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52 Cards in this Set
- Front
- Back
Hypoxia |
- a state of little oxygen - it is a clinical sign not a disease - sometimes goes in hand with hypercapnia |
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Hypercapnia |
- elevated concentrations of carbon dioxide - |
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Sensor Receptors Varibles |
- oxygen must be equate to support areobic respiration and ATP production - excretion of CO2 is important because high levels of CO2 are a central nervous depressant and also cause a state of acidosis - respiratory system monitors plasma pH and sues changes in ventilation to alter pH |
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Two Possible casues of Lowe Aveolar PO2 |
- the inspire air has low oxygen content - alveolar ventilation is indequate |
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Inspired Air |
- altitude is the main factor that affects atmospheric oxygen - partial pressure of oxygen in air decreases along with total atmospheric pressure as you move from sea level |
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Hyperventilation |
- low aveolar ventilation - lower than normal volumes of fresh air entering the alveoli - result from decreased lung compliance, increased air resistance or CNS depressant that slows ventilation rate and decreases depth |
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Diffusion Distance |
- diffusion if most rapid over short distances - concentration gradient between alveoli and blood as the primary factors affecting gas exchange in healthy people |
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Pathoolical changes That affect Gas exchange |
- a decreases in the amount of alveolar surface area available for gas exchange - an increase in the thickness of the alveolar capillary exchange barrier - an increase in the diffusion distance between the alveolar air space and the blood |
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Emphysema |
- phsyical loss of alveolar surface area - degenerative lung disease most often caused by cigarette smoking |
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Difussion Barrier Permeability |
- alters its properties and slows gas exchgne - lungs have build in reserve capacity, one third of the exchange epithelium must be incapacitate before arterial PO2 falls significantly |
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Pulmonary Edema |
- accumulation of intertestinal fluid increases the diffusion dsitance and slows gas exchange - if pulmonary blood pressure rises for some reason the normal filtration/reabsorption balance at the capillary is disrupted |
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Respiratory Distress Syndrome |
- when hypoxia is due to alveolar fluid accumulation is severe and cannot be corrected through oxygen therapy |
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Air into Liquid is Proportional to 3 factors |
- the pressure grandient of the gas - the solubility of the gas in the liquid - temperature |
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Pressure grandients of gas |
- if gas pressure is higher in the water than gasesous phase then gas molecules leave the water - if gas pressure is higher in the gaseous phase than in water, then the gas dissolves into the water |
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Partial Pressure Gas in Soltuion |
- the concentration of oxygen dissolved in the water at any given PO2 |
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Solubility |
- the ease in which the gas dissolves in a liquid - high solulbility = gas molecules need low gas partial pressure to go into the liquid - low solubility = gas molecules need high partial pressure to dissolve in liquid - oxygen is not very soluble |
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Solubility Importance |
- oxygen's low solubility in aqeous solution means that very little oxygen can be carried in dissolved plasma - low solubility means that oxygen is slower to cross the increases diffusion distance in pulmonary edema - carbon dioxide in not signficatically affected by pulmonary edema because it is soluble |
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Erythrocytes |
- red blood cells - have a critical role in ensuring that gas transport between lungs and cells is adequate to meet cell needs |
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Mass Flow |
- defined as amount of X moving per minute - concentration x volume flow - |
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Fick Equations |
- used to estimate cardiac output or oxgen comsumption, assuming arterial and venous blodo gases can be measured |
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Oxygen Transport in Blood Components |
- the oxygen that is dissolved in the plasma - oxygen bound to hemoglobin |
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Hemolglobin |
- carries 98% of the oxygen in blood - reversibly binds to oxygen the central iron atom of each heme group can bind reversibly with one oxygen molecule - |
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Oxyhemoglobin |
- hemogloin bound to oxygen |
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Law of Mass of Action |
- as the concentration of free O2 increases, more oxygen binds to hemoglobin - if the concentration of O2 decreases the amount of oxyhemoglobin decreases |
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Factors that affect Binidng of Oxygen and Hemoglobin |
- the PO2 in the plasma surronding the red blood cells - number of potential Hb binding sites available in the red blood cells |
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Percentage Saturation of Hemoglobulin |
- the percentage of avaliable hemoglohin biding sites are occupied by oxygen - the plasma PO2 determines the percent saturation of hemoglobin |
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Arterial PO2 is established by |
- the composition of inspired air - the alveolar ventilation rate - the efficiency of gas exchange from alveoli to blood |
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Oxygen Saturation Curves |
- reflects the properties of the hemoglobin molecule and its affinity to oxygen - as long as the alveoli stays above 60 mmHg hemoglobin is more than 90% saturated |
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Factors that Affect Oxygen Hb binding |
- increased temperature, increased Pco2, or decreased pH - decreases the affinity of hemoglobin for oxygen and shift the oxygen hemoglobin to the right |
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Bohr Effect |
- a shift in the hemoglobin staturation curve that results from a change in pH |
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pH Change in Blood |
- when the maximal exertion that pushes cell into anaerobic metabolism - as H+ increases, pH falls, and the affinity of hemoglobin for oxygen decreases |
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2, 3 Disphosphoglycerate |
- a compound made form an intermediate of the glycolysis pathway - increased levels lower the binding affinity of hemoglobin - increase due to high altitude and anemia |
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Chronic Hypoxia |
- extend periods of time of low oxygen - triggers an increase in 2,3 Diphosphoglycerate |
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Fetal Hemoglbin |
- has two gamma protein chains in place of the two beta chains found in adult hemoglobin - enhances the ability of fetal hemoglobin to bind to oxygen in low oxygen environment |
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Carbon Dioxide Trasnported |
- only 7% can dissolve in the plasma - 93% diffuses in the red blood cells - of the 93%, 70% is converted to bicarbonate ion and 23% binds to hemoglobin |
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Removal of CO2 Importance |
- elevated PCO2 caues the pH disturbance as acidosis - extremes of pH interfere with hydrogen bonding of molecules and can denature proteins - high levels depress the CNS and cause confusion, coma, or even death |
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Conversion of CO2 to bicarbonate |
- provides an additional means of CO2 transport from the cells to the lungs - bicarbonate is available to act as a buffer for metabolic acid thereby stabilizing the body's pH |
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Carbonic Anhydrase |
- en enzymes found concentrated in red blood cells - helps with the rapid conversion of CO2 into bicarbonate |
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Chloride Shift |
- bicarbonate leaves the red blood cell on an antiport protein - exchanges bicarbonate for Cl- |
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Respiratory Acidosis |
- excess H+ accumulates in the plasma |
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Carbaminohemoglobin |
- CO2 binds with hemoglobin - the presence of CO2 and H+ facilitates the the formation of carbamino hemoglobin and decrease its binding affinity to oxygen |
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Central Pattern Generator |
- brain stem controls the breathing |
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Model for control of ventilation |
- respiratory nuerons in the medulla controll inspiratory and expiratory muscles - neurons in the pons integrate sensory information and interact with the medulla neurons to influence ventilation - the rhythmic pattern of breathing arises from a neural network with spontaneously discharging neurons - Ventilation is subject to continuous modulation by various chemoreceptor and mechanoreceptor linked reflexes and by higher brain centers |
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Dorsal Respiratory Group |
- control mostly muscles of inspiration |
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Phrenic Nerves |
- transport output from DRG - to the diaphragm and the intercostal nerves to the intercostal muscles |
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Potine Respiratory Groups |
- another potine nuerons provide tonic input to medullary networks to help coordinate a smooth respiratory rythm |
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Ventral Respiratory Group |
- of the medulla has mutlple regions with differnt functions |
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Pre- Botzinger Complex |
- contains sponteneously firing neurons that may act as the basic pacemaker for the respiratory rhythm |
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Obstructive Sleep Apnea |
- inappropriate relaxation of these muscles during sleep - a sleeping disorder associated with sleep with snoring and excessive daytime sleepiness |
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Pheripheral Chemorecptors |
- located in the cartoid and arotic arteries - sense changes in the PO2, pH, and PCO2 of the plasma - when glomus cells sense changes, they trigger a reflex increase in ventilation - respond only to dramatic changes in arterial PO2 |
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Central Chemoreceptors |
- in the brain - respond to changes in the concentration of CO2 in the cerebrospinal fluid - actually respond to ph changes in eh cerebrospinal fluid - respond to decrease in arterial PCO2 as well as increase - respond by increasing ventilation |
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Irritant Receptors |
- send signals through sensory neurons to intergrating centers in the CNS that trigger bronchoconstriction |