2 What Physiological problems resulted from wearing a corset? Corsets were designed to constrict the waist—the tighter the corset the smaller the waist. A successfully corseted young lady might boast of a 12-inch diameter waist! Problem was, the upper part of the corset included the lower part of the rib cage. What was the result of this constant binding? The corset prevented adequate ventilation and caused a permanent deformity of the rib cage…to say nothing of the displaced abdominal organs. The corseted young lovely couldn’t breathe and often fainted. Herein lies the physiologic basis of the swoon and delicate weakness that characterized wealthy young women. They were not weak because of their female X chromosomes; they were merely hypoxic…no oxygen going to the brain. Fortunately, only the wealthiest could make this fashion statement.
3 4 Processes of Respiratory Function: supply O2 dispose of CO2 Pulmonary VentilationBreathing – movement of air into/out of lungsExternal VentilationOxygen from lungs to bloodCO2 from blood to lungsTransport of Respiratory GasesVia cardiovascular systemInternal RespirationOxygen from blood to tissue cellsCO2 from tissue cells to blood*Also involved with smell & speech
4 Respiratory Organs: Nose Airway for respirationMoistens & warms airFilters & cleans airOlfactory receptorsNasal CavityDivided by nasal septumLined w/vibressae hairsOlfactory mucosaRespiratory mucosa – psuedostratified ciliated epithelial tissue (cilia sluggish in cold weather)Goblet cells- Mucuswater to humidifyLysozymeDefensins - antibioticsSensory nerves for sneeze reflexSuperficial capillaries warm airSuperior, middle, and inferior conchaeincrease surface areaDeflect non-gas particles into mucus
5 Pharynx (AKA throat) 5”long Nasopharynx Oropharynx Laryngopharynx Air passageway onlyUvula & soft palate closes off during swallowing(fails when laughing!)Pharyngeal tonsil (AKA adenoids)OropharynxBoth swallowed food & air pass throughPalantine & lingual tonsilsLaryngopharynxStratified squamous epitheliumFood & air passageway (food has priority)Extends to epiglottis of larnyx & esophagus
6 Larynx (AKA Voice Box) 2” attached to hyoid bone 3 functions: Provide open airwaySwitching mechanism to direct air & foodVoice productionAdams Apple-laryngeal prominence of thyroid cartilage
7 Voice ProductionPitch determined by length & tension of chords changesTenser chords vibrate faster therefore higher pitchDeep tones produced by a wide glottisLoudness depends on force of air stream across chordsQuality depends on length of pharynx to amplify & enhance as well as oral, nasal, and sinus cavitiesEnunciation depends on muscles of pharynx, tongue, soft palate & lips
8 Trachea (AKA windpipe) 4”long, ¾” diameter, 3 layersMucosa - Pseudostratified ciliated epithelium w/goblet cellsSubmucosa – connective tissueAdventitia - reinforced by C shaped hyaline cartilage, trachealis smooth muscle decreases diameter of trachea when swallowing food or to produce cough to expel air up to 100mph!Smoking destroys cilia…leaving coughing as only mechanism for preventing debris from entering lungs
9 Bronchi Conducting Zone Respiratory Zone R/L primary bronchi branch off into 20 and 30 bronchi up to 23 orders of branchingBronchioles (1mm) lead to terminal bronchioles (0.5mm)Mucous, Cilia & supporting cartilage are sparseRespiratory ZoneAlveoli- thin walled air sacs300 million account for most of lung volumeSimple squamous epithelial tissueDensly covered w/cobweb of pulmonary capillariesGas exchnage occurs by simple diffusion
10 Lungs & Pleurae Each lung in its on plural cavity Left Lung Right Lung Visceral & parietal pleuraPleural fluid fills pleural cavityLeft Lungsuperior & inferior lobesRight Lungsuperior, middle & inferior lobesPulmonary arteries branch into pulmonary capillaries surrounding the alveoiliOxygenated blood is carried out of the lungs by pulmonary viensLungs innervated w/parasympathetic (constricts & sympathetic (dilates) motor fibers
11 Mechanics of Breathing Atmospheric Pressure = 760mmHgBoyle’s Law – pressure is inversely proportional to volumeInspirationDiaphragm & external intercostals contractIncreases volume of thoracic cavity by almost 500mLPulmonary pressure decreases about -6mmHgForced inspiration utilizes scalenes, sternocleidomastoid, pectoralis minor, & erector spinae musclesExpirationAs inspiratory muscles relax, lungs recoil & thoracic volume decreases increasing pressure to 761mmHgForced expiration utilizes oblique & transverse abdominals, and internal intercostals
13 Respiratory Volumes & Capacities Spirometer – measures respiratory capacitiesVital CapacityTidal VolumeNormal quiet breathing (500mL ea/breath)Inspiratory Reserve VolumeAir taken in forcibly ( mL over TV)Expiratory Reserve VolumeAir forcibly expelled (1200mL)Residual VolumeAir remaining in lungs that cannot be expelled (1200mL)Allows gas exchange between breaths, keeps alveoli inflatedDead Space VolumeAir remains in “passageways” and never reaches alveoli (150mL)
14 Transport of Respiratory Gases by blood Composition of Alveolar GasGas exchange in lungsHumidificationGas mixing w/ea breathOxygen TransportHHb + O2 ⇋ HbO2 + H+Deoxyhemoglobin ⇋ oxyhemoglobinEach molecule of hemoglobin can bind 4 O2, after 1 binds, changes shape easily picking up other O2 until saturatedVarious factors affect O2 affinity for HbGasAtmosphereAlveoliN278.6%74.9%O220.9%13.7%CO20.04%5.2%H2O0.46%6.2%
15 Carbon Dioxide Transport 7-10% Dissolved in Plasma20% Bound to a.a. of Hemoglobin70% as bicarbonate ionsIn Plasma:CO2 + H2O ⇋ H2CO3 (unstable) ⇋ H+ + HCO3-O2 release from Hb is enhanced by CO2 loadingCarbonic acid-bicarbonate buffer system – resists shifts in blood pHIn LungsDiffuses from blood into alveoli
16 Control of Respiration Neural MechanismsMedulla OblongataInspiratory neurons cycle w/ expiratory neuronsRespiratory rate: breaths per minuteCan be supressed by alcohol or morphineInfluencing FactorsLevels of CO2 (most influential), O2, and H+ in bloodHypothalmus – emotionsCerebral motor contral (voluntary) – limitedIrratants constrict bronchioles, stimulate couch or sneeze
17 What is COPD? Chronic Obstructuve Pulmonary Disease Irreversible decrease in the ability to force air out of lungs
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