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York University
Kinesiology & Health Science
KINE 2011
Gillian Wu

27 Jan, 2012 Physiology II 27 Jan, 2012 Physiology II What determines P GAs? F gas = Fractions of a g as P gas =pressure of gas in any given container Patm= atmospheric pressure Pgas (Patm x F gas) Know fraction of gas in the air for test. Inside our body we use O2 and produce CO2 ( use it to make energy): someone says yhou increase your metabolism you increased your energy -To increase metabolism we increase CO2 production and O2 usage and we match it to ventilation rate. -Hyperventilation Pressure on the gas on Y axis ---Metabolic rate doesn’t change but ventilation changes (its increased ) Hyper ventilation (drop in carbon dioxide and increase in oxygen) --Ventilation is the same, metabolic rate changes, metabolic rate its not keeping up with ventilation.. (increase in Co2 in aleveoli and drop in O2) --Last graph= Increased metabolic rate you don’t keep ventilation constant (you allow it to change) and as you see as metabolic rate goes up ventilation goes up (straight line) -Top end shows spike -Oxygen and Co2 do not change -For us we strive to maintain Oxygen and CO2 the same. How do we match metabolism and metabolism? What controls our breathing? th 27 Jan, 2012 Physiology II Rhythmic Breathing Inspiration is initiated by diaphragm (skeletal muscles) and intercostal muscles -They are both voluntary and involuntary ( breath when you want to or not) --Involuntary control is regulated by brainstem : pons and medulla -Inside these areas are inspiratory and expiratory neurons in medical control rhythm. How do we determine what respiratory rate should be? What regulates how much we should breath are: The concentrations of Oxygen, Carbon Dioxide, and Hydrogen. We monitor these things by chemoreceptors (chemical receptors) senses chemicals -2 Catogories: Peripheral (located in the aorta & carotid) -Arch has the aortic bodies -We sense the Co2, O2 coming out to the heart. -Carotid bodies sense these O2,Co2 in the brain. -Located in the arteries (arterial) -We don’t monitor these O2, CO2, H in the veins, the blood that has gone through end of the veins has n’t had chance to hit the lungs, and the since a lung or alveoli has a chance to exchange gases there is NO WAYTO KNOW IF YOU SHOULD CHANGE BREATHING PATTERN. -We monitor those in arterial sides, since all arterial blood has gone to the LUNG already so all gases have been exchanged. (AND WE CAN KNOW IF WE CAN CAHNGE OUR BREATHING PATTERN) Carotid dominates 2. Central (medulla) within the respiratory centre -measures the concentration of O2, Co2, H in the interstitial fluid Periphral Chemoreceptor Minute ventilation is a rate (L/min) Normal resting level =100mmHG 27 Jan, 2012 Physiology II as oxygen drops in blood we see increased ventilation But not much till 60mmHg only goes to 11.. But after 60mmHg huge increase in minute ventailation --At the capillaries , arterial oxygen is 40. Its arterial O2 not venous O2 in this graph. Peripheral Chemoreceptor at 100mmHg, (setpoint) -No urgency, soothing at SET POINT -When there is a drop in oxygen, that fireing rate is much more faster, urgent (40mmHg) Brain detecs this throught eh stress of chemoreceptors. ---When there is a higher increase in arterial oxgen these receptors decrease their firing rate. --Inccrease in CO2 / H will cause in increase FIRING RATE -Decrease in Co2/ H will cause in FIRING RATE -Changes in ventiolation (talking about chaning the firing rate in these repectors) --Going from 100mmHg to 60mmHg .. Hb Saturation goes to 90%. When arterial pressure is 60 we still have a lot of oxygen there. --As we start to dopr below 60, curve becomes more steeper. ,The Hb is becoming destaurated, so if we increase breathing rate and oxgen rate we will load a lot of hemoglobin to bind to oxgeyn. - O2 is a weak ,The ventilation rate doesn’t change saturation of Hb, we let is it sit in background, mulator of ventilation --O2 is a weak stimulator of Ventilation -because oxygen is saturated so increasing breathing doesn’t help us anyways. -Over 60-100 mm Hg range that we don’t really response to much changes. -Oxygen Not main regulator over physiological ranges. --Only with big changes in Pa O2. 27 Jan, 2012 Physiology II --Carbon dioxide is a much more strong stimulator of ventilation -At 40mmHg (normal) ev
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