Lecture 19- Respiration Major idea behind respiration: Get O2 from outside into deep tissuesGet CO2 out of tissues Cellular Respiration:O2 used by tissues in oxidative phosphorylation; CO2 produced as waste product by glycolysis.Terms to know: glottis- space between vocal folds, it is the place for vocalizationdiaphragm - divides thoracic cavity from abdominopelvic space-lowering diaphragm (inhaling) decrease in intrapulmonary pressure less than atmospheric pressure-raising diaphragm(exhaling) increase in intrapulmonary pressure greater than atmospheric pressureintrapleural space - space between outer lining of lungs and inner lining of thoraxOrder of Respiratory Order of Respiratory TracheaPrimary BronchusTerminal BronchiolesAlveolus-intrapleural pressure keeps elastic lung inflated-Pneumothorax “air chest”- air enters intrapleural space, lung collapses, and can’t pull air in during inspiration because lung isn’t against diaphragm-lung appears black or darker on X-RAY because of the air-treatment: insert catheter and suck air out of intrapleural spaceType I Alveolar Cell-cells that form the structure of the alveolar wallType II Alveolar Cells- produces surfactant, a protein, that breaks surface tension - increases capability to exchange gasesPhysical Properties of Lungs:Compliance: amount lung inflates with given pressureElasticity: amount lung resists inflation and recoils back to resting stateSurface Tension: thin film of fluid on inside of alveoli has surface tension (attraction of water molecules) after great tension collapse the alveoli-Type 2 alveoli cells produce surfactant a protein that breaks down surface tension/makesit easier to inflate alveoli-Smaller the radius of alveolar cells, the stronger the pressure exerted by surface tensionDisorders of Surface Tension: 1. Cystic Fibrosis - genetic defect of a Cl- transporter causes lack of fluid secretion, so airway fluid is excessively viscous2. Acute Respiratory Distress Syndrome (ARDS)- inflammation in lungs leads to excessive accumulation of fluid and reduced surfactant release3. Premature infant - surfactant not produced until late pregnancy (just before birth) thus premature infants have collapsed alveoli a. Treatment: administer exogenous surfactantInspiration and Expiration:At rest, intrapulmonary pressure (inside lungs)= atmospheric pressureBoyle’s Law- pressure drops as volume increasesEx. Increase in lung volume, decreases intrapulmonary pressure* Makes sense because when you inhale, you increase lung volume and intrapulmonary pressure is lowerLecture 20- Respiration continuedTotal Lung Capacity Vital Capacity- gas in lungs after maximum expansion -gas breathed in and out-“total” amount of air that can fill the lungs at maximum inspirationTidal Volume Residual Volume-gas breathed in and out at rest -gas left in lungs after maximum expirationtissues (where CO2 is high) and is the blood is deoxygenated sent to the heart sent to lung order to pick up oxygen-residual= “what’s left over, what resides”What’s the difference between the tidal volume and vital capacity of your lungs?RESERVE greatly reduced with diseases such as emphysemaGas concentration in Air and Blood: Pressure is measured in mmHgAtmospheric Pressure= 760mmHgIn order to determine gas concentration of things such as O2 and CO2 in the air and blood it is measured as a partial pressure fraction of total pressure exerted by the gasIf O2 comprises 20% of atmosphere, then PO2 = 0.20 × 760 (atmospheric pressure) = 152mmHg (partial pressure) O2 diffuses from higher PO2 to lower PO2 so it moves along concentration gradient in essence it diffuses high amounts to low amountGas exchange occurs in capillaries on Alveoli by diffusionFrom tissue to right ventricle: Blood from lung to left atrium:PO2= 40mmHg PO2= 100mmHgPCO2= 46mmHg PCO2= 40mmHg*PO2 less because the blood comes from the PCO2 less because blood from lungs is low in CO2 and is oxygenated thus being sent to the heart to go to tissues where CO2 concentration will be high againPO2 is high in blood leaving lungs, PO2 low in blood leaving tissue.PCO2 is low in blood leaving lungs, PCO2 is high in blood leaving tissue.Can measure Partial pressure of gas with sensitive electrode to that gas Ex. Measure PO2 with oxygen sensitive electrode1st: calibrate O2 electrode by placing electrode in water with dissolved O22nd: Place electrode in sample or arterial blood in order to measure PO2 of arterial bloodThe lower the air pressure lower PO2 less diffusion of O2Ex. Altitude (feet above sea level)Atmospheric Pressure (mmHg)PO2 in Air PO2 in Alveoli PO2 in Arterial Blood0 760 159 105 1002000 707 148 97 92The higher above sea level lower air pressure lower PO2 as shown less PO2 shows up in bloodPCO2 is constant in atmosphere as 0, so always good diffusion of CO2 out of bloodBreathingTwo breathing control areas:1) Pons2) Medulla OblongataRestful breathingVoluntary Breathing in cortexpositive=stimulationnegative=inhibitionInspiration:1) I nhalation caused by firing of I motor neurons from rhymicity area2) lowering of diaphragm Exhalation:1) inhalation terminated by feedback from lung stretch sensors that inhibit the I motor neurons2) this triggers the exciting of E motor neurons for Expiration Rhythmic breathing is modulated by 2 centers in Pons: Pneumotaxic Apneustic inhibits I motor neurons stimulates I motor neuronsVoluntary Breathing in cortex*A comes before P so Apneustic must stimulate I motor neurons to cause inhalation before inhibiting and exhalingChemoreceptors help detect and regulate pH by sending impulses to relay changes in CO2and O2 concentrations. They are found in-1) Aorta2) Carotid body3) Brainstem After signal to brain brain sends nerve impulses via motor neurons to respiratory muscles Drop in pH makes respiratory control centers speed up breathingIf CO2 too high, that means high HCO3-, lower pH (acidic) High or Low Breathing rate WhyCO2 levels High Increases To blow offCO2CO2 levels Low Does notchangeCO2 is easilyblown off inthis case, sobreathing ratedoes not changeO2 levels Low Does notchangeCO2 levelsmore heavilycontrolbreathing Holding breath hypoventiliation build up of CO2Faster breathing hyperventaliation blows off more CO2Rebreathing air in closed container: CO2 and O2 drop, breathing rate increasesRebreathing air in closed container with CO2 filter: O2 drops but CO2
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