Respiration part 1
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Transcript of Respiration part 1
RESPIRATION
• External respiration (Lungs):
- Pulmonary ventilation
- Gas exchange (lungs # blood # tissues)
- Gas transport
• Internal respiration (Mitochondria):
- O2 utilization.
Non respiratory functions of the lungs
• Acid base balance
• ACE (Activation : ATI ATII).
• Airway protection
• Vapor loss
• VR help
• Vocalization
Conducting & Respiratory Zones
Pneumocytes Types
Visceral & parietal pleura
Boyle’s Law
Pulmonary Pressures
Diaphragm
Pulmonary Pressures
Importance of Negative IPP
• Lung expansion
• Venous & lymph return
IPP become +ve in:
- Pneumothorax
- Valsalva manouver
Pneumothorax
Respiratory Muscles
Abdominal ms
Mechanism of Inspiration
Mechanism of Respiration
Inspiration Expiration
Process ActivePassive
Thorax +++_ _ _
IPPMore - veLess - ve
Lungs DistentionRecoil
IAP_ _ _+++
Air Rushes inRushes out
Pause
Surfactant
• Lipoprotein (phospholipid, apoproteins & Ca++).
• produced by alveolar type II cells.
• ST so prevents: - collapse of small alveoli in
expiration. - pulmonary edema.
Surfactant deficiency
• RDS• 100 % O2 inhalation.• Occlusion of pulmonary artery or major
bronchus.• Smoking.• Hyperinsulinism e.g baby of diabetic
mother.• Myxedema (hypothyroidism).• Hypocorticism
Physical Properties of the Lungs
–Elasticity. –Surface tension.
–Compliance (Distensibility).
Lung Compliance
• Definition change in lung volume/change in distending
pressure: C= V/P ml/cm H2O
• Types : # Static C ( lungs only, 200). # Dynamic C (lungs + thoracic wall, 110)
Static Lung Compliance
• 200 ml/cmH2O
• Hysteresis loop
• Surfactant conc. during deflation
Inflation
Deflation
Static Lung Compliance
Lung Compliance
++++++++ - - - - - - - - - - - - - -
Aging Lung fibrosisAtheletes Congestion
EmphysemaEdemaRDSPoliomyelitisobesity
Breath Work
• During inspiration or forced expiration.• 3 parts:1- Elastic work (or compliance).2- Air resistance work (medium bronchi).3- Tissue resistance work (viscosity).
• Air way resistance 1/a diameter of bronchi.• Breath work increases in : Surfactant
Compliance & Airway resistance.
Factors affecting bronchi diameters
Factors BronchodilationBronchoconstriction
ANSSymp. (B2 receptors).
Parasymp. (Muscarinic R)
PCO2 ++++++++++ - - - - - - - - - - - - -
RespirationInspiration (Lung expansion)
Expiration
Circadian rhythm
Max. at 6 PMMax. at 6 AM
Temp.Warm Cold
ChemicalsVIPHistamine,adenosine
Pulmonary Ventilation
• it is the air exchange (atmosphere & alveoli).• Normally: air vol. in insp. = air vol. in exp.• Spirometer measures lung volumes &
capacities.• High volumes in tall people, high altitude• low volumes in female, pregnancy, short & smokers
• The amount of air remaining in the lungs at the end of a maximum expiration.
• 1200 ml (30% TLC) during rest ( in exercise).
• in aging & obstructive lung diseases.
• Measured by Helium dilution method
(NOT spirometer).
Residual Volume
Helium Dilution Method
• RV = FRC – ERV
• TLC= FRC + IC
• Continuous gas exchange in between breathes.
• Prevent alveolar collapse.• D of asthma & emphysema ( 70%).• Medicolegal importance: lost in
pneumothorax but minimal air w is sufficient for floatation of lung in water & absent in stillbirth.
RV Significance
Vital Capacity
• Max. vol. of air can be expired after max. inspiration.
• Measured by spirometer.
• 4600 ml ( 2 - 2.5 L/m2).
• Index of pulmonary function & physical fitness.
Factors Affecting VC
+++++++++- - - - - - - - - -
Physiological Males Females
AtheletsPregnancy
Standing Recumbency
Pathological ______Chest/ lung diseases
Dead Space• The part of res. system with no gas
exchange.
• TYPES:
- Anatomical DS
- Alveolar DS - Physiological DS :Anatomical + Alveolar DS
Normally: Physiological = Anatomical DS
Lung diseases: Physiological > Anatomical DS
DS ImportanceWarms,filters & moistens inspired air.
Causes difference in composition between expired air & alveolar air (more CO2 & less O2).
Shallow rapid breath hypoxic hypoxia.
DS Measurement
• Anatomical DS : Fowler method (single breath N2 test).
• Physiological DS:Bohr equation.
• 150 – 167 ml.
• ANS can +++ or - - - - DS
Pulmonary Ventilation Tests
• Pulmonary ventilation ( minute respiratory volume):
RR X TV
• Alveolar ventilation:
RR X (TV – DS)
Pulmonary Function Tests
Pulmonary function tests
Static lung volumes
Dynamic lung volumes
Dynamic lung volumesVolume/unite time
Maximum breathing capacity
Breathing reserve
Timed vital capacity
Maximum flow rate
Maximum breathing capacity(Maximum ventilatory volume)
• Max. vol. of air inspired/expired using the deepest & fastest respiratory effort /min.
• Males: 80-180 L /min
• Females: 60-120 L /min
• Spirometer is used for 15 sec. to avoid fatigue & resp. alkalosis. Then X 4.
• Better index for physical fitness than VC.
Breathing Reserve
• BR = MBC - MV• BR/MBC > 90 %.• Dyspnic index : BR/MBC < 70 %.
• Max. velocity of expired air.• 10 L/m (by peak flowmeter).• --- in obstructive lung diseases.
Maximum flow rate
Timed vital capacity (Forced expiratory volume)
• % vol. of expired air at end of 1st sec.
• FEV1 (FEV/FVC) = 80 %.
• Measured by spirometer.
• Differentiates between restrictive & obstructive lung diseases.
FVC
<80% Normal
>80%
FEV1/FVC ratio
<80% Restrictive
>80% Obstructive
Spirometer Tests
FVC
<80% Normal
>80%
FEV1/FVC ratio
<80% Restrictive
>80% Obstructive
Forced expiratory flow
FEF 25%
FEF 50%
FEF 75%
Normal:70%
Small air ways obstruction <70%