1
Q
In what portion ofthe lungs does alveolar deadspace normally occur?
A
Apices
2
Q
Airway Resistance Formula
A
Change in pressure/flow
3
Q
Normal Airway Resistance
A
0.5-2.5 cmH2O/L/sec
4
Q
Under resting metabolic conditions, how much carbon dioxide does a normal adult produce per minute?
A
200ml/min
5
Q
What is the term for the opposition to ventilation caused by the movement of gas through the conducting airways?
A
Airway Resistance
6
Q
Compliance Formula
A
- Volume/Pressure
- 1/elastance
7
Q
Elastance Formula
A
- Pressure/Volume
- 1/compliance
8
Q
Total Compliance Formula
A
Lung compliance x Chest wall compliance/ Lung compliance + chest wall compliance
9
Q
Heart Pathway
A
Right Atrium->Right Ventricle->Pulmonary Artery->Pulmonary Capillaries->Pulmonary Vein->Left Atrium->Left Ventricle->Aorta->Systemic Capillaries->Vena Cava
10
Q
What kind of blood does the Pulmonary Arteries and Veins carry?
A
Pulmonary Artery: deoxygenated blood. Only artery in body that carries deoxygenated blood.
Pulmonary Vein: oxygenated blood. Only vein in the body that carries oxygenated blood.
11
Q
Whats the PaO2 in the pulmonary artery?
A
40 mmHg
12
Q
Whats the PaCO2 in the pulmonary artery?
A
46 mmHg
13
Q
Whats the PaO2 in the pulmonary vein?
A
100 mmHg
14
Q
Whats the PaCO2 in the pulmonary vein?
A
40 mmHg
15
Q
Time Constant Formula
A
Resistance x Compliance
16
Q
Pseudoglandular Stage
A
- 6th, 7th-16th week
- lung resembles hollow tube like (glandular) structure surrounded by mesenchymal cells
- lined with cuboidal epithelial cells
- first type II pneumocytes appear
- terminal bronchioles begin to differentiate to form respiratory bronchioles and alveolar ducts
- cartilage begins to form around larger airways and smooth muscles forms around airways and major blood vessels
- production of fetal lung liquid
- NOT capable of extrauterine survival
17
Q
Canalicular Stage
A
- canaliculi (canals) begin to branch out from terminal bronchioles
- all alveoli developed from a single terminal bronchiole form an acinus
- capillaries surround the acini in dense layer making gas exchange possible
- cuboidal Type II pneumocytes flatten into Type I pneumocytes
- alveolar septa start becoming thinner
18
Q
Saccular Stage
A
- 26th week-birth
- peripheral air spaces have saclike appearance
- sacs distal to terminal bronchioles begin to lengthen
- 1st generation of sacs that will become alveoli are formed
- interstitial material compressed, capillary and alveoli move closer
- Type II cells produce and store pulmonary surfactant
19
Q
Alveolar Stage
A
- 32nd week-8th or 10th year of life
- formation of the hexagonal shaped alveoli
- terminal saccule become enclosed in tissue sheath
- epithelial cells form crests that develop into alveolar septa
- septa separates individual alveoli and increase surface area for gas exchange
- number of alveoli provide 3-4m^2 of gas exchange surface area
- adult lung has a gas exchange surface area of 50-100m^2
20
Q
Fick’s Law of diffusion
A
rate of diffusion of a gas through a tissue sheet is directly proportional to the surface area
21
Q
Dead Space
A
1 cc or 1 ml per lb of body weight
-gas that doesn’t participate in gas exchange
physiological dead space= anatomical dead space + alveolar dead space
22
Q
Inspiratory Expiratory Ratio
A
Total Cycle Time= 60/Respiratory Rate Inspiratory Time + Expiratory Time = TCT TI=TCTx I/ I+E End Expiratory Pause = 25% of TE TE/TI= I:E
23
Q
Dead Space Tidal Volume Ratio
A
VD/VT= (PaCO2-PECO2)/PaCO2
VD=VT(PaCO2-PECO2)/PaCO2
24
Q
Alveolar Minute Ventilation
A
V(with dot on top)A= (VT-VD) x RR
25
Minute Ventilation
V(with dot)= VT x RR
26
Hemoglobin Arterial Oxygen Saturation Equation
SaO2= HbO2/Total Hb x 100
27
Oxygen Carrying Capacity of blood
grams/dl of Hb x 1.34ml/g
28
Total Oxygen Content of the blood equation
CaO2=(0.003 x PaO2)+(Hb total x 1.34 x SaO2)
29
Hemoglobin Saturation
```
PaO2 (torr) | Saturation
27 torr - 50%
40 torr - 70%
50 torr - 80%
60 torr - 90%
100 > more torr - 97%-100%
```
30
Alveolar Air Equation
```
PAO2= FiO2(PB-PH2O)-(PACO2/0.8)
PH2O= 47mmHg
PaCO2= 40mmHg
```
31
Oxyhemoglobin Dissociation Curve to the RIGHT
- occurs in the SYSTEMIC capillaries
- pH decreases: blood picks up CO2 causes pH decreases, lowers affinity for Oxygen
- Temperature increases, affinity for oxygen decreases when exercising
- occurs during hypoventilation
- increased 2,3 DPG, promotes O2 unloading and reduces affinity for O2
- RBCs produces more 2,3DPG when metabolically active, more when temperature is high
32
Oxygen Dissociation Curve to the LEFT
- occurs in the PULMONARY capillaries
- pH increases, when venous blood returning to the lungs and CO2 diffuses out causes pH increase
- this increases affinity of Hb for O2 and enhances its uptake of Oxygen from alveoli
- body temperature goes down, Oxygen affinity goes up
- 2,3 DPG production decreases, O2 affinity goes up
- occurs during hyperventilation
- RBCs producing less 2,3DPG
33
Oxygen Delivery Formula
D(with dot)O2= CaO2 x Q
| Oxygen minute delivery)=(oxygen content) x (Cardiac Output
34
Respiratory Exchange Ratio
R=V(with dot)CO2/V(with dot)O2
| R=(minute CO2 production)/(minute O2 consumption)
35
Normal Respiratory Exchange Ratio
R= 200/250= 0.8
36
Under resting metabolic conditions, how much Oxygen does the body consume per minute?
250ml/min
37
Hypoxemia
-when the PaO2 is lower than the predicted normal value based on age
Causes:
1. Inadequate amount of )2 is reaching the alveoli
-hypoventilation, tachypnea (rapid shallowing breathing)
2. Inadequate amount of O2 crossing A/C membrane
-low PB causing a low PO2, low FiO2
38
Haldane's Effect
- describes how high levels of O2 in the lungs increase Hb's affinity for O2 and decreases its affinity for CO2
- high O2 levels speed up loading of the O2 onto Hb at the lungs producing saturated Hb
- HbO2 has a low affinity for CO2 so unloading and loading of O2 are sped up at the lungs
- also works to a lesser degree in tissues
39
Bohr's Effect
- describes how high levels of CO2 and H+ in the tissue decrease Hb's affinity for O2 and increases affinity for CO2
- high CO2 and H+ speed up unloading of O2 to cells and producing deoxygenated Hb
- Deoxygenated Hb has high affinity for CO2 so loading of CO2 and unloading of O2 are sped up at the tissues
- also works to a lesser degree at the lungs
40
Hypoventilation
- CO2 levels increase, breathing too slow
- can cause hypoxemia and hypoxia
- can be caused by medication overdose causing the central chemoreceptors to become depressed
- shifts curve to the right
41
Hyperventilation
- O2 levels rise, CO2 levels fall
- breathing too fast causes exhaling of CO2 faster than cells are producing it
- shifts curve to the left
42
How does the changes in blood pH impact Hb affinity for O2? (Bohr's Effect)
- low pH shifts curve to the right, saturation decrease and Hb affinity decreases
- high pH shifts curve to the left, Hb saturated and Hb affinity increases
43
Percent Relative Humidity Formula
%RH=content/capacity x 100
| Normal Body Temperature alveolar capacity at body temp= 44 mg/L
44
Formula for Density of Air
Density=m/v
Density of Air= (FN2 x gmwN2) + (FO2 x gmwO2)/ 22.4 L
STP=22.4
45
F->C->K
- C= 5/9(F-32)
- K=C+273
- F=(9/5 x C) +32
46
Hydrostatic Pressure Formula
- PL= Height x Density
| - density = 1 g/cm3
47
Hamburger Effect
- when chloride ions shift from plasma into RBC
- Chloride shift
- to maintain a concentration equilibrium across cell membrane
- reverse chloride shift occurs in pulmonary capillaries
48
Boyles Law
V1 x P1= V2 x P2
49
Charles Law
V1/T1 = V2/T2
50
Gay Lussacs Law
P1/T1 = P1/T1
51
Henry's Law
The amount of dissolved gas is proportional to its partial pressure in the gas phase
52
Poiseuille's Law
Fluid flowing through a tube looses pressure as energy is converted to heat while overcoming frictional resistance
53
Obstructive diseases
- high compliance and low elastance
- pressure becomes positive to get air out
- emphysema (COPD)
- takes longer to inhale and exhale
54
Restrictive Diseases
- low compliance, high elastane
- asthma, pneumonia
- shorter time inhaling and exhaling
55
What causes the baby to take it's first breath?
- central chemoreceptor cells in the medulla signal the respiratory muscles to work in response to receptor stimulation by
- acidosis
56
Pump Handle movement of ribs
- muscle contraction rotates the rib heads around the costovertebral joints, pulls up the distal ends of the ribs, especially ribs 2-7
- lifting the sternum and displacing it anteriorly
- increases the anteroposterior dimension of thorax
57
Bucket Handle movement of ribs
- same muscle contraction rotates the long axis of the ribs and reduces their downward slant
- increases the lateral (transverse) dimension of the thorax
58
What muscles are the primary respiratory muscles?
- Diaphragm and external intercostals
| - both used during quiet breathing and exercising
59
Maximal contraction for the diaphragm is?
- 10 cm
| - normal contraction: 1.5 cm (1-2cm)
60
Internal intercostal muscles
- responsible for forced exhalation
| - depress the ribs and decrease space in the chest cavity
61
External intercostal muscles
- responsible for forced and quiet inhalation
| - raise the ribs and expand the chest cavity
62
What muscles are used when in the Tripod position?
Pectoralis muscles
-allows the patient to fix the head and the pectoral (shoulder) girdle allowing the pectoralis muscles to general some anterior thoracic lift
63
Trapezius Muscle Use
-produces visible clavicular lift where the clavicle rise > 5 cm with each inspiration
64
Retractions
- when airway resistance is high the patient must produce a large trans-chest wall pressure gradient
- causes atmospheric pressure to press the skin of the chest tightly against the ribs during spontaneous inspiration
65
Costophrenic Angles
-formed by the costophrenic recesses, the points where the hemidiaphragms meet the chest wall
66
Differences between the parietal and visceral layers
- the visceral layer is about 100 u thick, parietal layer is thinner at about 20 u
- only the parietal layer has stomata (openings) in the mesothelial layer
- only the parietal layer has nerve fibers that sense pain
67
Purpose of pleural fluid
- acts as a lubricant between the visceral and parietal layers to aid in lung movement during breathing
- acts to cohesively bind the two pleural layers together so that chest wall forces can be transmitted to the lungs
68
Transudative Pleural Effusion Fluid
- usually results from conditions that normally produce and remove pleural fluid to get out of balance
- fluid is clear, similar to blood plasma
69
Exudative Pleural Effusion Fluid
- often caused by disease of the pleura itself
| - fluid is usually cloudy and contains large amounts of protein
70
Hilus
a depression or pit at the part of an organ where vessels and nerves enter
71
Why are the lungs divided into lobes and lobules?
- each lung lobe has minimal connection with the other lobes
- the segments are functionally independent
- this increases efficiency and limits the spread of pathology throughout the lung
72
systemic circulatory system
high pressure, high resistance, long distance system that carries blood to the entire body
73
pulmonary circulatory system
low pressure, low resistance, short distance system that carries blood to the pulmonary capillary beds where gas exchange occur
74
Lymph fluid
- fluid flows out of arteriole end of the capillary
- about 90% is reabsorbed at the venous end
- 10% becomes part of interstitial fluid that surrounds the tissue cells
- Lymphatic capillaries pick up excess interstitial fluid and proteins and return them to the venous blood
75
Pulmonary Edema
occurs when the volume of liquid moving into the pulmonary interstitial from the capillaries is greater than the amount of fluid removed by reabsorption and lymphatic drainage
-will cause pulmonary restriction (reduced alveolar expansion)
76
Where are the peripheral and central chemoreceptors located in the brain?
- wall of aorta and carotid arteries
| - medulla oblongata
77
What controls the rate and depth of breathing in normal people?
The PaCO2 of the blood reaching the brain.
- increased H+ concentration in the ECF stimulates ventilation
- decreased H+ concentration in the ECF inhibits (reduces) ventilation
78
Ventral and Dorsal Respiratory Groups
VRG: contains both expiratory and Inspiratory neurons, but mostly associated with expiration
DRG: mostly contains inspiratory neurons
79
Scalene Muscles
- arise from the lower five or six cervical vertebrae and insert on the clavicle and first two ribs
- lift the upper chest when active
- slightly active during rating inhalation and become more active with forceful inspiration and when ventilatory demands increase
- when alveolar pressure decrease to -10 cmH2O
80
Sternocleidomastoid Muscles
- originate from the manubrium and clavicle and insert on the mastoid process of the temporal bone
- can function to lift the upper chest
- become active during forceful inspiration and become visible as thick bands on either side of the neck
- increases the anteroposterior diameter of the chest
81
What is the narrowest point in the airway of the adult an the older child?
glottis
82
What is the point of division between the upper and lower airways?
glottis
83
What is the narrowest point in the neonatal and younger child's upper airway?
Cricoid
84
Cricoid Cartilage
- lies below thyroid cartilage
- only complete tracheal ring
- thyroid and cricoid are connected by the cricothyroid membrane
85
Larynx
1. It's a gas conducting passage between the upper and lower airways
2. protects the lower airway from aspiration of foreign materials
3. participates in the cough mechanism
4. participates in speech
86
What is the epiglottis attached to?
- to the thyroid cartilage and the base of the tongue
| - it covers the glottis during swallowing
87
Where do the vocal cords lie?
in the center of the larynx
88
Tracheal Reflex
- vagovagal reflex
| - causes a violent cough when a foreign object or irritation stimulates the trachea
89
Carinal Reflex
- vagovagal reflex
| - causes a powerful cough when the tracheal carina is stimulated
90
Where does the two main stem bronchi divide?
at the angle of Louis (sternal angle)
91
Which bronchus is more directed into the lungs?
right bronchus because it is wider, shorter, and more vertical than the left main bronchus
92
Cartilaginous Airways
- provide structural support to the airways where bulk flow is primary mechanism of gas movement
- include: trachea, mainstem bronchi, lobar bronchi, segmental bronchi, and sub-segmental bronchi
93
Non-Cartilaginous Airways
- contain elastic fibers
- diffusional flow is primary mechanism for gas movement in these airways
- are the smallest units of conducting zone
- includes: bronchioles and terminal bronchioles (terminal and respiratory bronchioles, and alveolar ducts and sacs)
94
Where do cilia and goblet cells disappear?
at the respiratory bronchioles
95
What are contained in the lamina propria?
contains submucosal ducted mucous glands, fibrous tissue, blood and lymph vessels, branches of the vagus nerve and two bands of smooth muscle
-the peribronchial sheath covers the outer lamina propria
96
How much mucus does the goblet cells and mucus glands produce in a day?
100 ml/day
97
What makes up the anatomical dead space?
The airways from the nares to the terminal bronchioles
98
How much is dead space?
1 ml/lb of ideal body weight
99
Type I pneumocytes
- flatter squamous epithelial cells
| - become primary gas exchange cells in the lungs
100
Type II pneumocytes
- cuboidal secretory cells
- have microvilli and produce pulmonary surfactant
- can proliferate and differentiate into type I cells
101
Segmental Bronchi
- cartilaginous airways
1. have connective tissue coverings
2. are larger than 1 mm in diameter
102
Bronchioles
- non-cartilaginous airways
1. lack connective tissue coverings
2. are less than 1 mm in diamenter
103
Lobes
- Right lung divided into 3 sections
| - Left lungs divided into 2 sections
104
Clara cells
- non-mucous and non-ciliated secretory cells located in the bronchioles
- help protect the bronchiolar epithelium by
1. secreting a variety of products including Clara cell secretory protein an a chemical component of pulmonary surfactant
2. detoxifying harmful substances inhaled into the lungs
- can multiply and differentiate into ciliated cells to help regenerate damaged epithelium
105
Pores of Kohn
- small openings in the alveolar septa
- NOT sites of gas exchange
- about 10-14 micros in diameter
106
Canals of Lambert
-connect alveoli to secondary bronchioles
107
Purpose of the pores and canals
- may be an adaptation to permit collateral gas flow to alveoli that have been blocked by a proximal obstruction
- probably provide very little collateral ventilation in normal lungs
- contribute to the spread of bacterial infections and cancer cells
108
Pulmonary Surfactant functions
- decreases surface tension forces at the alveolar air/water interface
- helps prevent alveolar collapse at the end of expiration, especially smaller ones
- keeps distal airways and lung parenchyma clinically sterile
109
Causes of Edema
1. increased hydrostatic pressure inside capillaries
2. reduced oncotic pressure
3. increased capillary wall permeability (makes capillaries leaky)
4. reduced lymphatic draining
110
Barorecptors
- groups of cells specialized to respond to stretching of blood vessel walls caused by increases in arterial blood volume and pressure inside the vessel
- aortic body baroreceptors send messages to the cardiovascular control centers to regulate blood pressure
111
Dew Point
the gas temperature at which condensation occurs
112
Cohesion
- occurs molecules of the same material stick together
| - surface tension
113
Adhesion
- occurs when molecules of different materials stick together
- capillary action
114
Conduction
- the movement of heat energy through a stationary solid
| - heat transferred to the metal handle of the pot
115
Convection
- fluid motion
- movement of gases or liquids containing heat energy from warmer to cooler areas
- hotter molecules of water near the bottom of the pot transfer heat to colder molecules near the top
116
Critical pressure
the pressure needed to liquefy the vapor phase at temps below critical temp
117
Pascal's Principle
liquids and gases exert pressure equally in all directions
118
Pressure formula
pressure=force/area
119
Pressure Conversions
760mmHg=760torr, 1 atm, 101,325 Pa, 101.3 kPa, 14.7 psi, 1,034 cmH2O
120
Dalton's Law of Partial Pressure
-in a mixture of gases, each gas will exert a part of the total pressure
-in a normal person at sea level:
water vapor pressure = 47 mmHg
Nitrogen= 573mmHg
CO2= 40 mmHg
O2=100mmHg
121
Reynold's Number
predicts whether fluid flow will be laminar or turbulent
| -if # greater than 2000 its turbulent
122
Flow formula
flow=volume/time
123
Fluid Velocity
- law of continuity requires that the forward velocity of the water must increase to maintain a constant flow rate throughout the tube
- velocity of a fluid flowing through tube at a constant flow rate varies inversely with the cross-sectional area of tube
124
Bulk vs. Diffusional Flow
- large airways have bulk flow, more turbulent in larger airways
- small airways have diffusional flow, more laminar flow in smaller airways
125
Resistance to flow
- determined by tube radius, tube length, and fluid viscosity
- R=(P1-P2)/flow
126
Surface Tension
- cohesive forces pull the molecules at the liquid gas interface together strongly
- acts to increase elastic recoil
- helps lung to empty during exhalation
- too much will lead to low compliance and could cause lungs to collapse
- too little results in air trapping and lung hyperinflation
- during inspiration they have no effect on alveolar expansion or gas exchange
127
Pulmonary Surfactant
-reduce surface tension
128
Bernoulli's Principle
-as velocity increases, pressure decreases because of less collisions
129
Graham's Law of Diffusion
- diffusion is inversely proportional to the square root of the molecular weight of the gas (lighter molecules diffuse faster than heavy ones)
- CO2 diffuses across A/C membrane about 19 times faster than O2
- higher the concentration of O2 in the alveoli the more O2 diffuses across the A/C membrane
130
Solubility Coefficients
Oxygen: 0.023 ml O2 / ml plasma
CO2: 0.510 ml CO2 / ml plasma
-only 0.003 ml can dissolve in each dl of plasma for every 1 mmHg of PO2
131
Spirometry Pulmonary Functions
Box
1. TLC
2. VC+RV
3. IC+FRC
4. IRV+VT+ERV+RV
- IRV+VT+ERV=VC
- IRV+VT=IC
- ERV+RV=FRC
132
Transrespiratory Pressure Gradient
- across the entire respiratory system
- difference between atmosphere and alveoli
- book says: (Pao-Pbs)
- airway opening pressure and alveolar pressure are same during breathing
- responsible for moving air into and out of alveoli during breathing
133
Transpulmonary Pressure Gradient
- across the lungs
- responsible for moving air into and out of lungs
- (Pao-Ppl)
134
Transthoracic Pressure Gradient
- pressure across the chest wall
| - represents the total energy needed to expand or contract both the lungs and the chest wall
135
Regional factors affecting the distribution of gas in the normal lung result in which of the following?
More ventilation goes to the bases and lung periphery
136
A patient has a PCO2 of 56 mm Hg. Based on this information, what can you conclude?
The patient is hypoventilating
137
Which of the following pressure gradients is responsible for maintaining alveolar inflation?
Transpulmonary Pressure Gradient
138
Which of the following pressure gradients is responsible for the actual flow of gas into and out of the lungs during breathing?
Transrespiratory Pressure Gradient
139
The presence of surfactant in the alveoli tends to do which of the following?
Increases compliance
140
How can the body effectively compensate for physiologic deadspace?
increasing tidal volume
141
What is the single best indicator of the adequacy or effectiveness of alveolar ventilation?
PaCO2
142
An area with perfusion but no ventilation (and thus a V/Q of zero) is termed?
Shunt
143
An area with ventilation but no perfusion (and thus a V/Q undefined though approaching infinity) is termed
Dead space
144
Hypercapnia
excessive amount of CO2 in blood
145
What is the normal P(A - a)O2 range while breathing room air?
10 mm Hg to 25 mm Hg
146
Which pressure remains subambient throughout ventilation?
Pleural pressure
147
What are the two forces opposing lung inflation?
Elastic resistance and frictional resistance
148
Hysteresis
the difference between expiration and inspiration pressure curves
149
What does hysteresis in the lung show?
Shows that another force besides elastic recoil must be at work during deflation of the air filled lung which is surface tension
150
Work Formula
WOB=change in pressure x change in flow
| -force x distance moved
151
a/A Ratio
- evaluates the efficiency of O2 transfer from alveoli into blood
- normal a/A ratio is > or equal to 90%
- normally 90% of alveolar O2 diffuses across the A/C membrane
- a high P(A-a)O2 and a low a/A ratio are evidence of a diffusion defect
152
P(A-a)O2
- difference between alveolar and arterial PO2
- should be a very low number
- less than 5-10 torr on room air and less than or equal to 65 torr on 100% FiO2 or less than the patient's age
153
How is oxygen carried in the blood?
Dissolved in plasma and bound to hemoglobin
154
Dissolved O2 in blood
PaO2 x 0.003= 100 torr x 0.003 = 0.3 vol%
155
Factors that lower CaO2 without affecting PaO2
anemia(reduction in Hb), CO poisoning, metHb, and various conditions that cause an excessive and permanent shift in the HbO2 curve
156
Normal C(a-v)O2
about 5 vol%
157
Modes of CO2 transport
1. dissolved in plasma 5-10%
2. bound as carbamates: about 12-22%
3. as bicarbonate ions both in RBC and in plasma: about 80-90%
158
Anatomical Shunts
occur when blood passes from the right side of the circulation to the left side without entering the pulmonary capillaries
-congenital heart defects, and tumors of the pulmonary vasculature
159
Capillary Shunts
occur when the blood from the right circulation passes through the pulmonary capillaries but no gas exchange occurs
-most common cause is atelectasis
160
Shunt-like Effect
occurs when pulmonary perfusion exceeds alveolar ventilation
- most common causes are hypoventilation, uneven distribution of ventilation, and A/C diffusion defects
- usually responsive to oxygen therapy
161
Venous Admixture
final result of all types of shunting
| -deoxygenated blood mix with oxygenated blood and lower the overall O2 content of arterial blood
162
Cardiac Output
Stroke Volume x Heart Rate
163
V/Q ratio
- if ventilation decreases, V/Q ratio will become lower
- if perfusion decreases, V/Q ratio will become higher
- normally alveolar ventilation/cardiac output= 4.2 L/min / 4.9 L/min = 0.8
164
O2 attached to Hb
Not part of the PaO2
Respiratory Therapy 100
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