Self-Test Questions Flashcards
1
Q
What is TV?
A
the volume inspired or expired at each normal breath
2
Q
What is IRV?
A
Volume that can be inspired over and above tidal volume, usually during exercise
3
Q
What is ERV?
A
Volume that can be expired after expiration of the tidal volume
4
Q
What is RV?
A
volume that remians in the lungs after maxima expiration. cannot be measured by spirometry
5
Q
What is the difference between anatomic and physiological dead space?
A
anatomic is volume of conducting airways (150ml), and physiological is functional measurement of volume of lung that doesn’t participate in gas exchange, and therefore doesn’t contribute to expired CO2.
6
Q
What is the equation for physiological dead space?
A
Vd = Vt (PaCO2 - PeCO2/PaCO2)
7
Q
What is the equation for minute ventilation calculated?
A
Vt * breaths/min
8
Q
What is the equation for alveolar ventilation calculated?
A
Vt-Vd*breaths/min
9
Q
What is inspiratory capacity?
A
Vt + IRV
10
Q
What is FRC?
A
ERV + RV; the volume remaining in lung after volume is expired; cannot be measured by spirometry
11
Q
What is VC/FVC
A
Vt + IRV + ERV; volume that can be forcibly expired after maximal inspiration
12
Q
What parts of lung cannot be measured using spirometry?
A
RV, TLC, and FVC
13
Q
What is TLC?
A
sum of all lung volumes after maximal inspiration
14
Q
What is FEV1?
A
volume of air that can be expired in the first second of maximal expiration
15
Q
What is normal FEV1?
A
0.8
16
Q
What happens to FEV1/FVC ratio in obstructive/asthma?
A
FEV1 is reduced more than FVC, thus the ratio is decreased
17
Q
What happens to FEV1/FVC ratio in restrictive/fibrosis?
A
both FEV1 and FVA are reduced, and the ratio is either normal or increased
18
Q
What muscles participate in normal inspiration?
A
the diaphragm contracts pushing abdomen down and expanding ribs to increase volume of thoracic cavity and push air out of the lungs
19
Q
What muscles participate in exercise or respiratory distress inspiration?
A
external intercostal and accessory muscles
20
Q
What is compliance?
A
C =V/P; the distensibility of lungs and chest wall -> slope of pressure-volume curves
21
Q
What is transmural pressure?
A
Alveolar pressure - intrapleural pressure;
22
Q
How is the lung expanded and collapses
A
when pressure outside of lung is negative, the lung can expand and increase volume, when pressure outside of the lung is positive, it collapse and volume decreases
23
Q
What is Hysteresis?
A
When inflation of lung follows a different curve the deflation of the lung
24
Q
When is compliance greatest in hysteresis?
A
in the middle ranges of pressures
25
When is compliance lowest in hysteresis?
at high expanding pressures
26
What is pneumothorax?
When air is introduced into the intracellular space, and thus the intracellular space becomes equal to the atmosphere pressure and the lung collapse and the chest wall springs inward
27
What is emphysema?
There in an increase in compliance so the lung collapse is decreases, thus FRC is less than than the expanding of the chest wall
28
What is fibrosis of the lung?
Compliance is decreased and the tendency for the lung to collapse is decreased, thus the FRC of the lung to collapse is greater than the chest wall to expand
29
What is the role of surfactant in the alveoli?
made by Type 2 and reduces surface tension by disturbing intermolecular forces b/w liquid molecules, thus increasing compliance so the small alveoli doesn't collapse
30
What is neonatal respiratory distress syndrome?
occurs in premature babies because of lack of surfactant, and the infant exhibits atelecatasis (lung collapse), hypoxemia asa result of decrease V/Q
31
What is the relationship between Q and R?
Q = change in pressure/airway resistance
32
What is Poiseuille's Principle?
R = 8nl/pir4
33
Which size bronchi have the greatest resistance?
medium --> trachea
34
What is the difference between low and high volumes of the lung?
high - greater traction and decreased air resistance
| low - less traction and increased air resistance
35
What is the difference in resistance at deep sea level and helium?
deep sea- density and resistance of airway is increased
| helium - reduces resistance
36
What happens at rest prior to inspiration?
alveolar pressure = atmospheric pressure = 0, intrapleural pressure is negative (b/c opposing force of lung trying to collapse and chest wall trying to expand)
37
What happens during inspiration?
diaphragm contracts and increase volume of thorax and lung (FRC + 1Vt) and alveolar pressure and intrapleural pressures become more negative; alveolar < atmospheric pressure, and air flows into lungs
38
What happens during expiration?
alveolar > atmospheric --> alveolar pressure becomes positive due to compression, and air flows out of the lung , and lung volume returns to FRC
39
What happens during forced expiration?
intrapleural pressure becomes positive and compresses the airway, making expiration more difficult; seen in COPD
40
What is COPD?
chronic bronchitis + emphysema; and obstructive disease with increase lung compliance; characterized by decreased FEV1/FVC
41
What are the symptoms emphysema?
mild hypoxemia, no cor pulmonae, dyspenic, pink, normal pCO2
42
What are the symptoms of chronic bronchitis?
severe hypoxemia, cor pulmonae, edematous, blue, polycythemia, increase pCO2
43
What is the equation fo Dalton Law of partial pressures?
PP = total pressure * fractional gas concentration; gas dissolved in blood is proportional to its PP
44
How do you calculate PP of oxygen in dry and humid air
dry inspired air --> 760 mmHg * 0.21
humidified trachea air
--> 760mmHg - 47mmHg *0.21
45
What occurs in a physiological shunt?
the systemic bypass of pulmonary circulation resulting in a admixture of venous blood with oxygenated arterial blood that makes Po2 of arterial blood slightly higher than that of alveolar air
46
What is the importance of PP?
it is the difference in PP across the membrane that dictates the rate of diffusion of O2 an CO2
47
What is Perfusion-limited exchange?
illustrated by N2O in which the gas equilibrates and the PP of arterial blood becomes equal to PP in alveoli air
48
What is Difusion-limited exchange?
illustrated by CO during strenuous exercise, and emphysema, fibrosis, and the gas does not equilibrate and PP gradient is maintained
49
What is the difference between fetal and adult HB?
fetal HB has O2 affinity higher than adult (left shift b/c of less 2,3 DPG)
50
What happens at pO2 of 100 mmHg to Hb saturation?
it is 100% saturated and O2 bound to all 4 heme groups; diffusion is facilitated and O2 PP is kept low to maintain the PG
51
What happens at pO2 of 40 mmHg to Hb saturation?
Hb is saturated 75%, O2 bound to 3 heme groups
52
What happens at pO2 of 25 mmHg to Hb saturation?
HB is saturated 50%, O2 bound to 2 heme groups
53
What is positive cooperative?
binding of first O2 increases the affinity of the second O2 molecule, creating a sigmoidal shape curve
54
What does the flat line at 60-100 mmHg mean on the O2-HB dissociation curve?
humans can tolerate changes in atmospheric pressure without comprising O2 carrying-capacity of HB
55
What factors cause right shifts in the HB-O2 dissociation curve?
occurs when HB affinity for O2 is decreases (Bohr Effect), and P50 is increase/unloading of O2 from blood to tissue; this is caused by increase pCO2, decreased pH, increase temp and 2,3 DPG, and exercise
56
When is 2,3 DPG increased?
in adaptation to chronic hypoxemia such as living in high altitudes
57
What factors cause Left shifts in the HB-O2 dissociation curve?
occurs when affinity of Hb for O2 is increased and P50 is decreased/unloading of O2 from blood to tissue;; caused by increased pH, decreased pCO2, decrease temp and 2,3 DPG, increased affinity of HbF and CO for O2
58
What are the causes of hypoxemia?
decrease in arterial pO2; an A-a >10 mmHg
59
How do you calculate the A-a gradient/Gas equation?
A-a gradient = PAO2 - PaO2; PAO2 = PiO2 - PaCO2/R; normal A-a gradient <10 mmHg
60
What are the causes of hypoxia?
decrease in O2 to tissue caused by decreased Cardiac output, decrease O2-binding to HB, or decreased pO2
61
What is the Henderson Hasselback Equation
CO2 + H2O = HCO3- + H+ in RBC's; HCO3- is the major transport molecule of CO2 to the lungs
62
What is the difference between pulmonary and systemic circulation?
pulmonary - low pressure and resistance
63
What is the cardiac output of the RV?
the pulmonary blood flow which is = cardiac output of LV
64
What is the difference in Q of supine and standing position?
supine - uniform Q throughout the lung
| standing - uneven Q in lungs b/c of gravity--? Q is lowest at apex and highest at the base
65
What is the difference between the 3 zones of the lungs?
1 - alveolar > arterial > venous pressure
2 - arterial > alveolar > venous pressure
3 - arterial > venous > alveolar pressure
66
What happens to flow at Zone one?
high alveolar pressure may compress capillaries and reduce Q as seen in hemorrhage alveolar pressure is increased b/c positive pressure ventilation
67
What happens to flow at Zone Two?
moving down the lung arterial pressure progressively increase b/c of gravitational effects on hydrostatic pressure
68
What happens to flow at Zone Three?
moving down the base of the lung arterial pressure is highest b/c of gravity and venous pressure > alveolar pressure
69
What drives Q in Zone 2?
Q driven by difference between arterial and alveolar pressure
70
What drives Q in Zone 2?
Q drives by difference between arterial and venous pressure
71
What is the difference in the Q of hypoxia in the lungs and organs?
lung - hypoxia causes vasoconstriction
| tissues - hypoxia causes vasodilation
72
What is a right-to-left shunt?
2-50% of cardiac output bypasses as in Tretaology of Fallot , resulting in decrease arterial pO2 b/c of admixture of venous blood. can be measured by breathing in 100% O2
73
What is a left-to-right shunt?
most common b/c pressure higher on left side of heart; caused ductus arteriosum or traumatic injury, resulting in elevated pO2 on the right side of the heart
74
What is V/Q ratio?
the ratio of alveolar ventilation to pulmonary blood flow; an ideal V/Q =0.8 and results in pO2 of 100mmHg/pCO2 of 40mmHg
75
Where is V/Q highest and lowest in the lung?
highest V/Q and more gas exchange - base; high pO2/low pCO2
| lowest V/Q and less gas exchange - apex; low pO2/high pCO2
76
What happens to V/Q in obstructive airway?
V/Q = 0, airway is blocked (V=0) as in a shunt; no gas exchange and there is an increase in A-a gradient
77
What happens to V/Q in pulmonary embolism?
V/Q = infinite, no gas exchange as in dead space; Q is blocked = 0
78
What is the central control of respiration?
the brain stem
79
What is centers of the brain are responsible for breathing?
medullary, ventral, apenuestic, pneumotaxic, and cerebral cortex
80
What is the role of the medullary center?
its responsible for inspiration and the basic rhythm of breathing
81
What is the role of the ventral center?
expiration both active and passive
82
What is the role of the pneumotaxic center?
to inhibit inspiration, therefore regulating inspiratory volume and rate
83
What is the role of the apenustic center?
stimulated inspiration producing deep and prolonged inspiratory gasp
84
What is the role of the cerebral cortex?
hypo and hyperventillation
85
What is responsible for the input and output of medullary center?
input - from peripheral chemoreceptors to the vagus and glosspharyngeal nerves
output - phrenic nerve to diaphragm
86
What is the role of the vagus nerve?
relays info from peripheral chemoreceptors to mechanoreceptors in the lungs
87
Where are the central and peripheral chemoreceptors located?
central - medulla
| peripheral - carotid and aortic bodies
88
What are the central chemoreceptors sensitive to?
pH of CSF
89
What happens when you increase pH or pO2 in central chemoreceptors?
you increase breathing rate (hyperventilation)
| decrease pCO2 inhibits breathing
90
What happens to peripheral chemoreceptors when you decrease arterial pO2?
pO2 <60 mmHg increase breathing rate
91
What happens to peripheral chemoreceptors when you increase arterial pCO2?
increase breathing rate caused by hypoxemia
92
What happens to peripheral chemoreceptors when you increase arterial H+?
decreased pH leading metabolic acidosis causing hyperventilation
93
What is the Hering-Bruer Refex?
occurs when lung stretch receptors are stimulated by distention of the lungs causing frequent breathing
94
What physiologically happens during exercise?
increase breathing due to increase O2 consumption and CO2 production, mean arterial pO2/CO2/pH are unchanged, venous pCO2 increases b/c of excess CO2 produced, Q increases b/c cardiac output increases, decreased physiological dead space
95
What physiologically happens during high altitudes?
alveolar/arterial pO2 decreases (hypoxemia) --> hypoventilation, increases alkalosis, renal production of erythropoietin, HB concentration (thus increase O2), 2,3 DPG concentration (right shift), and vasoconstriction (increase resistance and arterial pressure)
96
What are the normal values?
Bicarbonate - 24 (22-26)
PaCO2 - 40 (38-42)
PaO2 - 95-100
anion - 10-15
97
What is Dalton's law of PP?
states that in a mixture of gases, each gas exerts a partial pressure proportional to its fractional concentration in the mixture.
98
What is the alveolar gas equation?
pA O2 = FiO2 X (760- 47) – pCO2/R
R is the Respiratory Quotient for the amount of CO2 generated per O2 molecule utilized
The value of R in basal metabolic conditions = 0.8
99
What factors affect lung compliance?
1. Volume: Compliance increases with decreasing lung volume
2. Hysteresis
3. Elasticity of the lung, or its tendency to return to resting position after inflation, leads to a negative pressure surrounding the lung, compared to atmospheric pressure. This elasticity is attributed to fibers of elastin and collagen in the alveolar walls, around vessels and bronchi.
4. Surfactant
100
How does lung volume affect airway resistance?
The greater the volume, the lower is the resistance, as expanding lung parenchyma exert radial traction on the airways, increase radius and thus decrease resistance. Conversely, as the lung collapses, airway resistance increases, and may even close down airways, especially at the base of the lung.
101
What is helium technique used to measures?
RV an FRC
102
What is the Heliox?
a combination of Helium and Oxygen, which renders the gas less dense: the pressure gradient needed to sustain flow is decreased. Thus, the work of breathing is decreased in pathological conditions of airway obstruction, such as asthma or croup, where flow is turbulent.
103
What is alveolar ventilation calculated?
```
Tidal Ventilation = Alveolar Ventilation + Anatomic Dead Space
Alveolar ventilation may be increased by increasing n, or increasing V(T)
Increasing V(T) or Tidal Volume is more effective, as it reduces the relative proportion of Anatomic Dead Space (V(D)), which is a constant value
```
104
How is anatomic dead space measured?
Fowler's method -It is based on the fact that N2, a significant component of inspired gas, does not participate in gas exchange and is present in expired alveolar gas. A single breath of 100% O2 displaces N2 from alveolar gas, into the dead space, and N2 concentration in the dead space increases: it is sampled continuously at the mouth.
105
How is Alveolar ventilation measured?
Because no gas exchange occurs in the anatomic dead space, there is no CO2 produced there at the end of inspiration: all the CO2 in expired air comes from the alveolus.
The volume of CO2 exhaled in unit time, or VCO2 = Alveolar Ventilation (VA) X %CO2/100
%CO2 /100 = Fractional CO2 or FCO2
Partial pressure of CO2 or pCO2 = FCO2 x K (K is a constant)
Solving the equation VA = VCO2/pCO2 x K
Since CO2 is extremely soluble in blood, pCO2 and arterial CO2 are virtually identical in a healthy subject. Thus, arterial CO2 can be used to measure alveolar ventilation
106
When does turbulence occur?
turbulence occurs when Reynold’s number exceeds 2000.
It follows that when velocity of flow is high, as occurs in the trachea during exercise, turbulence increases.
Generally, during quiet inspiration, flow in the larger airways such as the trachea, is laminar, but there are differences in airway resistance during inspiration and expiration.
107
What caused increase compliance?
```
Pulmonary Emphysema (due to reduced elasticity)
and in the Normal aging lung
```
108
How does V/Q mismatch happen?
When PO2 increased above the allowable 5-10 mm Hg, it is called V-Q mismatch, and often occurs in different forms of lung disease, needing artificial ventilation.
109
How compliance calculated?
Compliance = ΔV/ΔP, or the slope of the pressure-volume curve
The distensibility of the lung, or the change in volume for a given change in pressure. Compliance curves are also called pressure-volume curves.
110
What is Boyle's Law?
States that the product of pressure and volume of a gas is constant at constant temperature.
V x P = K (at constant temperature)
Another way of saying this would be that V is inversely proportional to P; as volume (V) increases, or pressure (P) decreases.
111
What decreases compliance?
Pulmonary Fibrosis, Alveolar edema, Atelectasis, Hypoventilated lung, Increased pulmonary venous pressure leading to pulmonary edema
112
What is hysteresis?
Lung volume at any given pressure is higher during deflation than during inflation.
113
What is the equation for reynold's number?
```
REYNOLD’S NUMBER = 2rvd/n
r = radius
v = velocity
d = density
n = viscosity
```
114
How is hypoxemia treated?
can be treated by increasing the partial pressure of oxygen in inspired air, and thus creating a larger pressure gradient, to overcome the difficulty in diffusion due to interface thickening.
115
What is the choke point?
impediment on expiration due to compressed airways by the intrathoracic pressure. once you cross the choke point, air rushes out, and expiration is effort independent, and occurs almost automatically.
116
What contributes to hysteresis?
Surfactant reduces surface tension at low lung volumes, keeping the alveoli open.
117
What is Fick's law of diffusion?
As the partial pressure of oxygen along the capillary increases as blood flows from deoxygenated to oxygenated side along the alveolocapillary membrane, the gradient decreases and diffusion slows down. The transfer of gas across this membrane can be diffusion or perfusion limited.
118
What are the causes of hypoxemia?
1. Hypoventilation
2. Diffusion limitation
3. Shunt
4. Ventilation-perfusion inequality
119
What is the critical opening pressure?
the pressure needed to raise a pulmonary artery/extraalveolar vessels at low lung or collapsed volumes in order to restore air flow
120
What is used to treat pulmonary hypertension in premature babies?
Nitric Oxide vasodilator
121
What causes left shift?
```
INCREASED AFFINITY OF Hb FOR O2
Alkalosis - Carbon Monoxide
Reduced CO2
Decreased temperature
Decreased 2-3 DPG (end product of red cell metabolism)
```
122
What causes right shift?
```
REDUCED AFFINITY OF Hb FOR O2. (UNLOADS EASILY)
Acidosis
Increased pCO2 (the Bohr effect)
Increased temperature
Increased 2-3 DPG
```
123
What comprised the conducting zone?
The conducting zone, comprising trachea, bronchi and terminal bronchioles (smallest airways without alveoli). Together, they conduct inspired air into the gas exchanging regions of the lung. The components of the conducting zone take no part in gas exchange, and constitute the anatomic Dead Space, with a volume of about 150 ml in each breath
124
What happens as lung volume increases?
As the lung expands, the lung volume increases, Alveolar vessel resistance increases, and the alveolar vessels are exposed to the alveolar pressures and become compressed
125
What is neonatal respiratory distress syndrome?
surfactant deficiency in premature babies, whose lungs are too immature to produce it in adequate amounts
126
What is the Haldane effect?
The lower the saturation of Hb with O2, the larger the concentration of CO2 for a given pCO2.
127
What is a vasodilator in pulmonary system?
bradykinin
128
What is Henry's Law?
states that the solubility of a gas in a liquid solution is proportional to the partial pressure of the gas and the solubility constant (a) of Bunsen. This constant is different for each gas
129
What happens to pressure as we move down the airway?
Pressure (change) = Force/Area
As gas moves down the airway, cross sectional area increases significantly. Pressure therefore decreases, which leads to reduction in the velocity of flow, and provides a favorable milieu for gas exchange.
130
What are the states of respiration?
* Stage 1 - Ventilation from the ambient air into the lung (pulmonary) alveoli
* Stage 2 - Pulmonary gas exchange from the alveoli into the pulmonary capillaries
* Stage 3 - Gas transport from the pulmonary capillaries to the peripheral (tissue) capillaries
* Stage 4 - Peripheral gas exchange from the tissue capillaries into the cells (mitochondria)
* Stage 5 - and CO2 back again, though this is not usually considered to be one of the stage
131
What is the differenced between acidosis and alkalosis?
Lower the pH, more H+ and less Bicarbonate
Low pH ACIDOSIS
High pH ALKALOSIS
132
What increases anion gap?
Diabetic Ketoacidosis
Lactic Acidosis
Uremia
Methyl Alcohol poisoning
133
What increases anion gap?
Heavy Metal poisoning ( Lithium)
134
What normal anion gap?
Renal diseases
Abnormal bicarbonate losses
From the gut
135
What is the role of buffering system?
Ph changes less because Amino acids and buffering system and RBCs contribute to buffering capacity (e.g. Hb)
136
What is respiratory acidosis?
decrease pH, increase pCO2 and bicarbonates
137
What is respiratory alkalosis?
increase pH, decrease pCO2 and bicarbonates
138
What is metabolic acidosis?
decrease pH, decrease pCO2 and bicarbonates
139
What is metabolic alkalosis?
Increase pH, pCO2 and bicarbonates
140
What is ketoacidosis?
near normal PaO2, decreased PaCO2, decreased pH, decreased HCO3-
141
What can result from intentional hyperventilation?
can reduce CO2 and lead to tetany, seizures, fainting
142
What is chyene stroke breathing?
Apnea for 10-20 seconds separated by equal periods of hyperventilation with waxing and waning tidal volumes
143
What is the response to exercise?
1. Oxygen consumption increases
2. Oxygen is supplied by increasing ventilation
3. CO2 production increases, blown off by increased ventilation
4. Mean arterial pO2 and pCO2 do NOT change during exercise
5. Cardiac Output and pulmonary blood flow increase.
6. Recruitment of pulmonary vessels decreases pulmonary vascular resistance and enhances pulmonary blood flow
7. Hb dissociation curve shifts to the RIGHT enhancing O2 delivery to tissues
144
What is the integrative function of fetal circulation
A. In Utero – Placental circulation is in parallel with peripheral tissues
B. PO2 is low at 30 mm Hg
C. Ductus arteriosus shunts blood from the PA to the descending aorta
D. Newborn baby takes its first breath there is a Dramatic fall in pulmonary vascular resistance so air flows into the lungs
1. Lung expansion decreasing extra alveolar resistance
2. Oxygen increases
3. Increased Pulmonary Blood flow
Left atrial pressure rises, foramen ovalve closes
145
What is the integrative function at high altitudes?
1. Hypoxemia occurs at high altitude (the percent of O2 isn't changed but pressure is lowered)
2. Severe reductions in pO2 of inspired and alveolar air
3. Pulmonary vasoconstriction due to hypoxemia
4. High altitude sickness, attributed to hypoxia
5. Adaptation by hyperventilation in response to hypoxemia leads to respiratory alkalosis
6. Polycythemia due to hypoxic stimulation of erythropoietin production, and increasing red cell production
7. Increased 2-3 DPG, shift to the right of O2 dissociation curve, enhancing O2 release
146
What do cortoid bodies respond to?
They respond to arterial, rather than venous pO2 levels, and the response is very rapid
