Y khoa, dược - The respiratory system

24The Respiratory System24-2Learning Outcomes24.1 Explain the functions of the respiratory system.24.2 Explain the difference between internal respiration and external respiration.24.3 Describe how the larynx produces voice sounds. 24.4 List the structures contained within the lungs. 24.5 Describe the coverings of the lungs and chest cavity.24-3Learning Outcomes (cont.)24.6 Describe the events that lead to the inspiration and expiration of air.24.7 Explain how the brain controls breathing and how normal breathing patterns can be disrupted.24.8 Describe how oxygen is transported from the lungs to body cells. 24-4Learning Outcomes (cont.)24.9 Describe how carbon dioxide is transported from body cells to the lungs.24.10 List and explain various respiratory volumes and tell how they are used to diagnose respiratory problems.24.11 Describe the causes, signs and symptoms, and treatments of various diseases and disorders of the respiratory system. 24-5IntroductionFunction Move air in and out of lungs (ventilation)Delivers oxygen (O2) Removes carbon dioxide (CO2) External respirationOccurs in the lungsInternal respirationOccurs in the hemoglobinO2O2O2CO2CO2CO2Lungs24-6Organs of the Respiratory System Nose Pharynx Larynx Trachea Bronchial tree Lungs24-7Nasal CavityNasal septum divides the cavity into right and left portionsNares – openings of the noseNasal conchae extend from walls of nasal cavity Mucous membrane warms and moistens the airCilia help eliminate particles24-8Paranasal SinusesAir-filled spaces within the skull bonesOpen into the nasal cavityReduce the weight of the skull Equalize pressureGive the voice its certain toneSkull bones with sinuses include:FrontalSphenoidEthmoidMaxillae bones24-9Pharynx and LarynxPharynxServes both the respiratory and digestive systemsLarynx Also called the “voice box”Moves air in and out of the trachea and produces voiceComposed of three cartilages:Thyroid cartilage Epiglottic cartilageCricoid cartilage 24-10Vocal CordsStretched between the thyroid cartilage and the cricoid cartilageUpper – false cords Lower – true vocal cordsGlottis – the opening between the vocal cordsStretch = pitch of voiceGlottisTrue Vocal CordsFalse Vocal CordsPosterior Portion of Tongue24-11TracheaReferred to as the windpipeTubular organ made of rings of cartilage and smooth muscleExtends from the larynx to the bronchiLined with cells possessing cilia (microscopic hair-like projections)Cilia move mucus up to the throat, where it is swallowed. Smoking destroys cilia. Trachea24-12Bronchial TreeBronchi Primary: First branches off tracheaSecondaryTertiary BronchiolesBranch off tertiary bronchiBronchiBronchiolesBronchioles24-13Bronchial Tree (cont.)AlveoliThin sacs of cells surrounded by capillariesSecrete surfactantFatty substanceHelps maintains the inflation of the alveoli between inspirations24-14The lungs contain connective tissue, the bronchial tree, nerves, lymphatic vessels, and blood vessels.LungsCone-shaped organsRight lung – three lobes Left lung – two lobesPleura – membranes surrounding the lungs24-15Apply Your Knowledge Which of the following sites would be the most lethal if obstructed by a foreign body?Right bronchusLeft bronchusTrachea SUPER!ANSWER:24-16The Mechanisms of BreathingInspirationExpirationBreathing, or pulmonary ventilation, consists of inspiration (inhalation) and expiration (exhalation). Air rich in O2 enters the lungs from the atmosphereThe diaphragm contracts or flattensThe intercostal muscles raise the ribsAir rich in C02 exits the lungsThe diaphragm relaxesThe intercostal muscles lower the ribs24-17The Mechanisms of Breathing (cont.)Respiratory center of the brainMedulla oblongata – controls rhythm and depth of breathingPons – controls the rate of breathingOther factorsCO2 levels in the bloodpH of the bloodFear and painInflation reflex24-18The Mechanisms of Breathing (cont.)Causes of altered breathing patternsCoughingSneezingLaughingCryingHiccupsYawningSpeaking 24-19Apply Your KnowledgeIndicated whether each statement refers to (I) inhalation or (E) exhalation:__ The intercostal muscles lower the ribs__ The diaphragm contracts or flattens__ The intercostal muscles raise the ribs__ The diaphragm relaxes__ Air rich in O2 enters the lungs from the atmosphere__ Air rich in C02 exits the lungs ANSWER:EEEIIIBRAVO!24-20The Transport of Oxygen and Carbon Dioxide in the BloodMost of the oxygen binds to hemoglobin Oxyhemoglobin Bright red in colorSome oxygen remains dissolved in plasmaIf CO2 combines with hemoglobin at O2 sites, it forms carboxyhemoglobin24-21The Transport of Oxygen and Carbon Dioxide in the Blood (cont.)Carbon dioxide gets into the bloodstreamReacts with water in plasma and forms carbonic acidCarbonic acid ionizes and releases hydrogen and bicarbonate ionsBicarbonate ions attach to hemoglobin Exhaled as waste product in the lungs24-22Apply Your KnowledgeDescribe what happens to carbon dioxide in the blood.ANSWER: Carbon dioxide can combine with hemoglobin and form carboxyhemoglobin. Most reacts with water in plasma to form carbonic acid. The carbonic acid ionizes and releases hydrogen and bicarbonate ions. The bicarbonate ions then attach to hemoglobin and are exhaled as a waste product from the lungs.Super!24-23Respiratory VolumesDifferent volumes of air move in and out of lungs with different intensities of breathingMeasured to assess health of respiratory system24-24Respiratory Volumes (cont.)Amount of air that moves in or out of the lungs during a normal breathAmount of air that can be forcefully inhaled following a normal inhalationAmount of air that can be forcefully exhaled following a normal exhalation Tidal VolumeInspiratoryReserve VolumeExpiratoryReserve Volume24-25Respiratory Volumes (cont.)Amount of air that can be forcefully exhaled after the deepest inhalation possibleVolume of air that always remains in the lungs even after a forceful exhalationThe total amount of air the lungs can holdResidual VolumeTotal LungCapacityVital Capacity24-26Apply Your Knowledge___ Amount of air that moves during  a normal breath___ Amount of air that always  remains in the lungs___ Total amount of air the lungs  can hold ___ Amount of air forcefully exhaled  after deepest inhalation possibleA. Total lung capacityB. Residual volumeC. Tidal volumeD. Vital capacityMatch the following: ANSWER:CABDGood Job!24-27SnoringDue to vibration of soft tissues when muscles of the palate, tongue, and throat relaxAffects approximately 50% of men and 25% of women over the age of 40Causes daytime sleepinessMay be associated with obstructive sleep apneaCommon CausesEnlargement of tonsils or adenoidsBeing overweightAlcohol consumptionNasal congestion Deviated nasal septum24-28Snoring (cont.)Mayo Clinic’s Sleep Disorders Center rating of snoring:Heard from close proximityGrade 1Grade 2Heard from anywhere in the bedroomGrade 3Heard from just outside the bedroom door with door openGrade 4Heard outside the bedroom door with the door closed24-29Snoring (cont.)Lifestyle modifications to reduce snoringLose weightChange sleeping positionAvoid using alcohol or medications that induce sleepUse nasal strips to widen the nasal passagesUse dental devices to keep airways openTreatmentsCPAPSurgery (uvulotomy)Laser surgery 24-30Common Diseases and Disorders DiseaseDescriptionAllergic rhinitisHypersensitivity reaction to various airborne allergens Asthma A condition in which the tubes of the bronchial tree become obstructed due to inflammationAtelectasisCollapsed lungBronchitisInflammation of the bronchi often follows a cold; one type of COPD 24-31Common Diseases and Disorders (cont.)DiseaseDescriptionChronic obstructive pulmonary disease (COPD)A group of lung disorders that limit airflow to lungs and usually cause enlargement of the alveoliEmphysemaA chronic condition associated with smoking that damages the alveoli; one type of COPDInfluenzaA viral disease that attacks the respiratory system; commonly called the flu 24-32Common Diseases and Disorders (cont.)DiseaseDescriptionLaryngitisAn acute inflammation of the larynx causing hoarseness (dysphonia)Legionnaire’s diseaseAcute bacterial pneumonia caused by Legionnaire bacteria that usually grows in the standing water of air conditioning systems Lung cancerCancer closely associated with smoking and exposure to second-hand smoke; four types of lung cancersPleural effusionA buildup of fluid in the pleural cavity24-33Common Diseases and Disorders (cont.) DiseaseDescriptionPleuritis/PleurisyInflammation of the membranes that cover the lungs, known as pleuraPneumoconiosisLung diseases that result from years environmental or occupational exposure to different types of dust; three types Pneumonia/ PneumonitisAn inflammation of the lungs that is most often caused by a bacterial, viral, or fungal infection24-34Common Diseases and Disorders (cont.) DiseaseDescriptionPneumothoraxA collection of air in the chest around the lungs, which may cause atelectasis Pulmonary edemaA condition in which fluids fill spaces within the lungs, making it very difficult for the lungs to oxygenate the blood Pulmonary embolism A blood clot (embolism) that travels usually from the legs and blocks an artery in the lungs24-35Common Diseases and Disorders (cont.)DiseaseDescriptionRespiratory distress syndrome (RDS)Syndrome in which a lack of surfactant in the lungs allows the alveoli to collapse on exhalation, resulting in poor oxygenationSevere acute respiratory syndrome (SARS) A viral respiratory disease that is very contagious and sometimes fatalSinusitisAn inflammation of the membranes lining the sinuses of the skull 24-36Common Diseases and Disorders (cont.)DiseaseDescriptionSudden infant death syndrome (SIDS) A syndrome without characteristic signs or symptoms; usually a baby with this disorder simply goes to sleep and never wakes upTuberculosisPrimarily a respiratory disease caused by various strains of the bacterium Mycobacterium tuberculosis Upper respiratory (tract) infection (URI)Coryza, or the common cold24-37The medical assistant working for a general practitioner is taking the medical history of a new patient. The patient states, “Even after sleeping 8 to 9 hours, I still feel really tired.” The patient’s spouse states, “Well, you sure snore loud, as if the sleep is so good.” Which of the following is a possible cause for the excessive fatigue? Sleep apnea Depression TuberculosisApply Your KnowledgeANSWER:Correct!24-38In Summary24.1 The function of the respiratory system is to move air in and out of the lungs in a process known as ventilation, respiration, or breathing. 24.2 The exchange of oxygen and carbon dioxide in the lungs is called external respiration. The same exchange within the hemoglobin of red blood cells is internal respiration.24.3 The larynx contains the vocal cords, which stretch between the thyroid and cricoid cartilages. The muscles of the lower (true) vocal cords stretch and relax them to produce different sounds. 24-39In Summary (cont.)24.4 The lungs contain connective tissue, the bronchial tree, nerves, lymphatic vessels, and blood vessels. The left lung consists of two lobes (upper and lower), and the right lung consists of three lobes (upper, middle, and lower). Within each lung are the primary, secondary, and tertiary branches of the bronchi, the bronchioles, and the alveoli.24.5 The lungs are covered by, and the chest cavity is lined with, the pleura. The outer membrane is the parietal pleura and the inner membrane is the visceral pleura.24-40In Summary (cont.)24.6 During inspiration, the diaphragm contracts and the intercostal muscles raise the ribs, increasing the space in the thoracic cavity. This decreases the pressure within the cavity so that the air outside the body passively flows into the thoracic cavity. During expiration, the diaphragm relaxes, pushing up into the thoracic cavity, and the intercostal muscles lower the ribs, forcing the air to flow out of the body.24-41In Summary (cont.)24.7 Breathing is controlled by the respiratory center of the brain located in the pons and medulla oblongata. Carbon dioxide levels and pH levels of the blood also affect breathing. Everyday situations such as coughing, sneezing, laughing, crying, hiccups, yawning, and speaking also alter breathing patterns.24.8 Most of the oxygen in the bloodstream binds to the hemoglobin within red blood cells, resulting in oxyhemoglobin, although a small amount does not bind to hemoglobin and remains dissolved in the plasma. 24-42In Summary (cont.)24.9 Carbon dioxide binds to hemoglobin, resulting in carboxyhemoglobin. Most of the carbon dioxide that enters the body reacts with water in blood and cerebral spinal fluid to form carbonic acid. As carbonic acid ionizes, it releases hydrogen and bicarbonate ions, which attach to hemoglobin making its way back to the lungs to be exhaled.24-43In Summary (cont.)24.10 Respiratory volumes are measured to check the health of the respiratory system. The volumes are listed here and the normal capacities are found in the chapter: tidal volume, inspiratory and expiratory reserve volumes, residual volume, inspiratory capacity, functional residual capacity, vital capacity, and total lung capacity.24-44In Summary (cont.)24.11 The diseases and disorders of the respiratory system are many and varied, as are the causes and treatments of these diseases. Many of the more common respiratory disorders, with their individual causes and treatments, are discussed in detail in the Pathophysiology section of this chapter.24-45End of Chapter 24The air of ideas is the only air worth breathing.~Edith Wharton