from Work of breathing to Dead space Flashcards
Define the work of breathing, its types, normal value.
the work performed by respiratory muscles during inspiration Normal value: 3% Types: 1) Elastic work 2) Resistive work (Non- Elastic Work)
List five conditions of increased work of breathing with explanations.
1- ↑ Elastic work - ↓ compliance - ↓ elastic recoil - ↓ surfactant 2- ↑ Resistive work - ↑ airway resistance - ↑tissue resistance - ↑ ventilation
Give the definition and normal values of lung volumes
1-Tidal volume (TV):
The volume of air inspired or expired during normal resting quiet breathing = ~ 500mL air
2- Inspiratory reserve volume (IRV):
The extra volume of air inspired during deep inspiration in excess of normal tidal inspiration = ~3000mL
3- Expiratory reserve volume (ERV):-
The extra volume of air expired by deep expiration in excess of normal tidal expiration = ~ 1000mL
4- Residual volume (RV):
The volume of air remaining in lungs after deep expiration = ~ 1200mL
Give the definition and normal values of lung capacities
1- Inspiratory capacity (I.C.):
The maximal volume of air inspired by deep inspiration after normal expiration = 3.5 L
2- Functional residual capacity (FRC):
The volume of air remaining in the lungs after normal expiration = 2.2 L
3- Vital capacity (V.C):-
The maximal volume of air expired by deep expiration after deep inspiration = ~ 4.5 L
4- Total lung capacity:
The volume of air present in lungs at the end of deep inspiration = ~ 5.7 L
explain the methods of measurement of lung capacities
- Inspiratory capacity (I.C.): = T.V + IRV = 3.5 L -Functional residual capacity (FRC): = ERV + RV = 1000 + 1200 = 2.2 L - Vital capacity (V.C):- = IRV + TV + ERV = ~ 4.5 L - Total lung capacity: = RV + ERV + TV + IRV = ~ 5.7 L = IC + FRC = RV + VC
All lung volumes & capacities are measured by spirometer EXCEPT:
RV
FRC
TLC
All lung volumes & capacities are:
Higher in Males than Females
Higher in large body than small body
Higher in athletic body than asthenic body
Discuss the vital capacity. List the factors affecting it, and its physiological importance
the maximal volume of air expired by deep expiration, after deep inspiration
Factors affecting:
1) Condition of muscles of chest (respiratory muscles)
2) Lung compliance
3) Range of movement of diaphragm
Importance: index of physical fitness
Give the definition Dynamic lung volumes
A measurement of lung volumes per unit time
Compare between obstructive and restrictive lung diseases
- Obstructive
↑ air way resistance → collapse of alveoli during expiration
Difficulty in Expiration, emptying [air remains in lungs]
↑compliance - Restrictive
↓ compliance
Difficulty in Inspiration, filling [↓ air entry in lungs]
Give the definition and the normal value of: respiratory minute volume, maximal breathing capacity, breathing reserve and dyspneic index.
-Respiratory minute volume (RMV):
Definition: the volume of air inspired or expired per minute
Normal = 6 L/minute
-Maximal breathing capacity (MBC)
Definition: the maximal volume of air inspired or expired per
minute using the deepest & fastest breathing
Normal: = 80-170 L/minute in male
=60-120 L/minute in female
- Breathing reserve (BR):- = MVV – RMV
It gives idea on reserve of respiratory system.
- Dyspneic index: 𝑩𝑹\MBC
normally > 90% ,If less than 70% → ↓ reserve → Dyspnea
Describe the residual volume , Normal value, Factors affecting
Definition: the volume of air remains in lungs after maximal
forced expiration
Normal value: 1200mL
Factors affecting: ↓ Elasticity → ↑ RV
Mention the Physiological significance of residual volume
1) Maintains aeration of alveoli between breathes.
2) Prevents marked changes in O2 & CO2 with breathes.
3) Facilitates lung inflation.
Define the dead space; list its importance
Definition: the volume of air in the respiratory system that
doesn’t share in gas exchange
Importance of :
1) Warms, filters & moistures inspired air
2) Voice production & smell sensation
3) Defensive function
4) It causes the difference in composition between alveolar air & expired air
5) It causes the difference between
6) A test of pulmonary function
Describe the Anatomical dead space
(150mL) - Air in conducting airways - From nose to terminal bronchioles ↑ by: ♯ Bronchodilatation ♯ Breathing through tube ♯ ↑ respiratory rate ↓ by: ♯ Bronchoconstriction ♯ Endotracheal intubation
