellular organisms have specialized organs and organ systems for gas exchange. PROTISTS: Diffusion directly through the cell membrane CO2 CO2 o2 o2 HYDRA • Diffusion directly from the environment to the cells of the gastrovascular cavity and into the endoderm • Diffusion directly from the fresh water into the cells of the ectoderm CO2 O2 CO2 O2 CO2 O2 GRASSHOPPER Blood does not carry gases System of branching tubes carry air to the cells • Air enters 10 pair of openings called spiracles • Tracheal tubes branch into smaller tubes and into fluid filled ends where there can be contact with the body cells – Here oxygen and carbon dioxide can diffuse • Air is pumped in and out of tracheal system by muscle contraction • Air sacs (connected to tubes) help pump air in and out GRASSHOPPER EARTHWORM Skin is the respiratory surface • Skin is thin and specialized cells secrete mucus • Just beneath the skin is a large number of capillaries Capillaries pick up oxygen and carry it to all the cells Oxygen is deposited and carbon dioxide gets picked up and returned to the skin • If the skin dries out – they suffocate • If there is flooding rain – they drown EARTHWORM MULTICELLED ANIMALS: air breathers (air is 21% oxygen) • must keep the respiratory surfaces moist • must have respiratory surfaces extending inside to protect surfaces and decrease water loss by evaporation • most have respiratory pigments in the blood to allow the blood to carry more gases than water • hemoglobin is the most common respiratory pigment MULTICELLED ANIMALS: water breathers (water has less than 1% oxygen) • less oxygen available and oxygen diffuses more slowly in water • therefore large amounts of water must pass over the respiratory surface GAS EXCHANGE IN GILLS • Gas exchange organ of water living organisms are gills • As water passes over, oxygen diffuses across to the blood vessels • A great deal of water must pass over them ORGANISM ORGAN WHERE GAS EXCHANGE TAKES PLACE PROTISTS (AMOEBA and PARAMECIUM) Cell membrane ADAPTATIONS OR SPECIALIZED STRUCTURES FUNCTION OF SPECIAL STRUCTURES none Endoderm to gastrovascular HYDRA (cell membrane) none Ectoderm to fresh water EARTHWORM Skin Specialized cells Blood GRASSHOPPER Spiracles to tracheal tubes to air sacs Air sacs Cell secrete mucus to keep skin moist Hemoglobin so blood carries more O2 than water Where diffusion of gases occurs Body movements squeeze air sacs and help move air in and out of the body General Structure • Lungs fill a large part of the chest cavity • Chest and abdomen are separated by the diaphragm • Lungs are enclosed by the pleura Structures The Nose • Air enters through the nostrils • Mucous membrane and cilia trap small particles of bacteria and dust • Blood vessels are close to the surface The nose 1. Filters air 2. Moistens air 3. Warms air The Pharynx • The throat – common passage from the nose and the mouth The Larynx • The voice box is made of cartilage • Contains two pair of vocal cords • Controlled vibrations make a variety of sounds • The epiglottis blocks the larynx from food during swallowing The Trachea • 12 cm long and 2.5 cm wide • Kept open by horseshoe shaped rings of cartilage • Ciliated mucous membranes push particles up into the throat • Smoking stops cilia from moving and increases production of mucous Bronchi • Two cartilage ringed tubes that branch off the trachea to the lungs • Cilia lines the tubes • Branch into the bronchial tubes in the lungs Bronchioles (tiny tubes) • The smallest branches of the bronchial tubes that lead to the alveoli BRONCHIOLE The Alveoli • Tiny air chambers one cell thick • Walls are moist and surrounded by capillaries • Site of gas exchange or external respiration • 300,000,000 alveoli • 70 square meters of surface area (40 x’s the surface area of the skin) Fill in the diagram on page 10. in the packet 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. Nose Nasal passage Pharynx Epiglottis Larynx Esophagus Trachea Lung (or pleura) Pleura Bronchi 11.Bronchioles 12.Diaphragm 13.Alveoli (air sacs) 14.Capillaries (blood vessels) 15.Capillary beds 16.Bronchioles 17.Alveoli RESPIRATORY SYSTEM PARTS AND FUNCTIONS Nose • Air enters • Hair filters out dust, dirt, and bacteria Nasal chamber • Warms and moistens air Pharynx (throat) • Passage to the trachea Epiglottis • Flap that closes over trachea • Keeps food and liquid out of the lungs Esophagus • Tube to the stomach RESPIRATORY SYSTEM PARTS AND FUNCTIONS Trachea (wind pipe) • Tube that carries air from the pharynx to the bronchi • Ciliated and has cartilage rings Bronchi (2 bronchi) • Short tubes from the trachea into the right and left lungs Bronchioles • Tiny tubes • Carry air from the bronchi to the alveoli Lung • Main organ of respiration • Contains tiny air sacs (alveoli) and capillaries RESPIRATORY SYSTEM PARTS AND FUNCTIONS Diaphragm • Muscle below the chest cavity • Moves down with inhalation (contracts) • Moves up with exhalation (relaxes) Capillaries • Surrounds the alveoli • SITE OF GAS EXCHANGE Alveoli • Air sacs • SITE OF GAS EXCHANGE THE FOUR PHASES OF HUMAN RESPIRATION THE FOUR PHASES OF HUMAN RESPIRATION I. BREATHING II. EXTERNAL RESPIRATION III. INTERNAL RESPIRATION IV. CELLULAR RESPIRATION I. BREATHING Movement of air into and out of the lungs Inhalation: • Ribs up and out • Diaphragm pulls down • Air rushes in Exhalation • Ribs relax and drop down • Diaphragm moves up • Air pushed out No muscles in the lungs, they are elastic and air is moved due to pressure changes Breathing controlled by • Respiratory center in the brain • Sensors in the aorta and other arteries that sense gas levels II. EXTERNAL RESPIRATION Exchange of oxygen and carbon dioxide between lungs (alveoli) and blood • Air flow moves with the concentration gradient III. INTERNAL RESPIRATION Exchange of oxygen and carbon dioxide between blood and tissues (body cells) • Exchange by diffusion III. INTERNAL RESPIRATION Exchange of oxygen and carbon dioxide between blood and tissues (body cells) Exchange by diffusion O2 CO2 O2 CO2 O2 CO2 O2 CO2 IV. CELLULAR RESPIRATION Using oxygen, the cells release energy (ATP) from food (glucose) TRANSPORT OF GASES IN BLOOD Oxygenated blood must be transported from the lungs to all the cells of the body TRANSPORT OF OXYGEN • Hemoglobin (Hb) carries O2 on red blood cells • Hb + O2 = oxyhemoglobin (HbO2) with a loose bond • CO has a stronger bond with hemoglobin than O2 therefore cigarette smokers’ blood carries less O2 than non-smokers’ blood TRANSPORT OF CARBON DIOXIDE 70% carried by water CO2 + H2O H2CO3 H2CO3 H + HCO3 20% carried by hemoglobin Hb + CO2 HbCO2 10% dissolves in plasma PHASES OF RESPIRATION BREATHING AIR → EXT. RESP → TRANSPORT → INT. RESP → CELL RESP ALVEOLI – CAPILLARY CAPILLARY – TISSUES O2 in / CO2 out BLOOD AEROBIC RESP BREATHING AIR → EXT. RESP → TRANSPORT → INT. RESP → O2 in / CO2 out ALVEOLI –CAPILLARY CAPILLARY – TISSUES → CELLULAR RESPIRATION BLOOD FLOW BREATHING INHALATION DIAPHRAGM RIB CAGE SIZE OF CHEST CAVITY AIR MOVEMENT PRESSURE EXHALATION INHALE CONTRACTS / MOVES DOWN UP AND OUT INCREASES INTO LUNGS LOWER IN LUNGS EXHALE RELAXES / MOVES UP DOWN AND IN DECREASES OUT OF LUNGS HIGHER IN LUNGS DISEASES OF THE RESPIRATORY SYSTEM ASTHMA • Chronic inflammation of the bronchi • Response to irritants with shortness of breath, coughing, and wheezing • Treated with medications and inhalers Asthma BRONCHITIS • Inflammation of the lining of the lower respiratory passages (bronchi and bronchioles) • Mucus production increases and impairs breathing • Risk of lung infection (pneumonia) increases Chronic Bronchitis EMPHYSEMA • Alveoli enlarge as the walls between the alveoli break down (airways collapse) • Chronic inflammation causes lungs to lose elasticity • It takes a large amount of energy just to breath • Over inflation of the lungs leads to a permanently expanded barrel chest emphysema lungs A normal lung PNEUMONIA • Infection in the lungs • Caused by – Bacteria (treatable with antibiotics) – Virus – fungus Pneumonia LUNG CANCER • Accounts for 1/3 of all cancer deaths in the United States • Second-hand smoke is the third leading cause of preventable death in America • Many have no symptoms in the early stages • Increased incidence associated with smoking (8 out of 10 lung cancers are caused by smoking) Lung Cancer