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THE RESPIRATORY SYSTEM THE RESPIRATORY SYSTEM In this chapter, you will learn: • The upper respiratory tract filters, warms, and moistens oxygencontaining air, and channels it into the lungs. • The lower respiratory tract is made up of specialized structures that exchange oxygen for carbon dioxide in the bloodstream. • Humans ventilate their lungs by the mechanism of breathing, which involves inspiration and expiration. • The volume of air that is taken into the lungs can increase if the need for oxygen increases, such as during exercise. • External respiration takes place in the lungs, between the air in the alveoli and the blood in the capillaries. THE RESPIRATORY SYSTEM In this chapter, you will learn: • Internal respiration takes place between the blood in the capillaries and tissue cells. • Gas exchange occurs through the processes of simple diffusion and facilitated diffusion. • Some disorders are specific to the respiratory system. Technologies are available to treat respiratory disorders, but they may not be able to restore the respiratory system to optimal health. • Smoking causes respiratory diseases. Technologies can help some symptoms of smoking, but many symptoms are untreatable. STRUCTURES OF THE RESPIRATORY SYSTEM In this section, you will: • identify the principal structures of the respiratory system • identify the principal functions of the respiratory system • observe and identify the major respiratory structures RESPIRATORY STRUCTURES Breathing involves two basic processes: inspiration (breathing in, or inhaling) and expiration (breathing out, or exhaling). Inspiration moves air from the external environment to the lungs inside the body. Expiration moves air from the lungs back to the external environment. • External respiration is the exchange of oxygen and carbon dioxide between the air and the blood. • Internal respiration is the exchange of oxygen and carbon dioxide between the body’s tissue cells and the blood. • Cellular respiration is the series of energy-releasing chemical reactions that take place inside the cells. Cellular respiration is the final stage in respiration. It is the sole means of providing energy for all cellular activities, and it helps the body maintain homeostasis. • ANATOMY https://www.youtube.com/watch?v=o2OcGgJbiUk THE RESPIRATORY TRACT • The respiratory tract is what brings air from the atmosphere to the lungs • Your body needs oxygen in the air to undergo aerobic cellular respiration to create energy • There is an upper and lower respiratory tract RESPIRATORY STRUCTURES • Air enters via the nasal cavities and mouth • The nasal cavities contain hairs and mucus that traps particles and keeps cells moist • At the same time, the large number of blood vessels inside the nose also warm the incoming air • The air then travels through the pharynx, which separates the trachea (windpipe) and the esophagus • When eating, an enlarged flap of cartilage called the epiglottis covers the trachea to prevent food from entering • Food and drink that enter the trachea stimulates cilia that lines the respiratory tract, producing a cough • Beyond the pharynx is the larynx, which is composed of thin sheets of elastic ligaments • When air passes past the larynx, sounds are produced (these are the vocal cords) • During speech, muscles contract and move these cords closer together • Males have thicker vocal cords, which results in a deeper voice NASAL CAVITY- UPPER RESPIRATORY TRACT • Turbinate bones increase SA in nasal cavity • Air cleaned warmed and moistened before passing to lungs • Well supplied with blood, moisture from secretions of epithelial tissues moisten air and together with small hairs (cilia) trap dust EUSTACHIAN TUBEUPPER RESPIRATORY TRACT • Connects nasopharynx to middle ear PHARYNX- UPPER RESPIRATORY TRACT • Common passageway for air and food • Nasopharynx contains ciliated epithelial cells LARYNX- UPPER RESPIRATORY TRACT • Voice box - located at opening to trachea - formed by several pairs of cartilage • Contains vocal cords • When you speak the muscles around the larynx contract drawing the vocal cords together [♂ voice change due to enlargement of larynx] https://www.youtube.com/watch?v=Z_ZGqn1tZn8 VOCAL CORDSUPPER RESPIRATORY TRACT • Two folds of tissue stretched across the larynx • Air in larynx, pharynx and mouth vibrated to produce sound - change in tension gives change in pitch [inflamed vocal cords thicken & produce husky voice or laryngitis] TRACHEA- UPPER RESPIRATORY TRACT • Major air tube of respiratory system (12 cm long) • Loosely attached to esophagus • Composed of smooth muscle and held open by cartilage rings cartilage prevents the trachea from collapsing • Lined with mucus producing cells that are ciliated & sweep toward the pharynx https://www.youtube.com/watch?v=d_5eKkwnIRs BRONCHI- LOWER RESPIRATORY TRACT • Trachea spits into 2 smaller pathways called bronchi • These bronchi lead to the left and right lungs • Once they reach the lungs the bronchi split into even smaller tubes called bronchioles • Both Bronchi and bronchioles are lined with cilia and mucus-producing cells BRONCHIOLES- LOWER RESPIRATORY TRACT • Each bronchus divided into many smaller passages without cartilage ("respiratory tree") ALVEOLAR DUCTS • Smaller ducts leading into alveolus ALVEOLILOWER RESPIRATORY TRACT • “Grape-like" clusters of tiny sacs in which air exchange takes place • Each is about 0.1 - 0.2 mm diameter and is surrounded by capillaries [about 300 million alveoli in 2 adult lungs] • Walls of capillaries and alveolus consist of single layer of epithelial cells which allows diffusion of gases to occur EACH BRONCHIOLE ENDS IN SEVERAL CLUSTERS OF ALVEOLI. SURROUNDING EACH ALVEOLUS IS A FINE NETWORK OF CAPILLARIES FROM THE CIRCULATORY SYSTEM. GAS EXCHANGE OCCURS BETWEEN THE BLOOD IN THE CAPILLARIES AND THE AIR IN THE ALVEOLUS, SO THAT BLOOD LEAVING THE LUNGS HAS A HIGH OXYGEN CONTENT. https://www.youtube.com/watch?v=XTMYSGXhJ4E PLEURA- LOWER RESPIRATORY TRACT • Two membranous sacs which surround lungs • Parietal - lines inner surface of chest wall & top of diaphragm • Visceral - adheres to surface of lungs • Film of fluid between two pleura serves as lubricant and to pull lung as chest wall expands [glass slide analogy] [pleurisy - inflammation of pleura caused by pneumonia, influenza or tuberculosis - breathing becomes painful] [collapsed lung - seal between the pleura is broken, air is eventually taken up by tissue and seal re-established] https://www.youtube.com/watch?v=cWQ14x1URXo LUNGS- LOWER RESPIRATORY TRACT • Left lung has 2 lobes (leaves room for heart), right lung has 3 lobes (larger than left) https://www.youtube.com/watch?v=CUUq7fLMruM https://www.youtube.com/watch?v=I40Qr9bOLOY RIBS • Move up and down as intercostal muscles contract and relax RIBS DIAPHRAGM • Thin, dome shaped sheet of muscle stretched across the bottom of the thoracic cavity • Separates thoracic from abdominal cavity https://www.youtube.com/watch?v=hp-gCvW8PRY THE MECHANISM OF BREATHING https://www.youtube.com/watch?v=hc1YtXc_84A BREATHING RATE • The breathing rate is the number of times you need to breathe in each minute • This rate is controlled by the amount of carbon dioxide in the blood not the amount of oxygen • If the carbon dioxide is high because of increased exercise, your breathing rate will speed up in order to get rid of the excess carbon dioxide RATE OF BREATHING • The normal breathing rate is between 12-20 times per minute depending on the body size • Physical activity increases the breathing rate because of the increased build up of Carbon dioxide • However, athletes at rest tend to use oxygen more effectively and have more developed lung capacity, which causes their respiration rate to be lower than normal • Children breathe twice as fast as adults because their lungs have less surface area for gas exchange BREATHING AND RESPIRATION • Air will flow if there is a pressure difference between the alveoli and the atmosphere https://www.youtube.com/watch?v=sKY6FXo3g-0 • Air needs help to flow in and out of the lungs • The diaphragm and the intercostal (chest) muscles work together during inhalation and exhalation • They control the air pressure in the lungs https://www.youtube.com/watch?v=SWJHSTAWTCk THE MECHANICS OF BREATHING Fig. 7.5 INHALATION • Inspiration is an active process of muscles contracting • Increase in volume of thoracic cavity results in a pressure differential decreases the air pressure around the lungs • The lungs are drawn outwards and the air pressure in the lungs decreases • Air moves from an area of high pressure to low pressure so moves from the environment to the lungs i diaphragm - on inspiration pulls downward, flattening shape -> pressure falls which draws air in ii intercostal muscles - contract moving ribs upward and outward [ about 500 mL enter respiratory tract (350 mL to lung & 150 mL to upper respiratory tract)] EXHALATION • The intercostal muscles and the diaphragm relax which makes the space in thoracic cavity smaller • This causes the lungs size to decrease which increases the air pressure inside the lungs • The pressure is now greater inside the lungs than in the environment so the air wants to move out NOW FOR THE QUESTION THAT YOU HAVE ALL BEEN ASKING…. AND THEN MAKING UP RANDOM STUFF TO EXPLAIN • The muscles that control breathing are controlled and regulated by the nervous system. Sometimes nerves misfire and cause irregular contractions of the diaphragm. This interrupts the normal rhythm of breathing and causes air to rush in to the lungs unexpectedly. • The brain immediately tries to correct this by causing the epiglottis to snap shut and close off the trachea • Air hits this closed opening, which is near the vocal cords, resulting in the “hic” sound of the hiccup YOUR TASK GAS EXCHANGE AND RESPIRATION • Respiration is a combination of external and internal respiration • External Respiration: happens in the lungs where gases are exchanged between the alveoli and the blood in capillaries • Internal Respiration: occurs between the blood and tissue cells in our body • Most oxygen in the blood is carried by hemoglobin which is only found in red blood cells When oxygen dissolves into the plasma, hemoglobin forms a weak bond with the oxygen molecule to form oxyhemoglobin • Very little carbon dioxide, 23%, is carried by hemoglobin • Most carbon dioxide is carried in the blood as bicarbonate ion (HCO3-), 70% • The final 7% is carried by plasma REGULATION OF BREATHING MOVEMENTS • Breathing movements are controlled by nerves from the medulla oblongata in the brain • Information about the accumulation of carbon dioxide and acids and the need for oxygen is detected by chemoreceptors • Two different types of receptors are: • Oxygen chemoreceptors • Carbon dioxide, or acid chemoreceptors (most sensitive and are the main regulators of breathing movements) REGULATION OF BREATHING MOVEMENTS • Carbon dioxide dissolves in the blood to form an acid • Carbon dioxide accumulates and chemoreceptors in the medulla oblongata relay message to the intercostal muscles and diaphragm to increase breathing movements • Accelerated breathing rate decreases the levels of Carbon dioxide in the blood • Once Carbon dioxide levels fall, chemoreceptors become inactive • Breathing returns to normal REGULATION OF BREATHING MOVEMENTS • A second monitoring system, relies on chemoreceptors sensitive to oxygen found in the carotid and aortic arteries • Specialized receptors are responsible for detecting low levels of oxygen • When stimulated they send a nerve impulses to the intercostal muscles and diaphragm to increase breathing movements. • Increased ventilation increases blood oxygen LUNG CAPACITY • 14 - 20 breaths/minute for a healthy adult TIDAL VOLUME • Amount of air moved by an individual at rest EXPIRATORY RESERVE VOLUME • Air left in lungs after normal exhalation INSPIRATORY RESERVE VOLUME • Air which can be added to lungs after normal inhalation VITAL CAPACITY • 3 volumes added together [varies according to age, size, and physical condition] RESIDUAL AIR CAPACITY • Air which cannot be forced from lungs A TYPICAL SPIROGRAPH Fig. 7.6 YOUR TASK • Practice Questions Page 288 #1 and 2 you will need to use the graph on the side of the page • Practice Questions Page 291 #2, 3, 5 • Explain Carbon monoxide poisoning page 293 • Practice Questions Page 297 # 1, 2, 4, 5 UPPER RESPIRATORY TRACT INFECTIONS - TONSILLITIS Infection of the tonsils (located in the pharynx) A viral infection is the common cause of tonsillitis UPPER RESPIRATORY TRACT INFECTIONS - TONSILLITIS Can be removed surgically if the infections are frequent and breathing is impaired. [In the past, many children had their tonsils removed as a precaution, but surgery is no longer as common.] Tonsils help to prevent bacteria and foreign pathogens from entering the body, so removing them can increase the number of infections later in life. UPPER RESPIRATORY TRACT INFECTIONS - LARYNGITIS Inflammation of the larynx - vocal cords are not able to vibrate normally Symptoms of laryngitis include a sore throat and hoarseness Most common cause of laryngitis is a viral infection; allergies and overstraining of the voice LOWER RESPIRATORY TRACT DISORDERS Fig. 7.8 LOWER RESPIRATORY TRACT INFECTIONS - BRONCHITIS Causes the bronchi to become inflamed and filled with mucus, which is expelled by coughing LOWER RESPIRATORY TRACT INFECTIONS - PNEUMONIA Alveoli in the lungs become inflamed and fill with liquids interfering with gas exchange -> body becomes starved for oxygen LOWER RESPIRATORY TRACT INFECTIONS - PLEURISY A lung disorder that is caused by the swelling and irritation of the pleura, the membranes that surround the lungs LOWER RESPIRATORY TRACT INFECTIONS - EMPHYSEMA Is an obstructive respiratory disorder in which the walls of the alveoli break down and lose their elasticity Reduces the SA for gas exchange and causes hypoxia in the tissues. LOWER RESPIRATORY TRACT INFECTIONS - CYSTIC FIBROSIS Serious genetic condition affecting the lungs An abnormal gene disrupts the function of the cells lining the passageways of the lungs LOWER RESPIRATORY TRACT INFECTIONS - ASTHMA Chronic obstructive lung disease that affects the bronchi and bronchioles Making breathing difficult or impossible because of reduced air flow. LOWER RESPIRATORY TRACT INFECTIONS - LUNG CANCER Uncontrolled and invasive growth of abnormal cells in the lungs Leading cause of cancer deaths for men and women in Canada. NORMAL LUNGS VS. DISEASED LUNGS A. normal lungs have healthy red tissue. (The heart is visible near the lower centre.) B. diseased lungs have black tissue caused by heavy smoking & white tumors, or carcinomas. CARCINOMA OF THE LUNG The large ball of cells in the centre of the image is a carcinoma that has developed from the interior surface cells of the human lung. The carcinoma continues to grow and invade surrounding tissues, including the lymphatic and blood vessels in the lung. The lymphatic and blood vessels circulate through the body and carry the cancerous cells, or metastatic cells, to new locations where they can grow and invade new tissues. SUPERFICIAL REASONS NOT TO SMOKE REASONS NOT TO “CHEW” • Chewing tobacco is every bit as dangerous as smoking • Cancer - lips, tongue, the floor of the mouth, the roof of the mouth, the cheeks, gums, lining of your stomach, your esophagus, and into your bladder THE BENDS • The blood and tissues of divers absorb extra amounts of gases because of the increased pressure under water. • This is not a problem unless the individual comes to the surface too quickly • If this happens, the gases will bubble in the tissue which can cause dizziness, nausea as well as muscle and joint pain. • In extreme cases it can be fatal TUBERCULOSIS • Communicable disease among humans and animals that is caused by bacteria • Manifests in the lungs, bones, urinary tract, brain and other parts of the body • Affects the pulmonary system the most • Can cause mental illness and has a high infant death rate • Tuberculosis kills more people than all other communicable diseases combined • Symptoms include: fatigue, abnormal sound in the lungs, afternoon fevers, buildup of blood in the lungs • Treatment includes collapsing the lung in order to rest it or surgically removing infected area CONCEPT ORGANIZER CHAPTER SUMMARY • Respiration enables the body to take oxygen from the external environment and process it for delivery to the cells and, at the same time, rid itself of carbon dioxide. • O2 is delivered to the cells and CO2 is removed from the cells and the body in a number of exchanges. • Inspiration and expiration (breathing) exchange air between the environment and the lungs. • External respiration exchanges oxygen and carbon dioxide between the air in the lungs and the blood. • Internal respiration exchanges oxygen and carbon dioxide between the blood and the body’s tissue cells. • Cellular respiration is the final step, when the oxygen delivered to the cells is used to provide the energy for all cellular activities. CHAPTER SUMMARY • The respiratory tract is the passageway for air to move from the external environment to the lungs. • The upper respiratory tract begins at the nostrils and includes the nasal passages, pharynx, larynx, and trachea. • These passageways all clean and warm the air as it passes through. • Infections of the upper respiratory tract, such as tonsillitis and laryngitis are short term infections that do not obstruct breathing. • The lower respiratory tract consists of two bronchi that each lead to a lung. • Within the lungs are small, fine tubes called bronchioles, where the air continues to be cleaned and warmed. • The exchange of gases takes place in a cluster of tiny sacs at the end of each bronchiole, called alveoli, where the oxygen diffuses through the membranes of the alveoli into the capillaries of the circulatory system. CHAPTER SUMMARY • Disorders of the lower respiratory tract can impair the delivery of oxygen to the cells • Examples include: bronchitis, pneumonia, pleurisy, emphysema, cystic fibrosis, asthma, and lung cancer. YOUR TASK