CB Quiz 4 Flashcards
What are the two processes referred to as respiration?
External respiration
Internal or cellular respiration
What is cellular respiration
Intracellular metabolic process that uses oxygen to produce ATP and CO2. It can also perform anaerobic respiration.
What are the 4 steps of respiration and indicate which are internal and which are external
- Ventilation or gas exchange between the atmosphere and air sacks in the lungs (external)
- Exchange of O2 and CO2 between air in alveoli and blood in pulmonary capillaries (external)
- Transport of O2 and CO2 by the blood between the lungs and tissues
- Exchange of O2 and CO2 between the blood in the systemic capillaries and the tissue cells (Cellular respiration => internal)
What are the two main parts of the basic anatomy of the respiratory system?
Extra-thoracic and Intra-thoracic
What components of the respiratory system are located in the extra-thoracic portion?
Nasal passages
Mouth
Pharynx
Larynx
What components of the respiratory system are located in the intra-thoracic portion
Trachea
Bronchus
Bronchioles
Alveoli
Does gas exchange use ATP? Why or Why not?
No ATP is used in gas exchange as gas exchange is driven by diffusion along the concentration gradient => Passive
What is ventilation driven by? how does air move in and out of lungs?
Mechanical forces where air is moved into and out of the lungs across pressure gradients
How are pressure and volume related at constant temperature?
They are inversely proportional
Where does a pressure differential exist in the respiratory system? How do they compare?
Between the lungs and pleural cavity.
Pleural pressure < Pulmonary pressure
Why is Pleural pressure < Pulmonary pressure?
Lungs are normally stretched and pull inwards => the decreased pleural pressure allows the lungs to remain stretched
When is the pressure equilibrium in lungs disrupted?
Inspiration and exhalation
How does the pressure change during inspiration and expiration?
The pressure difference between the pleural cavity and lungs remain the same. These values decrease during inspiration to allow for air to flow in and increase during expiration to force air out.
List the events that occur during inspiration
- Inspiratory muscles contract
- Diameter of thoracic cage increases
- Intrapleural pressure becomes more negative
- Transmural pressure increases and causes alveoli to swell or open
(Due to pleural pressure decreasing, air particles come from the environment into the alveoli increasing its pressure and causing it to swell)
- Intra-alveolar pressure falls relative to atmospheric pressure
- Air flows down pressure gradient from atmosphere to alveoli
- At the end of inspiration - No airflow and intra-alveolar pressure = atmospheric pressure
How does the diameter or volume of the thoracic cage change as a result of inspiration
Increases in diameter => increase in volume
What are the primary muscles involved in inspiration? Briefly state their involvement
Diaphragm: Flattens upon contraction
External intercostales: Lifts ribs upwards and outwards
Both of these motions expand the volume of the thoracic cavity allowing for more air to flow in
What are the accessory muscles involved in inspiration and briefly state their function
Scalenes: Raise first 2 ribs
Sternomastoid: Raise the Sternum
They are used during exercise and respiratory disease
What are some diseases that require the use of accessory muscle activity? State 2
Chronic bronchitis Asthma Chronic obstructive pulmonary disease Emphysema Bronchiolitis
What are the airway muscles and what’re their overall function during inspiration?
Laryngeal
Pharyngeal
Genioglossus
They enlarge the airway reducing flow and resistance as well as maintaining stabilisation of the airways preventing collapse
What are the two types of expiration and describe each briefly
Passive expiration: Passive process and occurs when at rest. The relaxation of inspiratory muscles are sufficient for expiration.
Active expiration: Contraction of abdominal muscles which involve pushing up the diaphragm as well as internal intercostal muscles
What device is used to obtain a Spirogram
Spirometer
An increased RV (Residual volume) is an indication of?
Obstructive Disease
What are 3 signs of restrictive lung disease?
Decreased TV or total volume
FEV1 decreased
FEV1/FVC is normal or increased
RV normal
Decreased compliance in lungs
What are 3 signs of obstructive lung disease and give 3 examples
FEV 1 and FEV1/FVC reduced
Airflow rate reduces
Airway obstruction
Higher RV
Examples include; Asthma COPD Chronic bronchitis Emphysema
What cannot be measured by a spirometer? What method can be used to fix that?
A spirometer cannot measure RV, FRC, TLC
The Helium Dilution Technique can be used to calculate FRC which involved a helium/oxygen mixture in spirometer. Review the physics behind it on the slides
FRC can also be calculated by Body Plethysmography.
What is required to fully characterize lung volumes and capacities?
Helium dilution technique/ Plethsymography + Spirometry
What is dead space and what are the three different types?
Dead space is the volume occupied by gas in the lungs which does not participate in gas exchange
- Anatomical dead space
- Alveolar dead space
- Physiological dead space
What is anatomical dead space?
Is its the components of the respiratory system that are filled with air but dont have any pulmonary capillaries such as Trachea and bronchus
Is dead space included in total volume or tidal volume?
Yes
What is alveolar dead space?
Alveolar dead space represents the air in the alveoli that are surrounded by pulmonary capillaries without blood flow.
What is average amount of alveolar dead space present within a healthy individual? What increases it?
Usually negligible in healthy people
Can increase in disease such as pulmonary embolism
What is the physiological dead space
It is the total dead space found within an individual
=> Anatomical dead space + Alveolar dead space
How is anatomical dead space measured?
Fowler’s method: Nitrogen washout
What does the slope in the graph obtained by Fowler’s method represent? Explain briefly
Mixture of dead space and alveolar air
Patients take in 100% O2 after an initial inhalation. When exhalation beings, the first part of the air exhaled will be 100% O2 => no N2. The next part of the air will be alveolar air which is N2-rich
=> Volume of N2-free air represents the anatomical dead space
The line that bisects the exponential increase of expired N2 represents the anatomical deadspace
This is due to mixture of deadspace and alveolar air
What method is used to calculate physiological and Alveolar dead space? Explain briefly
Bohr’s method
Detects expired CO2 concentration. Atmospheric CO2 is neglected. Partial pressure of CO2 in the alveoli is the same as that of the arterial blood (PaCO2). The alveolar dead space, or non-functioning alveoli due to no blood supply, will represent a difference between PaCO2 and PeCO2 (Exhaled air). The more dead space present, the less PeCO2 is present and the more PaCO2 is present. => we look at PeCO2/PaCO2.
VD/VT = 1 - (PeCO2/PaCO2)
Define the work of breathing
It is the work required to move the lung and chest wall (W = P x DeltaV)
It is the energy necessary to perform tidal ventilation over a set unit of time
What muscles are involved in quiet breathing?
Inspiratory muscles as expiration is passive
What are the two types of work present during breathing and what percentage does each contribute?
Elastic work 70%
Non-elastic work 30%
Do respiratory muscles consume much oxygen? If so, approximately how much?
Respiratory muscles consume only 2-3% of total oxygen consumption
What are two conditions that involve increased energy expenditure on breathing?
Exercise which increases minute volumes
Disease which limits exercise tolerance
What are the components of minute ventilation/volume?
Tidal volume and rate
What is the relationship between?
Tidal volume and Respiratory rate Tidal volume and Elastic Work Rate of Respiration and Flow Rate of Respiration and resistive work Resistive work and elastic work Elastic Work and Non-elastic work Tidal volume and Flow Respiratory rate and elastic work
Inversely proportional =NP
Proportional = P
NP P P P NP NP NP NP
Define Compliance/Elastic Work
Force required to expand lung against its elastic properties
Define Frictional/Resistive Work
Non-elastic
Force to overcome air-flow resistance (force to move air through airways)
Force to overcome viscosity resistance
Define Compliance
Measure off the ease with which the lungs can be stretched or inflated
Define how each of the following are measured
Static Compliance
Dynamic Compliance
Specific Compliance
Static compliance is compliance measured when there is no airflow
Dynamic Compliance is compliance measured during airflow
Specific Compliance measures elastic properties correcting for lung volume
In terms of the pressure-volume relationship, what do the following represent?
Slope
Steep slope
Area within inspiration and expiration curves
Large area
Slope measures the compliance
Steep slope indicates more compliance
Area represents the work
A large area indicates greater work required
What does specific compliance measure and how is it calculated?
Specific compliance measures the intrinsic elastic properties of the lung tissue
Calculated as: Compliance/FRC (Lung volume)
How does a disease alter compliance?
A disease can either increase compliance or decrease it:
Increased compliance is due to the loss of elastin fibres which are the elastic tissue found in lung tissue
Decreased compliance affects chest wall compliance causing scoliosis and pulmonary fibrosis
Define Elastance. How are compliance and elastance related? How are they affected by Emphysema and Fibrosis
Elastance is the measure of the “Snap back” or elastic recoil force of the lungs
Elastance is inversely related to compliance
Emphysema causes increased compliance and decreased elastance
Fibrosis causes decreased compliance and increased elastance
What are the two main contributors to Elastic work and explain each briefly
The two main contributors to this phenomenon are Tissue elasticity due to the presence of elastin fibers in connective tissue as well as surface tension of the film of fluid that lines the alveoli called Pulmonary Surfactant
Describe tissue elasticity during inhalation and exhalation
Inhalation: Energy is required to stretch lungs open such as diaphragm and intercostals
Exhalation: Elastic recoil of the stretched lung occurs
What is the film of fluid that lines the alveoli?
Pulmonary Surfactant
Learning Outcome: Explain the role of surfactant in elastic work
The pulmonary surfactant is a complex mais true of proteins (10%) and lipids (90%).
It is synthesized by type II pneumocystis and stored in cytoplasmic lamellar bodies until released to surface of alveolus at the air-liquid interface.
It’s main function is to reduce surface tension by interfering with water molecule interactions increasing compliance of the lung
Another important role is the stabilisation of alveoli of different sizes. Usually alveoli with small radius => volume causes it to have a high pressure which would empty the air into larger alveoli causing its collapse. The surfactant will position itself with its hydrophilic end on the lining of the alveoli and it’s hydrophobic fatty acid chain projecting into the alveolar air which causes repulsion due to lipid.
It also contributes to defense mechanisms in the lung enhancing macrophage activity
Overall, the surfactant differentials reduces surface tension in alveoli, more at lower volumes and less at higher volumes leading to alveolar stability and co-existence of large and small alveoli
Briefly explain the Newborn Respiratory Distress Syndrome
Developing fetal lungs to not normally synthesis surfactant until late in pregnancy => premature infants may not have enough pulmonary surfactant and struggle to breath
Briefly describe Alveolar Interdependence
Where an alveolus in a group of interconnected alveoli begin to collapse, the surrounding alveoli are stretched. Neighboring alveoli, in response, pull outwards on the collapsing alveoli and keep it open
Define Airway Resistance
Is it present during Inspiration and expiration?
Airway resistance is the impedance of air flow through the tracheobronchial tree as a result of friction of gas molecules
Yes
Describe Airway resistance at rest and the effects of increased resistance on the maintenance of tidal volume
At rest, airway resistance is low. Normal pressure difference between mouth and alveoli is sufficient to give normal resting tidal volume. Increased resistance requires greater pressure gradients to drive airflow in order to maintain the same tidal volume.
What is the typical tidal volume?
500 ml
What are the components that determine airway resistance
Diameter of airway (cross sectional area)
Distance air needs to travel
Flow type/pattern (laminar vs. Turbulent)
What is the relationship between airway radius and flow rate
Radius has a strong influence (r^4) on Flow rate where an increase in the radius also increases flow rate
What is the relationship between resistance and airway radius
There is a strong influence of airway radius on resistance (r^4). Radius is inversely proportional to resistance
Is resistance greater in the trachea or bronchioles? Explain
An individual bronchiole has a far smaller radius than the trachea but has a lower resistance. Although the radius is smaller, the large number of bronchioles means that overall the airway widens => resistance in the trachea and bronchus is greater than in the bronchioles.
Is airway resistance greater at high lung volume (inspiration) or low lung volume (expiration)? Give reasoning
Resistance to airflow decreases during inspiration where lung volume increases due to airways expanding
Resistance to airflow increases during exhalation where lung volume decreases due to airways contracting
What prevents the trachea and main bronchi from collapsing?
Cartilage
Although bronchioles offer little resistance, what is the effect of disease on airway resistance?
Resistance in bronchioles are significant in disease as they are subject to physical, neural, and humoral factors
What are the determinants of airway diameter? Give an example of each
Outside the airway: Radial traction of elastic tissue and pressure from lymph nodes
In the wall: Smooth muscle tone and thickness of mucosa/submucosa
In the lumen: Mucus
What the extrinsic factors (Neural and hormonal control) involved in the control of smooth muscle tone with regards to bronchioles?
Circulating Catecholamines such as adrenaline cause bronchodilation via Beta 2 receptors
The peripheral nervous system causes bronchoconstriction via acetylcholine release and muscarinic receptors.
Non-adrenergic non-cholinergic (NANC) autonomic systems releasing dilators (nitric oxide) or constrictors (neurokinin A)
What the Intrinsic factors (chemical mediators) involved in the control of smooth muscle tone with regards to bronchioles?
Mast cell degranulation (release of histamine) and inflammatory mediators cause bronchoconstriction.
CO2 exerts direct effect on smooth muscle:
- When levels are raised, bronchodilation
- When levels are low, bronchoconstriction
what are the factors influencing secretions of seromucous glands and goblet cells in the respiratory system?
These secretions are controlled by parasympathetic nervous system reflexes and by local chemical stimulation. Secretions are decreased by atropine and increased in bronchitis
What effect does increased mucus production have on the work of breathing? Why?
It increases non-elastic/ flow-resistive work. Mucus decreases the diameter of the airway hence increasing air resistance which increases non-elastic work
What are the two types or patterns of flow?
Laminar flow and turbulent flow
Define laminar flow
Streamline, well ordered flow
Define turbulent flow and it’s effects on air flow
Chaotic, non-streamline flow. Turbulent flow is very inefficient and consumes energy due to an increase in airflow resistance
According to Reynold’s number, what is considered as turbulent flow?
R>2000
\_\_\_\_\_\_ velocities and \_\_\_\_\_\_\_ diameters promote turbulent flow. Answers can be: High Low Large Small Increased Decreased
High/increased
Large/Increased
Under what conditions is turbulent flow exhibited in:
Upper airways
Bronchioles
Upper airways: During exercise
Bronchioles: No turbulence