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The Respiratory System Chapter 23 Functions of the Respiratory System Pulmonary __________ - provides for gas exchange Intake of O2 Elimination of CO2 Helps to __________________ Receptors for _________, _________ inspired air, _____________ vocal sounds, and __________ small amounts of water and heat Gas exchange Pulmonary ventilation- breathing External respiration- (____________) Exchange of gases between alveoli and blood in pulmonary capillaries across respiratory membrane Blood gains O2, loses CO2 Internal respiration- (______________) Inhalation (_________) & exhalation (___________) of air between atmosphere and alveoli of lungs Blood systemic capillaries and tissue cells Blood loses O2, gains CO2 Cells consume O2 ATP = cellular respiration Anatomy of the Respiratory System _______________ Zone- filter, warm, moisten air Nose Pharynx Larynx Trachea Bronchi & Subdivisions ______________________- gas exchange Alveolar ducts, sacs, alveoli Pleural membrane- 1 for each lung Visceral pleura- deep, covers lungs Parietal pleura- superficial, lines thoracic cavity Pleural cavity- contains pleural fluid causing: Pleurisy/pleuritis = inflammation of pleural mem. Reduction of friction Increases surface tension Pain due to friction between layers If persists pleural effusion Pneumothorax - cavity filled with air Cells of the alveoli Type I cells – ___________________, nearly continuous w/alveolar lining Type II cells – _________, fewer, produce surfactant Round or cuboidal, free surfaces w/microvilli Alveolar fluid keeps surface between cells & air moist Surfactant – complex mix of phospholipids and lipoproteins surface tension of fluid tendency of alveoli to collapse Water–water interface would cause collapse of alveoli & make walls difficult to separate once collapsed surfactant necessary ____________ – macrophages, remove dust and other debris in alveolar spaces Alveolus-capillary Together these create – ___________________ O2 & CO2 easily diffuse back & forth These gases will move due to pressure difference Move from high to low pressure Consist of 4 layers: fig 23.12 Alveolar wall- type I & II alveolar cells, macrophages Epithelial basement membrane Capillary basement membrane Capillary endothelium Only _____________ thick Musculature in breathing ___________- most imp inhalation muscle Contraction causes it to flatten lowering the dome shape, vertical diameter of thoracic cavity Contraction responsible for almost 75% of air that enters during quiet breathing Descent of diaphragm inhibited by: advanced pregnancy, excessive obesity, confining clothing Musculature in breathing (2) _________________-2nd most important- inhalation Others- involved in labored inhalation only: when contract elevate rib diameter of chest cavity 25% air that enters during quiet breathing sternocleidomastoid scalenes pectoralis minor _________________&________________________ active only when exhalation is forceful exercise, playing wind instruments Pressure and volume Prior to inhalation, Patm = Palv For air to enter alveoli, Palv must be < Patm Done by ↑ lung volume P inversely proportional to volume (P = 1/V) Ideal gas law: PV = nRT, P = nRT/V Intrapleural P is always subatmospheric Thoracic cavity volume ↑, slight Intrapleural P Boyle’s Law Pleurae adhere to each other, pulled outward as expansion occurs As lung volume ↑, Palv & air moves to area of P Surface tension & compliance ________________- fluids exert this At all air-water interfaces: water-water attraction >watergas attraction Must be overcome to expand the alveoli Surfactant reduces compared to pure water Respiratory distress syndrome (RDS)- lack of surfactant, collapse alveoli during exhalation, IRDS in infants __________________- effort required to stretch Elasticity and surface tension compliance: 1. scar lung tissue, 2. pulmonary edema, 3. surfactant, 4. impede expansion (ex- muscle paralysis) Rate of airflow depends on: Pressure difference Resistance Airflow = (Palv-Patm )/R Larger diameter of airway, resistance Regulated by smooth muscle contraction (symp NS) Bronchodilation resistance Narrow or obstructed airway ↑ resistance Asthma- usually allergic rxn, bronchi smooth muscle spasms COPD- chronic obstructive pulmonary disease Emphysema or chronic bronchitis Gas Exchange and Transport Basic Properties of Gases Dalton’s Law Henry’s Law Gas Exchange Between the blood and lungs Gas Exchange Between the blood and tissues Oxygen transport Carbon dioxide transport Dalton’s Law Each gas in a mixture exerts its own pressure as if there were no other gases present Partial pressure (pp) Determine the movement of O2 and CO2 between atmosphere and lungs AND blood and body cells Diffusion from high to low partial pressure > difference in partial pressure faster the diffusion Total pressure is the sum of partial pressures Explains which way O2 and CO2 move from place to place in the body Henry’s Law Quantity of gas dissolved in a liquid is proportional to pp of the gas & its solubility In body fluids: gas tends to stay in solution when: Partial pressure is great High solubility in water CO2 is 24X more soluble than O2 more CO2 dissolved in plasma N2 is majority of air BUT very little dissolves in plasma Hyperbaric oxygenation- use of pressure to cause more O2 to dissolve in blood Gas exchange depends upon: _________________ differences of the gases ______________ available for gas exchange Emphysema causes alveolar disintegration __________________ Altitude sickness Pulmonary edema slows gas exchange Molecular weight and solubility of the gases MW usually faster diffusion, but solubility changes that Hemoglobin and oxygen 1.5% is dissolved O2 O2 does not dissolve easily in water Only this 1.5% can diffuse from blood tissue 98.5% blood O2 is bound to Hb in RBC ↑ the PO2 , more O2 binds Hb Hb completely Hb-O2 then: fully saturated > PO2, more O2 will bind Hb Affinity affects binding Dissociation curves Shift right = less affinity, shift left = more affinity Factors affecting Hb affinity for O2 As acidity ↑ Hb affinity for O2 Acidity increases the ability to unload O2 PCO2 ↑ has same effect as ↑ acidity Acidity related to PCO2 : CO2 is converted to carbonic acid which BECOMES: H+ & bicarbonate ions ↑ temperature ↑ O2 release from Hb Bohr effect- more H2 the more O2 unloaded from Hb Same effect as ↑ acidity, CO2, BPG BPG- bisphosphoglycerate Hb affinity for O2 Forms when glycolysis is occuring Fetal hemoglobin Hb-F has higher affinity for O2 than Hb-A BPG in metabolically active fetus causes Hb to affinity for O2 and release it Hb-F curve is shifted to the left of Hb-A curve O2 readily transferred to fetal blood from the maternal blood in the placenta Carbon Monoxide poisoning CO binds Hb 200x more strongly than O2 More CO binding reduces O2 carrying capacity Red lips and muscosa due to Hb bound to CO Possible to save victim by administering pure oxygen Speeds up separation of CO from Hb Carbon Dioxide Transport Dissolved CO2 – 9%, diffuse into alveolar air Carbamino compounds – 13%, Hb is a protein most CO2 moving this way is Hb bound Formation of Hb-CO2 depends on PCO2 Bicarbonate ions – 78%, CO2 diffuses into systemic capillaries RBC, rxn w/H2O in presence carbonic anhydrase carbonic acid Bicarbonate ions As blood picks up CO2, HCO3- accum in RBC Some HCO3- moves to plasma In exchange, Cl- moves into RBC = chloride shift fig 23.24 Maintain electical balance between plasma & cytosol CO2 + H2O ↔ H2CO3 ↔ H+ + HCO3At lungs, rxns reverse and CO2 is exhaled Control of Respiration _______________- widely dispersed neurons Medullary rhythmicity area Pneumotaxic area in pons Apneustic area in pons *The respiratory center is regulated by: Cortical influences Chemoreceptor regulation Proprioceptors, inflation reflex Medullary Rhythmicity Area Controls basic rhythm of respiration Inspiratory area: generates basic rhythm 2 sec impulse to external intercostals & diaphragm Muscles contract, inhalation occurs Relaxation and passive elastic recoil Expiratory area: inactive during quiet breathing During forceful breathing contraction of internal intercostals and abs Decrease size of cavity forceful expiration Pons-- Pneumotaxic & apneustic areas _____________- coordinate transition between inhalation & exhalation upper pons Transmits inhibitory impulses inspiratory area Turn off lungs before too full of air Can over ride the apneustic _________________- also coordinates Lower pons Stimulatory impulse to inspiratory area Results in long, deep inhalation Regulation of Respiratory Center Cerebral cortex resp center can alter breathing or refuse to breath for short time Chemoreceptors: monitor H+, CO2 and O2 Build up of CO2 and H+ limits that ↑ PCO2 or H+ strongly stim. inspiratory center Central: in CNS Peripheral: in aortic bodies & carotid bodies Vagal stretch receptors- if overinflation of lungs, vagus nerve communicates with inspiratory and apneustic areas, inhibits inspiration (inflation reflex) More about ventilation rate & depth Proprioceptors- exercise rate & depth ↑ Inflation reflex- stretched during overinflation Baro or stretch receptors in bronchi, bronchioles Limbic system- excite ↑ rate and depth Temperature ↑ rate See table 23.2 on 883 Lung volumes Tidal volume Inspiratory reserve volume Expiratory reserve volume vital capacity Residual volume Total lung capacity IRV= VC –(TV+ERV) fig. 23.17 Smoking Nicotine restricts airflow CO binds Hb & reduces O2 carrying capacity ↑ mucous restricted airflow Impair and destroy cilia Destruction of elastic fibersemphysema Collapse bronchioles & trap air after exhale terms Apnea- temporary cessation of breathing Eupnea- normal quiet breathing Dyspnea- shortness of breath; painful, labored Hypernea- abnormally deep or rapid breathing Cyanosis- blue/purple due to ↑ deoxy-Hb Hypoxia- O2 at tissue level (4 types, p882) Hypercapnia- ↑ in arterial PCO2 above 40 mmHg (aka hypercarbia)