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SC BIOL 101 - Chapter 22

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Gross anatomy of respiratory systemSerous membrane line internal structuresVisceral and parietal (connects adjacent to the rib cage)Each lung has own pleural membrane, not connectedRibs form fairly sealed chamber2 critical intercostal musclesDiaphragm forms bottom of sealed chamberVentilation: movement of air into or out of the pulmonary structures **Inhaling through nose:Cleaner air and more moistureNose hairs trap dust particlesInside nasal cavity is pseudo stratified epithelia: goblet and columnar cells, not usually ciliatedMucus helps trap dirt and moisten airNasal meatus: grooves that increase the area and cause turbulence; more air mixes and comes in contact with mucus membranes, allowing us to trap even more dirtPharyngotympanic tube: leads to earsPharynx: connects sinus and mouth to lower structuresMouth lined with stratified squamousPalantine tonsils, lingual tonsil, uvula (not necessary)Larynx: cartilaginous structure; voice box with two musclesEpiglottis: elastic cartilage; epiglottis closes when you swallow and blocks trachea, leading food down esophagus and to the stomach; when you breathe epiglottis is openThe trachea is a fairly rigid tube due to C shaped rings of hyaline cartilage; trachealis muscle functions to contract and relax which alters lumen shape and alsoSubmucosaMucus membrane: pseudostratified epithelia (ciliated); goblet cells that secrete mucinBronchiole: primarily smooth muscleConducting zone: refers to the structures in the lung that are solely related to ventilation; no gas exchangeRespiratory zone: respiratory bronchiole will divide into alveolar duct and on these are alveoli (means sac; tiny air sacs where respiration takes place)Alveoli made of simple squamous epitheliumOxygen and co2 are lipid soluble (simple diffusion)Alveolar pores are holes that connect adjacent alveoli which prevents over inflating of some of the alveoliCapillaries are where there is the exchange of nutrients; yellow fibers of elastin (elastic connective tissue), serves to help you exhale without expending energySurfactant makes water wetter; prevents water molecules from interacting with each otherAlveolar respiration: exchange of gases between alveoli and capillariesPleural cavity: filled with viscous substance that decreases frictionVentilation requires contraction/relaxation of the diaphragm to change pressures within the thoracic cavitySequence of events:Inspiratory muscle contractThoracic cavity volume increasesLungs stretched intrapulmonary volume increasesIntrapulmonary pressure dropsAir (gases) flows into lungs down its pressure gradient until intrapulmonary pressure is 0 (equal to atmospheric pressure)Changes in anterior-posterior and superior-inferior dimensionRibs elevated and sternum flares as external intercostals contractDiaphragm moves inferiorly during contractionChanges in lateral dimensionsRibs elevated and sternum flares as external intercostals contractDiaphragm moves inferiorly during contractionExpirationPassive under normal conditionsInspiratory muscles relax (diaphragm rises; rib cage descends due to recoil of costal cartilages)Thoracic cavity volume decreasesElastic lung recoil passively; intrapulmonary volume decreases)Intrapulmonary pressure risesAir gases flows out of lungs down its pressure gradient until intrapulmonary pressure is 0Internal intercostals and external obliques/ab muscles are related to forced expirationBoyles lawThe pressure of a gas varies inversely with its volumeP1V1=P2V2Ventilation simply refers to the movement of air and its contentsRespiration involves the exchange of gas molecules that make up the airDaltons law of partial pressureThe total pressure exerted by a mixture of gases is the sum of the pressures exerted independently by each gasBarometric pressure: 760 mm HG; multiply by concentration to get partial pressure of each gasConcentration of gasesO2: 20.93CO2: 0.003N2: 78.60H20: 0.46TOTAL=100How is oxygen transported in the bloodHemoglobin transports oxygen4 proteins have heme core that contain iron and is where oxygen is bindedshape is closed or openclose: no oxygen can bind to heme grouphigh partial pressure of oxygen (bombarding hemoglobin) heme group catches oxygen moleculelow partial pressure, hemoglobin closesoxygen diffuses across membranes from alveoli to blood down a partial pressure gradientno meaningful exchange of oxygen in pulmonary veins, heart, and arteries (because exchange of gas only occurs in the capillaries)HemoglobinEach subunit is from a different gene; 4 separate proteins work together and each protein has a heme group with iron in the centerOxygen binds to iron and as a gasHemoglobin within the RBCsExists in two states; opens when bombarded with oxygen, when loses oxygen it closesOxyhemoglobin dissociation curveDescribes the relationshipPercent oxygen saturation: 100 percent maxHemoglobin has a bonding affinity for oxygenLungs have high p.p. of oxygen; a lot of oxygen molecules present; low partial pressure of oxygen in the tissuesAt the tissues, much lower p.p.; as the oxygenated blood travels through systemic arteries down to capillaries in the tissues, high p.p arriving to low p.p of oxygen=gradient; hemoglobins affinity is therefore lower at this pointHemoglobins affinity for oxygen variesMedium partial pressure a little oxygen is knocked off hemoglobin; low partial pressure more oxygen is knocked offHigh partial pressure, curve is relatively flatWhat happens when barometric pressure is lower; partial pressure of oxygen also decreasesPercent saturation of hemoglobinHemoglobins affinity for oxygen is influenced by temperatureAs you increase the temp of blood, rightward shift of oxyhemoglobin dissociation curve (unload more oxygen)Deliver/unload less oxygen at lower temperatureDecrease in blood pH, also rightward shift of oxyhemogloblin dissociation curve (unload more oxygen)Transit time and oxygenation of bloodAt rest rBC spends 3 quarters of a second in the capillaryLoading oxygen onto the hemoglobin is not limited (in a healthy person)Henrys lawWhen a mixture of gases is in contact with a liquid, each gas will dissolve in the liquid in proportion to its partial pressureAlso dependent on solubility of particular gas02 low solubility in liquidCo2 high solubility in liquidO2 and CO2 transfer at the tissues02 is transported bound to Hb (98.5%); only 1.5% of 02 is dissolved in plasmaCO2 is transported by 3 mechanismsdissolved in plasma (7-10%)bound to Hb (about 20%)as a bicarbonate ion in


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