15. Mechanism of Respiration Pause Recoil Distention Lungs +++ _ _ _ IAP Rushes out Rushes in Air Less - ve More - ve IPP _ _ _ +++ Thorax Passive Active Process Expiration Inspiration
37. Dynamic lung volumes Volume/unite time Maximum breathing capacity Breathing reserve Timed vital capacity Maximum flow rate
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41. FVC > 80 % Normal < 80 % FEV1/FVC ratio > 80 % Restrictive < 80 % Obstructive
42. Spirometer Tests Normal:70 % Small air ways obstruction <70 % FVC > 80 % Normal < 80 % FEV1/FVC ratio > 80 % Restrictive < 80 % Obstructive Forced expiratory flow FEF 25% FEF 50% FEF 75%
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Editor's Notes
Cartilage & smooth muscle . Graps like clusters
O2 utilization = cellular ventilation : ins & expiration
Gas exchange
Flat cells + capillary = resp. mem 0.2 u, 100m2
Dec volume ………………..> inc pressure
760, 759, 761
Recoil due tosurface tension & elasticity : the attractive force Bn molecules
Normal lt lung : capillaries
Diaphragm 75 % of resp. drive
Reduces attractive forces of hydrogen bonding by becoming interspersed between H 2 0 molecules
L / S ratio from amniotic fluid: licithin/ shyngomyeline :2-2.5
100 x more distensible than a balloon.
Recoil by elasticity 1/3 & ST 2/3
No ST so recoil by elsticity only
++++ C : difficult expiration
No work in normal exp. Due to elstic recoil of lungs. Forced expiration in exercise or asthma
High altitude has less Po2 i.e less diffusion, so large lungs means large area 4 diffusion. 10 % less in females.
Best of 3 trials RV = 20 % TLC.
More with age: closure of smalll airways.
When he is born and takes a deep breath, his Eustachian tubes open and air enters through them to the middle ear . So if you find a small bubble in the middle ear, you can be quite sure, the baby was born alive . On the contrary if you find just jelly like material in the middle ear, the baby was most probably born dead .
Obstructive lung disease : asthma & COPD ( reduced diameter + damage of tissues like emphysema) Prediction FEV1 : FEV1 OF PATIENT DIVIDED BY that of normal population of same character (age ,sex …etc..) In obstructive: FEV1 much reduced than FVC ( DIFFICULT expiration > inspiration). But in restrictive, both FVC & FEV1 are reduced in equal proportionate.
FEF - Forced Expiratory Flow - Forced expiratory Flow is a measure of how much air can be expired from the lungs . It is a flow rate measurement . It is measured as liters / second or liters / minute . The FVC expiratory curve is divided into quartiles and therefore there is a FEF that exists for each quartile . The quartiles are expressed as FEF25%, FEF50%, and FEF75% of FVC . FEF25% - This measurement describes the amount of air that was forcibly expelled in the first 25% of the total forced vital capacity test. FEV 1 < 65-80 % mild obstruction FEV 1 < 50-65% moderate obstruction FEV 1 < 50% severe obstruction .
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