Physiology, the study of how life works, is based on Ventilation, complience,

Transcription

1 Respiratory System The goal of these lectures is to discuss basic respiratory physiology. This lecture will introduce the topic and discuss lung mechanics. The sections for this lecture are: 13 Introduction Structure / function, gas laws, lung/chest wall relations, pressures / forces Life is a series of chemical reactions occurring in compartmentalized environments. The main purpose of life is to keep itself alive Lungs mechanics Physiology, the study of how life works, is based on Ventilation, complience, the simultaneous occurrence of the following three capacities, pressures concepts: levels of organization Alveolar gas pressures, structure / function relationship ventilation, blood flow homeostatic regulation Gas exchange in tissues PCO2 PO2 ph Pa inputs neural CV center cardio + cardio - vasoconstriction output chemo & baroreceptors extrinsic periphery heart intrinsic lung (local control) (local control) baroreceptor mechanism (e.g. carotid sinus) where we would like to be at the end of the cardiovascular and respiratory sections, by the end of this week 1

2 Respiratory System Introduction, today lecture Structure / function, gas laws, lungs / chest wall relations, Lung mechanics, today lecture expiration, complience / alveolar ventilation / dead and their diffusion in alveolar - blood exchange and alveolar blood flow Transport of O2, CO2 and H ions in blood, next lecture Hemoglobin (Hb), effect of PO2 on Hb saturation Blood PCO2, H + conc, t C, DPG on Hb saturation Carbamino compounds and carbonic anhydrase Total blood carbon dioxide and the Haldane effect Respiratory acidosis and respiratory alkalosis Control of respiration, next lecture Neural generation of rhythmical breathing Control of ventilation by PO2, PCO2, and H + conc Control of ventilation during exercise Other ventilatory responses Hypoxia and non-respiratory functions of lungs, next lecture Hypoxia and acclimatization to high altitude Non-respiratory functions of the lungs Respiratory System levels of organization structure - function homeostatic regulation 2

3 Respiratory System what it actually is (info from feedback), is compared with what it should be (info from set-point) in a comparator / integrator Homeostasis, or constancy of the internal environment, is needed for chemical reactions underlying life to occur. It is maintained, predominantly, through negative feedback mechanisms error signal amplification S E effect effectors mechanism integrators compare what it should be with what it actually is and generate an error signal Respiratory System Homeostatic Control central integration center afferent efferent S receptor E effector negative feedback signal integrators compare what it should be with what it actually is and generate an error signal 3

4 Respiratory System S receptor E Respiratory / cardiovascular interaction DR=PD x A x DC / D (DC, CO2 = 20 DC, O2) V=RF x TV CO=HR x SV control of amplitud & frequency venous return VA / Q ventilatory pump circulatory pump CNS PO2 chemoreceptors baroreceptors BP O2 content O2 supply blood flow Hemoglobin integrators compare what it should be with what it actually is and generate an error signal Respiratory System S receptor E integrators compare what it should be with what it actually is and generate an error signal 4

5 Respiratory System AP NEURAL RESPIRATORY CENTER inputs AP inspiratory expiratory O2 CO2 THORACIC COMPO- NENTS O2 CO2 O2 CO2 DISTRIBUTION CENTER distribution center PCO2 ph PO2 Pa O2 CO2 S receptor E METABOLIC COMPONENTS (all cells) blood related neurogenics AP integrators compare what it should be with what it actually is and generate an error signal Respiratory System Why do we need a respiratory system??? S receptor E integrators compare what it should be with what it actually is and generate an error signal 5

6 Respiratory System Functions of the Respiratory System: Introduction 6

7 Introduction Functions of Airway Conducting Zone Introduction Anatomy of respiratory zone 7

8 Introduction Blood supply to lungs Introduction 8

9 Introduction Introduction 9

10 Introduction inspiration expiration Introduction 10

11 Lung mechanics (surfactant) Lung mechanics Some important facts on Pulmonary Surfactant (volumes) 11

12 Lung mechanics resistance spirometry Lung mechanics resistance spirometry 12

13 Lung mechanics Lung mechanics resistance Effects of Breathing Patterns on Alveolar Ventilation 13

14 Lung mechanics Lung mechanics 14

15 Lung mechanics Normal Gas Pressure Lung mechanics 15

16 Lung mechanics Gas exchange as function of capillary length PO 2 PCO 2 Lung mechanics Effects of Various Conditions on Alveolar Gas Pressure Condition alvpo2 alvpco2 Breathing air with low PO2 decrease no change Increase alveolar ventilation and unchanged metabolism increase decrease Decrease alveolar ventilation and unchanged metabolism decrease increase Increased metabolism and unchanged alveolar ventilation decrease increase Decreased metabolism and unchanged alveolar ventilation increase decrease Proportional increase in alveolar ventilation and metabolism no change no change 16

17 Lung mechanics V/Q Lung mechanics Fick's first law of diffusion J= -DA dc/dx J= net rate diffusion, moles or grs per unit time A= area of the plane dc/dx= concentration gradient across plane D= diffusion coefficient (proportionality cte) 17