Exam 2: 20 Feb 25 Anatomy And Function Of The Respiratory System

Question 1

What is the diaphragm’s role in the respiratory system?

Answer 1

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.

Question 2

Why is the right lung larger than the left lung?

Answer 2

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.

Question 3

What are the two types of pleura surrounding the lungs?

Answer 3

• Visceral pleura
• Parietal pleura

Visceral pleura covers the lungs, while parietal pleura lines the thoracic cavity.

Question 4

Define tidal volume. What is normal TV?

Answer 4

It represents the amount of air inhaled or exhaled during normal breathing.

Tidal volume is 500 cc

Question 5

Define functional residual capacity (FRC). What is a normal FRC?

Answer 5

FRC is the volume of air remaining in the lungs after a normal expiration.

Functional residual capacity is 3 liters

Question 6

What is the normal respiratory rate?

Answer 6

The normal respiratory rate is 12 breaths per minute

This rate can vary based on age, fitness, and health status.

Question 7

What is transpulmonary pressure?

Answer 7

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.

Question 8

List the three perfusion zones in the lungs.

Answer 8

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

Question 9

What happens during positive pressure ventilation?

Answer 9

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.

Question 10

What is the role of accessory muscles in ventilation?

Answer 10

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

Question 11

Fill in the blank: The respiratory cycle involves a _______ second inspiration and a _______ second expiration.

Answer 11

2; 2
- There is typically a 1-second pause in between breaths making a standard respiratory cycle 5 seconds total

Question 12

What is atelectasis?

Answer 12

Atelectasis refers to lung collapse

It can occur due to blockage of air passages or pressure from outside the lung.

Question 13

True or False: The diaphragm is the only muscle involved in ventilation.

Answer 13

False

While the diaphragm is the main muscle, accessory muscles also assist during increased demand.

Question 14

What is the significance of the central tendon of the diaphragm?

Answer 14

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.

Question 15

What is the primary function of the phrenic nerve?
What spinal nerves become the phrenic nerve?

Answer 15

The phrenic nerve innervates the diaphragm, allowing for respiration to occur.
- It originates from cervical vertebrae C3,C4,C5 and is essential for breathing.

Question 16

What is the role of gravity in lung perfusion?

Answer 16

Gravity affects blood flow distribution, with higher blood flow in lower lung regions

This is important for efficient gas exchange.

Question 17

Fill in the blank: The normal intrapleural pressure is _______ cm H2O.

Answer 17

-5
- This negative pressure is essential for lung inflation.

Question 18

What are the major lung volumes and capacities?

Answer 18

• 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.

Question 19

How many generations of airways are there in the respiratory system?
How much of this is deadspace?

Answer 19

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.

Question 20

What is the primary function of bronchioles?

Answer 20

Conducting air without gas exchange

Bronchioles are part of the conducting zone in the respiratory system.

Question 21

What are the airway diameters of the trachea, mainstem bronchi, and alveolar sacs?

Answer 21

• 1.8cm
• 1.22cm
• 0.04cm

Question 22

What term describes the zones where gas exchange occurs in the respiratory system?

Answer 22

Respiratory zones
- This includes alveoli and terminal alveolar sacs.

Question 23

What set of bronchials is dubbed the “transitional zone”? What does that mean?
What generations are these?

Answer 23

• 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

Question 24

What is the definition of orthopnea?

Answer 24

Difficulty breathing when lying down

Patients may breathe normally in an upright position but struggle when supine.

Question 25

True or False: Hyperventilation refers to insufficient ventilation for metabolic demands.

Answer 25

False - Hyperventilation is excessive ventilation beyond metabolic needs.

Question 26

What is cyanosis and what does it indicate?

Answer 26

A bluish discoloration due to deoxyhemoglobin - Specifically, it means DeoxyHb of >5gm/dL

Question 27

What do hypoxia and hypoxemia describe?

Answer 27

Hypoxia refers to low oxygen at the tissue level; hypoxemia refers to low oxygen in the arterial blood ## Footnote Hypoxia is localized, while hypoxemia is a systemic/global issue.

Question 28

What unit is used to measure intrathoracic pressure? How does it relate to mmHg?

Answer 28

Centimeters of water - 1cmH2O=1.36mmHg ## Footnote This unit provides greater resolution for low thoracic pressures compared to millimeters of mercury.

Question 29

How is the content of oxygen in arterial blood measured?

Answer 29

Oxygen content includes both oxygen attached to hemoglobin and dissolved in solution ## Footnote Normal arterial blood has about 20 mls of O2 per deciliter.

Question 30

Fill in the blank: The abbreviation for arterial blood gas is ________. What about alveolar blood gas?

Answer 30

P _a O2 P _A O2

Question 31

What does the term compliance refer to in respiratory physiology?

Answer 31

The ability of lung tissue to stretch and expand ## Footnote High compliance indicates easier expansion, while low compliance indicates stiffness.

Question 32

What is the compliance formula?

Answer 32

DeltaV/DeltaP

Question 33

What is normal atmospheric pressure?

Answer 33

760mmHg(torr)=1ATM

Question 34

What is the tidal volume for a typical adult during normal breathing?

Answer 34

500mL ## Footnote This is the amount of air inhaled or exhaled during a normal breath.

Question 35

What is the relationship between compliance and elastance?

Answer 35

Compliance is **inversely** related to elastance ## Footnote Low compliance indicates high elastance and vice versa.

Question 36

What is the total lung capacity for a healthy adult?

Answer 36

6L ## Footnote This is the maximum amount of air the lungs can hold.

Question 37

How much air does each lung hold in a healthy adult?

Answer 37

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!**

Question 38

What is a normal functional residual capacity (FRC).

Answer 38

Three liters FRC is the amount of air remaining in the lungs after a normal expiration.

Question 39

What happens to the air in the lungs when a person holds their breath?

Answer 39

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. ## Footnote If there was no air reservoir of air to mix with in the lungs, blood gasses would be seriously screwed up and inconsistent.

Question 40

What is the expiratory reserve volume (ERV) for a healthy 20-year-old?

Answer 40

1.5L ## Footnote ERV is the volume of air that can be forcibly exhaled after a normal tidal expiration.

Question 41

What is the residual volume (RV)?

Answer 41

1.5L RV is the amount of air that remains in the lungs after maximal exhalation. **you cannot exhale this volume**

Question 42

What is the inspiratory reserve volume (IRV) for a healthy 20-year-old?

Answer 42

2.5L ## Footnote IRV is the amount of air that can be inhaled beyond a normal tidal volume.

Question 43

Define vital capacity.

Answer 43

The total amount of air that can be exhaled/inhaled after a maximal inhalation/exhalation ## Footnote This includes tidal volume, ERV, and IRV.

Question 44

What is the inspiratory capacity (IC)?

Answer 44

3L ## Footnote IC is the maximum amount of air that can be inhaled from the end of a normal expiration. (Tidal volume+IRV)

Question 45

What is the normal respiratory rate for a healthy adult?

Answer 45

12 breaths per minute ## Footnote This rate is based on a respiratory cycle lasting five seconds.

Question 46

What is the thoracic pressure in between breaths? How about 1 second into inspiration or expiration?

Answer 46

- -5cmH2O - -6.25cmH2O ## Footnote This pressure helps facilitate the inflow of air during inspiration.

Question 47

During inspiration, what happens to thoracic pressure?

Answer 47

It drops to -7.5cmH20 - Midway through (at 1sec) inspiration or expiration, the pressure is -6.25cmH2O ## Footnote This creates a vacuum that pulls air into the lungs.

Question 48

How long does a normal respiratory cycle take?

Answer 48

Five seconds * (2ins&2exp) with a 1 second (autonomic) pause between breaths.

Question 49

What is the flow rate of inspired air at its peak during a normal breath?

Answer 49

0.5 liters per second ## Footnote This occurs at the halfway point of inspiration or expiration (1 second into either cycle respectively)

Question 50

What happens to the air flow rate during expiration?

Answer 50

It peaks at the halfway point and then tapers off ## Footnote Expired air flow is measured as positive while inspired airflow is negative.

Question 51

FRC is a combination of which two volumes?

Answer 51

Expiratory reserve volume (ERV) and residual volume (RV) ## Footnote FRC is essential for maintaining stable blood gases.

Question 52

What is the role of the 3L FRC?

Answer 52

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

Question 53

What occurs to lung volumes when a person lies down?

Answer 53

Some air is squeezed out of the lungs ## Footnote This is due to the weight of the stomach pushing the diaphragm up.

Question 54

What happens to pressure during normal inspiration? What about positive pressure ventilation?

Answer 54

- 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! ## Footnote This process occurs over the course of two seconds.

Question 55

When does peak air flow inspiration rate occur?

Answer 55

Halfway into inspiration, at the one second mark. ## Footnote This corresponds to the point where alveolar pressure is the lowest.

Question 56

What is the alveolar pressure at one second into inspiration?

Answer 56

-1cmH2O ## Footnote It starts at zero and goes to -1 before returning to 0 and then +1 at the 3 second mark of the breath

Question 57

What happens to alveolar pressure during normal breathing?

Answer 57

It is zero centimeters of water between breaths. ## Footnote This is in comparison to the outside environment at STP

Question 58

What occurs when the diaphragm contracts?

Answer 58

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

Question 59

What is transpulmonary pressure?

Answer 59

The difference between pleural pressure and alveolar pressure. ## Footnote It is a key factor in determining airflow into the lungs.

Question 60

What happens during expiration?

Answer 60

The diaphragm relaxes, making alveolar pressure positive, pushing air out. ## Footnote This process relies on the elastic recoil of lung tissue.

Question 61

What is the role of elastic recoil in expiration?

Answer 61

It helps push air out of the lungs without using muscle effort. ## Footnote Abnormal amounts of recoil can lead to breathing difficulties.

Question 62

When does expired air flow rate peak?

Answer 62

About halfway through expiration. ## Footnote This corresponds to the highest alveolar pressure.

Question 63

What characterizes Zone 2 of lung perfusion?

Answer 63

Intermittent blood flow depending on pulmonary blood pressure. ## Footnote Arterial pressure is greater than alveolar pressure, which is greater than venous pressure.

Question 64

What is the condition for Zone 3 blood flow?

Answer 64

Continuous blood flow throughout the cardiac cycle. ## Footnote Arterial pressure is always higher than venous and alveolar pressures.

Question 65

What happens in Zone 1 of lung perfusion?

Answer 65

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

Question 66

What happens in Zone 4 of lung perfusion?

Answer 66

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.

Question 67

What happens when the pressures in the lungs equilibrate during inspiration?

Answer 67

Alveolar pressure returns to zero. ## Footnote This occurs after air is sucked into the lungs.

Question 68

True or False: The alveolar pressure is always lower than the environmental pressure during inspiration.

Answer 68

True. - For any flow to occur, we need a deltaP - This negative pressure is what allows air to be sucked into the lungs.

Question 69

What is the effect of gravity on lung perfusion?

Answer 69

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

Question 70

What is the primary risk location for zone one blood flow in the lung?

Answer 70

The top of the lung - This area has lower vascular pressures, making perfusion more difficult. - Bloodflow must also fight gravity to perfuse these areas

Question 71

What conditions define zone one in terms of blood flow?

Answer 71

If alveolar pressure (P _A ) is higher than both arterial (P _a ) and venous (P _v ) blood pressures ## Footnote 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.

Question 72

What effect does positive pressure ventilation have on lung blood flow?

Answer 72

It can compress blood vessels, increasing workload on the right side of the heart ## Footnote This can lead to altered blood flow distribution patterns.

Question 73

How does blood flow through the lung vary by location?

Answer 73

Higher blood flow occurs further down in the lung ## Footnote This is due to higher vascular pressure and lower pulmonary vascular resistance.

Question 74

What is the average blood flow rate through the lungs?

Answer 74

5L/min (The lung receives 100% of CO) - Most of this blood flow occurs in the lower parts of the lung (zone 3).

Question 75

What is zone four in the context of lung perfusion?

Answer 75

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

Question 76

What is the typical fluctuation of alveolar pressure during normal breathing?

Answer 76

Fluctuates between 0, -1, and 1 cmH2O

Question 77

True or False: The lungs are suspended in the chest and supported at the base.

Answer 77

True

Question 78

In what position is the risk for zone one blood flow highest? When is it normal for zone 1 to occur?

Answer 78

Upright position Trick question, it is not normal for zone 1 to occur. - Zone 1 occurs D/T pathology or excessive positive pressure ventilation. ## Footnote This position leads to lower vascular pressures at the top of the lungs.

Question 79

What is the role of the diaphragm in respiration? Name the structural openings in the diaphragm.

Answer 79

To assist in the expansion and contraction of the lungs - Caval aperture (for vena cava) - Esophageal aperture (for esophagus) - Aortic aperture (for aorta) ## Footnote The diaphragm is a major muscle involved in breathing.

Question 80

Which accessory muscles are primarily responsible for inspiration?

Answer 80

Scalene muscles ## Footnote The scalene muscles include anterior, middle, and posterior scalene.

Question 81

What are the key respiratory terms related to breathing patterns?

Answer 81

* 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

Question 82

What does hypoxia refer to? How about hypoxemia?

Answer 82

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)

Question 83

What is the significance of pulmonary vascular resistance (PVR)?

Answer 83

It affects pulmonary blood flow and gas exchange efficiency ## Footnote PVR is influenced by factors like blood vessel recruitment and distention.

Question 84

What is the normal value for alveolar ventilation?

Answer 84

4,200 mL/minute ## Footnote This value indicates the amount of fresh air reaching the alveoli per minute.

Question 85

What is the formula for transpulmonary pressure?

Answer 85

P _TP = P _A - P _IP ## Footnote This equation helps to understand lung inflation.

Question 86

Fill in the blank: The partial pressure of oxygen in **dry** atmospheric gas is approximately _______.

Answer 86

159.0 mmHg ## Footnote This value is based on the concentration of oxygen in the atmosphere.

Question 87

What is the significance of the Starling capillary equation?

Answer 87

It describes the forces governing fluid movement across capillary membranes ## Footnote This equation is important for understanding pulmonary capillary dynamics.

Question 88

What is the normal alveolar P _A O2 after equilibration?

Answer 88

100 mmHg (104mmHg is the most precise number here) ## Footnote 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.

Question 89

True or False: Alveolar compliance is typically higher at the top of the lung than at the bottom.

Answer 89

False ## Footnote 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)

Question 90

What is a key function of the interstitial hydrostatic pressures?

Answer 90

Regulates fluid movement in and out of capillaries ## Footnote This is influenced by atmospheric pressure and other factors.