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Respiratory system

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Respiratory system

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    1. Respiratory system

    2. What is respiration? Multiple definitions Ventilation of lungs (breathing) Exchange of gases between air and blood Also between blood and tissues Oxygen consumption during metabolic activities Happens in what organelle?

    3. What organs are involved? Conducting regions Nose Larynx Epiglottis Trachea Bronchi Lungs Bronchioles Respiratory region Alveoli Upper respiratory Head and neck Lower respiratory Trachea to lungs

    4. What does the nose do? Receive and humidify incoming air Smells Voice resonating chamber Filter out bacteria

    5. Why do I only breath out of one chamber at a time? Nasal fossa = chamber Divided by nasal septum Lamina propria of inferior concha swell Every 30-60 minutes Alternate chambers Allows for rehydration Epistaxis Nose bleed; most common in inferior concha

    6. Whats up with the pharynx and larynx? Pharynx extends from nose/mouth to larynx Good at trapping large dust particles Larynx = voice box Job: keep food/water out of trachea Also produces sound Glottis (opening) guarded by epiglottis

    7. What does the trachea do? Hyaline cartilage rings stiffen tube Directs air to lungs via bronchi Pseudostratified epithelium Mucociliary escalator: cilia sweep mucus upward to pharynx

    8. What parts make up the lungs? Right lung: superior, middle, inferior lobes Left lung: superior and inferior lobes only Bronchial tree Branched air tubes from primary bronchi (two) to secondary bronchi to tertiary bronchi to bronchioles Overlapping plates of cartilage give shape

    9. What parts make up the lungs? Bronchioles (no cartilage) have smooth muscle to dilate/contract Asthma Bronchiolconstriction (irritants, cold air, histamine) and bronchioldilation Click below for asthma movie!

    10. What parts make up the lungs? Terminal bronchioles follow after bronchioles Final branches of conducting division (region) Cilia prevent congestion via mucociliary escalator Next are respiratory bronchioles Beginning of respiratory division Divide into alveolar ducts End in alveolar sacs

    11. What do the alveoli do? Approx. 150 million = great S.A. Mostly squamous alveolar cellswhy? A few cuboidal cells (great alveolar cells) Secrete pulmonary surfactant Disrupts hydrogen bonds Prevents alveolar collapse during expiration Premature infants lack

    12. What do the alveoli do? Alveolar macrophages consume anything mucus doesnt strain out Items smaller than 2 micrometers Capillaries surround each alveolus Distance air must travel Called respiratory membrane Squamous alveolar cell, basement membrane, capillary squamous cell

    13. What are the pleurae and why are they there? Moist serous membrane covering outside of lungs Visceral pleura inside Folds out at hillum to form outer parietal pleura Pleural cavity: between parietal and visceral layers Filled with pleural (serous) fluid Pleurae functions Reduce friction Create pressure gradient to help with lung inflation Compartmentalization: prevent infection spread to neighboring organs

    14. How does breathing occur? Atmospheric pressure drives respiration Atm. pressure = weight of air column 1 atm. = 760 mmHg Boyles law: pressure and volume are inversely proportional Intrapulmonary pressure changes opposite to volume load Lower intrapulmonary pressure below 760 mmHg to draw breath

    15. What happens during inspiration? Diaphragm does most of the work Phrenic nerves cause diaphragm to flatten External intercostals also contract, elevating (expanding) ribcage Increases lung volume so pressure ______ Parietal pleurae cling to external intercostals Visceral pleurae cling to parietal pleurae Helps increase volume

    16. What happens during inspiration? Air is warmed to assist volume expansion 500 ml air inhaled during resting inspiration 150 ml is dead air (held in conducting regions) Thus only 350 ml to alveoli (respiratory division) Alveolar ventilation rate (AVR) = 350 ml (or whatever value) X number of breath per minute

    17. What happens during expiration? Passive process Diaphragm and external intercostals allowed to relax Natural elasticity of ribcage, lungs and tendons assist via recoil Boyles law: volume decreases so pressure ___________ and air ______ Hard exhale: use internal intercostals to depress ribcage

    18. Why does a lung collapse? Pneumothorax: air in the pleural cavity Can happen if thoracic wall is punctured Separates visceral and parietal pleurae Result? Lung collapse = atelectasis Can also happen if area of lung is blocked Blood absorbs air and lung collapses X-Ray shows complete atelectasis of the right lung. X-Ray shows complete atelectasis of the right lung.

    19. How is ventilation measured? Spirometer Measures respiratory volumes Tidal volume: amount of air inhaled or exhaled when relaxed Inspiratory reserve volume: amount can breath in above tidal volume with maximum effort Expiratory reserve volume Residual volume: what remains in lungs after maximum expiration (keeps alveoli inflated)

    20. What are some breathing variations? Apnea: temporary breath cessation Dyspnea: gasping, labored breathing, shortness of breath Orthopnea: dyspnea while lying down Eupnea: normal, quiet breathing Hyperpnea: increased rate and depth of breathing Tachypnea: accelerated respiration Hyperventilation: expels too much CO2, raising pH Hypoventilation: increases CO2, lower pH

    21. What controls breathing? Medulla oblongata Inspiratory neurons Expiratory neurons (dont fire during eupnea) Unknown how rate of breathing is set Pons Regulates ventilation via pneumotaxic center Sends inhibitory signals to med. Obl. inspiratory center More impulses = shorter breath Voluntary control: motor cortex of frontal lobe Automatic controls can override to protect organism Ondine's curse: person must remember to take each breath. Cant sleep without the help of a mechanical ventilator. From German legend: Ondine (a water nymph) took a mortal lover. The lover was unfaithful to her and so king of nymphs placed curse: lover had to remember to take each breath. Couldnt go to sleep or would suffocate. Died from suffocation due to exhaustion.Ondine's curse: person must remember to take each breath. Cant sleep without the help of a mechanical ventilator. From German legend: Ondine (a water nymph) took a mortal lover. The lover was unfaithful to her and so king of nymphs placed curse: lover had to remember to take each breath. Couldnt go to sleep or would suffocate. Died from suffocation due to exhaustion.

    22. What happens during gas exchange? Air composition: O2, N2, H2O, CO2 Daltons law: partial pressure of each adds up to total pressure What should they add up to at sea level?

    23. What affects gas exchange? Takes about 0.25 secs to create equilibrium Erythrocyte takes 0.75 sec to pass through alveolar cap. During exercise erythrocyte present for 0.3 sec

    24. What affects gas exchange? Concentration gradients of gases Blood entering lungs PO2 = 40 mmHg PCO2 = 46 mmHg Blood leaving lungs PO2 = 95 mmHg PCO2 = 40 mmHg Solubility: Same amount of gases exchange, though, bec. CO2 is about 20 times as soluble in water

    25. What affects gas exchange? Membrane thickness: respiratory membrane v. thin Left ventricular failure = edema and thickened resp. memb. Result: gases cant equilibrate fast enough Membrane area: more resp. memb. S.A. = better gas exchange Emphysema, tuberculosis decrease S.A.

    26. How is oxygen transported? Oxygen: 98% bound to hemoglobin Review hemoglobin structure How many molecules of oxygen can one hemoglobin hold? As more oxygen bind to hemoglobin, affinity for oxygen increases Oxyhemoglobin vs. deoxyhemoglobin CO poisoning: carboxyhemoglobin (HbCO): competes with oxygen for binding site Binds 210 times more tightly than oxygen to heme group

    27. How is carbon dioxide transported? Three ways Carbonic acid 70% of CO2 is hydrated CO2 + H2O ? H2CO3 ? HCO3- + H+ Carbamino compounds (23%) To plasma proteins and hemoglobin to form carboaminohemoglobinHbCO2 (different from carboxyhemoglobin) Binds to polypeptides, not to heme groups Dissolved gas (7%) Dissolves in plasma like CO2 in soda pop

    28. What is carbon dioxide loading? Carbonic acid reaction occurs in plasma and erythrocytes Carbonic anhydrase in RBCs speeds reaction Chloride shift: HCO3 diffuse out of RBCs, replaced with Cl- H+ binds to Hb (this buffers RBC pH)

    29. What is oxygen unloading? H+ bound to HBO2 decreases affinity for O2 Causes RBC to offload oxygen more easily Under what conditions would this happen? Venous reserve: oxygen not offloaded Can sustain life for up to five minutes

    30. What happens in exhalation? Carbon dioxide offloading Exact reverse of loading process Oxygen loading Reverse of offloading

    31. Does Hb always offload the same amount of O2? No! If PO2 of tissue is lower, more is offloaded Higher temp = more offloaded Bohr effect: active tissues put off more CO2 which lowers blood pH This causes more O2 offloading = Bohr effect BPG (bisphosphoglycerate) binds to Hb and promotes O2 offloading RBS anaerobic fermentation intermediate Fever, growth hormone, NE stimulate BPG synthesis

    32. Does Hb always load the same amount of CO2? No! Haldane effect: low HbO2 allows more CO2 transport HbO2 doesnt bind CO2 as well as deoxyhemoglobin (HHb) HHb binds more H+ which removes H+ from solution How does this affect the reaction CO2 + H2O ? H2CO3 ? HCO3- + H+?

    33. How does blood chemistry affect ventilation? Peripheral chemoreceptors monitor Carotid bodies and aortic bodies Central chemoreceptors also monitor In brainstem Both monitor blood pH How does this relate to O2 and CO2 levels?

    34. How does blood chemistry affect ventilation? H+ in CSF is main site of monitoring H+ doesnt cross blood-brain barrier but CO2 does, then reacts with water Problem: few proteins present to buffer H+ Acidosis: blood pH lower than 7.35 Common cause: hypercapnia (high CO2 value) To correct: blow off CO2 rapidly (hyperventilation) Alkalosis: above 7.45 Common cause: hypocapnia To correct: take up CO2 rapidly (hypoventilation)

    35. How does blood chemistry affect ventilation? Ketoacidosis: from diabetes mellitus Lipid oxidation produces ketone bodies Leads to low pH Hyperventilation called Kussmaul respiration Blowing off CO2 helps remove H+ and compensate for ketone body H+ production

    36. What are some respiratory disorders? Hypoxia: oxygen deficiency Hypoxemic hypoxia: low arterial PO2 High altitude, impaired pulmonary function, respiratory arrest, lung disease Ischemic hypoxia: inadequate blood circulation e.g. from congestive heart failure Anemic hypoxia: from anemia Histotoxic hypoxia: from metabolic poison (e.g. cyanide) Hyperoxia: produces hydrogen peroxide and free radicals

    37. What are some respiratory disorders? Chronic obstructive pulmonary disease (COPD) Long-term obstruction of airflow Asthma Chronic bronchitis: cilia immobilized and reduced in number More goblet cells present: produces sputum Emphysema: alveolar walls destroyed Smokers often have one or more of these

    38. How does smoking and cancer affect the lungs? Lung cancer accounts for the most cancer-related deaths Causes: smoking, followed by pollution Tobacco: more than 15 carcinogens Adam picture is a lateral view of a CXR in a patient with central cancer of the lung. Adam picture is a lateral view of a CXR in a patient with central cancer of the lung.

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