BIOL 460 1st Edition Lecture 28Outline of Last Lecture I. Boyle’s LawII. SpirometerIII. Lung Diseases a. Restrictive b. ObstructiveIV. Gas exchange in LungsOutline of Current Lecture I. Starling’s ForcesII. Regulation of Breathing III. Chemoreceptors a. centralb. peripheralc. Hypoventilation d. HyperventilationCurrent Lecture1. Starling’s Forcesa. Fluid out – fluid in = BFb. Different in pulmonary circuitc. BF = deltaP/Rd. deltaP = 15mmHg – 5mmHg = 10 mmHg (10% of systemic circuit)e. Resistance must also be 10% of systemic resistancef. Pulmonary – low pressure, low resistanceg. (15+0) – (1+25) = -11mmHgh. (5+0) – (1+25) = -21mmHgi. Negative indicates inward component is greater, more fluid in than out (fluid moves from alveoli to blood)These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.j. If either was positive, as in pulmonary hypertension, it would cause pulmonary congestion due to failure of L ventriclek. Heart attack can cause pulmonary edema (accumulation of fluid in lungs, fatal in 30 minutes)l. Systemic Circuit: Reactive hyperemia due to Co2 increase, which causes pH drop, causing vasodilationm. Pulmonary arterioles: vasodilation with high O2, low CO2, basic pH, sends blood to better parts of lungs (more diffusion at these parts)2. Regulation of breathinga. Brainstem respiratory centers send axons to somatic motor neurons in spinal cord, which supply breathing musclesb. Responsible for automatic control of respiratory ratec. Rhythmicity Area in Medulla Oblongatad. Inspiratory Neurons somatic motor neurons for inspiratory musclese. Expiratory Neurons somatic motor neurons for expiratory muscles (less important)f. Have HCN channels – generate action potentials at a certain paceg. Inspiratory neurons stimulate somatic motor neurons with an EPSPh. Expiratory neurons stimulate somatic motor neurons with an EPSPi. Inspiratory neurons and expiratory neurons create IPSPs for each otherj. Most expiration due to elastic recoilk. When one fatigues, the IPSP is inactivel. For respiratory centers to control respiration rate, they must have sensory input3. Chemoreceptorsa. Centrali. Medullaii. Long term changes in respiratory rateb. Peripherali. Aortaii. Carotid Sinus (behind earlobe)iii. Short term modificationsc. Much more sensitive to CO2 than O2i. Hypoventilation1. Quick increase in CO2 – hypercapnia (above 40mmHg)2. Slow decrease of O2ii. Hyperventilation1. No change in ppO22. Amount of CO2 decreases dramatically – hypocapnia (below 40mmHg)iii. Respond to CO2 levels indirectly1. Senses carbonic acid2. CO2 + H2O H2CO3 H+ + HCO3-3. Makes pH more acidic4. Chemoreceptors respond to drop in pHiv. Set to maintain ppCO2 of 40mmHg in bloodv. Figure 16.29 H+ cant cross blood brain barrier, CO2 crosses, then converted to carbonic acid in interstitial fluid of
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