Respiratory Physiology Flashcards
1
Q
To inhale and exhale
A
respire
2
Q
Physiological components of respiration
A
transport of oxygen from ambient air to tissue cells and transport of CO2 from tissue to air; combo of airflow and gas exchange
3
Q
4 phases of respiration
A
ventilation, diffusion, transport, diffusion
4
Q
How does the architecture of the lung subserve respiratory function?
A
conduction (for ventilation)
5
Q
How many lobes on the left lung?
A
2; upper and middle lobes
6
Q
How many lobes on the right lung?
A
3; UL, ML, LL
7
Q
Bulk flow in the conducting apparaturs occurs in response to
A
Pressure gradient
8
Q
How many generations
A
23
9
Q
Generations: Trachea
A
z,0
10
Q
Generations: bronchi
A
1-3
11
Q
Generations: Bronchioles
A
4
12
Q
Generations: Terminal bronchioles
A
5-16
13
Q
Generations: Respiratory bronchioles
A
17-19
14
Q
Generations: Alveolar ducts
A
20-22
15
Q
Generations: alveolar sacs
A
23
16
Q
flow is affected by
A
frictional resistance, shape of the conduit and the nature of the gas
17
Q
Conducting zone consists of
A
trachea, bronchi, bronchioles, terminal bronchiloes
18
Q
Transitional and respiratory zones consist of
A
respiratory bronchioles, alveolar ducts, alveolar sacs
19
Q
Optimizing velocity of air flow
A
Conducting zone:fast, respiratory zone: slow
20
Q
Delta P
A
flow or volume/ time occurs in response to pressure gradient
21
Q
flow= pressure difference/ Resistance
A
aka Ohm’s law
22
Q
Pressure =
A
force/area
23
Q
Optimizing velocity of airflow
A
flow=deltaP/resistance; pressure=force/area; cross sectional area increases, pressure gradient decreases and velocity of flow decreases; exchange can occur; conducting airways: trachea and bronchi - very high; respiratory zone, compromises respiratory bronchioles and alveolar ducts
24
Q
How does the architecture of the lung subserve respiratory function?
A
diffusion
25
Maximizing gas exchange
o2 and co2 move from air to blood by simple diffusion in response to pressure gradient aka ficks law
26
Fick's law
o2 and co2 move from air to blood by simple diffusion in response to pressure gradient
27
Vgas=Area/thickness x D x pressure difference
ficks law
28
d=solubility/square root of molecular weight
D
29
O2 and CO2 move from air to blood by
simple diffusion in response to pressure gradient
30
CO2 is more diffusable than
O2 by about 20x
31
PaCO2 AND P ACO2 is nearly
identical
32
A-A gradient
5-10mmHg
33
Ohm's law
flow = pressure difference/resistance
34
Airflow: Resistance is maximum in the ____ generation of airways
7th
35
Vascular flow: pulmonary vascular system is a ____ resistance circuit
low
36
Factors increasing airway resistance:
```
forced expiration
beta blockers
histamine
acetylcholine
decreased lung volumes
```
37
Factors DECREASING airway resistance
increased lung volumes
heliox
beta stimulants
38
How does Heliox decrease airway resistance?
Decreases reynolds number by decreasing the gas
39
alveolar vessels are within the
alveolus
40
At high lung volumes, as the lung stretches, the vessels in the wall stretch and get thin ... An analogy is
fish net stocking
41
Extra Alveolar vessels: all arteries and veins that run through
lung parenchyma
42
As the lungs expand, the vessels pull apart =
extra alveolar resistance
43
extra alveolar vessels
reduces resistance
44
an analogy for extra alveolar resistance
sponge - seinfield
45
Vascular resistance increases at
extremes of low and high lung volumes
46
need optimum lung volumes to maintain
perfect vascular resistance
47
When extra alveolar resistance increases will .... lung volume
decrease (squashed down)
48
When pulled apart
the alveolar resistance increases
49
Factors increasing pulmonary vascular resistance
increased lung volumes (alveolar)
decreased lung volume (extra alveolar)
lung disease
persistant pulmonary HTN of the newborn (full term)
50
Factors DECREASING pulmonary vascular resistance
oxygen
| nitric oxide
51
Problem of pulmonary vascular resistance of preterm baby
lack of surfactant
| respiratory stress syndrome
52
Surfactant gets produced around ___ gestational weeks
around 32
53
Oxygen and Nitric Oxide are potent
vasodilators
54
What does hypoxemia do to pulmonary vascular resistance?
increases resistance
55
Hypoxic pulmonary vasoconstriction
- diverts blood flow from hypoxic to non-hypoxic lung areas
| - is reduced by increasing intravascular resistance
56
When the lung sees some of it is hypoxic
the lung will divert blood away from the hypoxic area
57
In RDS, the lung tends to collapse due to
surface tension
58
Surfactant lines up on a
gas-liquid-surface interface
59
Fill up a lung with saline, there will be no
surface tension bc no interface
60
need surfactant to
push each other away which is why it works best with low lung volumes
61
Inhaled nitric oxide
does not drop blood pressure bc it binds to Hgb
62
During forced inspiration/expiration, you create a
choke point
63
A choke point does what?
direct squashing of the airway by the increased thoracic pressure before flowing on through any type of resistance
64
beyond the choke point, is effort independent or dependent?
effort independent
65
Which part of the slope do we use when assessing pulmonary function of a patient on a bronchdilator?
expiration
66
Compliance
change in volume for a given change in pressure (high compliance=everything will blow up easy)
67
compliance equation
difference in volume / difference in pressure
68
increasing negative pressure around the lung will ...
increase expansion
69
surfactant contributes to
hysteresis
70
hysteresis
more compliance on deflation. at any given pressure there will be a larger volume on deflation and actually speaks to elastic recoil
negative pressure pulls the lung apart
71
If I increase negative pressure around the lung, would that enhance expansion?
yes
72
Why do these changes occur between the apex and the base?
gravity
73
which is aerated better: apex or base?
apex
74
Which one is more responsive to a change in pressure?
base
75
Ventilation is Increased or decreased at the base compared to the apex?
increased
76
what happens if the pt is lying down?
sandwiched
77
Both Ventilation and perfusion go down from base to apex but ventilation goes down more so what happens to the V/Q ratio?
it goes up
78
v goes down, q goes down, v goes down more so
v/q ratio goes up
79
What can NOT be measured by spirometery?
anything with residual volume, FRC
80
anatomic dead space
```
volume in CONDUCTING airways
about 150mL/breath
N2 washout technique
individual breaths through a valve box
eliminated air N2 is continuously sampled
```
81
ADS is derived
the midpoint of transition form dead space to alveolar gas
82
ADS
When we give someone 100% O2, it displaces the N2 and then we analyze this Nitrogen and plot it against a graph and when 50% of the Nitrogen is excreted we can get a volume that maybe tells you the non exchange in gas in the lungs based on nearly what was initiated in the airways
83
do we all have ADS?
YES
84
In a perfect world, anatomic dead space and physiological dead space would be the
same
85
In asthma, increased dead space, lots of gas flow, very little air flow, very little vascular flow, no exchange =
physiological dead space increases
86
Nitrogen washout for residual volume
```
body does not produce N2
breathe 100%
collect expired air
measure expired nitrogen content
Air has 80% N2, so multiply by 1.25
```
87
FRC measurement
Helium: Gas dilution technique (sugar bucket/cup)
subject connected to spirometer, containing a known concentration of helium
Helium is insoluble in blood
take a few breaths: equilibration
C1,V1= C2(V1+V2) = C2V1 +C2V2
V2 = V1( C1-C2)/C2
88
Helium
Helium is insoluble in blood
89
FRC: EQUILIBRATION equation
```
C1,V1= C2(V1+V2) = C2V1 +C2V2
V2 = V1( C1-C2)/C2
```
90
FRC does not give you what is behind trapped airways but it does give you...
what is being communicated
91
FRC measurement by body plethysmogram
```
large airtight box
Close the shutter after a few breaths
Subject breathes int a closed mouthpiece
Subject breathes in
2 Box pressures: before and after inspiration (P1 AND P2)
v1 - Preinspiratory box volume
Delta V = change in volume of the box
```
P1V1 = P2(V1-difference in volume)
2 Mouth pressures before and after inspiratory effort (P3 AND P4)
V2 is FRC
92
FRC measurement by body plethysmogram
Will tell you how much gas is behind closed airways (the gas that is trapped) ; the way you measure it is by how much the lung expands
93
Calculate dead space
Arterial CO2 - expired CO2
94
Diffusion of oxygen is
efficient
95
Diffusion of oxygen is efficient:
```
pressure drop
Soluble
Thin membrane
Less Dense
PaO2 ~ 40mmHg
PAO2 ~ 100 mmHg
```
96
Oxygen transfer is thus
perfusion limited
97
Diffusion limitation
Oxygen delivery to tissues depends on perfusion
Diffusion limitation can be overcome by increasing pO2 in the alveolus, if the alveolus is perfused
Increase in pO2 in alveolus will increase gradient and increase arterial pO2
This can be done by increasing inspired O2
98
If you have a 100% shunt can you overcome it?
no
99
100% shunt V/Q =
0
100
Blood that enters the arterial system without going through ventilated areas of the lung in other words
do not exchange gas
101
100% shunt v/q=0: physiological
bronchial circulation and coronary circulation;
102
100% shunt v/q = 0: pathological
communications rt to left by passing lung
103
100% cardiac shunt can not be reversed by
oxygen
104
physiological shunts
cause a difference between A-a gradient
| Normal 5-10mmHg with breathing quietly
105
Normal mmHg for A-a gradient
5-10 mmHg
106
if you increase your pressures too much on the ventilator what do you end up with ?
dead space physiology - you squashed the alveoli vessels
Low etco2 bc very little return of CO2 to the blood bc you squashed off the vessel
HIGH arterial blood exchange
107
if you have an adult with a collapsed lung, and you say well its a shunt ...
it may help some bc it may decrease pulmonary vasoconstriction in some areas or enhance flow to some of the hypoxic areas that respond to oxygen
108
A-a gradient: Pt received a bunch of morphine, is supposed to breath at 20bpm but now is breathing at 10 bpm, what do we think happened to the patient's CO2?
it went up by exactly mathematically double (from 40 to 80)
109
A-a gradient: Pt received a bunch of morphine, is supposed to breath at 20bpm but now is breathing at 10 bpm, what do we think happened to the patient's CO2? (DOUBLED) How does oxygen help this patient?
you apply the alveolar gas equation.
The central chemoreceptors are down regulated bc the CO2 is going down and he is not responding bc he knocked out by the morphine ... Alveolar available oxygen went down bc you subtracted it
110
A-a gradient in hypoxemia: Normal:
Low inspired O2
Hypoventilation
oxygen helps
111
A-a gradient in hypoxemia: increased
diffusion limitation
Ventilation-perfusioon inequality
oxygen helps
112
A-a gradient in hypoxemia: shunt
oxygen does not help
113
Dead Space - shunt
```
ASD
VSD
PULMONARY
-Mixed venous point
V/Q= 0
```
114
Dead Space-
Pulmonary Embolism
Inspired gas point
V/Q - a
cardiac arrest
115
Ventilation - perfusion relationship
ventilation goes down from base to apex
116
West Zones - 1
alveolar pressure : well aerated APEX
117
West Zones 2-3
arterial pressure (base - most likely to shunt at base) is greater than alveolar pressure is greater than venous pressure ... zone 2 LVEDP can be calculated
118
West Zone 4
very little blood flow; vascular resistance goes up a lot when lung is collapsed in this zone
119
Alveolar gas equation
pAlveolar o2 = FiO2 x 713 - pACO2 (same as paCO2) x RQ
120
In room air FiO2
21% or 0.21
121
Partial pressure of water vapor
47mmHg
122
Barometric pressure of atmosphere
760 mmHg
123
PaO2 is measured
arterial O2
124
The difference (pAO2-paO2) is the
A-a gradient
125
Arterial oxygen content equation
Hb(g/dl) x 1.36 x %sat + pao2 x 0.003
126
Arterial oxygen delivery equation
Content x CO
| Tells you how much oxygen you are getting in the tissues
127
o2 dissociation curves: shift to the right
exercise, high CO2, hyperthermina, fever, acidosis
128
o2 dissociation curves: shift to the left
carbon monoxide, alkalosis
129
O2 dissociation curve: decreased
2-3dgp
130
peripheral chemoreceptors
sensitive to blood not CSF
131
Haldane effect
the deoxygenation of Hb helps loading of CO2 from tissue to blood
132
HALDANE EFFECT: the dissociation curve for co2 in blood IS
LINEAR
133
HALDANE EFFECT: it is shifted to the left when Hgb is in the form of deoxyhemoglobin, as in
venous blood
134
Haldane effect: as a result, Hgb is deoxygenated in systemic capilaries, its affinity for CO2 is increased, facilitating CO2 transport AND
the bind affinity for H+ (generated in RBC along with HCO3-) is also increased
135
Haldane effect: in pulmonary circulation, as hgb is oxygenated, its affinity for CO2 is reduced, and as a result, transfer of CO2 from blood to alveolar air is
facilitated
136
CO2 transport affects acid-base
profoundly
137
a rise in pCO2 invariable causes an increase
in alveolar ventilation (metabolic activity)
138
Lung excretes ..... carbonic acid/day
10.000 mEq
139
kidney excretes less than .... fixed acids/day
100 mEq
140
Altering alveolar ventilation to get rid of CO2 control over
acid-base balance
141
Respiratory acidosis
low pH, increase pCO2, increased Bicarb
breath holding infant, snoring adult
142
Respiratory alkalosis
high pH, decreased pCO2, decreased bicarb
hysterical teenager
143
Metabolic acidosis
decreased pH, decreased bicarb, decreased pCO2
DKA
144
Metabolic alkalosis
increased pH, increased bicarb, increased pCO2
diuretic, vomiting
145
Anion gap
used to differentiate between acidosis resulting from acid gain and acidosis caused by bicarbonate loss; difference between major cation, Na, and the major plasma anions, Cl and HCO3. When Cl and HCO3 are subtracted form the Na concentration, the anion gap is normally ~8-12 mEq.
AG= Na - (Cl + HCO3)
146
AG: INCREASED
DKA, Lactic Acidosis, Uremia, Methyl Alcohol poisoning
147
AG: decreased:
heavy metal poisoning
148
AG: normal
renal diseases
from the gut
abnormal bicarbonate losses
149
Clinical applications: PFT
FVC decreased in obstructive and restrictive
FEV1 decreased relatively MORE in obstructive (problem with airway breathing out)
FEV1/FVC decreased in obstructive, NOT in restrictive
150
Clinical applications: PFT: normal to increased
restrictive lung disease
spondylitis
fibrosis
anything to restrict your chest cage
nothing wrong with your airway
151
Clinical applications: PFT: decreased
asthma
chronic bronchitis
emphysema
152
In emphysema, do you have problems with expansion or recoil?
recoil
153
In emphysema, the reason your FEV1/FEV RATIO is low is bc
your recoil is not good so you dont push out your FEV1 but your FVC (where you have time) does not change very much and will not be as low as obstructive
154
Blue bloater
blue, not dyspneic bc body got used to high CO2, polycythemia, edematous (cor pulmonae) bc PVR is high (severe hypoxemia
155
Pink puffer
pink, dyspneic, mild hypoxemia, NO cor pulmonale, not edematous,
156
```
How does lung compliance change with aging?
pulm fibrosis?
emphysema?
normal lung?
presence of surfactant?
```
```
goes up
down
up
normal
up
```
157
What would not lead to hypoxemia?
polycythemia
