Respiratory 1 Flashcards
Which structures ar involved in the conducting zone
Trachea
Bronchi
Bronchioles
Terminal bronchioles
Which structures ar involved in the respiratory zone
Respiratory bronchioles
Alveolar ducts
Alveolar sacs
Difference between conducting zone and respiratory zone
Conducting zone : only a passage way for air (no gas exchange)
Respiratory zone: gas exchange occurs
Types of alveolar cells
Type 1 alveolar cells
Type 2 alveolar cells (septal cells)
Alveolar dust cells
What are type 1 alveolar cells
Simple squamous cells where gas exchange occurs
What are type 2 alveolar cells
Septal cells that secrete surfactant
What are alveolar dust cells ?
Macrophages that remove debris
True or false
the respiratory membrane is extremely thin
True
( < 1/2 μm)
Purpose of surfactant
Reduces surface tension to keep alveoli open and prevents them from collapsing during exhalation.
Don’t know if this is important so just read
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Functions of respiratory system
Acid-base balance
Water and heat balance
Phonation
Pulmonary defense
Metabolism
Gas exchange (ventilation)
How does the respiratory system help maintain acid-base balance
By regulating arterial CO2 level and eventually pH
How does the respiratory system help maintain water and heat balance
Water loss through saturation of inhaled air
Heat loss through respiratory water evaporation
How does the respiratory system help with phonation
Production of sounds occur by the movement of air through the vocal cords
How does the respiratory system aid in pulmonary defense
Filtration of inspired air and removal of particulate matter such as dust, pollen, fungal spores, micro organisms, etc.
What is the respiratory system‘s role in metabolism
Formation and release of substances such as pulmonary surfactant and repair of alveolar surface in response to injury
Read
What is meant by ventilation
Movement of gas into and out of the lungs
What is meant by alveolar gas exchange
Diffusion of O2 from alveoli to blood
Diffusion of CO2 from blood to alveoli
What is meant by blood gas transport
Gas is present in the blood either in dissolved form, bound to hemoglobin or as other chemical forms
What is meant by cellular gas exchange
Diffusion of O2 from blood to cells
Diffusion of CO2 from cells to blood
Regulation of ventilation is done by ________________.
Central nervous system CNS
Appreciate the diaphragm in this picture
During inspiration, the diaphragm contracts and moves downward providing more space for the lungs to expand
During expiration, the diaphragm relaxes and moves upward
Accessory muscles of inspiration for forceful inhalation
Sternocleidomastoid
Scalene
Pectoralis major
Principle (main) muscles of inspiration for quiet breathing
External intercostals
Interchondral part of internal intercostals
Diaphragm
Muscles of expiration for active breathing (forceful exhalation)
Internal intercostals (except interchondral part)
Abdominals
Quadratus lumborum
Pressures involved in breathing are :
Airway pressure (P aw)
Alveolar pressure (PA , P alv )
Intrapleural pressure (P pl)
What is the visceral pleura
Delicate serous membrane that covers the surface of each lung and dips into the fissures between the lobes
What is the parietal pleura
Outer membrane which is attached to the inner surface of the thoracic cavity. It also separates the pleural cavity from the mediastinum
What is pneumothorax
Abnormal collection of air in the pleural space
What causes pneumothorax and what is its effect on the lungs
Cause: Results from rupture or puncture of the lung or chest wall
Effect on lung: lung elastic recoil causes collapse of the lung
Airflow (Q) in and out of the lungs depends on:
What causes air to move in and out of the lungs
Changes in alveolar pressure
What happens if alveolar pressure (Palv) is LESS than atmospheric pressure (Patm)
Palv < Patm
Air flows INTO the lungs = INSPIRATION
What happens if alveolar pressure (Palv) is MORE than atmospheric pressure (Patm)
Palv > Patm
Air flows out of the lungs = EXPIRATION
What happens if alveolar pressure (Palv) is EQUAL TO atmospheric pressure (Patm)
Palv = Patm
No pressure gradient so no air is moving in or out of lungs (no air flow)
Explain the pressure change during inspiration
Explain the pressure change during expiration
What happens to pleural pressure during inspiration
Becomes MORE negative
What happens to pleural pressure during expiration
Becomes LESS negative
What is the relationship between air flow (Q) and airway resistance (Raw)
Inversely proportional
Airway resistance (Raw) is determined by which law
Poiseuille law
Relationship between the airway resistance (Raw) and air viscosity ?
Directly proportional
Relationship between the airway resistance (Raw) and airway length ?
Directly proportional
Relationship between the airway resistance (Raw) and airway radius ?
Inversely proportional (to the 4th power)
Factors affecting radius of airways
Long volume
Airway smooth muscle tone
Airway inflammation
Airway mucous secretions
How does lung volume affect the radius/resistance of airways (bronchioles and small airway diameter)
How does the ANS control the diameter of the bronchioles and affect the radius of airways ?
Effect of parasympathetic cholinergic fibers on airway radius
- smooth muscle constriction
- increased mucus secretion
= high airway resistance ( high Raw)
Effect of sympathetic adrenergic fibers on airway radius
- smooth muscle relaxation
- inhibition of mucus secretion
= decrease airway resistance (Low Raw)
How does the sympathetic adrenergic fibers inhibit mucus secretion
Through action on bronchial B2 adrenergic receptors
Asthmatic patient gets inhaler / nebulaizer.
Should it contain cholinergic or anti-cholinergic drugs?
anti-cholinergic drugs
(Because cholinergic increase mucus secretion)
Asthmatic patient gets inhaler / nebulaizer.
Should it contain B2 adrengeric receptor agonist or B2 adrenergic receptor antagonist?
B2 adrenergic receptor AGONIST
Local irritants can cause an increase in inflammatory mediators like:
Effect of inflammatory mediators on airway radius and airway resistance
- Constriction of bronchioles
- obstruction of airways
= INCREASE in airway resistance due to decrease in airway radius
Diseases that cause airway narrowing are called
Obstructive pulmonary diseases
Obstructive pulmonary diseases
Diseases that cause airway narrowing
How does obstructive airway diseases effect airway resistance
Increases airway resistance (Raw) due to narrowing of airways
Name some diseases that affect small airways
Asthma
Emphysema
Bronchitis
(Hint: BAE)
Name some diseases that effect large airways
Trauma
Infectious diseases
Congenital tracheobronchial abnormalities
Inflammatory diseases
Neoplasm
(Hint: TICIN)
What are the three basic components of the elastic properties of the lungs
- Compliance / distensibility
- Stiffness
- Elasticity
What is meant by compliance and dispensability of the lung
The ease with which of the lungs can be stretched or inflated
What is meant by stiffness
Resistance to stretch or inflation
What is meant by elasticity
The ability of a stretched or inflated Lunk to return to its resting volume (functional residual capacity FCR)
Difference between compliance and elasticity of
Compliance reflects the ability to change the shape of the structure such as stretching,
whereas elasticity reflects resistance to the change in shape ( the ability to return to the normal state )
Lung compliance
The change in lung volume resulting from 1 cm H2O change in the descending pressure of the lung
Formula for lung compliance
Compliance of a normal human lung is about:
0.2 L/cm H2O
Lung compliance decreases in what type of disease + provide example
Restrictive pulmonary disease
Example: fibrosis
Lung compliance increases in what type of disease + provide example
Obstructive pulmonary disease with air trapping
Example : emphysema
Describe the lung compliance for stiff lung
Low lung compliance
Describe the lung compliance for distensible lung
High lung compliance
Understand this graph
The higher the compliance = the greater the total lung capacity TLC
The lower the compliance = the lesser the total lung capacity TLC
Fibrosis = restrictive pulmonary disease = low compliance
Emphysema = obstructive pulmonary disease = high compliance
Effect of surface tension on alveoli
High surface tension causes alveoli to collapse since fluid molecules are attracted and pulled closer together, closing off the alveoli
What is pulmonary surfactant
Phospholipoprotein formed by type 2 alveolar cells
What is the main lipid components of surfactant
Dipalmitoylphosphatidylcholine DPPC
Purpose of pulmonary surfactant
Reduces the surface tension by adsorbing (NOT ABSORBING) to the air-water interface of alveoli, with protein (hydrophilic heads) in the water and the lipid (hydrophobic tails) facing the air
By reducing surface tension, surfactant functions to:
What is neonatal respiratory distress syndrome
What two complications can occur as a result of immature lungs in premature neonates ?
Pulmonary edema
Atelectasis (collapse of lung)
What are mothers who are expected to give birth prematurely given and why?
They are given Glucocorticoid injections (Betamethasone)
To stimulate surfactant formation and improve lung function
What is tidal volume (TV or VT)
Volume inspired or expired during quiet breathing
What is inspiratory reserved volume IRV
Maximum air inhaled from end of normal tidal inspiration
What is expiratory reserved volume ERV
Maximum air exhaled from end of normal tidal expiration
What is residual volume RV
Air remaining at end of maximum expiration
Can residual volume RV be measured by spirometry
NO
How can we measure residual volume
Helium dilution method
Nitrogen washout
Whole body plethysmography
What is total lung capacity TLC
Air in the lungs after a maximum inspiration
What is vital capacity VC
Air that can be exhaled after maximum inspiration
What is inspiratory capacity IC
Maximum air that can be inhaled from the end of normal expiration
What is functional residual capacity FRC
Volume of air remaining in the lungs at the end of normal expiration
Normal tidal volume TV
0.5 L
Normal inspiratory reserved volume IRV
3.0 L
Normal expiratory reserved volume ERV
1.3 L
Normal residual volume RV
1.2 L
Normal inspiratory capacity IC
3.5 L
Normal functional residual capacity FRC
2.5 L
Normal vital capacity VC
4.8 L
Normal total lung capacity TLC
6.0 L
What is the IRV
IRV = IC - VT = 2.3 - 0.4 = 1.9 L
What is ERV
ERV = TLC - IC - RV = 4 - 2.3 - 0.8 = 0.9 L
What is VC (or IVC)
VC = TLC - RV = 4 - 0.8 = 3.2 L
What is FRC
FRC = TLC - IC = 4 - 2.3 = 1.7 L
What does it mean if all lung volumes and capacities are BELOW normal range ?
Lung have smaller size = Restrictive pulmonary disease (ex: fibrosis)
We can assess restrictive pulmonary disease using spirometry that will show values that are all below average ,
But how can we assess obstructive pulmonary disease?
FEV1/FVC ratio
How is the FEV1/FVC ratio taken?
The subject takes a deep breath and blows out forcefully into a vitalograph that measures the volume exhaled per second
Normal subject can blow out most of his vital capacity VC ( >75% of VC) in the first second
Patient with obstruction cannot because of narrowing of his airways
If the FEV1/FVC ratio is equal or above 0.75 
Normal
If the FEV1/FVC ratio is less than 0.75
Obstructive pulmonary disease
What is FEV1
Forced expired volume in the first second
What is FVC
Forced vital capacity is the total volume of air exhaled in the maneuver
Difference in pathophysiology of obstructive and restrictive pulmonary diseases
Obstructive pathophysiology:
Limitation of airflow due to increased airway resistance causing partial or complete obstruction
Restrictive pathophysiology:
Reduce expansion of lungs decreasing all lung volumes
Examples of obstructive pulmonary disease
Asthma
Bronchitis
Emphysema
(Hint: BAE)
Examples of restrictive pulmonary diseases
Fibrosis
pneumonia
asbestosis
pleural effusion
(Hint: FAPP)
Compare total long capacity TLC in both obstructive and restrictive pulmonary diseases
Obstructive: TLC is normal or high
Restrictive: TLC is low ( all lung volumes are low)
Compare FEV1/FVC ratio between obstructive and restrictive pulmonary diseases
Obstructive:
FEV1/FVC : LESS than 0.75
Restrictive:
FEV1/FVC : EQUAL or MORE than 0.75
Compare lung compliance between obstructive and restrictive pulmonary diseases
Obstructive: high lung compliance
Restrictive: low lung compliance
What is physiologic dead space VD (wasted ventilation)
The volume of air that enters the lungs but does not participate in gas exchange
Two types of dead space
Anatomic dead space
Alveolar dead space
What is anatomic dead space
The volume of air in the conducting airways including the nose/mouth, pharynx, trachea, bronchi and bronchioles which does not participate in gas exchange
What is alveolar dead space
The volume of air in the alveoli that are ventilated but not perfused
How to calculate physiologic dead space
Anatomic dead space + alveolar dead space
What is minute ventilation VE
Volume of air entering or leaving the nose/mouth per minute
How to calculate minute ventilation
Tidal volume TV ( ml) x respiratory rate (breaths per minute)
VE = TV x RR
Unit of minute ventilation
Ml/min
What is alveolar ventilation VA
The volume of air that reaches the alveoli per minute and contributes to gas exchange (Excluding dead space volume VD)
How to calculate alveolar ventilation
VA = (Tidal volume - dead space) x respiratory rate
VA = (TV-VD) x RR
Unit: ml/min
