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NAl Gas exchange student.pdf Powerpoint Presentation
- 2. Cos its beena while….. • https://www.youtube.com/watch?v=- qi7OZzXJjg • Jam campus
- 3. Gas exchange What isthe name given to the system involved in gas exchange (1) Name the organs of this system (2) Where is the site of gas exchange in mammals? (1) What are the adaptations of this site that are suited for its function? (1) What are the gases that are exchanged? (2) What is the name given to the taking in of air into the lungs? (1) What is the name given to the expulsion of air from the lungs? (1)
- 4. Remember this? 1. 2. 3. 4. 5. 6.Oxygenated blood leaves the heart to the rest of the body via which vessel?
- 5. 1.Trachea 2. Bronchus 3. Bronchiole 4.Alveoli 5. Diaphragm 6. Aorta
- 6. How many partsof the respiratory system can you label correctly? EXT: add their functions
- 7. Trachea Windpipe Lung Takes in oxygenand release carbon dioxide into the atmosphere Diaphragm Muscle, contracts to allow air to be drawn into the lungs Ribs Enable the lungs to expand Alveoli Gas exchange surface Intercostal Muscles Form and move the chest wall Bronchus (p) / Bronchi (s) Allows passage of air to the lungs Bronchioles Passageway for the air Larynx (Voicebox) Self-Assess
- 13. GASEOUS EXCHANGE THE NEEDFOR A RESPIRATORY SURFACE •In small organisms, surface area : volume ratio is large, so diffusion is sufficient •In larger organisms, surface area : volume ratio is small so a gaseous exchange system has evolved.
- 14. Features of arespiratory surface 1. Large surface area for gaseous exchange 2. Moist surface for gases to dissolve 3. Short diffusion distance - alveoli and capillary walls only one cell thick 4. Richly supplied with capillaries to maintain a concentration gradient
- 15. Structure of thegaseous exchange system • Pharynx – throat • Epiglottis –flap of cartilage which seals off trachea • Larynx – voice box • Goblet cells – in between ciliated epithelial lining, secrete sticky mucus (a glycoprotein) to trap pathogens. • Cilia – beat rhythmically to sweep mucus up the trachea at 1cm/min, to be swallowed. • Macrophages – WBC which scavenge pathogens from lining of airways.
- 17. Trachea - mainairway • C- shaped cartilagenous rings keep it open, and prevent it from collapsing under changes in air pressure. • Lined with goblet cells (produce mucus) and cilia (sweeps mucus with pathogens up to the larynx to be swallowed) • Has elastic fibres and collagen for stretch and flexibility • Has smooth muscle – this can contract and cause spasm (asthma) – bronchodilators are drugs to relax the muscles of the airways.
- 19. Bronchus x2 bronchi •Irregular cartilagenous blocks • Goblet cells and cilia • Smooth muscle • Elastic fibres and collagen Bronchioles • Branches • No cartilage – allows for muscle relaxation and contraction, eg during exercise relaxes to let more air in. • Cilia and goblet cells • Smooth muscle • Elastic fibres
- 20. Alveolar ducts –small tubes which join bronchioles and alveoli Alveolus – single layer of epithelial cells • No cartilage • No muscle • No goblet cells or cilia • Elastic fibres present to allow stretch and recoil during inspiration and expiration, large volume created • Secretions from alveolar lining allow gases to dissolve • Richly supplied with capillary blood • Forms gaseous exchange surface.
- 22. Surfactant : • asecretion from the alveoli which reduces surface tension in alveolus wall x10 thus reducing the effort needed to inflate the alveoli. • Antibacterial properties • Assists diffusion
- 25. structure cartilage goblet cells ciliaSmooth muscle Elastic fibres Size (mm) Trachea √ Bronchus √ irregular √ Bronchioles Alveoli X Copy and complete the table
- 26. structure cartilage goblet cells ciliaSmooth muscle Elastic fibres Size Trachea √ C- shaped √ √ √ √ 18mm Bronchus √ irregular √ √ √ √ 12mm Bronchioles X √ √ √ √ 0.5mm Alveoli X X X X √ 0.25mm
- 28. Use your textbooksto describe how the trachea and lining of lungs are protected TASK
- 29. Pleural membranes • Linethe lungs on the outside and the thoracic cavity on the inside forming a pleural sac • The membrane secretes pleural fluid which reduces friction of lungs against ribs • The fluid filled sac is non compressible , so when the thorax volume decreases, air is forced out of the alveoli. When the volume increases the alveoli ‘stick’ to the chest wall and are pulled open i.e inflate thus drawing air in.
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- 31. Blood flow throughthe pulmonary capillaries maintains a concentration gradient.
- 33. Breathing movements constantlyventilating the lungs, and action of the heart constantly circulating the blood around the alveoli. Concentration gradient is maintained
- 36. 6 mark question •Diffusion of gases between the alveoli and the blood will be very rapid, why?
- 37. Swap and assess(green pen) • Red blood cells are slowed as they pass through pulmonary capillaries, allowing more time for diffusion. • Reduced distance between alveolar air and red blood cells • Very tin wall, both alveoli and capillaries. Therefore very short diffusion pathway. • Alveoli and pulmonary capillaries have a large surface area • Breathing movements constantly ventilating the lungs, and action of the heart constantly circulating the blood around the alveoli. Concentration gradient is maintained • Blood flow through the pulmonary capillaries maintains a concentration gradient.
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- 40. Ventilation Inspiration: • External intercostalmuscles contract • Internal intercostal muscles relax • Ribcage pulled up and out • Diaphragm muscles contracts – flattens/pulls down • Increase in thoracic cavity volume, lowers pressure, thus drawing in air
- 41. Expiration • External intercostalmuscles relax • Internal intercostal muscles contract • Diaphragm relaxes – moves up • Ribcage moves down and in • Thoracic cavity volume decreases • Pleural fluid is non compressible and assists in forcing out air due to increased pressure
- 42. Control of Breathing Respiratorycentre Chemoreceptor pCO2 Low pH
- 43. Effects of gasconcentration on breathing rate •When pO2 decrease and pCO2 increases, the rate and depth of breathing increases •When pO2 increases and pCO2 decreases, the rate and depth of breathing decreases
- 44. Importance of Partialpressure of CO2 pCO2 increase Detected by chemoreceptor Impulse to respiratory centre Impulse to intercostal and diaphragm muscle by efferent nerve Rate and depth of breathing increase pCO2 back to normal Feedback
- 45. GAS COMPOSITION INBREATHING GAS INHALED (%) EXHALED (%) NITROGEN 78 78 OXYGEN 21 16 CARBON DIOXIDE 0.04 4