Biol107 Lecture 18 - Chapter 15 PDF

Chapter 15 Respiratory System Copyright © 2017 McGraw-Hill Education. Permission required for reproduction or display. 1  The Respiratory System The primary function of the r...

Chapter 15 Respiratory System Copyright © 2017 McGraw-Hill Education. Permission required for reproduction or display. 1  The Respiratory System The primary function of the respiratory system is to allow oxygen from the air to enter the blood and carbon dioxide from the blood to exit into the air. Ventilation, or breathing, has two parts. Inspiration, or inhaling, conducts air toward the lungs. Expiration, or exhaling, conducts air away from the lungs. 2  The Respiratory System The respiratory system and the cardiovascular system work together to accomplish: 1. Exchange of gases (O2 and CO2) between air and the blood (external respiration). 2. Transport of gases to and from the lungs and the tissues. 3. Exchange of gases (O2 and CO2) between blood and tissue fluid (internal respiration). 3  The Respiratory System Figure 15.1(a) Copyright © 2017 McGraw-Hill Education. Permission required for reproduction or display. 4  The Respiratory System Figure 15.1(b) Copyright © 2017 McGraw-Hill Education. Permission required for reproduction or display. 5  The Respiratory Tract As air moves in along the airways, it is: – Cleansed - by nostril hair and cilia and mucus along nasal cavities and trachea; – Warmed – by the heat given off by the blood vessels lying close to the surface of airway lining – Moistened – by the wet surfaces of the air passages. As air moves out, it cools and loses moisture 6  The Respiratory Tract TABLE 15.1 Path of Air. Structure Description Function Upper Respiratory Tract Nasal cavities Hollow spaces in nose Filter, warm, and moisten air Pharynx Chamber posterior to oral cavity; lies Connection to surrounding regions between nasal cavity and larynx Glottis Opening into larynx Passage of air into larynx Larynx Cartilaginous organ that houses the Sound production vocal cords; voice box Lower Respiratory Tract Trachea Flexible tube that connects Passage of air to larynx with bronchi bronchi Bronchi Paired tubes inferior to the trachea that Passage of air to lungs enter the lungs Bronchioles Branched tubes that lead from bronchi Passage of air to each alveolus to alveoli Lungs Soft, cone-shaped organs of thoracic Contain alveoli and blood vessels cavity Alveoli Thin-walled microscopic air Gas exchange between air and sacs in lungs blood 7  The Nose The Nose – Part of upper respiratory tract Includes nasal cavities, pharynx, and larynx – Air enters through nostrils (external openings) – Contains two nasal cavities Warms and moistens air during inhalation Contains odor receptors Tear glands drain into nasal cavity Separated from mouth by hard and soft palate 8  The Pharynx Pharynx connects nasal and oral cavities to larynx – Three parts Nasopharynx – where the nasal cavities open posterior to soft palate Oropharynx – where the mouth opens Laryngopharynx – opens into the larynx – Uvula - soft extension of soft plate projects into oropharynx – Tonsils - a protective ring Lymphatic tissue that protects against inhaled microbes 9  The Pharynx Jump to long image description Figure 15.2 Copyright © 2017 McGraw-Hill Education. Permission required for reproduction or display. 10  The Pharynx-3 Larynx – cartilaginous structure – Passageway for air between pharynx and trachea – Vocal cords Folds of mucosa that vibrate to make sounds – Glottis - opening between folds Epiglottis – Flap preventing food from entering the respiratory tract Jump to long image description Figure 15.3 left: © CNRI/Phototake Copyright © 2017 McGraw-Hill Education. Permission required for reproduction or display. 11  The Trachea Trachea (windpipe) – Tube connecting larynx to primary bronchi – Held open by C-shaped cartilage rings – Cilia sweep mucus toward the pharynx Smoking can destroy cilia Jump to long image description Figure 15.4 Copyright © 2017 McGraw-Hill Education. Permission required for reproduction or display. 12  The Bronchial Tree Trachea divides into right and left primary bronchi Lead into right and left lungs – Branch to secondary bronchi Eventually lead to bronchioles – As airways divide and subdivide, the walls become thinner The small rings of cartilage are no longer present – Each bronchiole leads into sac called alveoli 13  The Bronchial Tree Figure 15.1(c) Copyright © 2017 McGraw-Hill Education. Permission required for reproduction or display. 14  The Lungs The lungs are paired, cone-shaped organs. – Occupy thoracic cavity Diaphragm separates it from abdominal cavity – Right lung has 3 lobes – Left lung has 2 lobes Allows room for heart – Each lobe subdivided into lobules Each lobule has a bronchiole serving many alveoli 15  The Lungs – Each lung is covered by very thin serous membranes called pleura. – Another pleura covers the internal chest wall and diaphragm. – Both pleura produce lubricating serous fluid that helps the pleurae slide freely against each other during inspiration and expiration. – Surface tension holds the two pleura layers together when the lungs recoil in expiration. 16  The Lungs The alveoli are made up of simple squamous epithelium surrounded by blood capillaries. – Gas exchange occurs between the air in the alveolus and the blood in the capillaries. Oxygen diffuses across the walls into blood. Carbon dioxide diffuses into alveoli. – Alveoli must stay open to receive air. Pulmonary surfactant helps prevent them from closing. – Infant respiratory distress syndrome – premature infants lack surfactant 17  The Lungs Figure 15.5 Access the text alternative for these images 18  Mechanisms of Breathing During ventilation (breathing), free air flow is vitally important. Medical professionals use a device called a spirometer to record volume. – The volume of air exchanged during both normal and deep breathing can be measured. – Breathing patterns are a useful way of understanding normal inspiration and expiration. 19  Mechanisms of Breathing Spirometer – Records the volume of air exchanged during both normal and deep breathing Spirogram – Shows the measurements recorded when a person breathes as directed by a technician Figure 15.6(a) © Yoav Levy/Phototake 20  Respiratory Volumes Tidal volume – Amount of air inhaled and exhaled with each breath at rest – Normally is about 500 ml Vital capacity – Maximum volume moved in and out in a breath – Illness can affect vital capacity 21  Respiratory Volumes Inspiratory reserve volume – Forced inhalation of air moved in above tidal volume Roughly an additional 3.0 liters from tidal volume Expiratory reserve volume – Forced exhalation of air moved out beyond tidal volume Roughly 1.5 liters additional to tidal volume These together = vital capacity All volumes depend on age, gender, physical conditioning 22  Respiratory Volumes Figure 15.6(b) Copyright © 2017 McGraw-Hill Education. Permission required for reproduction or display. 23  Respiratory Volumes During normal breathing, only about 70% of the tidal volume reaches the alveoli. – 30% remains in the airways – Even after deep exhalation, air remains in the lungs Residual volume – Amount of air always remaining in lungs – Typically about 1000ml of air 24  Inspiration and Expiration Understanding Ventilation 1. There is a continuous column of air from pharynx to alveoli. 2. The lungs lie in the sealed-off thoracic cavity. Rib cage forms top and sides Intercostal muscles lie between the ribs Diaphragm forms the floor 25  Inspiration and Expiration 3. The lungs adhere to the thoracic wall by way of the pleura. 4. Ventilation is governed by Boyle’s Law: – at a constant temperature the pressure of a quantity of gas is inversely proportional to its volume. 26  Inspiration and Expiration Jump to long image Figure 15.7 description Copyright © 2017 McGraw-Hill Education. Permission required for reproduction or display. 27  Inspiration and Expiration Inspiration The active phase – Diaphragm contracts Becomes flattened – Internal intercostals contract Raises rib cage up and out – Volume of thoracic cavity increases – Air pressure inside alveoli lowers – Air rushes in due to negative pressure Figure 15.8a Copyright © 2017 McGraw-Hill Education. Permission required for reproduction or display. 28  Inspiration and Expiration Expiration The passive phase – Diaphragm and internal intercostals relax – Recoil returns them to original shape – Volume of thoracic cavity decreases – Air pressure inside alveoli increases – Air rushes out Figure 15.8b Copyright © 2017 McGraw-Hill Education. Permission required for reproduction or display. 29  Control of Breathing Normally, adults have a resting breathing rate of 12 to 20 ventilations per minute. The respiratory center, located in the medulla oblongata of the brain, controls the ventilation rhythm. This center stimulates inspiration by sending signals to certain muscles. When the center temporarily stops, signals are not sent to the muscles. 30  Control of Breathing Inspiration begins when the respiratory center sends out nerve impulses to the diaphragm via the phrenic nerve and the intercostal muscles via the intercostal nerves, causing contraction. Expiration begins when the respiratory center ceases to send out nerve impulses to the diaphragm and rib cage; relaxation occurs. The respiratory center is also influenced by nervous and chemical input. After forced inhalation, stretch receptors send inhibitory nerve impulses via the vagus nerve to inhibit the respiratory center temporarily. 31  Control of Breathing Chemical input to respiratory center: – Directly sensitive to the levels of CO2 and H+ When levels rise, respiratory center increases rate and depth of breathing – Indirectly responsive to O2 Chemoreceptors in the carotid and aortic bodies sensitive to oxygen levels in blood – When levels decrease, impulses are sent to the respiratory center. – Respiratory center then increases rate and depth of breathing. 32  Control of Breathing Jump to long image description Figure 15.9 Copyright © 2017 McGraw-Hill Education. Permission required for reproduction or display. 33  Gas Exchanges in the Body Respiration includes the exchange of gases in the lungs (external respiration) and the exchange of gases in the tissues (internal respiration). Most of the O2 carried in the blood is attached to the iron-containing heme portion of the protein hemoglobin. 34  External Respiration Exchange of gas between air in alveoli and blood – Partial pressure refers to the amount of pressure each gas in a mixture exerts. Symbolized by Pco2 and Po2 – Blood in pulmonary capillaries has a higher Pco 2 than atmospheric air. CO2 diffuses from blood into alveoli 35  External Respiration Most CO2 is carried in the blood as bicarbonate ions (HCO3−) in blood plasma. As free CO2 diffuses out of the blood at the lungs, the enzyme carbonic anhydrase catalyzes the breakdown of carbonic acid to free up more CO2 to be expelled at lungs. carbonic anhydrase H  HCO3 H2CO3     H2O CO2 hydrogen bicabonate carbonic water carbon ion ion acid dioxide 36  External Respiration The pressure gradient for O2 is the reverse of CO2. Po2 is low in pulmonary capillaries and high in alveoli. O2 diffuses into blood from alveoli. Hemoglobin in red blood cells picks up O2 and becomes oxyhemoglobin. Hb  O2 HbO2 hemoglobin oxygen oxyhemoglobin 37  Internal Respiration Exchange of gas between systemic capillaries and the interstitial fluid. Services tissue cells, which use up O2. Partial pressure of O2 is greater in capillaries than interstitial fluid. Oxygen diffuses out of blood and into tissues as oxyhemoglobin gives up O2. HbO2 Hb  O2 oxyhemoglobin hemoglobin oxygen 38  Internal Respiration CO2 diffuses into the blood. A small amount combines with hemoglobin to form carbaminohemoglobin. Most CO2 combines with H2O to form carbonic acid, which dissociates into H+ and HCO3−. Carbonic anhydrase speeds up the reaction. carbonic anhydrase CO2  H2O     H2CO3   H  HCO3 carbon water carbonic hydrogen bicarbonate dioxide acid ion ion 39  Internal and External Respiration Jump to long image description Figure 15.10(a) Copyright © 2017 McGraw-Hill Education. Permission required for reproduction or display. 40  External Respiration at Lungs 1 CO2 exits blood Figure 15.10(b) Copyright © 2017 McGraw-Hill Education. Permission required for reproduction or display. 41  External Respiration at Lungs 1 O2 enters blood Figure 15.10(c) Copyright © 2017 McGraw-Hill Education. Permission required for reproduction or display. 42  Internal Respiration at Tissues CO2 enters blood Figure 15.10(d) Copyright © 2017 McGraw-Hill Education. Permission required for reproduction or display. 43  Internal Respiration at Tissues O2 exits blood Figure 15.10(e) Copyright © 2017 McGraw-Hill Education. Permission required for reproduction or display. 44  Disorders of the Respiratory System The respiratory tract is constantly exposed to the air in our environment and thus susceptible to: – Various infectious agents – Pollution – In some individuals, tobacco smoke 45 Disorders of the Upper Respiratory Tract Upper respiratory tract – Includes nasal cavities, the pharynx, and the larynx – Susceptible to a variety of viral and bacterial infections due to its air filtering function – Upper respiratory infections can also spread from these areas to the middle ear or the sinuses 46  The Common Cold Most are caused by relatively mild viruses Most common are rhinoviruses – Symptoms include sneezing, runny nose, and mild fever – Last a few days to a week for individuals with a healthy immune system – Antibiotics are ineffective against viral infections – Medications may be used to treat symptoms 47  Pharyngitis, Tonsillitis, and Laryngitis Pharyngitis – Inflammation of the throat due to infection – Streptococcus pyogenes causes “strep throat” – Symptoms are sore throat, fever, and white patches Treated by antibiotics Jump to long image description Figure 15.11 © Dr. P Marazzi/Science Source 48 Pharyngitis, Tonsillitis, and Laryngitis Tonsillitis – Tonsils (lymphoid tissue) become inflamed and enlarged – Frequent inflammation can lead to surgical removal by tonsillectomy Laryngitis – Inflammation of the larynx – Causes hoarseness with difficulty in speaking Benign polyps can develop on vocal cords, especially individuals that use them excessively. 49  Sinusitis Inflammation of the cranial sinuses within the facial skeleton that drain into the nasal cavities. Develops when nasal congestion blocks sinus openings. Symptoms include postnasal discharge, headache, and facial pain. Up to 10% of upper respiratory infections are accompanied by sinusitis. 50  Otitis Media Inflammation of the middle ear – Nasal infections spread to the ear by way of the auditory (eustachian) tubes. – Tympanostomy tubes are helpful in children with chronic otitis media. Jump to long image description Figure 15.12 © Clinica Claros/Phototake 51 Disorders of the Lower Respiratory Tract Several disorders of the lower respiratory tract cause problems by obstructing normal airflow. Causes: – Foreign objects lodged in the trachea – Excessive mucus in bronchi or bronchioles – Conditions that tend to restrict normal elasticity 52  Disorders of the Trachea and Bronchi Choking – Obstruction of the trachea – Heimlich maneuver - physical technique to expel blockage – Tracheotomy - insertion of a breathing tube into the trachea (tracheostomy) Individuals whose larynx or trachea have been damaged or destroyed may require a permanent tracheostomy tube. 53 Disorders of the Trachea and Bronchi Acute bronchitis – Inflammation of the primary and secondary bronchi – Usually preceded by a viral infection that leads to a secondary bacterial infection Chronic bronchitis – Airways are inflamed and filled with mucus – Bronchi have undergone degenerative change including the loss of cilia – Smoking is the most common cause 54 Disorders of the Trachea and Bronchi Asthma – A disease of the bronchi and bronchioles – Marked by wheezing, breathlessness Sometimes coughing and expectoration of mucus – Triggered by specific irritants Smooth muscle in bronchioles spasms – Incurable but can be treated with medicines 55  Diseases of the Lungs Pneumonia – Infection in which bronchi or alveoli fill with thick fluid – Symptoms include high fever, chest pain, and headache – Caused by bacteria, viruses, and other infectious agents Pulmonary tuberculosis – Caused by the bacterium Mycobacterium tuberculosis – Lung cells build a protective capsule (tubercle) around invading bacteria – If resistance is low, bacteria escape and spread – TB skin test – checks for exposure to M. tuberculosis 56  Diseases of the Lungs Emphysema – A chronic and incurable disease – Damages the walls of the alveoli – Reduces surface area for gas exchange – COPD usually associated with smoking Cystic fibrosis (CF) – Recessive genetic condition – Caused by defective protein needed for Cl- transport – Mucus in the lungs becomes very thick and sticky – Interferes with breathing 57  Diseases of the Lungs Pulmonary fibrosis – Fibrous connective tissue builds up in the lungs, causing a lack of elasticity. – Vital capacity is consequently reduced. 58  Diseases of the Lungs mucus Acute Bronchitis Airways are inflamed due to infection (acute) or due to an irritant (chronic). Coughing brings up mucus and pus. Figure 15.13a Copyright © 2017 McGraw-Hill Education. Permission required for reproduction or display.0 59  Diseases of the Lungs Asthma Airways are inflamed due to irritation, and bronchioles constrict due to muscle spasms. Figure 15.13b Copyright © 2017 McGraw-Hill Education. Permission required for reproduction or display. 60  Diseases of the Lungs Pneumonia Alveoli fill with pus and fluid, making gas exchange difficult. Figure 15.13c Copyright © 2017 McGraw-Hill Education. Permission required for reproduction or display. 61  Diseases of the Lungs tubercle Pulmonary Tuberculosis Tubercles encapsulate bacteria, and elasticity of lungs is reduced. Figure 15.13d Copyright © 2017 McGraw-Hill Education. Permission required for reproduction or display. 62  Diseases of the Lungs Emphysema Alveoli burst and fuse into enlarged air spaces. Surface area for gas exchange is reduced. Figure 15.13e Copyright © 2017 McGraw-Hill Education. Permission required for reproduction or display. 63  Diseases of the Lungs asbestos body Pulmonary Fibrosis Fibrous connective tissue builds up in lungs, reducing their elasticity. Figure 15.13f Copyright © 2017 McGraw-Hill Education. Permission required for reproduction or display. 64  Diseases of the Lungs Lung Cancer – Leading cause of cancer death in men and women – 87% of cases associated with cigarette smoking – Series of progressive steps Thickening of cells lining bronchi Loss of cilia Appearance of cells with atypical nuclei Tumor formation – disordered cells with atypical nuclei Metastasis – cancerous cells spread to other parts of the body 65  Normal Lung versus Cancerous Lung Figure 15.14 Jump to long image description (a): © Matt Meadows/Getty Images; (b): © Biophoto Associates/Science Source 66