Respiratory Flashcards
1
Q
Respiratory zone goes from _____ to _____
A
Nose, alveoli
2
Q
Lungs extend ______ “ above the clavicles
A
1 inch
3
Q
Adult trachea starts at ___
A
C6
4
Q
How long is the adult trachea?
A
11-15 cm
5
Q
What anatomical landmarks is the trachea at?
A
T4-T5
6
Q
The trachea is made up of _____ (how many) “C” shaped rings, joined by _____ in the posterior portion
A
20, muscle (the esophagus)
7
Q
What is the capacity of the trachea, and how much of it makes up dead space?
A
30 ml, 20% of dead space
8
Q
What part of the airway is in the CONDUCTING ZONE
A
Trachea, bronchi, terminal bronchioles
9
Q
What part of the airway is in the RESPIRATORY ZONE
A
Respiratory bronchioles, alveolar ducts, alveoli
10
Q
Does gas exchange occur in the CONDUCTING ZONE?
A
No
11
Q
Does gas exchange occur in the RESPIRATORY ZONE?
A
Yes
12
Q
The conducting zone is considered _______ dead space
A
Anatomic
13
Q
What is the volume of the conducting airways? = Dead space volume
A
150 ml (2ml/kg)
14
Q
Innervation of the conducting airways
A
SNS and PNS
15
Q
Is there smooth muscle in the respiratory zone of the airway? (Respiratory bronchioles, alveolar ducts, alveoli)
A
No
16
Q
What is the dead space volume in an adult?
A
150 ml (2ml/kg)
17
Q
What types of cells do alveoli consist of?
A
Type I: support alveolar structure
Type II: surfactant production
18
Q
What are Type I alveolar cells responsible for?
A
Support alveolar structure
19
Q
What are Type II alveolar cells responsible for?
A
Surfactant production
20
Q
What exists on the outside of alveoli to reduce surface tension and help them remain compliant and dry?
A
Surfactant
21
Q
When is surfactant produced?
A
+/- 36 weeks in the fetus
22
Q
Surfactant is a ____________ lining the ___________
A
Phospholipid, alveoli
23
Q
Circulation of the lungs is ____ % EBV
A
10%
24
Q
Pulmonary arteries carry ____________(oxygenated/deoxygenated) blood TO the lungs
A
Deoxygenated
25
Pulmonary blood flow
RV
Pulmonary arteries
Pulmonary arterioles
Pulmonary capillaries
Alveoli
Pulmonary venules
Pulmonary veins
LA
26
Pulmonary veins carry _________ (oxygenated/deoxygenated) blood FROM the lungs
Oxygenated
27
Innervation of the lungs
Autonomic afferent: sensory via stretch, irritant receptors
Parasympathetic efferent via vagus (CN X): smooth muscle contraction (cholinergic-mediated)
Sympathetic efferent: relax bronchial smooth muscle
28
Innervation of diaphragm
Phrenic nerve (C3-C5)
29
During inspiration:
The diaphragm pulls abdominal contents _______, lifts ______ up and out (along with __________ intercostals)
down, ribs, external
30
Muscles of inspiration
Diaphragm
External intercostals
ACCESSORY
Scalenes
Sternocleidomastoid
31
Inspiration __________ intrathoracic pressure
decreases
32
Inspiration
initiates flow of air _______ lungs, ___________ intrathoracic volume
into, increasing
33
End inspiration
Inspiratory mucles relax, ______ _______ allows _______ expiration
elastic recoil, passive
34
What pressures is air flow governed by?
Atmospheric
Intra-alveolar
Intrapleural
35
_______ (negative, positive) pressures promote airflow
Negative
36
Intrapleural pressure is slightly _________ (negative, positive) to intra-alveolar pressure = necessary to keep lungs _______
Negative, inflated
37
_________ (negative/positive) pressures promote airflow
Negative
38
Lung volume at any given pressure of inhalation is ______ (less than/greater than) lung volume at any given pressure of exhalation
less than
MORE pressure is required to INFLATE lung than it is to keep lung open during exhalation
39
What term explains lung compliance?
Hysteresis
40
As a result of hysteresis, is inflation or exhalation easier?
Inhalation
41
As a result of hysteresis, lungs trap a minute amount of _____ in the alveoli after exhalation
Air
42
Formula for compliance
Compliance = Change in Volume/Change in pressure
43
What does the slope of the Pressure-Volume curve represent?
Compliance
44
What does a steep slope on the Pressure-Volume curve represent?
Increased compliance
= less pressure needed to increase volume
45
What does a flatter slope on the Pressure-Volume curve represent?
Decreased compliance
= more pressure needed to increase volume
46
For every 1 cm H2O change in pressure, there is a ______ - _____ mL change in volume
100-150 mL
47
What do higher pressures on inspiration mean?
Less compliance (e.g. restrictive pathologies)
48
On a normal Pressure-Volume curve, where are the slopes the flattest?
At LOW lung volumes
-Alveoli more resistant to expand d/t surfactant/reopening alveoli; more pressure is needed
At HIGH lung volumes
-At maximal inflation, lung tissue fully expanded; elastic recoil resists further expansion
49
In decreased compliance, the Pressure-Volume curve shifts _______ and _______
Downward, flattens
50
In increased compliance, the Pressure-Volume curve shifts ______ and _____
Upwards, steepens
51
What does the decreased compliance Pressure-Volume curve indicate?
Less change in volume at equal pressures
=More pressure required to produce change in volume
52
Examples of decreased compliance
High lung volumes
Restrictive diseases (Pulmonary fibrosis, ARDS, Pulmonary edema)
Tissue fibrosis
Alveolar Edema
Atelectasis
Pulmonary hypertension
Low Surfactant
Stiffer lungs, harder to get air IN
53
What does the increased compliance Pressure-Volume curve indicate?
Loss of elastic recoil of tissue, alveolar destruction
54
Examples of increased compliance
Obstructive diseases (Emphysema, COPD)
+/- asthma
+/- chronic bronchitis
Age
Easy to get in, hard to get out
55
What is airway closure?
Compressed region of the lung base retains air as intrapleural pressure is greater than atmospheric (or alveolar)
Small airways (bronchioles) close during expiration, trapping air in the lung (when pleural pressure > airway pressure
56
In airway closure, what closes first
Bronchioles (small airways collapse first)
57
When the bronchioles close during airway closure, what happens?
Gas trapped in alveoli
58
What happens to airway closure/closing volume with age?
Closing volume increases with age
Around 40% VC, may be present at FRC
59
What happens to airway closure/closing volumes in neonates?
Increase, > 40% VC
60
What is the closing volume for young, normal patients?
10% VC
Lungs empty more
61
What happens when closing volumes increase? When they begin to approach FRC
Leads to defective gas exchange
Airway closure occurs during tidal breathing, contributes to intrapulmonary shunting + hypoxemia
62
Factors that increase closing volume
CLOSE-P
COPD
Left ventricular failure
Obesity
Surgery
Extremes in age (neonate,
elderly)
Pregnancy
63
Pattern of gas flow through trachea
Turbulent
64
Pattern of gas flow through Bronchial tree (most of respiratory system)
Transitional
65
Pattern of gas flow through terminal bronchioles
Laminar
66
What is the most important factor of resistance in laminar flow?
Resistance
67
Poiseuille's Law
R = 8nl/πr^4
R: Resistance to laminar flow
n: viscosity
l: length of tube
r: radius
68
What happens to resistance if you INCREASE the radius?
Decreases resistance
69
What happens to resistance if you INCREASE the length
Increase resistance
70
What does the PNS response mediated by acetylcholine and histamine cause?
Bronchial smooth muscle contraction
Decreased airway radius
Bronchoconstriction
71
Which region of the lung is better ventilated?
Lower region
72
Why is the lower region of the lung better ventilated?
Increased alveolar compliance in lower region
Lower regions able to "accept" more gas
73
Ventilation
Upright: Base ____ apex
>
74
Ventilation
Supine: Posterior ____ anterior
>
75
Ventilation
Lateral: Dependent _____ top
>
76
What does spirometry measure?
Lung volumes
Lung capacities (2 or more
volumes)
77
Tidal volume
350-500 ml
78
Inspiratory reserve volume
(max forced inhalation)
3000 ml
79
Expiratory reserve volume
(max forced expiration)
1100 ml
80
Residual volume
(air remaining after forced exhalation)
1200 ml
81
FORCED vital capacity
(max inhalation/expiration)
5000 ml
82
FEV1: FVC in 1st second
4000 ml
83
FEV1/FVC %
80%
84
Vital Capacity
IRV + TV + ERV
85
FRC
(amount of air remaining in lungs at end expiration)
ERV + RV
86
TLC
(total lung capacity)
IRV + TV + ERV + RV
(all lung volumes)
87
Max inspiratory volume
TLC
5800 ml
88
All lung volumes and capacities are ___ - ____ % less in women
20-25%
89
What are some things that decrease lung volumes and capacities
Pregnancy
Pathology decrease
90
Amount of air remaining in lungs after end expiration
FRC = Functional residual capacity
=2300 ml
91
Volume of gas that can be forcibly inhaled after a tidal inhalation
IRV (Inspiratory reserve volume)
n=3000 ml
92
Volume of gas that enters and exits the lung during tidal breathing
TV (tidal volume)
350-500 ml
93
Volume of gas that can be forcibly exhaled after a tidal exhalation
ERV (expiratory reserve volume)
1100 ml
94
Volume of gas that remains in the lungs after a complete exhalation
cant be exhaled from the lungs
RV (residual volume)
1200 ml
95
The volume above residual volume where the small airways begin to close
Closing volume
96
Vital capacity
IRV + TV + ERV
4500
97
Inspiratory capacity
IRV + TV
3500
98
Functional residual capacity
lung volume at end-expiration
RV + ERV
2300
99
Closing capacity
RV + CV
100
Alveolar gas from the ________ volume is used for oxygenation between breaths and periods of apnea
Residual
101
Can residual volumes be removed from lungs voluntarily?
No
102
________ capacity changes with position, strength of respiration
Vital
103
FEF25-FEF75: mid portion of the FVC (forced vital capacity) , indicates what?
Small airway disease
104
Where is the respiratory center located?
Brainstem: Medullary respiratory center in reticular formation below 7th ventricle
105
What does the respiratory center in the brainstem do?
Generates rhythmic SPONTANEOUS breathing
106
Where is the Dorsal Respiratory Group (DRG) located
Tractus solitarius in the MEDULLA
107
Where is the Ventral Respiratory Group (VRG) located?
Nucleus ambiguous and nucleus retroambiguus in the MEDULLA
108
What cranial nerves project into the tractus solitarius?
CN IX
CN X
109
Function of Dorsal Respiratory Group (DRG)
Pacemaker of normal breathing
Pacemaker for normal inspiration
110
Function of Ventral Respiratory Group (VRG)
Controls inspiration/expiration, silent during normal ventilation
111
Where is the apneustic center located
Lower pons
112
Where is the pneumotaxic center located
Upper pons
113
Function of apneustic center
Unknown purpose
Possible excitatory inspiratory effect (stimulates DRG)
114
Function of pneumotaxic center
Inspiratory cut off switch
Inhibits DRG
115
_______ is responsible for voluntary control of breathing, overriding central control centers
Cortex
116
Other control centers for breathing (2)
Limbic system
Hypothalamus
117
What kind of chemoreceptors exist for respiratory regulation
Central
Peripheral
118
_________: most important for normal ventilation
Chemoreceptors
119
Location of central respiratory chemoreceptors
Medulla
120
How do central chemoreceptors play a role in ventilation?
Sensitive to H+ (PaCO2) crossing BBB, where change is CSF pH is detected
121
What receptor is the first to respond to hypoxia?
Peripheral chemoreceptor
122
Where are the peripheral chemoreceptors located?
Carotid bifurcation
Aortic arch (not important in humans)
123
When does the carotid bifurcation chemoreceptor respond to PaO2
When PaO2 is 50 mmHg
124
The peripheral chemoreceptors in the aortic arch act via CN ___
X
125
Hering-Breur reflex
Stretch receptors in the lung sense overinflation, decrease respiratory rate (Via CN X to DRG)
126
Irritant Receptors
Located in epithelium; initiate cough reflex to mechanical/chemical stimuli
127
J receptors
Respond to hypoxic conditions, increase respiratory rate
Activated by things that "Jam" traffic (PE, CHF)
128
Bronchial c-fibers
Unmyelinated, slow-conducting sensory nerve endings in bronchioles
Sense pain
Bronchoconstriction, cough reflex, increased mucus secretion
129
What are normal pressures in the pulmonary circulation?
Low (e.g. PA = 25/8)
130
normal PVR
Pulmonary vascular resistance
100-200 dynes/sec/cm-5
131
What happens to PVR during exercise?
Why?
Decreases
Recruitment and distention of capillaries
132
What happens to PVR at high and low lung volumes, alveolar hypoxia
Why?
Increases
Constriction of pulmonary arteries (e.g. hypoxic pulmonary vasoconstriction)
Extra-alveolar vessels collapse
133
Zone 1 pressures
PA > Pa > Pv
134
Describe what is happening in zone 1
No blood flow
Dead space
135
Zone 1 receives some blood flow unless ________ or alveolar pressure is _________ (e.g. PPV)
hypotensive, raised
136
Zone 2 pressures
Pa > PA > Pv
137
Describe what's happening in zone 2
Moderate blood flow
138
Zone 3 pressures
Pa > Pv > PA
139
What is happening is zone 3
Best blood flow
140
In zone 1, it is _______ but under- __________ without gas exchange: alveolar dead space
Ventilated, perfused
141
Active response of lung to low alveolar PaO2
Occurs in congenital heart disease, one-lung ventilation
Hypoxic Pulmonary Vasoconstriction (HPV)
142
HPV is ___________ of pulmonary circulation in __________ area
vasoconstriction, hypoxic
143
In HPV, blood is diverted to better ventilated areas, improving systemic _________
oxygenation
144
What is something the lungs do to better optimize V/Q matching?
HPV
145
What kind of drugs inhibit HPV?
Some inhalational agents
Potent vasodilators
(nitroprusside, nitroglycerine)
146
O2 and CO2 move by _______ through the blood-gas barrier
diffusion
147
How big is blood gas barrier
0.3 µm over an area of 50-100m2
148
What is dead space
Ventilation without perfusion
149
Physiologic dead space is ______ and ______
Anatomic, alveolar
150
What is anatomic dead space
Conducting airways
151
An ETT _______(increases, reduces) anatomic dead space
Reduces
152
How large is Anatomic dead space?
150 ml
153
What is alveolar dead space?
Ventilated but under-perfused parts of the lung which normally have gas exchange
154
Factors increasing dead space
Age: increases with age
Body size: increases with larger
body habitus
Smoking: Increases with
smoking
PE: Increased
Emphysema: Increased
General anesthesia: increased
PPV: increased
155
Factors decreasing dead space
Posture: decreased when supine
ETT
Inspiration: decreased with
inspiration
156
What is a shunt?
Perfusion without ventilation
157
What types of shunts are there?
Physiologic, anatomic
158
What is a physiologic shunt?
Venous admixture
Total amount of unoxygenated blood returned to arterial system
159
What is an anatomic shunt?
Venous blood bypasses respiratory exchange area and returned to left side of heart (i.e. bronchial arteries, thebesian veins)
160
Examples of anatomic shunts
Thebesian veins
Bronchial arteries
Pleural viens
CHD
Pulmonary arteriovenous shunt
161
Examples of physiologic shunt
Pulmonary edema
Infection
Neoplasm
Atelectasis
Pneumo-/hemothorax
162
In hypoventilation, PaO2 _____ (falls/rises), PaCO2 _____ (falls/rises)
Falls, rises
163
What percent of cardiac output do anatomic shunts account for?
2-5%
164
PaO2 doesn't rise with increasing FiO2. EtCO2 usually does not rise- may fall. What do you think this is an example of?
Shunt
165
Hypoventilation
Diffusion limitation (thick blood-gas barrier, exercise, low FiO2)
Shunt
V/Q mismatch
Can all cause?
Hypoxia
166
What is a normal V/Q ratio?
0.8
167
Alveolar ventilation is ____ % of pulmonary blood flow
80%
168
Alveolar ventilation is ____L/min (Cardiac output 5.0L/min)
4.2
169
Shunt, dead space, pathology, infection, can affect ____ ratio
V/Q
170
What positions cause a decreased FRC
Supine (decreases by 20%)
Trandelenburg
Reverse t-burg
171
Anesthesia related causes of decreased FRC
Change in muscle tone by 20% = shifts diaphragm up
NMB shifts diaphragm up
Surgical retractors
172
How can you increase FRC?
Sigh maneuvers increase PEEP, recruit more collapsed alveoli
173
Basal O2 requirements
Adult: 4ml/kg/min (250ml/min)
Newborn: 6-7 ml/kg/min
174
1 gm Hgb combines with _____ ml O2
1.39
175
P50 is where PaO2 is at ___ % oxygen saturation
50
176
P50 for an adult
27 mmHg
177
P50 for a child
19 mmHg
178
The Bohr Effect
An increased partial pressure of CO2 and decreased pH cause Hgb to release O2
179
The Haldane Effect
O2 displaces CO2; O2 binding to Hgb decreases Hgb's affinity for CO2 = fascilitates CO2 unloading in the lungs and CO2 uptake in the tissues
