2 The Respiratory System Process by which O2 and CO2 are exchanged between cells, the blood, and air in the lungs = respirationThe human respiratory system has three phases of gas exchange:breathing, the ventilation of the lungs by alternate inhalation and exhalation,transport of oxygen from the lungs to the rest of the body via the circulatory system, anddiffusion of oxygen from the blood and release of CO2 into the blood by cells of the body.
3 The Respiratory System (continued) Human Respiratory SystemConsists of the nose, pharynx, larynx, trachea, bronchi (singular bronchus), and lungs
4 The Respiratory System Figure 23.19aThe Respiratory SystemPharynxNasal cavityEsophagusLarynx (voice box)Left lungTrachea (windpipe)Right lungBronchusBronchioleDiaphragmHeart(a) Overview of the human respiratory system
5 Passageway of Air Into the Lungs Air entering the lungs is warmed, moistened, and filtered by the nose and mouth, keeping lung tissue healthyAir enters pharynx – passageway for food and airAir then passes through the larynx – area containing vocal cordsAir passes through trachea – the windpipe – which is covered by the epiglottis (flap of cartilage) when you swallow
6 Passageway of Air Into the Lungs (continued) Air then passes from the trachea into two large tubes in the chest called bronchi. Each bronchus leads to one of the lungs. The bronchi then branch out and get smaller and are called bronchiolesBronchi and bronchioles are surrounded by smooth muscle and help regulate the size of air passagewaysBronchioles continue to get smaller and read “dead ends” – millions of tiny air sacs called alveoli. Alveoli are grouped into little clusters (like grapes) with capillaries surrounding each alveolus. This is where gas exchange takes place.
7 carbon dioxide exchange at Movement of Oxygen and Carbon Dioxide In and Out of the Respiratory SystemNasalcavitiesOxygen-richair from environmentPharynxTracheaBronchiOxygen andcarbon dioxide exchange atalveoliBronchiBronchiolesAlveoliBronchiolesNasalcavitiesCarbondioxide-richair to the environmentTracheaPharynx
8 Gas Exchange 350 million alveoli in healthy lung O2 dissolves on wet surface of alveoli and then diffuses into capillariesCO2 in blood, diffuses across membrane of alveolus and into the air of the lungAlveoliBronchioleCapillary
9 Gas ExchangeHowever, there is one problem with this simple gas delivery system.Problem: Oxygen does not readily dissolve in blood.Solution: Oxygen is carried in hemoglobin molecules within red blood cells.
10 Hemoglobin in Red Blood Cells Figure 23.23Hemoglobin in Red Blood CellsHemegroupIronatomO2O2 loadedin lungsO2O2 unloadedin tissuesPolypeptide chain
11 Breathing Movement of air into and out of lungs Air is driven into lungs by air pressureBottom of chest cavity is the muscular diaphragmWhen you inhale, the diaphragm contracts and expands chest cavity = less pressure inside = vacuum that brings air into lungsWhen you exhale, the diaphragm relaxes and makes the chest cavity smaller = more pressure inside = air rushes out of lungsIf chest cavity punctured, probably not be able to breathe
12 Breathing Inhalation Exhalation Air exhaled Air inhaled Rib cage descendsRib cage risesDiaphragmDiaphragmInhalationExhalation
13 Breathing Inhalation Exhalation Air exhaled Air inhaled Rib cage descendsRib cage risesDiaphragmDiaphragmInhalationExhalation
15 How Breathing is Controlled Breathing is NOT voluntaryNervous system controls breathing in the medulla oblongata which “senses” when CO2 levels rise = impulses sent to diaphragm to contract = breathe
16 Tobacco and the Respiratory System Tobacco destroys lung tissueCarbon Monoxide (CO) in tobacco prevents O2 from getting into blood and deprives body of O2Smokers cough due to mucus and trapped smoke particles building up in airways
18 Tobacco and the Respiratory System (continued) Smoking causes chronic bronchitis, emphysema, cancer, and heart diseaseChronic Bronchitis – swollen bronchi = exercise difficultEmphysema – loss of elasticity of lungs = breathing difficultLung cancer – can spread to other parts of the bodyHeart disease – smoking causes high blood pressure = heart has to work harder