Pulmonary Flashcards
1
Q
Most important muscles that raise the rib cage to facilitate inspiration
A
Diaphragm 75%
1 external intercostals
2 SCM
3 anterior serratus
4 scalenes
2
Q
Muscles that pull ribs downward during expiration
A
1 abdominal recti
2 internal intercostals
Elastic recoil of lung, chest wall and abdominal structures
3
Q
Pressure of fluid in thin space bet lung pleura and chest wall pleura
A
Pleural pressure
4
Q
Pleural pressure is
A
slightly negative -5 cmH20 beginning inspiration
5
Q
Normal inspiration creates a more
A
negative pleural pressure from -5 to -7.5
6
Q
Pressure of air inside the lung alveoli
A
Alveolar pressure 0cm when glottis is open and no airflow
7
Q
During inspiration, to cause inward flow alveolar pressure must
A
fall to slightly below atm pressure at -1cmH20
During expiration, alveolar pressure rises to +1cmH2O
8
Q
Difference between pleural and alveolar pressure; measure of elastic force in lungs that tend to collapse lungs at each instant of respiration
A
Transpulmonary pressure
Recoil pressure
9
Q
Extent to which lungs will expand for each unit increase in transpulmonary pressure
A
Compliance
Everytime the transpulmo pressure increases by 1cm H2O the lung volume after 10-20 sec will expand by 200mL
10
Q
Compliance is determined by
A
1 elastic forces of lung tissue
2 elastic forces by surface tension of fluid lining inside walls of alveoli and other lung air space
11
Q
Elastin forces of lung are determined by
A
elastin and collagen
12
Q
Surface active agent in water greatly reducing surface tension of alveoli and subsequently, decrease the work of breathing
Complex phospholipid secreted by Type II epithelial cell
A
Surfactant
Produced in terminal saccular stage
13
Q
Tendency of water molecules on surface to contract via their strong attraction for one another such as in raindrop
In alveoli, it attempts to force air out of alveoli through bronchi leading to alveolar collapse
Created by attractive forces between water molecules producing collapsed alveoli
A
Surface tension
14
Q
Surfactants are secreted by
A
type II alveolar epithelial cells
15
Q
Most important components of surfactant
A
1 dipalmitoylphosphatidylcholine
2 Ca ion
16
Q
Blocking the passages leading to alveoli lead to
A
Inc surface tension and collapse creating positive pressure attempting to push the air out
17
Q
Pressure from blocked alveoli attempting to push air out =
A
Pressure = (2xsurface tension)/radius of alveolus
18
Q
Reducing alveolar surface tension
A
Reduces effort required by muscles to expand lungs
19
Q
Pressure is inversely proportional to
A
radius of alveoli
hence in small babies, tendency to collapse is much greater due to greater pressure, smaller radius and lack of surfactant
Law of Laplace
Collapsing pressure = 2 x surface tension/aveolar radius
20
Q
Inspiration 3 fractions
Work of breathing
A
1 compliance work / elastic work - req to expand the lungs against lung and chest elastic forces
2 tissue resistance work - req to overcome viscosity of lung and chest wall
3 airway resistance work - req to overcome airway resistance to movement of air into lungs
21
Q
Volume of air inspired or expired with each normal breath amounting to about 500mL in adult male
A
Tidal volume
22
Q
Extra volume of air that can be inspired over and above normal tidal volume when the person inspires with full force
Equal to about 3000 mL
A
Inspiratory reserve volume
23
Q
Maximum extra volume of air that can be expired by forceful expiration after end of a normal tidal expiration
Amounts to 1100 mL
A
Expiratory reserve volume
24
Q
Volume of air remaining in lungs after most forceful expiration
Averages about 1200 mL
A
Residual volume
25
Total Lung Capacity =
TLC = IRV + TV + ERV + RV
26
Pulmonary volumes
1 TV
2 IRV
3 ERV
4 RV
27
Pulmonary capacities
1 Inspiratory capacity
2 functional residual capacity
3 vital capacity
4 total lung capacity
28
Amount of air a person can breathe un beginning at normal expiratory level and distending lungs to maximum amount
IRV + TV
Inspiratory capacity
29
Amount of air that remains in lungs at the end of normal expiration 2300 mL
ERV + RV
Functional residual capacity
30
Maximum amount of air a person can expel from lungs after first filling the lungs to maximum extent and then expiring to maximum extent 4600mL
IRV + TV + ERV
Vital capacity
31
Maximum volume to which lungs can be expanded with the greatest possible effort 5800mL
VC (TV+IRV+ERV) + RV
Total lung capacity
32
RV =
RV = FRC - ERV
33
TLC =
TLC = FRC + IC
34
Lung volumes and capacities directly measured by spirometry
FRC
ERV
IC
TLC
35
Total amount of new air moved into respiratory passages each minute
TV x RRperminute
Minute respiratory volume
Minute ventilation
Ave 6L/min
36
Air that fills passages where gas exchange does not occur
Portions of the lungs that are ventilated but in which no gas exchange occurs
Dead air space
37
All space of respiratory system other than alveoli and closely related gas exchange areas
Volume of conducting airways not involved in gas exchange
150mL
Anatomic dead space
38
When not only the anatomic dead space is taken into account but also the nonfunctional alveoli
Sum of the anatomic and alveolar dead spaces
Physiologic dead space
39
Total volume of new air entering alveoli and adjacent gas exchange areas each minute
Ventilated alveoli that are not perfused
Negligible amount
Alveolar ventilation per minute
40
Alveolar ventilation =
VA = freq x (VT - VD)
Freq respiration per minute
VT tidal volume
VD physiologic deadspace
41
The greatest amount of resistance to airflow occurs through
passages of larger bronchioles and bronchi near trachea
bec these are relatively few in comparison with the approximately 66k parallel terminal bronchioles with only minute amount of air must pass
42
Substances that cause bronchiolar constriction by mast cell
Histamine
| Slow reactive substance of anaphylaxis
43
Cilia beats continually and the direction of their power stroke is always toward
the pharynx
| beat upward
44
Cilia in the lungs
beat upward
45
Cilia in the nose
Beat downward
46
Nasal cavity function
Warming
Humidifying
Filtering
47
Removal of particles by air hitting many obstructing vabes (conchae, septum, turbulence)
turbulent precipitation
48
Two circulations of the lungs
1 high pressure-low flow - systemic blood to trachea, bronchial, terminal bronchiole
2 low pressure-high flow - venous blood from body to alveolar capillary
49
Pulmonary artery has
Large compliance 7ml/min bec of large diameter and thin distensible vessel
50
Bronchial artery empties directly into
Pulmonary veins and left atrium rather than back to the right atrium making flow of L side of heart 1-2% greater
51
Systolic pulmo arterial pressure
Diastolic pulmo arterial pressure
Mean pulmonary arterial pressure
25mmHg
8mmHg
15mmHg
52
Left atrial pressure is estimated using
Pulmonary wedge pressure
Cath in pulmonary artery with direct connection to pulmonary capillary
5mmHg but bec of direct connection only 2-3mmHg greater than left atrial pressure
53
In response to a dec in oxygen in air alveolar (below 70%) the adjacent blood vessels
constrict
vascular resistance inc 5x at extremely low O2 level
believed to be due to a vasocon secreted by alveolar epithelial cell
54
In systemic vessels, a low oxygen concentration will promote
vasodilation
55
Vasoconstriction in pulmo vessels is important bec
poor ventilation will drive blood flow to be shunted to areas that are better aerated for maximal gas exchange
56
Zone 1 of lungs
No blood flow during all portions of cardiac cycle (collapsed)
Alveolar air pressure greater than arterial pressure
57
Zone 2
Intermittent flow during peaks of pulmonary arterial pressure
Systolic arterial pressure rises higher than alveolar air pressure (blood flow) 10cm above midlevel of heart
Diastolic arterial pressure falls below alveolar air pressure
58
Zone 3
Continuous flow
| Arterial pressure and pulmonary capillary pressure greater than alveolar air pressure all the time
59
During supine, blood flow is entirely on
zone 3
60
Zone 1 no blood flow occurs in abnormal conditions such as
Upright person breathing against positive air pressure
| Low pulmo systolic arterial pressure in severe blood loss
61
During exercise, pulmonary vasculature pressure rises enough
converts lung apices from zone 2 to 3 pattern
62
During heavy exercise, blood flow through lungs increase but accomodated by
1 inc no. of open capillaries
2 distending capillaries and inc rate of flow through each capillary
3 inc pulmonary arterial pressure
First two, dec vascular resistance
63
Inc blood flow in lungs during exercises without increasing pulmonary arterial pressure conserves energy of
rigt side of the heart
prevents significant rise of PCP preventing edema
64
Alveoli are kept dry bec
There is a slight negative pressure in interstitial spaces that keeps it dry sucking mechanically into the interstitium
65
Pulmonary edema develops bec
1 inc fluid filtration out of pulmonary capillary
2 impedance in pulmonary lymphatic function causing interstitial fluid pressure to rise from negative (sucking) to positive
Inc in left atrial pressure (LSHF & mitral valve disease) -> Inc pulmonary venous and pulmonary capillary pressure
66
Acute safety factor against pulmonary edema
21 mmHg pulmonary capillary pressure
7 - 28 mmHg
Greatly adapted to safety factor in chronic conditions such as mitral valve stenosis bec of lymphatic accomodation
67
To keep the lungs expanded,
a negative force is always required on the outside of the lungs by negative pressure in pleural space
-4mm but actually -7mmHg
68
Pleural effusion caused by
1 blockage of lymphatic drainage from pleural cavity
2 cardiac failure causing excessive peripheral and pulmonary capillary pressure, excessive transudation of fluid into pleural cavity
3 greatly reduced plasma colloid osmotic pressure
4 infection
69
Gas pressure =
directly proportional to the concentration of gas molecules and the solubility coefficient
70
The rate of diffusion of the gasses in the system is directly proportional to the pressure caused by that gas alone.
Partial pressure
71
Henry’s law
Partial pressure = concentration of dissolved gas / solubility coefficient
72
Partial pressure that water molecules exert to escape through surface
Vapor pressure of water
At body temp, 47mmHg
73
Factors that determine rapidity of diffusion
1 thickness of membrane (pulmo edema, fibrosis)
2 surface area of membrane (emphysema, removal of a lung segment)
3 diffusion coefficient
4 partial pressure difference of gas
74
Volume of gas that will diffuse through membrane each minute for a partial pressure difference of 1
Respiratory membrane diffusing capacity
75
In lung areas with 0 V/Q, the partial pressure of gasses in the alveoli
equals that of the venous blood
PO2 40mmHg
PCO2 45mmHg
76
When V/Q equals infinity, the alveolar partial pressure is
equal to humidified inspired air bec there is no capillary bf to carry O2 and CO2 to alveoli
PO2 149mmHg
PCO2 0mmHg
77
Whenever V/Q is below normal and a fraction of venous blood passing through the capillary does not become oxygenated there is
shunted blood
78
When V/Q is greater and far more available oxygen in the alveoli can be transported away from alveoli by flowing blood, ventilation is said to be
Anatomic dead space + areas of poor flow but excellent ventilation
wasted
Physiologic dead space
79
At the top of the lung,
physiologic dead space
| V/Q is 2.5 x as great as the ideal value
80
In the bottom of the lung,
Physiologic shunt
Too little ventilation with V/Q as low as 0.6 times ideal
81
A high PO2 in the capillary promotes
oxygen binding with hemoglobin
| and vice versa
82
Factors that shift O2 dissociation curve to the right
1 inc CO2
2 inc blood temp
3 inc 2-3 bisphosphoglycerate (hypoxia)
4 dec pH
83
Inc in blood carbon dioxide and H ions enhance release of oxygen from blood to tissues
Bohr effect
84
Inspiration
Diaphragmatic contraction
External intercostal contraction
Internal intercostal relaxation
Increased AP diameter
85
Abdomen is sucked in while accessory muscles of inspiration are contracting
Indicator of impending respiratory failure
Flail chest
Paradoxical breathing
86
Inflow and outflow of air between the atmosphere and lung alveoli
Pulmonary ventilation
87
Lung distensibility
Compliant lungs are easy to distend
Compliance
Normal = 200 ml/cmH20
88
Resits deformation
E= delta P/ delta V
Elastance
89
Increased compliance
| Reduced elastance
Obstructive lung disease
90
Increased elastance
| Reduced compliance in lung fibrosis
Restrictive lung disease
91
In conditions like pulmonary fibrosis
alveolar edema
atelectasis
Increased surface tension, the compliance work is
reduced because the fibrotic tissue requires more work to expand
92
What type of cells secrete surfactant?
Type II Pneumocyte
93
Type II pneumocyte histology
Cuboidal epithelial
94
Surfactant
Dipalmitoylphosphatidylcholine
| Dipalmitoylecithin
95
States that collapsing pressure is inversely proportional to the alveolar radius, such that smaller alveoli experience a larger collapsing pressure
Laplace’s law
Ex: smaller alveoli in preterm babies -> dec surfactant/inc surface tension-> larger collapsing pressure in <34 weeks -> NRD
96
Work required to overcome resistance in the conducting airways
Airway resistance 20%
97
Work required to expand the lungs against the lung and chest elastic forces
Compliance/Resistance 75%
98
Work required to overcome the viscosity of the lung and chest wall structures
Tissue resistance
99
Airflow resistance =
| Poiseuille’s Equation
Airflow resistance = (air viscosity x airway length)/ airway radius
100
Reduction of airway diameter (smooth muscle contraction, excess secretion) airway resistance is
increased
Obstructive LD
101
Combinations of two or more pulmonary volumes
Pulmonary capacities
102
In restrictive disease, lung volumes are
Decreased
103
In obstructive LD, lung volumes are
increased
104
Air trapping in COPD
Inc RV
Inc AP diameter
Barrel-chested
105
Total lung capacity is the
Maximum lung volume
106
Total lung capacity in obstructive disease
Increased
107
TLC in restrictive lung disease
Decreased
108
Maximum amount of air that can be exhaled in 1 second after a maximal inspiration
Constitutes about 80% of FVC
FEV1
109
FEV1/FVC =
0.8
110
FEV1/FVC ratio in obstructive lung disease
Decreased
111
FEV1/FVC ratio in restrictive lung disease
Normal/increased
112
Reversibility is demonstrated if
>12%
>200 ml increase in FEV1
15 mins after an inhaled beta 2 agonist
Or 2-4 week trial or oral corticosteroids (Prednisolone or Prednisone 30-40mg daily)
113
Minute Ventilation =
Minute Ventilation = Respiratory rate x Tidal volume
12bpm x 500 ml = 6L/min
114
RR x (TV - Dead Space)
12 bpm x (500ml - 150ml) = 4.2L/min
Rate at which new air reaches the gas exchange areas
Alveolar ventilation
115
Increases during mechanical ventilation
Anatomic dead space
116
Basic control of respiratory rhythm originates from the
Dorsal and ventral respiratory groups located within the medulla
117
Located along entire length of the dorsal medulla
Controls basic rhythm of respiration
Accomplished by neurons that spontaneously generate action potentials (similar to the sinoatrial node) which stimulate inspiratory muscles.
Dorsal respiratory group
118
Located on ventral aspect of the medulla
Stimulates expiratory muscles as in forced expiration
Muscles which are inactive during normal quiet respiration because expiration is a passive process under normal condition, become important only when ventilation is high (eg. with exercise)
Ventral respiratory group
119
Fine control of respiratory rhythm originates from the
Pneumotaxic
| Apneustic center of pons
120
Located in superior pons, its neurons project to the dorsal respiratory group
Inhibits inspiration
Limiting the size of tidal volume, and secondarily increasing the breathing rate
Pneumotaxic center
121
Located in the inferior pons, it projects to the dorsal respiratory group
Increases the duration of respiratory signals, increasing duration of diaphragmatic contraction resulting in more complete lung filling and a decreased breathing rate
Apneustic center
122
Inhibits inspiration
Dec lung filling
Inc RR
Pneumotaxic
123
Increased duration of inspiration
Inc lung filling
Dec RR
Apneustic
124
Lung over inflation
DRG takes over
Switches off inspiration
Tidal volume 3x normal (>1.5L)
Hering-Breuer Inflation Reflex
125
Control by higher brain centers can
override basic controls of brainstem
126
Chemical control of breathing
Co2 (central)
H (central)
O2 (peripheral) carotid bodies, aortic bodies
127
Carotid bodies
Aortic bodies
Respond to changes in the arterial blood
Stimulated by:
Peripheral chemoreceptors
Decreased PO2
Increased H ion concentration
128
Located in the medulla oblongata
Respond to changes in the brain’s extracellular fluid
Stimulated by increased
Central chemoreceptor
PCO2 related to H concentration
129
Blood pCO2 changes have potent
Acute effect
But weak chronic effect after few days because renal takes over
130
Transport of CO2 in the blood:
1 Transport in the form of bicarbonate ions (70%)
2 Transport in combination with hemoglobin (carbaminohemoglobin) (23%)
3 Transport in the dissolved state (7%)
131
Inside RBC, CO2 reacts with water to form carbonic acid
Reaction is catalyzed by carbonic anhydrase
Most carbonic acid dissociates into bicarbobate ions and hydrogen ions
Bicarb ions diffuse from RBC into plasma & chloride ions diffuse into RBC to take their place, phenomenon is called chloride shift
Hydrogen ions on the other hand combine with hemoglobin
Transport in the form of bicarbonate ions (70%)
132
An enzyme found in RBCs, gastric mucosa, pancreatic cells and renal tubules
Catalyzes the interconversion of carbon dioxide CO2 and carbonic acid H2CO3
Carbonic anhydrase
133
Oxygen from the lungs is carried in chemical combination with hemoglobin
97%
134
Binding of O2 to hemoglobin with
| CO2 release
Haldane effect
135
Each gram of hemoglobin combines with how much oxygen
1.34 mL
Under normal conditions, 5 ml O2 is transported from lungs to tissues for every 100ml of blood
136
CO2 combines with hgb to form carbaminohgb
| This combi is a reversible rxn
Transport in combi with hgb (carbaminohgb) 23%
137
Blood contains how much hemoglobin
15 g hgb/dl
Under normal conditions 5 ml O2 is transported from lungs to tissues for every 100 ml of blood
138
Drug used to treat glaucoma and high altitude or mountain sickness
Can cause acidosis
Hydrocephalus to dec ICP
Carbonic anhydrase inhibitors
139
Maximum volume to which lungs can be expanded with the greatest possible effort 5800mL
VC + RV
Total lung capacity
140
Most important components of surfactant
1 dipalmitoylphosphatidylcholine
| 2 Ca ion
141
Blocking the passages leading to alveoli lead to
Inc surface tension and collapse creating positive pressure attempting to push the air out
142
Pressure from blocked alveoli attempting to push air out =
Pressure = (2xsurface tension)/radius of alveolus
143
Reducing alveolar surface tension
Reduces effort required by muscles to expand lungs
144
Pressure is inversely proportional to
radius of alveoli
hence in small babies, tendency to collapse is much greater due to greater pressure, smaller radius and lack of surfactant
145
Inspiration 3 fractions
1 compliance work / elastic work - req to expand the lungs against lung and chest elastic forces
2 tissue resistance work - req to overcome viscosity of lung and chest wall
3 airway resistance work - req to overcome airway resistance to movement of air into lungs
146
Volume of air inspired or expired with each normal breath amounting to about 500mL in adult male
Tidal volume
147
Extra volume of air that can be inspired over and above normal tidal volume when the person inspires with full force
Equal to about 3000 mL
Inspiratory reserve volume
148
Maximum extra volume of air that can be expired by forceful expiration after end of a normal tidal expiration
Amounts to 1100 mL
Expiratory reserve volume
149
Volume of air remaining in lungs after most forceful expiration
Averages about 1200 mL
Residual volume
150
Total Lung Capacity =
TLC = IRV + TV + ERV + RV
151
Pulmonary volumes
1 TV
2 IRV
3 ERV
4 RV
152
Pulmonary capacities
1 Inspiratory capacity
2 functional residual capacity
3 vital capacity
4 total lung capacity
153
Amount of air a person can breathe un beginning at normal expiratory level and distending lungs to maximum amount
IRV + TV
3000 + 500 = 3500 ml
Inspiratory capacity
154
Amount of air that remains in lungs at the end of normal expiration 2300 mL
ERV + RV
1100 + 1200 = 2300 mL
Functional residual capacity
155
Maximum amount of air a person can expel from lungs after first filling the lungs to maximum extent and then expiring to maximum extent 4600mL
IRV + TV + ERV
3000 + 500 + 1100 = 4600 mL
Vital capacity
