Ch38 Pulmonary Ventilation Flashcards
1
Q
What are the main functions of respiration?
A
To provide oxygen to the tissues and remove carbon dioxide
The four major components of respiration are: pulmonary ventilation, diffusion of gases, transport of gases, and regulation of ventilation.
2
Q
What does pulmonary ventilation refer to?
A
The inflow and outflow of air between the atmosphere and the lung alveoli
3
Q
What are the two primary methods for expanding the lungs?
A
- Downward or upward movement of the diaphragm
- Elevation or depression of the ribs
4
Q
What primarily accomplishes normal quiet breathing?
A
Movement of the diaphragm
5
Q
During heavy breathing, which muscles assist in expiration?
A
- Abdominal muscles
- Internal intercostals
6
Q
Which muscles are classified as muscles of inspiration?
A
- External intercostals
- Sternocleidomastoid muscles
- Anterior serrati
- Scaleni
7
Q
What is pleural pressure?
A
The pressure of the fluid in the thin space between the lung pleura and chest wall pleura
8
Q
What is the normal pleural pressure at the beginning of inspiration?
A
About -5 cm H2O
9
Q
What happens to pleural pressure during normal inspiration?
A
It becomes more negative, averaging about -7.5 cm H2O
10
Q
What is alveolar pressure?
A
Air pressure inside the lung alveoli
11
Q
What must alveolar pressure do during inspiration?
A
Fall to a value slightly below atmospheric pressure
12
Q
What is transpulmonary pressure?
A
The difference between alveolar pressure and pleural pressure
13
Q
What is lung compliance?
A
The extent to which the lungs will expand for each unit increase in transpulmonary pressure
14
Q
What are the two parts of elastic forces in the lungs?
A
- Elastic forces of the lung tissue
- Elastic forces caused by surface tension of the fluid lining the alveoli
15
Q
What is the effect of surfactant on surface tension?
A
It greatly reduces the surface tension of water
16
Q
What cells secrete surfactant in the alveoli?
A
Type II alveolar epithelial cells
17
Q
What are the main components of surfactant?
A
- Dipalmitoyl phosphatidylcholine
- Surfactant apoproteins
- Calcium ions
18
Q
What happens to the thoracic cage’s elasticity when the lungs are not present?
A
Muscular effort is still required to expand the thoracic cage
19
Q
True or False: The thoracic cage has no effect on lung expansibility.
A
False
20
Q
What is the primary role of the diaphragm during expiration?
A
To relax, allowing elastic recoil of the lungs to expel air
21
Q
Fill in the blank: The most important muscles that raise the rib cage are the _______.
A
external intercostals
22
Q
What are lipids responsible for in the lungs?
A
Reducing the surface tension
Lipids play a crucial role in maintaining lung function by lowering the surface tension in alveoli.
23
Q
What effect does the thoracic cage have on lung expansibility?
A
Requires muscular effort to expand
The thoracic cage has its own elastic and viscous characteristics affecting lung expansion.
24
Q
What is the surface tension of pure water?
A
72 dynes/cm
Surface tension varies with different fluids; pure water has the highest surface tension.
25
What is the surface tension of normal fluids lining the alveoli without surfactant?
50 dynes/cm
## Footnote
Surfactant significantly reduces surface tension in the alveoli.
26
What is the surface tension range for fluids lining the alveoli with normal surfactant?
5 to 30 dynes/cm
## Footnote
Surfactant is essential for preventing alveolar collapse.
27
What happens to occluded alveoli due to surface tension?
They tend to collapse, creating positive pressure
## Footnote
This positive pressure attempts to push air out of the alveoli.
28
What is the compliance of the combined lung-thorax system compared to the lungs alone?
Half that of the lungs alone
## Footnote
Compliance is measured under relaxed or paralyzed conditions.
29
How much pressure is required to inflate the combined lung-thorax system?
110 ml/cm H2O pressure
## Footnote
This is compared to 200 ml/cm H2O for the lungs alone.
30
What is the work of breathing primarily required for?
Inspiration
## Footnote
Expiration is mostly passive due to elastic recoil of the lungs.
31
What are the three fractions of the work of inspiration?
* Compliance work
* Tissue resistance work
* Airway resistance work
## Footnote
These components outline the efforts needed for effective breathing.
32
How much energy is typically expended for pulmonary ventilation during normal quiet respiration?
3% to 5% of total energy
## Footnote
Energy expenditure increases significantly during heavy exercise.
33
What is tidal volume?
Volume of air inspired or expired with each normal breath
## Footnote
Approximately 500 ml in the average healthy man.
34
What is inspiratory reserve volume?
Extra volume of air that can be inspired over tidal volume
## Footnote
Usually about 3000 ml.
35
What is expiratory reserve volume?
Maximum extra volume of air that can be expired by forceful expiration
## Footnote
Normally about 1100 ml in men.
36
What is residual volume?
Volume of air remaining in the lungs after forceful expiration
## Footnote
Averages about 1200 ml.
37
What is inspiratory capacity?
Tidal volume plus inspiratory reserve volume
## Footnote
Approximately 3500 ml.
38
What is functional residual capacity?
Expiratory reserve volume plus residual volume
## Footnote
This capacity is about 2300 ml.
39
What is vital capacity?
Inspiratory reserve volume plus tidal volume plus expiratory reserve volume
## Footnote
Maximum amount of air a person can expel from the lungs, about 4600 ml.
40
What is total lung capacity?
Maximum volume to which the lungs can be expanded
## Footnote
Approximately 5800 ml; equal to vital capacity plus residual volume.
41
What does spirometry measure?
Volume movement of air into and out of the lungs
## Footnote
It is a common method for assessing pulmonary function.
42
What is functional residual capacity (FRC) important for?
Lung function assessment
## Footnote
Changes in FRC can indicate various pulmonary diseases.
43
How is FRC measured using the helium dilution method?
By calculating the dilution of helium in the spirometer
## Footnote
This indirect method helps estimate FRC since residual volume cannot be directly measured.
44
What is the formula for calculating FRC in the helium dilution method?
FRC = (CiHe * ViSpir) / CfHe
## Footnote
Where CiHe is initial helium concentration, CfHe is final concentration, and ViSpir is the initial volume of the spirometer.
45
What is the formula to calculate Total Lung Capacity (TLC)?
TLC = Inspiratory Capacity (IC) + Functional Residual Capacity (FRC)
## Footnote
TLC is a key measurement in respiratory physiology, reflecting the total volume of air the lungs can hold.
46
What does dead space air refer to?
Air that does not reach gas exchange areas and fills respiratory passages
## Footnote
Dead space air is not useful for gas exchange and includes areas like the nose, pharynx, and trachea.
47
How is the Minute Respiratory Volume calculated?
Minute Respiratory Volume = Respiratory Rate × Tidal Volume
## Footnote
The normal tidal volume is about 500 ml, and the normal respiratory rate is about 12 breaths/min.
48
What is the average Minute Respiratory Volume in a healthy adult?
About 6 L/min
## Footnote
A person can survive temporarily with a Minute Respiratory Volume as low as 1.5 L/min.
49
What is the significance of alveolar ventilation?
It renews air in the gas exchange areas of the lungs
## Footnote
Alveolar ventilation is crucial for maintaining proper oxygen and carbon dioxide levels.
50
What is the formula for calculating alveolar ventilation?
VA = Freq × (VT − VD)
## Footnote
VA represents alveolar ventilation per minute, Freq is the frequency of respiration, VT is tidal volume, and VD is physiological dead space volume.
51
What is the normal dead space volume in a young man?
About 150 ml
## Footnote
Dead space volume can increase slightly with age.
52
Differentiate between anatomical dead space and physiological dead space.
Anatomical dead space is the volume of all respiratory space excluding alveoli, while physiological dead space includes nonfunctional alveoli
## Footnote
In healthy lungs, anatomical and physiological dead spaces are nearly equal.
53
What role do cartilage rings play in the trachea?
They maintain tracheal rigidity to prevent collapse
## Footnote
Cartilage rings extend about five-sixths around the trachea.
54
What is the primary factor keeping bronchioles expanded?
Transpulmonary pressures that expand the alveoli
## Footnote
As the alveoli enlarge, the bronchioles also enlarge but not as much.
55
What substances can cause bronchiolar constriction?
Histamine and slow reactive substance of anaphylaxis
## Footnote
These substances are released during allergic reactions and can lead to airway obstruction.
56
What is the primary function of the mucus in respiratory passages?
To keep surfaces moist and trap small particles
## Footnote
Mucus is secreted by goblet cells and submucosal glands in the respiratory epithelium.
57
How does the cough reflex function?
It is triggered by irritation in the respiratory passages, leading to rapid inspiration and forced expiration
## Footnote
The cough reflex can expel air at high velocities, often used to clear irritants.
58
True or False: The majority of air resistance occurs in the terminal bronchioles.
False
## Footnote
The greatest resistance to airflow occurs in larger bronchi near the trachea, not in terminal bronchioles.
59
What can cause airway obstruction in asthma?
Excessive contraction of smooth muscle in bronchioles
## Footnote
Asthma causes narrowing of the air passages, leading to difficulty in breathing.
60
Fill in the blank: The volume of air that enters the alveoli each minute is called _______.
Alveolar ventilation
61
What can increase physiological dead space significantly in diseased lungs?
Presence of nonfunctional or partially functional alveoli
## Footnote
Physiological dead space can be 10 times that of anatomical dead space in compromised lung conditions.
62
What is the sneeze reflex?
A reflex triggered by irritation in the nasal passageways, involving a rapid expulsion of air to clear foreign matter
## Footnote
The afferent impulses pass through the fifth cranial nerve to the medulla.
63
How does the sneeze reflex differ from the cough reflex?
The sneeze reflex applies to the nasal passageways, while the cough reflex applies to the lower respiratory passages.
64
What are the three normal respiratory functions of the nose?
* Air warming
* Humidification
* Air filtration
## Footnote
These functions are collectively referred to as the air-conditioning function of the upper respiratory passageways.
65
What is the primary role of the vocal cords?
To vibrate and produce sound during phonation.
66
What structure is especially adapted to act as a vibrator in speech?
The larynx.
67
What is phonation?
The production of sound by the vibration of the vocal cords.
68
What are the three major organs of articulation?
* Lips
* Tongue
* Soft palate
69
What is the filtration function of the nose?
To remove particles from air through turbulent precipitation and mucous coating.
70
What size particles are typically trapped by the nasal turbulence mechanism?
Almost no particles larger than 6 micrometers in diameter enter the lungs through the nose.
71
What happens to particles smaller than 0.5 micrometers in diameter in the alveoli?
They remain suspended in alveolar air and are expelled by expiration.
72
How do vocal cords change pitch?
By adjusting the degree of stretch and approximation of the cords.
73
What is the role of alveolar macrophages?
To remove particles that become entrapped in the alveoli.
74
What can an excess of particles in the alveoli lead to?
Growth of fibrous tissue in the alveolar septa, causing permanent debility.
75
Fill in the blank: The _______ is the cartilage that projects forward from the anterior surface of the neck and is called the Adam’s apple.
Thyroid cartilage
76
What is the function of the nasal resonators?
To modify voice quality based on the state of the nasal passages.
77
What is the typical temperature of inspired air before it reaches the trachea?
Within 1°F of body temperature.
78
True or False: The vocal cords are wide open during phonation.
False.
79
What muscles are responsible for stretching the vocal cords?
Muscles stretching from the thyroid cartilage and arytenoid cartilages to the cricoid cartilage.
80
What is the anatomical significance of the arytenoid cartilages?
They articulate with the thyroid cartilage and are involved in changing the tension of the vocal cords.
81
What is articulation in speech?
The shaping of sounds using the lips, tongue, and soft palate.
