Exam 2: 20 Feb 25 Anatomy And Function Of The Respiratory System Flashcards
What is the diaphragm’s role in the respiratory system?
The diaphragm’s contraction creates negative pressure, drawing air into the lungs
The diaphragm is the main muscle of ventilation and has two leaflets that work together.
Why is the right lung larger than the left lung?
The right lung is slightly larger due to the space taken up by the heart
The heart’s position creates a cardiac notch in the left lung.
What are the two types of pleura surrounding the lungs?
- Visceral pleura
- Parietal pleura
Visceral pleura covers the lungs, while parietal pleura lines the thoracic cavity.
Define tidal volume. What is normal TV?
It represents the amount of air inhaled or exhaled during normal breathing.
Tidal volume is 500 cc
Define functional residual capacity (FRC). What is a normal FRC?
FRC is the volume of air remaining in the lungs after a normal expiration.
Functional residual capacity is 3 liters
What is the normal respiratory rate?
The normal respiratory rate is 12 breaths per minute
This rate can vary based on age, fitness, and health status.
What is transpulmonary pressure?
Transpulmonary pressure is the difference between alveolar pressure and intrapleural pressure
Primary formula is:
P A =P IP -P TP
It is crucial for maintaining lung inflation.
List the three perfusion zones in the lungs.
This is basically a trick question because there are 4 zones according to Dr. Schmidt and Dr. West
* Zone one (always off-part of lung isn’t being used)
* Zone two (intermittent/pulsitile)
* Zone three (continuous)
* Zone four (pressure on lungs sitting against diaphragm D/T gravity)
Zone one shouldn’t exist in healthy lungs
What happens during positive pressure ventilation?
An unnatural increase in alveolar pressure can compress extra-alveolar blood vessels, affecting blood flow distribution
- Picture is of normal ventilation
It may increase workload on the right side of the heart.
What is the role of accessory muscles in ventilation?
Accessory muscles (scalene muscles and intercostal muscles) assist the diaphragm during stress or exercise.
- The help create negative plural pressure when under stress
- They assist in lifting the ribcage during respiration and/or prevent the ribcage from being pulled down when the diaphragm contracts
Fill in the blank: The respiratory cycle involves a _______ second inspiration and a _______ second expiration.
2; 2
- There is typically a 1-second pause in between breaths making a standard respiratory cycle 5 seconds total
What is atelectasis?
Atelectasis refers to lung collapse
It can occur due to blockage of air passages or pressure from outside the lung.
True or False: The diaphragm is the only muscle involved in ventilation.
False
While the diaphragm is the main muscle, accessory muscles also assist during increased demand.
What is the significance of the central tendon of the diaphragm?
The central tendon supports the heart and provides a platform for diaphragm movement
It is the only tendon made of connective tissue that **does not attach to bone.
What is the primary function of the phrenic nerve?
What spinal nerves become the phrenic nerve?
The phrenic nerve innervates the diaphragm, allowing for respiration to occur.
- It originates from cervical vertebrae C3,C4,C5 and is essential for breathing.
What is the role of gravity in lung perfusion?
Gravity affects blood flow distribution, with higher blood flow in lower lung regions
This is important for efficient gas exchange.
Fill in the blank: The normal intrapleural pressure is _______ cm H2O.
-5
- This negative pressure is essential for lung inflation.
What are the major lung volumes and capacities?
- IC= amount of air we can inspire starting from resting volume
- FRC= amount of air left after normal expiration
- IRV= amount of air that can be inspired after V T
- ERV= amount of air that can be expired after V T
- RV= amount of air left in lung than cannot ever be expired
- VC= the working capacity (total inspiration after total expiration)
These measurements are important for pulmonary function tests.
How many generations of airways are there in the respiratory system?
How much of this is deadspace?
About 24 generations
- approx 150mL (precisely 1cc/lb of IBW) of anatomical deadspace (from oro/nasopharynx through the conducting zone has no alveoli to perform gas exchange)
Starting from the trachea (generation zero) to the alveoli.
What is the primary function of bronchioles?
Conducting air without gas exchange
Bronchioles are part of the conducting zone in the respiratory system.
What are the airway diameters of the trachea, mainstem bronchi, and alveolar sacs?
- 1.8cm
- 1.22cm
- 0.04cm
What term describes the zones where gas exchange occurs in the respiratory system?
Respiratory zones
- This includes alveoli and terminal alveolar sacs.
What set of bronchials is dubbed the “transitional zone”? What does that mean?
What generations are these?
- Respiratory bronchioles are considered a transitional zone b/c while they technically have alveoli, there are far less than alveolar ducts and alveolar sacs.
- Generations 17-19
What is the definition of orthopnea?
Difficulty breathing when lying down
Patients may breathe normally in an upright position but struggle when supine.
True or False: Hyperventilation refers to insufficient ventilation for metabolic demands.
False
- Hyperventilation is excessive ventilation beyond metabolic needs.
What is cyanosis and what does it indicate?
A bluish discoloration due to deoxyhemoglobin
- Specifically, it means DeoxyHb of >5gm/dL
What do hypoxia and hypoxemia describe?
Hypoxia refers to low oxygen at the tissue level; hypoxemia refers to low oxygen in the arterial blood
Hypoxia is localized, while hypoxemia is a systemic/global issue.
What unit is used to measure intrathoracic pressure?
How does it relate to mmHg?
Centimeters of water
- 1cmH2O=1.36mmHg
This unit provides greater resolution for low thoracic pressures compared to millimeters of mercury.
How is the content of oxygen in arterial blood measured?
Oxygen content includes both oxygen attached to hemoglobin and dissolved in solution
Normal arterial blood has about 20 mls of O2 per deciliter.
Fill in the blank: The abbreviation for arterial blood gas is ________. What about alveolar blood gas?
P a O2
P A O2
What does the term compliance refer to in respiratory physiology?
The ability of lung tissue to stretch and expand
High compliance indicates easier expansion, while low compliance indicates stiffness.
What is the compliance formula?
DeltaV/DeltaP
What is normal atmospheric pressure?
760mmHg(torr)=1ATM
What is the tidal volume for a typical adult during normal breathing?
500mL
This is the amount of air inhaled or exhaled during a normal breath.
What is the relationship between compliance and elastance?
Compliance is inversely related to elastance
Low compliance indicates high elastance and vice versa.
What is the total lung capacity for a healthy adult?
6L
This is the maximum amount of air the lungs can hold.
How much air does each lung hold in a healthy adult?
Three liters
- Remember that total lung capacity is divided between the two lungs.
- If Schmidtt asks FRC of the left lung, it is 1.5L not 3L!
What is a normal functional residual capacity (FRC).
Three liters
FRC is the amount of air remaining in the lungs after a normal expiration.
What happens to the air in the lungs when a person holds their breath?
They can hold their breath for a couple of minutes due to the reservoir of air in the lungs
- Atmospheric air mixes with lung air during normal respiration allowing stabilization of blood gases.
If there was no air reservoir of air to mix with in the lungs, blood gasses would be seriously screwed up and inconsistent.
What is the expiratory reserve volume (ERV) for a healthy 20-year-old?
1.5L
ERV is the volume of air that can be forcibly exhaled after a normal tidal expiration.
What is the residual volume (RV)?
1.5L
RV is the amount of air that remains in the lungs after maximal exhalation. you cannot exhale this volume
What is the inspiratory reserve volume (IRV) for a healthy 20-year-old?
2.5L
IRV is the amount of air that can be inhaled beyond a normal tidal volume.
Define vital capacity.
The total amount of air that can be exhaled/inhaled after a maximal inhalation/exhalation
This includes tidal volume, ERV, and IRV.
What is the inspiratory capacity (IC)?
3L
IC is the maximum amount of air that can be inhaled from the end of a normal expiration. (Tidal volume+IRV)
What is the normal respiratory rate for a healthy adult?
12 breaths per minute
This rate is based on a respiratory cycle lasting five seconds.
What is the thoracic pressure in between breaths? How about 1 second into inspiration or expiration?
- -5cmH2O
- -6.25cmH2O
This pressure helps facilitate the inflow of air during inspiration.
During inspiration, what happens to thoracic pressure?
It drops to -7.5cmH20
- Midway through (at 1sec) inspiration or expiration, the pressure is -6.25cmH2O
This creates a vacuum that pulls air into the lungs.
How long does a normal respiratory cycle take?
Five seconds
* (2ins&2exp) with a 1 second (autonomic) pause between breaths.
What is the flow rate of inspired air at its peak during a normal breath?
0.5 liters per second
This occurs at the halfway point of inspiration or expiration (1 second into either cycle respectively)
What happens to the air flow rate during expiration?
It peaks at the halfway point and then tapers off
Expired air flow is measured as positive while inspired airflow is negative.
FRC is a combination of which two volumes?
Expiratory reserve volume (ERV) and residual volume (RV)
FRC is essential for maintaining stable blood gases.
What is the role of the 3L FRC?
Helps stabilize blood gases and holds airways open
- This reservoir is critical for efficient gas exchange and prevents extreme moment-tomoment changes in arterial bloodd gasses
What occurs to lung volumes when a person lies down?
Some air is squeezed out of the lungs
This is due to the weight of the stomach pushing the diaphragm up.
What happens to pressure during normal inspiration?
What about positive pressure ventilation?
- Pressure decreases (becomes more negative), pulling air into the chest.
- During positive pressure ventilation, air is forced into the lungs discounting the need for more negative IP pressures. This is unnatural and actually collapses (instead of dilates) extra-alveolar vessels leading to increased PVR!
This process occurs over the course of two seconds.
When does peak air flow inspiration rate occur?
Halfway into inspiration, at the one second mark.
This corresponds to the point where alveolar pressure is the lowest.
What is the alveolar pressure at one second into inspiration?
-1cmH2O
It starts at zero and goes to -1 before returning to 0 and then +1 at the 3 second mark of the breath
What happens to alveolar pressure during normal breathing?
It is zero centimeters of water between breaths.
This is in comparison to the outside environment at STP
What occurs when the diaphragm contracts?
IP pressure decreases, resulting in more negative alveolar pressure, pulling air into the lungs.
- Diaphragm contraction/relaxation creates a delta P, allowing for air movement
What is transpulmonary pressure?
The difference between pleural pressure and alveolar pressure.
It is a key factor in determining airflow into the lungs.
What happens during expiration?
The diaphragm relaxes, making alveolar pressure positive, pushing air out.
This process relies on the elastic recoil of lung tissue.
What is the role of elastic recoil in expiration?
It helps push air out of the lungs without using muscle effort.
Abnormal amounts of recoil can lead to breathing difficulties.
When does expired air flow rate peak?
About halfway through expiration.
This corresponds to the highest alveolar pressure.
What characterizes Zone 2 of lung perfusion?
Intermittent blood flow depending on pulmonary blood pressure.
Arterial pressure is greater than alveolar pressure, which is greater than venous pressure.
What is the condition for Zone 3 blood flow?
Continuous blood flow throughout the cardiac cycle.
Arterial pressure is always higher than venous and alveolar pressures.
What happens in Zone 1 of lung perfusion?
There is no blood flow.
- This should only occur in unhealthy individuals or if the patient is receiving positive-pressure ventilation b/c the smallest PEEP is 5cmH2O
What happens in Zone 4 of lung perfusion?
Bloodflow tapers off at the base of the lung whe the patient is upright.
- This positioning causes compression at the base of the lungs D/T gravity and the lungs sitting on top of the diaphragm leading to minimal vessel collapse.
- Zone 4 is still like zone 3 where Pa>Pv>PA but there is mildly reduced flow d/t the increased resistance.
What happens when the pressures in the lungs equilibrate during inspiration?
Alveolar pressure returns to zero.
This occurs after air is sucked into the lungs.
True or False: The alveolar pressure is always lower than the environmental pressure during inspiration.
True.
- For any flow to occur, we need a deltaP
- This negative pressure is what allows air to be sucked into the lungs.
What is the effect of gravity on lung perfusion?
It determines which parts of the lungs receive the most blood flow.
- Blood flow is typically higher at the areas of the lung closest to the ground D/T gravity (approx 15cm from the 2nd rib in an upright patient) but is slightly lower at the very base of the lung D/T compression against the diaphragm
What is the primary risk location for zone one blood flow in the lung?
The top of the lung
- This area has lower vascular pressures, making perfusion more difficult.
- Bloodflow must also fight gravity to perfuse these areas
What conditions define zone one in terms of blood flow?
If alveolar pressure (P A ) is higher than both arterial (P a ) and venous (P v ) blood pressures
This causes capillaries to be compressed, preventing blood flow and should only occur in unhealthy patients. However, this can also occur in positive pressure ventilation.
What effect does positive pressure ventilation have on lung blood flow?
It can compress blood vessels, increasing workload on the right side of the heart
This can lead to altered blood flow distribution patterns.
How does blood flow through the lung vary by location?
Higher blood flow occurs further down in the lung
This is due to higher vascular pressure and lower pulmonary vascular resistance.
What is the average blood flow rate through the lungs?
5L/min (The lung receives 100% of CO)
- Most of this blood flow occurs in the lower parts of the lung (zone 3).
What is zone four in the context of lung perfusion?
An area at the very base of the lung where blood flow is slightly less due to vessel compression from gravity and the lung directly interfacing with the diaphragm
What is the typical fluctuation of alveolar pressure during normal breathing?
Fluctuates between 0, -1, and 1 cmH2O
True or False: The lungs are suspended in the chest and supported at the base.
True
In what position is the risk for zone one blood flow highest?
When is it normal for zone 1 to occur?
Upright position
Trick question, it is not normal for zone 1 to occur.
- Zone 1 occurs D/T pathology or excessive positive pressure ventilation.
This position leads to lower vascular pressures at the top of the lungs.
What is the role of the diaphragm in respiration?
Name the structural openings in the diaphragm.
To assist in the expansion and contraction of the lungs
- Caval aperture (for vena cava)
- Esophageal aperture (for esophagus)
- Aortic aperture (for aorta)
The diaphragm is a major muscle involved in breathing.
Which accessory muscles are primarily responsible for inspiration?
Scalene muscles
The scalene muscles include anterior, middle, and posterior scalene.
What are the key respiratory terms related to breathing patterns?
- Eupnea: Normal breathing
- Dyspnea: Respiratory distress
- Apnea: 0 Breathing
- Stridor: Funny sounds from lungs (asthma/tumor?)
- Bradypnea: Slow breathing
- Tachypnea: Fast breathing
- Orthopnea: Change of breathing when there is a change in position (usually from supine to upright)
- Hyperpnea: Fast/Over-Breathing
- Hyperventilation: Ventilation well in excess of metabolic demand
What does hypoxia refer to? How about hypoxemia?
Decreased amount of O2 at the level of a tissue (local problem)
- This can lead to cellular dysfunction.
Decreased O2 in the blood (Systemic problem/Global O2 deficit)
What is the significance of pulmonary vascular resistance (PVR)?
It affects pulmonary blood flow and gas exchange efficiency
PVR is influenced by factors like blood vessel recruitment and distention.
What is the normal value for alveolar ventilation?
4,200 mL/minute
This value indicates the amount of fresh air reaching the alveoli per minute.
What is the formula for transpulmonary pressure?
P TP = P A - P IP
This equation helps to understand lung inflation.
Fill in the blank: The partial pressure of oxygen in dry atmospheric gas is approximately _______.
159.0 mmHg
This value is based on the concentration of oxygen in the atmosphere.
What is the significance of the Starling capillary equation?
It describes the forces governing fluid movement across capillary membranes
This equation is important for understanding pulmonary capillary dynamics.
What is the normal alveolar P A O2 after equilibration?
100 mmHg (104mmHg is the most precise number here)
As the blood is entering the LA from the pulmonary vein, it’s PAO2 is 104mmHg. At this point, it mixes with venous blood from pulmonary tissue that is somewhat deoxygenated. This reduces the PAO2 to approximately 100mmHg.
True or False: Alveolar compliance is typically higher at the top of the lung than at the bottom.
False
Alveolar compliance is lower at the top of the lung b/c these alevoli remain more expanded than lower lung alveoli during the repiratory cycle. Because the alveoli at the top of the lung are more expanded than those at the bottom, they do not stretch as much during inspiration (i.e., have lower compliance)
What is a key function of the interstitial hydrostatic pressures?
Regulates fluid movement in and out of capillaries
This is influenced by atmospheric pressure and other factors.
