6.4 Gas exchange

1. 6.4 Gas exchange http://www.siumed.edu/surgery/cardiothoracic/emphysema.html http://www.emphysemafoundation.org/index.php/about-uss/our-mission

2. 6.4 • Essential idea: The lungs are actively ventilated to ensure that gas exchange can occur passively.

3. Cellular respiration is the controlled release of energy in the form of ATP from organic compounds in cells. It is a continuous process in all cells. Aerobic: C6H12O6+ 6O2 6CO2 + 6H2O + ATP

4. To support aerobic cellular respiration, cells take in oxygen from their environment and give out carbon dioxide, by a process called . • Gas exchange ultimately .

5. All animal respiratory systems share two features that facilitate diffusion: • Respiratory system (gases must be dissolved in water to diffuse into or out of cells) • Respiratory system • Most animals have evolved specialized respiratory systems

6. 6.4.U1 Ventilation maintains concentration gradients of oxygen and carbon dioxide between air in alveoli and blood flowing in adjacent capillaries. • In general, gas exchange in most respiratory systems occurs in the following stages: • Air or water, containing oxygen, is moved past a respiratory system by bulk flow( ) – commonly facilitated by

7. 6.4.U1 Ventilation maintains concentration gradients of oxygen and carbon dioxide between air in alveoli and blood flowing in adjacent capillaries. O2 • Oxygen and carbon dioxide are exchanged through the respiratory surface by ; is carried of circulatory system and CO2 Capillary

8. 6.4.U1 Ventilation maintains concentration gradients of oxygen and carbon dioxide between air in alveoli and blood flowing in adjacent capillaries. • Gases are transported between

9. 6.4.U1 Ventilation maintains concentration gradients of oxygen and carbon dioxide between air in alveoli and blood flowing in adjacent capillaries. • Gases are exchanged between (oxygen diffuses out into tissue and carbon dioxide diffuses into capillaries based on concentration gradients)

10. 6.4.U1 Ventilation maintains concentration gradients of oxygen and carbon dioxide between air in alveoli and blood flowing in adjacent capillaries. • Because the lungs are protected in the thorax (chest), air must be brought in. • This results in the need for a ventilation system: • A ventilation system is a

11. 6.4.U1 Ventilation maintains concentration gradients of oxygen and carbon dioxide between air in alveoli and blood flowing in adjacent capillaries. • Human Respiratory System (and other vertebrates) is divided into two parts: • The conducting portion – • The gas exchange portion –

12. 6.4.U4 Air is carried to the lungs in the trachea and bronchi and then to the alveoli in bronchioles. Passageway of air in respiratory system: • Nostrils – air enters body • Nasal cavities – air is warmed, filtered and moistened • Lined with Cilia

13. 6.4.U4 Air is carried to the lungs in the trachea and bronchi and then to the alveoli in bronchioles. #3 Pharynx #1 Nose • Pharynx – back of nasal cavities that is continuous with the throat; #2 Mouth

14. 6.4.U4 Air is carried to the lungs in the trachea and bronchi and then to the alveoli in bronchioles. #5 Larynx • Epiglottis – flap of tissue that automatically covers opening to larynx during swallowing; • Larynx – Pharynx leads to Larynx “voice box” • Contains • Cartilage is embedded in walls to prevent collapse #4 Epiglottis Epiglottis

15. 6.4.U4 Air is carried to the lungs in the trachea and bronchi and then to the alveoli in bronchioles. Lungs • Trachea – also called windpipe; tube that carries air down to lungs – • Bronchi – two branches off the trachea that #6 #7 Trachea Bronchus

16. 6.4.U4 Air is carried to the lungs in the trachea and bronchi and then to the alveoli in bronchioles. #9 Alveoli • Bronchioles – smaller tubes of the bronchi that Bronchiole #8 Bronchioles

17. Lungs – large, paired spongy organs • Right lung is divided into 3 lobes • Left lung is divided into 2 lobes • Each is covered by a pleural membrane – forms a sac and lines the thoracic cavity • Secretes a fluid that provides lubrication between lungs and chest wall *The pleural membrane protects the lung tissue and the lubricant helps reduce friction as the lung expand and rub against other parts inside the body.

18. 6.4.U4 Air is carried to the lungs in the trachea and bronchi and then to the alveoli in bronchioles. • Alveoli – each bronchiole ends in a cluster of tiny air sacs • Numerous small clusters for • Walls of alveoli are extremely thin ( )

19. 6.4.U2 Type I pneumocytes are extremely thin alveolar cells that are adapted to carry out gas exchange. AND 6.4.U3 Type II pneumocytes secrete a solution containing surfactant that creates a moist surface inside the alveoli to prevent the sides of the alveolus adhering to each other by reducing surface tension. • Two types of cells make up the alveoli wall: • Type I pneumocytes – • Type II pneumocytes – secrete a solution containing surfactant that allow http://www.ubccriticalcaremedicine.ca/rotating/material/Lecture_1%20for%20Residents.pdf

20. 6.4.U1 Students should be able to draw a diagram to show the structure of an alveolus and an adjacent capillary A. D. C. B.

21. 6.4.U4 Air is carried to the lungs in the trachea and bronchi and then to the alveoli in bronchioles. • Alveoli are surrounded by capillaries • Gases diffuse freely through the wall of the alveolus and capillary (oxygen diffuses into blood and CO2 diffuses into alveoli) CO2 Capillary

23. 6.4.U5 Muscle contractions cause the pressure changes inside the thorax that force air in and out of the lungs to ventilate them. • Breathing (ventilation) is the mechanical process of moving air from the environment into the lungs and expelling air from the lungs • The is an airtight chamber and pressure changes in the lungs occurs when the volume of the thorax changes • Pressure changes

24. 6.4.U6 Different muscles are required for inspiration and expiration because muscles only do work when they contract. • Inspiration (inhalation): • Diaphragm(dome-shaped muscle forming floor of thoracic cavity) • Abdominal muscles • External intercostal rib muscles (internal intercostal muscles ) • This (below atmospheric pressure) • Air from outside

25. 6.4.U6 Different muscles are required for inspiration and expiration because muscles only do work when they contract. • Expiration (exhalation) • Diaphragm(moves up) • Internal intercostal muscles (external intercostal muscles ) • This • Air from inside lungs • When you breathe forcefully, your abdominal muscles also contract. This squeezes your abdominal organs which puts pressure on the diaphragm.

26. 6.4.A3 External and internal intercostal muscles, and diaphragm and abdominal muscles as examples of antagonistic muscle action. Expiration Inspiration Diaphragm relaxes (moves up)Abdominal muscles contract Diaphragm contracts (moves down)Abdominal muscles relax External intercostal muscles contract Internal intercostal muscles relax External intercostal muscles relax Internal intercostal muscles contract

27. Control of Breathing Rate • Breathing rate is controlled by the – located in medulla just above spinal cord • muscles are stimulated to contract by impulses from respiratory center • nerve cells in respiratory center generate cyclic bursts of impulses that cause the alternating contraction and relaxation of respiratory muscles

28. Respiratory center receives input from several sources and adjusts breathing rate and volume to meet body’s changing needs • is the most important chemical stimulus for regulating rate of respiration • Chemoreceptors in medulla, and in walls of the aorta and carotid arteries are sensitive to changes in arterial CO2 concentration

29. 6.4.A2 Causes and consequences of emphysema. Emphysemais a chronic lung disease. The . http://www.humanillnesses.com/original/images/hdc_0001_0002_0_img0097.jpg

30. 6.4.A2 Causes and consequences of emphysema. Consequences: Total & the , so gas exchange is much less effective. Lungs become less elastic, so ventilation is more difficult. Symptoms are . It is a type of chronic obstructive pulmonary disease (COPD) - a group of lung diseases that block airflow and make it difficult to breathe. It is a progressive disease for which there is no cure. http://img.webmd.com/dtmcms/live/webmd/consumer_assets/site_images/articles/health_tools/dey_copd_slideshow/photolibrary_rf_photo_of_mature_woman_using_oxygen.jpg

31. 6.4.A2 Causes and consequences of emphysema. • Causes: • Cigarette smoking • Air pollution • Marijuana smoking • Manufacturing fumes • Alpha-1-antitrypsin deficiency emphysema (rare): “Mutations in the SERPINA1 gene cause alpha-1 antitrypsin deficiency. This gene provides instructions for making a protein called alpha-1 antitrypsin, which protects the body from a powerful enzyme called neutrophil elastase. Neutrophil elastase is released from white blood cells to fight infection, but it can attack normal tissues (especially the lungs) if not tightly controlled by alpha-1 antitrypsin.” https://ghr.nlm.nih.gov/condition/alpha-1-antitrypsin-deficiency#genes Leading causes Eric Lawson, known as the Marlboro man, died of respiratory failure as a result of COPD. He began smoking at age 14. http://www.huffingtonpost.com/2014/01/27/eric-lawson-marlboro-man-dies_n_4671746.html

32. 6.4.A2 Causes and consequences of emphysema. How do the alveoli become damaged? • Cilia become damaged and cease to function and mucus builds up, causing infection. • Toxins in cigarette smoke and polluted air cause inflammation in the lungs. • Protease (trypsin) is released by phagocytes, while anti-protease is inhibited and elastic fibers in the lungs are digested - eventually causes complete breakdown of alveolus walls.

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35. 6.4.A1 Causes and consequences of lung cancer. Lung cancer is the most common cancer in the world, both in terms of the . http://www.lungevity.org/about-lung-cancer/lung-cancer-101/screening-early-detection

36. 6.4.A1 Causes and consequences of lung cancer. • Causes: • Cigarette smoking – tobacco smoke contains many carcinogens; causes • Second hand smoke (passive smoking) • Air pollution • Radon gas – in some areas it leaks out of rocks, especially granite • Asbestos and silica http://www.bbc.co.uk/education/guides/zpn9q6f/revision/5 Healthy lung Lung with tar deposits http://www.who.int/tobacco/healthwarningsdatabase/tobacco_large_canada_lung_05_en/en/

37. 6.4.A1 Causes and consequences of lung cancer. • Consequences: • Difficulties breathing • Persistent coughing • Coughing up blood • General fatigue • Chest pain • Loss of appetite • Weight loss Only 15% of patients with lung cancer survive for more than 5 years. If caught early enough, all or part of the affected lung may be removed. Chemotherapy and radiation may also be needed.

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