Chapter 22 - Gas Exchange - Biology PDF

Gas Exchange The Respiratory System and Homeostasis The respiratory system contributes to homeostasis by providing for the exchange of gases – O2 and CO2 – between the atmospheric air, blood, and tissue cells. It also helps adjust the pH of body fluids. Campbell Biology: Concepts & Connections 9th...

Gas Exchange The Respiratory System and Homeostasis The respiratory system contributes to homeostasis by providing for the exchange of gases – O2 and CO2 – between the atmospheric air, blood, and tissue cells. It also helps adjust the pH of body fluids. Campbell Biology: Concepts & Connections 9th Edition Taylor Simon Dickey Hogan Reece OBJECTIVES Describe the three main phases of gas exchange in a human Describe the structures and corresponding functions of a mammalian respiratory system  Gas exchange in humans involves breathing, transport of gases, and 22.1 exchange with body cells giving Co2 ❑ Gas exchange enables you to harvest energy from the food molecules ❑ The three phases of gas exchange: fromhighconc to lowconc ▪ Breathing: Inhalation exposes lungs to air, allowing gas diffusion (O₂ and CO₂) between blood and lungs. Exhalation expels CO2 from the body. ▪ Transport of gases: O2 molecules are carried in the blood attached to RBCs Plasma haemoglobin in RBCs. CO2 is also transported in blood in different forms. ▪ Exchange of gases: Cells take up O2 from the blood to be used in the cellular respiration by mitochondria. Cells release CO2, which is a waste product of cellular respiration, to the blood. 22.2 Animals exchange O2 and CO2 across moist body surfaces 18ᵗʰ ❑ Respiratory Surface: It is the site of gas exchange. It is made of a single Iiii intiiit ins layer of cells that should be always moist to facilitate gas exchange. i ❑ Diffusion is the key process for gas exchange. partialpressure ❑ The surface area of the respiratory surface must be sufficiently large to meet the body’s needs of O2. hyperventilation I.in Breathing hypoventilation ❑ Ventilation is the flow of air over the respiratory surface. ❑ Lungs are internal sacs lined with moist epithelium. The inner surfaces of exchange gas the lungs are extensively subdivided, forming a large respiratory surface.  In mammals, branching tubes convey air to lungs located in the chest 22.6 cavity Rateiagem.MSn s ❑ Lungs are located in the thoracic cavity and are hair throat thelungconnect to it protected by the supportive rib cage. pluramembrane Iamsu ▪ the thoracic cavity is separated from the abdominal cavity by a sophagus cartilageaggrevent hindthe sheet of muscle called the diaphragm. achea ❑ Components of the Respiratory System: the respiratory cavity 8I nasal system consists of the nose, pharynx (throat), larynx (voice box), trachea (windpipe), bronchi, and lungs. p ñ volanters is  In mammals, branching tubes convey air to lungs located in the chest 22.6 cavity ❑ Larynx (voice box) ▪ it is a passageway that connects the pharynx with the trachea. ▪ it has vocal folds: two bands of elastic tissue that can be stretched by laryngeal muscles Breathing quietly ❑ Voice production ▪ sound produced when exhaled air vibrate vocal cords ▪ Is is controlled by the tension on the vocal folds. imPitch tightly stretched folds vibrate very fast, producing high pitches female less tense folds vibrate slowly, producing low pitches because of Talking male testerone ❑ Speech production hormone ▪ Precise coordination of muscle actions in the pharynx, mouth, nasal cavity is necessary for converting the sound into recognizable speech. Swallowing  In mammals, branching tubes convey air to lungs located in the chest 22.6 cavity ❑ Trachea, bronchi & bronchioles topreyapsing from qiii.la ▪ Rings of cartilage reinforce the walls of the larynx and trachea, keeping them open. ▪ The trachea forks into two bronchi (right main and left main) ▪ Each bronchus then branches repeatedly into finer tubes called bronchioles ▪ Major branches have moist epithelium covered by cilia and mucus (the cleaning system). as the branching becomes more extensive in the bronchial tree, epithelial cells gradually become non-ciliated, cartilage in the tube walls gradually decreases, and amount of smooth muscles increases. 5 o Bronchitis is a condition in which these small tubes become inflamed and constricted, making breathing 3,9 difficult.  In mammals, branching tubes convey air to lungs located in the chest 22.6 cavity grapes likestructure ❑ Alveoli ▪ Bronchioles dead-end in grapelike clusters of air sacs called alveoli ▪ The structure of alveoli enhance the efficiently of gas exchange: the numerous alveoli provide great surface area for ………………… gasexchange pS provide inner surface of each alveolus is lined with a thin layer of epithelial cells greatsurf Thhange surfactant alveolar cells secrete fluid, which keeps the surface between cells and air moist alveoli are surrounded by a dense web of blood capillaries alveolus 22.8 Negative pressure breathing ventilates your lungs Clinical Connection eachothercausingthecollapse of thealveolismaller watermolecules polar attract ❑ Respiratory Problems surfactantcomes betweenthewatermoleculesandpreventthemfrombindingtoeach ✓ Respiratory distress syndrome (RDS) lowersthesurfacetensionofthealveolarfluid ▪ alveolar cells secrete surfactant, which is complex mixture of phospholipids and lipoproteins. surfactant lowers surface tension of alveolar fluid, which reduces the tendency of alveoli to collapse and thus maintains their patency RDS is a breathing disorder of premature newborns in which the alveoli do not remain open due to a lack of surfactant Ignatythe8ᵗʰ 9th month ✓ Chronic obstructive pulmonary disease (COPD) ▪ y.IE it COPD is characterized by chronic and recurrent obstruction of airflow, which increases airway resistance pp n Emphysema wall ofthealveoli is broken in migrati T.it ain n id re tace seexiiange and inflammation of the lungs. 55m iway results from long-term exposure to contaminants (cigarette smoke, air pollution or enzyme imbalance), which cause continual irritation characterized by destruction of the walls of the alveoli (↓ surface area, ↓ gas exchange) and decrease in lung elastic recoil that helps expel air during exhalation (→ laboured breathing) sins Chronic Bronchitis s.ws coughwith results from long-term exposure to contaminants (mainly, cigarette smoke) a mucus characterized by excessive secretion of bronchial mucus accompanied by a productive cough  in I uns asenma s of alveoli Oarn In.fiT anout ii athiofie omwgoing n'eas collapsing voice It containtsvocal foldsthatvebrateswhenwe exhale air p roduction mouth tongue pharynx muscle ofthemouth are important for speech respiratory membrane Discribe thehistologyand function of the In tofacilitate gas exchangediffusion wide surfaceareamustbeenoughforthe gasexchange cigarettsfor years and is having Mrjaber has smoked breathing difficultiesHe hasbeendiagnosedwithemphy whou pe kinds ofstructural changesyou Describe specific respiratorysystemHow are airflowand Jaber's to observe in Mr these structural changes affected by gasexchange elastic fiber brokenarteryline there is broken is Inma iiiatinTia aimmation of the lung decreased exchange both will be air flow andgas The right lung composed of middle inferior 3 lobes superior The leftlung composed of 2106 Throat pharynx inferior superior Larynx Trachea bronchi Bronchioles lung OBJECTIVES Explain how humans breathe air into and out of their lungs Explain how breathing is controlled in humans  movingfromareaofhighpartailpressure 22.8 Negative pressure breathing ventilates your lungs toareaoflowpartial p ressure ❑ Breathing (pulmonary ventilation) is the flow of air into and out of the lungs (inhalation and exhalation). ▪ the continual movement of air maintains high O2 and low CO2 concentrations at the respiratory surface because a below 160 mmHg movefrom ▪ ventilation occurs by negative pressure breathing – a system in which air is pulled (not pushed) into the lungs... How?areaof o air tends to move from a region of higher pressure to a region of lower pressure, that is, down a pressure gradient. o Intra-alveolar pressure can be changed by altering the volume of the lungs, in accordance with Boyle’s law Air moves into the lungs when the air pressure inside the lungs is less than the air pressure in the atmosphere. atin number Air moves out of the lungs when the air pressure inside the lungs is greater than the air pressure in the atmosphere. walls same ofsmaller particles volum in Ii pressure greater collisions more inverselyproportional  22.8 Negative pressure breathing ventilates your lungs ❑ Breathing (pulmonary ventilation) is the flow of air into and out of the lungs (inhalation and exhalation). ▪ Structures important for the ventilation process – diaphragm, intercostal muscles (external & internal) and pleura membrane L douple chality pullthethoracic cavity P gangliac outward namemeans the pissure binding 11min negative always itis eitherin pressure ennqiiaiat.ion dig p coltraction fluid raignt.ttpiraoijmuscie iii Each lung is enclosed and protected by a double- y layered serous membrane called pleura – parietal pleura, visceral pleura and pleural cavity (fluid) dying.gg afa'pre i c fi iingsattacned ma greatning the thoraciccavity  22.8 Negative pressure breathing ventilates your lungs ❑ Breathing (pulmonary ventilation) is the flow of air into and out of the lungs (inhalation and exhalation). ▪ How does negative pressure breathing work? During inhalation: During exhalation contraction of diaphragm and relaxation of diaphragm and external intercostals external intercostals results increases the size of the in elastic recoil of the chest thoracic cavity and therefore, wall and lungs the lungs expand as lung volume decreases, lungs expansion decreases alveolar pressure increases, alveolar pressure so that air so air moves from the lungs moves down a pressure to the atmosphere gradient from the atmosphere decreases increase's into the lungs pismire volume ofthelungsincreases Active process passive process pressuredecreases 22.8 Negative pressure breathing ventilates your lungs ❑ Breathing (pulmonary ventilation) is the flow of air into and out of the lungs (inhalation and exhalation). ▪ Varying amounts of air move into and out of the lungs during inhalation and exhalation The different amounts of air can be classified into: lung volumes (measured by spirometer) and lungs capacities (combinations of different lung volumes) theamountvolume ofair Tidal volume thatyoucaninhalebeyond The volume of air inhaled or exhaled thetidalvolume with each breath Residual volume Training The minimum volume of air remaining in the lungs even after a maximal expiration Vital capacity The volume of air that can be exhaled after maximal inspiration in 1 i iiniisiiona a.in ii iaiion  Whatifthewalls of alveolicontainelasticfiberthatallowthealveolitoexpandand contract witheachbreath Ifthealveolilosttheirelasticityhowcouldthataffectgasexchange inthelung residualvolumewillincrease alveolivolume asthey losetheirelasticitymeansthe more c remain niniration iii is andthe exchangeof 02 freshair withthebloodwill belessefficiency Ings thepleuraof rightlung is separated If an injury tore a smallhole in themembranes surroundingyour fromleftlung so if oneofthem isdamage whateffectonlungfunctionwouldyou expect theotheronewillstillfunctioningbuthard as pleura connectsthe lungs with thoracic cavity If thereis noteinpleura aboutbreathing II ing Sican's here manycoffassed connect orsupportwiththoraciccavity If someonehadanaccident and hehadbroken rib pleurahas ahole thepressure willnotbenegative the pressurewillbeequal sonothing willkeepthelungpushed tothethoraciccavity andthatwilllead tothelungcollapse rate PH increase heart Drop in the CONTROL OF BREATHING & TRANSPORT OF GASES OBJECTIVES Explain how breathing is controlled in humans Explain Dalton’s law and Henry’s law Describe the exchange of oxygen and carbon dioxide in external and internal respiration  22.9 Breathing is automatically controlled ❑ Breathing must occur in a continuous cyclic pattern to sustain life processes diaphragmand intercostalexternal ▪ inspiratory muscles must rhythmically contract and relax to alternately fill the inhale exhale lungs with air and empty them giggem ❑ Although you can consciously control your breathing, most of the time your breathing is regulated by involuntary mechanisms 11hmieEffing hold send pulses intercostal Émentifainwistigning todiaphragm → to ensure that gas exchange is coordinated with blood circulation and with and metabolic demand ❑ Breathing rhythm is established by a pair of breathing control centers located in the medulla iiiiiii.it i ns → it stimulates the motor neurons that innervate the effector skeletal muscles (intercostals and diaphragm). phrenicnerve  22.9 Breathing is automatically controlled when we exercise producemoreenergy H PH 02 ❑ Regulation of Breathing comovefrommusclestotheblood ▪the most potent chemical stimulus for increasing ventilation is arterial partial pressure of toomuch 102 number CO2 (PCO2) – because it causes changes in [H+] in n At can'tmove to nervous central iemoecue name gwai.la mail.IE jia y emibecausei.nu qq.iq prevented by barrier bloodbrain cerebrospinal move 02 can Central chemoreceptors – located in medulla and respond to changes in [H+] in the CSF glyidounds www a & carotid bodies and respond to p Peripheral chemoreceptors – located in the aortic at Enervous major blood i changes in arterial PCO2, [H+] and PO2 vessels Ineart 5 the blood O2 level usually has little effect on the breathing control centers as peripheral chemoreceptors are only stimulated when the arterial PO2 has fallen to the point of being life threatening (