Ventilation Flashcards

1
Q

What makes up the respiratory membrane?

A

2 cell layers: alveoli and pulmonary capillaries

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2
Q

What sets the basic drive of ventilation?

A

Respiratory neurons in the brain stem

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3
Q

How do the respiratory neurons in the brain stem exert their control?

A

Descending neural traffic to spinal cord to activate muscles of respiration

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4
Q

Where can central chemoreceptors be found?

A

Brain stem

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5
Q

Where can peripheral chemoreceptors be found?

A

Aorta and carotid body

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6
Q

Golgi tendon organs are an example of what kind of receptors?

A

Mechanoreceptors

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7
Q

What specific respiratory centers are located in the brain stem?

A

Dorsal and ventral medullary group, pneumotaxic and apneustic centers

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8
Q

What can influence the respiratory centers in the brain stem?

A

Higher brain centers (voluntary control), peripheral mechanoreceptors, peripheral and central chemoreceptors

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9
Q

How do the respiratory centers in the brain stem affect ventilation?

A

Affect rate of depth of ventilation

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10
Q

Which is considered an active process: inspiration or expiration?

A

Inspiration

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11
Q

Which is considered a passive process: inspiration or expiration?

A

Expiration (under resting conditions…can be forceful sometimes which would be active)

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12
Q

Which group of muscles increases thoracic cage volume?

A

Inspiratory

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13
Q

Which group of muscles decreases thoracic cage volume?

A

Expiratory

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14
Q

What are the inspiratory muscles?

A

Diaphragm, external intercostals, SCM, anterior and posterior superior serratus, scalenes, levator costarum

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15
Q

What are the expiratory muscles?

A

Abdominals, internal intercostals, posterior inferior serratus, transversus thoracis, pyramidal

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16
Q

What is the function of the diaphragm?

A

Drops the floor of the thoracic cage during inspiration

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17
Q

Does the diaphragm lift the rib cage?

A

No (the rest of the inspiratory muscles do)

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18
Q

Which expiratory muscle plays an extra role in causing low back pain?

A

Transversus abdominis

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19
Q

Which is associated with recoil of the lungs: inspiration or expiration?

A

Expiration

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20
Q

What is the normal range of pleural pressure between the parietal and visceral pleura?

A

-5 and -7.5 (NEGATIVE!)

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21
Q

What is the purpose of having a NEGATIVE pleural pressure?

A

Keeps lung inflated against chest wall

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22
Q

What is the term for the difference between alveolar and pleural pressures?

A

Transpulmonary presssure

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23
Q

What does the transpulmonary pressure measure?

A

Recoil tendency of the lung

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24
Q

When does transpulmonary pressure peak?

A

At the end of inspiration

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25
Alveolar pressure is subatmospheric during which: inspiration or expiration?
Inspiration (-1)
26
Alveolar pressure is supra-atmospheric during which:inspiration or expiration?
Expiration (+1)
27
Which is easier to inflate: saline-filled or air-filled lung?
Saline-filled
28
Why is it easier to inflate a saline-filled lung?
Surface tension forces have therefore been eliminated
29
What is pulmonary hysteresis?
The difference between the pleural pressure and lung volume at the onset of inspiration (pleural pressure changes at a faster rate)
30
Average breaths per minute?
12
31
Average total cycle length for breathing?
5 seconds
32
What is compliance?
Change of volume over the change in pressure
33
When is compliance greatly reduced?
At high or low lung volumes
34
What effect does the thoracic cage have on lung compliance?
Reduces it by about 50% around functional residual capacity (FRC) at the end of a normal expiration
35
What accounts for the majority of the work of breathing?
Compliance (elastic) work
36
What makes up the tissue resistance work?
Viscosity of chest wall and lung
37
How much total body energy is required for ventilation?
3-5%
38
What is the term for normal breathing and what are the average rates?
Eupnea | 12-17 B/min, 500-600 ml/B
39
What is the term for when increased pulmonary ventilation matches increased metabolic demand (example = exercise)?
Hyperpnea
40
What is the term for when increased pulmonary ventilation is GREATER than metabolic demand?
Hyperventilation
41
What are CO2 levels like during hyperventilation?
Decreased (less than 40 mmHg)
42
What is the term for when decreased pulmonary ventilation is LESS than metabolic demand?
Hypoventilation
43
What are CO2 levels like during hypoventilation?
Increased (greater than 40mmHg)
44
What is the term for increased frequency of respiratory rate?
Tachypnea
45
What is the term for absence of breathing?
Apnea (example = sleep apnea)
46
What is dyspnea?
Difficult or labored breathing
47
What is orthopnea?
Dyspnea when recumbent, relieved when upright
48
In what clinical conditions can orthopnea occur?
Congestive heart failure, asthma, lung failure
49
What is the reason for the suction of the lungs against the chest wall that overcomes the natural tendency for the lungs to collapse?
Negative pleural pressure
50
Which has a greater impact on the lungs: surface tension forces or elastic fibers?
Surface tension forces (responsible for 2/3 of the collapse tendency of the lung)
51
What happens when the pleural space communicates with the atmosphere (example = Dr. Freedman stabbing you in the chest with a spear)?
Pleural pressure then equals atmospheric pressure and lung will collapse
52
What are the possible causes for lung collapse?
Puncture of parietal pleura Erosion of visceral pleura If major airway is blocked, air trapped distal to block will be absorbed by blood and that segment of lung will collapse
53
What is pleural fluid?
Few milliliters of a thin layer of mucoid fluid made of transudate (interstitial fluid and protein)
54
Excess pleural fluid is removed by lymphatics in what locations?
Mediastinum, superior surface of diaphragm, lateral surfaces of parietal pleura
55
How does the removal of excess pleural fluid affect pleural pressure?
Helps make it negative
56
What is pleural effusion?
Collection of large amounts of free fluid in pleural space (edema of pleural cavity)
57
What are possible causes of pleural edema?
Blockage of lymphatic drainage Cardiac failure ---> increased capillary filtration pressure Reduced plasma colloid osmotic pressure Infection/inflammation of pleural surfaces which breaks down capillary membranes
58
What effect does surfactant have on surface tension?
Reduces it
59
How does surfactant reduce surface tension?
By forming a mononuclear layer between aqueous fluid lining alveoli and air preventing a water-air interface
60
What produces surfactant?
Alveolar type II epithelial cells
61
What makes up surfactant?
Complex mix-phospholipids, proteins, ions, dipalmitoyl lecithin, surfactant apoproteins, calcium ions
62
What is the concept of interdependence when it comes to the size of one alveolus?
Determined by surrounding alveoli
63
What is the role of surfactant?
Prevents small alveoli from having increased collapsing potential
64
What is the relationship between alveolar size, concentration of surfactant, surface tension forces, and the radii of vessels?
All decrease as a unit thanks to surfactant (Law of LaPlace)
65
What is normally responsible for the majority of the collapse tendency of the lung?
Surface tension forces