Question Answer
what is ventilation the process that moves gases between the external environment and the aveoli. mechanism by which oxygen is carried from the atmosphere to the aveloi and by which carbon dioxide is carried from the aveoli
Pressure difference across the lungs relative to the atmospheric pressure and is an essential buling block in the study of ventilation and pulmonary mechanics
Pressure gradient Difference between 2 pressures
What is pressure gradient responsible for moving air in and out of the lung
gas always flows from high to low pressures
No gas flows between 2 equal points
Driving pressure pressure difference between 2 points in a tube or vessel. It is the force moving gas or fluid through the tube or vessel
Transairway pressure or transrespiratory pressure the barometric pressure difference between the mouth pressure Pm and the alveolar pressure (Palv)
Transairway pressure is written Pta = Pm – Palv (mmHg)
Transmural pressure the pressure differences that occur across the airway wall (Ptm)
How is the transmural pressure calculated by subtracting the intra-airway pressure (Piaw) from the Pressure on the outside of the airway (Poaw)
Transmural pressure is written Ptm = Piaw – Poaw
Define Positive transmural pressure Said to exist when pressure is greater within the airway than the pressure outside the airway
Define Negative transmural pressure Said to exist when pressure is greater outside the airway than the pressure inside the airway
Transpulmonary pressure difference between the alveolar pressure (Palv) and the pleural pressure (Ppl)
Transpulmonary pressure is writeen Ptp = Palv – Ppl
Transthoracic pressure (Ptt)the difference between the alveolar pressure (Palv) and the body surface pressure (Pbs)
Transthoracic pressure is written Ptt = Palv – Pbs
the flow of gas in and out of the lungs is caused by the transpulmonary and transairway pressure changes that occur in response to the action of the diaphragm
When the diaphragm moves down thoracic volume increases and intrapleural and intra-alveolar pressure decreases
When the diaphragm moves up Thoracic volume decreases and intraplueral and intra-alveolar pressure increase
Define end-inspiration During inspiration gas from the atmosphere moves down the trachea-bronchial tree until the intra-alveolar pressure ant he barometric pressure are in equalibrium (pre-expiration)
Define end-expiration gas flows out of the lungs until the intra-alveolar pressure and the barometric pressure are once again in equilibrium (pre-inspiration)
at rest normal excursion (movement) of the diaphragm is about 1.5 cm
normal intra pleural change is about 3 to 6 cm H20 pressure (2 to 4 mmHg)
during deep inspiration the diaphragm may move 6 to 10 cm
during food expiration the intrapleural pressure may climbe between 70 and 100 cmH2O above atmospheric pressure
when the patient receives a positive pressure breath from a mechanical ventilator… the intra-alveolar pressure progressively rises above atmospheric pressure
during exhalation… the intra-alveolar pressure decreases toward atmospheric pressure
at end-expiration the intra-alveolar pressure is in equilibrium with atmospheric pressure
botht he lungs and the chest wall each have their own elastic properties
the chest wall has a natural tendancy properties of the lung tissue to move outward or expand as a result of the bones of the thorax and surrounding muscles
The lungs have a natural tendancy to move inward or collapse, because of the natural elastic
What is lung compliance how readily the elastic force of the lungs accepts a volume of inspired air, defined as the change in lung volume per unit pressure change (CL)
mathematically lung compliance is expressed in liters per centimeter of water pressure (L/cm H2O)
at rest the average CL for each breath is about 0.1 L/cm H2O (Approximately 100mL of air is delivered into the lungs per 1 cm H2O pressure change)
when lung compliance is increased the lungs accept a greater volume of gas per unit of pressure change
Both in the normal and abnormal lung CL progressively decreases as the alveoli approach their total filling capacity
What is FRC Functional residual capacity
Hooke’s law provides another way to explain compliance by describing the physical properties of an elastic substance
What is Elastance The natural ability of matter to respond directly to force and to return to its original resting position or shape after external force no longer exists (change in pressure per change in volume)
Elastance is the reciprocal of compliance
Hookes law states when a truely elastic body like a spring is acted on by 1 unit of force, the elastic body will stretch 1 unit of length, and when acted on by 2 units of force it will stretch 2 units of length and so forth
When Hookes law is applied to the elastic properties of the lungs, volume is substituted for _________ and pressure is substituted for _________ length, force
tension pneumothorax is a condition if the presssure during mechanical ventilation (positive pressure breath) causes the lung unit to expand beyond its elastic capability the lung unit could rupture allowing alveolar gas to move into intrapleural space and thus causing the lungs to collapse
Define surface tension When a liquid-gas interface exists the liquid molecues at the liquid-gas interface are strongly attracted to the liquid molecues within the liquid mass This molecular cohesive force at the liquid-gas interface is called surface tension
surface tension is measured in dynes per centimeter
one dyne/cm is the force necessary to cause a tear 1 cm long in the surface layer of a liquid.
1 cm H2O pressure equals 980 dynes/cm
laplace’s law describes how the distending pressure of a liquid bubble(not an alveolus) is influenced by (1) the surface tension of the bubble and (2) the size of the bubble itself.
WHen laplaces law is applied to a sphere with one liquid-gas interface the equasion is written as 2 ST P = —- r where P is the pressure difference (dynes/cm2), ST is surface tension (dynes/cm) and r is the radius of the liquid sphere (cm) The factor 2 is required when the law is applied to a liquid sphere with one liquid-gas interface
when laplace’s law is applied to a bubble with two liquid-gas interfaces the numerator contains the factor 4 rather than 2
Laplace’s law shows that the distending pressure of a liquid sphere is directly proportional to the surface tension of the liquid, inversely proportional to the radius of the sphere
the numerator of laplaces law shows as the surface tension of a liquid bubble increases the distending pressure necessary to hold the bubble open increases, or the opposite– when the surface tension of a liquid bubble decreases, the distending pressure of the bubble decreases
the denominator of laplace’s law shows tht when the size of a liquid bubble inccreases the distending pressure necessary to hold the bubble open decreases, or when the size of the bubble decreases the distending pressure of the bubble increases
Define critical opoening pressure the high pressure (With little volume change) that is initially required to overcome the liquid molecular force during the formation of a new bubble
Before the bubble is formed the distending pressure is directly proportional to the radius of the bubble (opposite of what laplace’s law states)
define critical closing pressure when the size of the bubble decreases beyond this point, the liquid molecular force of the bubble becomes greater than the distending pressure and the bubble collapses
Laplace’s law can be restated as k P = — r K = constand (surface tension) P = pressure and is inversely proportional to R (radius) Can be stated as Pr = k
The liquid film that lines the alveolus resembles a bubble or sphere
when the alveolar fluid is permitted to behave according to its natural tendency, a high transpulmonary pressure must be generated to keep the small alveoli open
Pulmonary surfactand is an important and complex substance that is produced and stored in the alveolar type II cells
Pulmonary surfactant is composed of phospholipids (about 90 percent) and protein (about 10 percent)
the primary surface tension-lowering chemical in pulmonary surfactant is the phospholipid dipalmitoyl phosphatidylcholine (DPPC)
The DPPC molecule at the alveolar gas-liquid interface causes surface tension to decrease in proportion to its ratio to alveolar surface area
it is estimated that surface tension of the average alveolus varies from 5 to 15 dynes/cm when the alveolus is small to about 50 dynes/cm when the alveolus is full distended
what are the 2 major elastic forces in the lungs that cause an inflated lung to recoil inward the elastic properties of the lungs, the surface tension of the liquid film that lines the alveoli
define atelectasis complete alveolar collapse
define dynamic refers to the study of forces in action
in the lungs dynamic refers to the movement of gas in and out of the lungs and the pressure changes required to move the gas.
general causes of pulmonary surfactant deficiency acidosis, hypoxia, hyperoxia, atelectasis, pulmonary vascular congestion
specific causes of pulmonary surfactant deficiency acute respiratory distress syndrome (ARDS), infant resporatory distress syndrome (IRDS), pulmonary edema, pulmonary embolism, pneumonia, excessive pulmonary lavage or hydration, drowning, extracorporeal oxygenation
What structures pierce the diaphragm vena cava, esophagus, aorta
What are the 4 critical life functions in order of importance Ventilation, Oxygenation, Circulation, perfusion
Ventilation includes the movement of air down to and including the terminal bronchioles
the best ways to assess ventilation Measure PaCO2
Normal PaCO2 is 35-45 mmHg
Any PaCO2 reading below 35 is hypocapnea
hypocapnea is caused by hyperventilation
any PaCO2 reading above 45 is hypercapnea
hypercapnea is caused by hypoventilation (Failure to ventilate well)
How is PaCO2 measured ABG
Oxygenation is oxygen moving into the blood and transported to the body tissue
define external respiration oxygen getting to the bloodstream
define internal respiration oxygen getting from the blood stream to the body tissues
what are 3 ways to measure oxygenation SpO2, SaO2, PaO2
What are the normals for SpO2, SaO2, and PaO2 SpO2 and SaO2 norms are 95 to 98% and PaO2 is 80 to 100%
What is a critical factor of oxygenation hemoglobin
What are two ways to check circulation pulse, blood pressure
define circulation movement of blood throughout the body
define perfusion pushing or forcing of oxygenated blood into the tissues
shock is a drop in blood pressure
what monitors CO2 levels Medulla
What does FRC stand for Functional Residual Capacity
Define FRC amount of air left in your lungs following a normal exhalation
what creates transairway pressure diaphragm moving downward
diaphragms natural tendency is to relax and move upward
movement of intrathoracic airways tend to what when you breath dialate when ou breath in and constrict womewhat when you exhale
intrapleural pressure is always sub atmospheric (Negative)
compliance is the ease at which lungs accept air
measurement of normal compliance 100 ml per cm of water
during a normal inspiration, intrapleural pressure decreases from its normal resting level which causes the bronchial airways to lengthen and to increase in diameter (passive dialation)
during expiration intrapleural pressure increases which causes the bronchial airways to decrease in length and in diameter
poiseuille’s law arranged for flow states flow is directly proportional to P and r4 and inversely proportional to l and n (Flow will decrease in response to decreased P andn tube radius
flow is profoundly affected by the radius of the tube
poiseuille’s law arranged for pressure states pressure is directly proportional to v, l, and n (presssure will increase in response to a decreased tube radius and decreased in response to a decreased flow rate, tube length, or viscosity)
pressure is a function of the radius to the forth power and therefore is profoundly affected by the radius of a tube
based on the proportionality for flow, it can be stated that because gas flow varies directly with r4 of teh bronchial airway, flow must diminish during exhalation because radius of the bronchial airways decreases
airway resistance (Raw) teh pressure difference between the mouth and the alveoli divided by flow rate.
normal Raw in the tracheobronchial tree is about .5 to 1.5 cm H2O/L/sec
the movement of gas through a tube or bronchial airway can be classified as laminar flow, turbulent flow, or a combination of laminar flow and turbulent flow (tracheobronchial flow)
define laminar gas flow gas flow that is streamlined
define turbulent flow gas molecules that move through a tue in random manner
tracheobronchial or transitional flow occurs in the areas where the airways branch. one or the other may be dominant
dynamic compliance clinically how readily a lung region fills with gas during a specific timie period
frequency dependent the alveoli distal to the obstruction do not have enough time to fill to their potiential filling capacity as the breathing frequency increases. The compliance of such alveoli is said to be frequency dependent
positive end-expiratory pressure (PEEP) the pressure in the alveoli distal to the airways with Raw may still be positive when the next inspiration begins


Question Answer
 1.3 Types of Dead Space Ventilation: Anatomic, Alveolar, Physiologic
 2. Airway Resistance:  The pressure difference (ΔP) between the mouth and the alveoli divided by flow rate (V).

The rate at which a certain volume of gas flows though the bronchial airways is a function of the pressure gradient and the resistance created by the airways themselves (Raw –> Resistance of AirWays).
Mnemonic device: Raw Pig Van
Raw = ΔP/V
 3. Alveolar Dead Space: occurs when an alveolus is ventilated but not perfused with pulmonary blood. Thus, the air that enters the alveolus is not effective in terms of gas exchange, because there is no pulmonary capillary blood flow.
 4. Anatomic Dead Space: Volume of gas in the conducting airways (nose, mouth, pharynx, larynx, and lower airways)

1 mL of anatomic dead space per pound (1 mL/lb).
 5. Apnea: Complete absence of spontaneous breathing.
 6. Biot’s Respiration: Short episodes of rapid, uniformly deep inspirations followed by 10 to 30 seconds of apnea. Seen in sufferers of meningitis.
 7. Cheyne-Stokes Breathing: 10 to 30 seconds of apnea, followed by a gradual increase in the volume and frequency of breathing, followed by a gradual decrease in the volume of breathing until another period of apnea.
 8. Driving Pressure: The pressure difference between two points in a tube or vessel. Gas/liquids always move from high to low pressure.
 9. Dynamic Compliance: The change in volume of the lungs divided by the change in pulmonary pressure during the time required for one breath. DIffers from lung compliance in that lung compliance is determined during a period of no gas flow, whereas dynamic compliance is measured during a period of gas flow. In a healthy lung, the two are about equal (1:1 ratio).
 10. Dyspnea: Breathing difficulty of which the patient is aware.
 11. Effect of Compliance on Ventilatory Patterns: Decrease in compliance = increase in respiratory rate and a decrease in tidal volume (lots of shallows breaths).
 12. Effect of Resistance on Ventilatory Patterns. Increase in resistance = decrease in respiratory rate and increase in tidal volume (long, deep breaths).
 13. Eupnea: Normal, spontaneous breathing
 14. Factors that decrease the time to fill the lung: Decreased resistance and decreased compliance. If all other factors are constant, then a decrease is compliance is directly proportional with a decrease in time constant and potential filling capacity. (1:1 ratio)
 15. Factors that increase time to fill the lung: Increased resistance and increased compliance. If all other factors are constant, then increase in resistance is directly proportional with increase in time constant. (1:1 ratio)
 16. Hooke’s Law: Describes compliance using the physical properties of an elastic substance (elastance).

 Mnemonic device: Every Person Votes
 EL = ΔP/ΔV
 Elastance is the reciprocal of compliance; thus, lungs with high compliance have low elastance and vice versa.
 Fun fact: when the pressure exceeds the elastic limits of the lung, the ability of lung to increase in response to said pressure rapidly decreases. Should pressure continue to rise, the elastic substance (i.e. the lung) will ultimately break.
 17. How surface tension affects different sized liquid bubbles according to Laplace’s Law: Laplace’s law shows that the distending pressure of a liquid sphere is (1) directly proportional to the surface tension of the liquid and (2) inversely proportional to the radius of the sphere.

Thus, if a bubble has the same surface tension (ST) as a bubble with half its radius (r), then the smaller bubble will require twice the amount of distending pressure (P) to stay open as the larger bubble.
P = 4*ST/r
 18. Hyperpnea: Increased depth/volume of breathing without increased frequency.
 19. Hyperventilation: Increased alveolar ventilation, caused any pattern that causes increased volume or increased breathing frequency
 20. Hypoventilation: Decreased alveolar ventilation, caused by any pattern that causes decreased volume or decreased breathing frequency.
 21. Kussmaul’s Breathing: Increased depth (hyperpnea) and increased rate (tachypnea). Associated with diabetic acidosis
 22. Laminar Flow:  Smooth, streamlined gas flow. Gas moves in a pattern that is parallel to the tube.

Occurs at low flow rates and low pressure gradients.
 23. Laplace’s Law: The distending pressure (P) of a liquid bubble is influenced by the surface tension (ST) of the bubble and the size (radius = r) of the bubble itself.

Mnemonic device: Pizza 4 STudying Rules!
P = 4*ST/r
This concept is applied to the liquid film lining of alveoli. When alveoli are permitted to behave according to their natural tendency (i.e. collapsing), a high transpulmonary pressure must be generated to keep small alveoli open.
 24.Lung compliance:  How readily the elastic force of the lungs accepts a volume of inspired air. Compliance (CL) is defined as the change in lung volume (ΔV) per unit of pressure change (ΔP).

 Mnemonic device: CLinton for Vice President
CL = ΔV/ΔP
 25. Minute Alveolar ventilation: Minute alveolar ventilation (Va) is the difference between tidal volume (Vt) and anatomic dead space (Vd), multiplied by the respiratory rate (breaths/min).

Va = (Vt – Vd) x breaths/min
In general, higher Va = Higher Vt, lower Vd, and lower breaths/min (although high breaths/min + high Vt would also = higher Va)
 26. Natural tendencies of the lungs: The lungs have a natural tendency to collapse due to their natural elastic properties, while the chest wall has a natural tendency to expand.
 27. Normal, high, and low compliance: At rest, the average CL for each breath is about 0.1L/cm H20 (or

100mL/cm H20).
High compliance means the lungs will accept a greater volume of gas per unit of pressure change.
Low means that the lungs will accept a lower volume of gas per pressure change.
Fun fact: as pressure increases, both volume and compliance will progressively decrease, because the alveoli cannot be filled to infinity.
 28. Orthopnea:  Patient can only breath comfortably while sitting upright
 29. Physiologic Dead Space:  sum of the anatomic dead space and alveolar dead space
 30. Poiseuille’s Law:  Poiseuille’s (pronounces PWAH-SOY) law is a way of explaining the dynamic characteristics of the lungs (i.e. the in and out movement of air int he lungs and the pressure needs to move the gas) using flow and resistance.

 Key point: pressure is directly proportional to flow and inversely proportional to tube radius; flow is directly proportional to both tube radius and pressure.
 31. Poiseuille’s Law Arranged for Flow:
Flow (V) will increase if pressure (P) increases and/or tube radius (r) increases.
Flow will decrease if pressure decreases and/or tube radius decreases.
V = ΔPr^4.
Fun fact: Supposing that pressure remains constant, if tube radius decreases by 50%, then flow will decrease to 1/16th.
 32. Poiseuille’s Law Arranged for Pressure: Pressure will increase if flow increases and/or tube radius decreases. (Will also increase if tube length and viscosity increase).

Pressure will decrease if flow decreases and tube radius increases.
P = V/(r^4).
Fun fact: if flow remains constant, then when tube radius decreases by 50%, driving pressure increases 16x.
 33. Role of diaphragm and pressure changes in positive pressure ventilation: 1. Inspiration: Gas is forced in, and so alveolar pressure increases above atmospheric pressure; intrapleural pressure increases above atmospheric pressure; the diaphragm is pushed downward.

2. End-inspiration: Intra-alveolar pressure and intrapleural pressure are both 30 cm H20 above atmospheric pressure; downward pushing of diaphragm stops.
3. Expiration: Gas flows outward as the intra-alveolar pressure decreases towards atmospheric pressure; intrapleural pressure decreases towards its resting level below atmospheric pressure; the diaphragm moves upward towards its resting level.
4. End-expiration: No gas flow; intra-alveolar pressure is at equilibrium with atmospheric pressure; intrapleural pressure is resting below atmospheric pressure; the upward movement of the diaphragm stops.
 34. Role of the diaphragm and pressure changes in normal ventilation: 1. Inspiration: diaphragm move downward, and intra-pleural pressure decreases. Intra-alveolar pressure is below atmospheric pressure, so gas flows inward.

2. End-Inspiration: the diaphragm stops moving, and the intra-pleural pressure holds at a level below resting level. The intra-alveolar pressure is in equilibrium with the atmospheric pressure.
3. Expiration: the diaphragm relaxes and moves upward, and so the intrapleural pressure increases. Intra-alveolar pressure is now above atmospheric pressure.
4. End-Expiration: upward movement of the diaphragm stops, and the intra-pleural pressure holds at resting level. Intra-alveolar pressure is in equilibrium with atmospheric pressure.
 35. Surface Tension: The molecular cohesive force at the liquid-gas interface.
 36. Surfactant: A substance that decreases surface tension. Pulmonary surfactant is produced and stored in the alveolar type II cells, and is composed of 90% phospholipids and 10% protein.

By decreasing alveolar surface tension, surfactant prevents alveoli from collapsing, which is especially important in the smaller alveoli.
 37. Surfactant Deficiency (general): Acidosis (diabetes), hypoxia, hyperoxia, atelectasis, and pulmonary vascular congestion.
 38. Tachypnea: Rapid breathing frequency
 39. Time Constant: The time (measured in seconds) necessary to inflate a particular lung region to 60% of its potential filling capacity.
 40. Transairway Pressure: The barometric pressure difference between mouth pressure and alveolar pressure
 41. Transmural Pressure: The differences in pressure that occur between the inside and outside of the airway wall.
 42. Transpulmonary Pressure: The difference between alveoli pressure and pleural pressure
 43. Transthoracic Pressure: The difference between alveoli pressure and body surface pressure (i.e. the pressure outside the thoracic cavity).
 44. Turbulent Flow: Molecules that move through a tube in a random manner. Gas flow encounters resistance from both sides of the tube and collisions with other gas molecules.



1. Driving Pressure The pressure difference between two points in a tube or vessel; it is the force moving gas or fluid through the tube or vessel.
2. Negative Transmural Pressure Is said to exist when the pressure greater outside the airway than the pressure inside the airway.
3. Positive Transmural Pressure Is said to exist when the pressure is greater within the airway than the pressure outside the airway.
4. Pressure Gradient The difference between two pressures.
5. Pressure Gradients are responsible for: 1. Moving air in and out of the the lungs. 2. Maintaining the lungs in an inflated state.
6. Transairway Pressure (Pta) (also called transrespiratory pressure) is the barometric pressure difference between the mouth pressure (Pm) and the alveolar pressure (Palv).
7. Transmural Pressure (Ptm) is the pressure differences that occur across the airway wall.
8. Transpersonal Pressure (Ptp) is the difference between the alveolar pressure (Palv) and the pleural pressure (Ppl)
9. Transthoracic Pressure (Ptt) is the difference between the alveolar pressure (Palv) and the body surface pressure (Pbs)
10. Ventilation The process that moves gases between the external environment and the alveoli.

 

Question Answer
 1. What is Ventilation? Ventilation is the process that moves gases between the external environment and the alveoli. It is the mechanism which oxygen is carried from the atmosphere to the alveoli and which carbon dioxide is carried from the alveoli to the atmosphere.
 2. What is another name for atmospheric pressure? Barometric pressure is another name for atmospheric pressure.
 3. What is the abbreviation for atmospheric pressure and barometric pressure? Patm is atmospheric pressure and PB is barometric pressure.
 4. What is atmospheric pressure? The force exerted by the air that surrounds the earth and the body
 5. What is the barometric pressure under standard conditions at sea level? Under standard conditions the atmospheric pressure/barometric pressure is 760 mmHg
 6. What are the units for expressing atmospheric pressure? The units for expressing atmospheric pressure is either mmHg which is millimeters of mercury/torr or cmH2O which is centimeters of water
 7. When pulmonary pressures are used to describe ventilation pressures what is the baseline? The baseline is 0 but it is referenced to 760mmHG
 8. What is a pressure difference called? A pressure gradient
 9. Pressures must move from an area of what to what? High pressure to low pressure
 10. In order for gas to flow from one point to another what must there be? A pressure difference
 11. What are the mechanisms of pulmonary ventilation that create a pressure gradient? The primary principles of ventilation
 12. What must be established for pulmonary ventilation to occur? A mechanism that causes a pressure gradient between the atmosphere and the intra alveoli
 13. Atmospheric pressure is _____ than intra alveoli pressure, air moves _____ the pressure gradient. Gas moves from the ____ to the _____ and inspiration occurs. higher ; Down; Atmosphere; Alveoli
 14. Intra-alveolar pressure is ____ than the atmospheric pressure, Air moves ____ the pressure gradient from the ____ to the ____ and expiration occurs. greater; down; alveoli; atmosphere
 15. In order for either expiration or inspiration to occur what must be created? A means to create a pressure gradient for inspiration, in which the intra alveolar pressure is lower than the atmospheric pressure, and a pressure gradient for expiration in which the intra alveolar pressure is greater than the atmospheric pressure.
 16. What is Boyle’s law? Boyle’s Law states that the pressure of a gas is inversely proportional to its volume; so if pressure is increased volume is decreased if volume is increased pressure is decreased.
 17. Applying Boyle’s law if the thoracic cavity increases in size which means volume what happens to the pressure? The pressure decreases.
 18. What causes the thoracic cavity to increase in size? The downward contraction of the diaphragm.
 19. During inspiration how does the pressure gradient move? From the atmosphere to the alveoli.
 20. What stimulates inspiration? The diaphragm is pulled downward.
 21. What is equilibrium point? The point at which the pressure inside equals the pressure outside.
 22. What ends inspiration? The end of inspiration occurs when the equilibrium point is reached and gas flow stops.
 23. What stimulates expiration? The relaxation/ recoiling upward of the diaphragm
 24. What ends expiration? The point at which the pressure inside equals the pressure outside
 25. What is the respiratory cycle? The respiratory cycle is inspiration, end inspiration, expiration, and end expiration
 26. During inspiration gas moves through what three regions? The atmosphere, tracheobronchial tree, and the alveoli.
 27. During expiration gas moves through what three regions? The alveoli, Tracheobronchial tree, and the atmosphere.
 28. What is the Driving pressure? The driving pressure is the force moving gas or fluid through the tube or vessel. In other words the force required to move the gas through the tube. It is the difference between two points.
 29. What is the Transrespiratory pressure? Prs is also called transairway pressure It is the difference between the barometric/mouth pressure and the alveolar pressure.
 30. What is the Transmural pressure? The pressure difference that occurs across the airway wall.
 31. What is the Transpulmonary pressure? The difference between the alveolar pressure and the pleural pressure.
 32. What is the transthoracic pressure? The difference between thee alveolar pressure and the body surface pressure.
 33. The chest wall has a natural tendency to what? move outward/ expand
 34. The lungs have a natural tendency to what? move inward/collapse
 35. What is lung compliance? How readily the elastic force of the lungs accepts a volume of inspired air. Lung compliance is the change in lung volume per unit pressure change it determines how much air in liters the lungs will accommodate for each centimeter of water pressure change
 36. What is elastance? The natural ability of matter to respond directly to force and to return to its original resting position or shape. It is the change in pressure per change in volume. It is the opposite of compliance. So if you have an increased compliance there will be a decreased elastance.
 37. What happens when a force exceeds the elastic limits of the substance? The ability of length to increase in response to force decreases rapidly if the force continues to rise the substance will break.
 38. What is tension pneumothorax? Pressure causing the lung unit to expand beyond its elastic capability could cause the lung to rupture allowing alveolar gas to enter into the pleural space resulting in a collapsing of the lungs.
 39. What is Hooke’s Law? When an elastic body is acted on by one unit of force the elastic body will stretch one unit of length and so on this is only true within the normal function range of the elastic body if it exceeds the elastic limits the ability of the length to increase in response to force decreases rapidly and the body will break if the force is continued.
 40. What is surface tension? It is the molecular, cohesive force at the liquid gas interface, it decreases the size of the alveoli, and it is formed from water molecules being attracted by other water molecules below and beside them.
 41. What is Laplace’s law? Laplace’s law states that the distending pressure of a liquid sphere is directly proportional to the surface tension of the liquid and inversely proportional to the radius of the sphere.
 42. What is critical opening pressure? The high pressure that is initially required to overcome the liquid molecular force during the formation of a new bubble.
 43. What is pulmonary surfactant? The water molecules in surface tension repel surfactant molecules breaking the tension surfactant is a shield that protects the liquid from contacting air.
 44. When is more surfactant needed and why? More surfactant is needed at the end of expiration because air is about to be inhaled.
 45. What is atelectasis? Atelectasis is the collapsing of the lungs
 46. What is dynamic? It refers to the study of forces in action. In the lungs it is the movement of gas in and out of the lungs and the pressure changes required to move to gas.
 47. What is static? Things that are not moving
 48. What is Poiseuille’s law arranged for flow? According to Poiseuille’s Law flow is directly proportional to Pressure and Radius and inversely proportional to the length and viscosity. So flow will decrease in response to a decrease pressure and radius but increase in response to a decreased length and viscosity.
 49. What is Poiseuille’s law applied to the bronchial airways? During inspiration according to Poiseuille’s law pleural pressure decreases from its normal resting level which causes the bronchial airways to lengthen and increase in diameter During expiration pleural pressure increases causing the bronchial airways to decrease in length and diameter.
 50. What is Poiseuille’s law arranged for pressure? According to Poiseuille’s Law pressure is directly proportional to viscosity length and volume and inversely proportional to the radius. So pressure will increase in response to a decreased radius and decrease in response to a decreased rate, length, and viscosity. Pressure will decrease in response to an increased radius and increase in response to an increased rate, length or viscosity.
 51. What is airway resistance? The pressure difference between the mouth and the alveoli divided by flow rate. The rate at which a certain volume of gas flows through the bronchial airways is a function of the pressure gradient and the resistance created by the airways to the flow of gas.
 52. What is Raw? Raw is airway resistance it is the units cmH2O dived by L/sec.
 53. What is the normal values of Raw? The normal values is 0.5 to 1.5 patients with COPD normal would be higher than 1.5 and newborns have a higher normal value.
 54. What is Laminar flow? The gas flow that is streamlined, this pattern occurs at low flow rates and at low pressure gradients the molecules move in a pattern parallel to the sides of the tube.
 55. What is Turbulent flow? Gas molecules move in a random manner, This pattern occurs at high flow rates and at high pressure gradients, the flow encounters resistance from sides and collisions.
 56. What is time constant? The time necessary to inflate a particular lung region to about 60% of its potential filling capacity, it is the product of airway resistance and lung compliance.
 57. What is meant by long time constant? Lung regions that have an increased resistance or compliance require more time to inflate.
 58. What is meant by short time constant? Lung regions that have a decreased resistance or compliance require less time to inflate.
 59. How is time constant calculated? Airway resistance multiplied by the lung compliance.
 60. What is dynamic compliance? The change in the volume of the lungs divided by the change in the transpulmonary pressure during the time required for one breath.
 61. what is meant by frequency dependent? The alveoli do not have enough time to fill to their potential filling capacity as the breathing increases.
 62. What is tidal volume? The volume of air that normally moves in and out of the lungs in one breath.
 63. What is the normal ventilatory rate? The normal ventilator rate is 12 to 18 breaths per minute in adults.
 64. What is the I:E ratio? The I:E ratio is 1:2 this means the time required to inhale a normal breath is about half the time required to exhale the same breath.
 65. What is alveolar ventilation? The inspired air that reaches the alveoli.
 66. Does alveolar ventilation have an effect on gas exchange? yes
 67. What is dead space ventilation? The inspired air that does not reach the alveoli.
 68. What is anatomic dead space? It is normal and it is the volume of gas in the conducting airways down to the respiratory bronchioles which are not included so the nose mouth pharynx larynx and lower airways not including the respiratory bronchioles. It is the weight times breaths per minute.
 69. What gas combination is found in the anatomic dead space? A combination of non fresh gas (anatomic dead space) and fresh gas (gas from atmosphere).
 70. What is more effective in alveolar ventilation taking less breaths with more depth or more breaths with less depth? Taking less breaths with more depth (breathing deeper)
 71. What is physiologic dead space? It is the sum of the anatomic dead space and alveolar dead space
 72. If the lung is constricted it is ____ to put air in than to excel air easier
 73. What is apnea? Complete absence of spontaneous ventilation.
 74. What is eupnea? Eupnea normal spontaneous breathing, typical ratio of 1:2.
 75. What is Biot’s breathing? Biot’s breathing short episodes of rapid uniformly deep inspiration followed by 10 to 30 seconds of apnea associated with patients that have head injuries.
 76. What is hypernea? Increased depth/volume of breathing with or without an increased frequency.
 77. What is hyperventilation? Increased alveolar ventilation that the PAco2 dcreases.
 78. What is hypoventilation? Decreased alveolar ventilation that causes the PAco2 to also decrease.
 79. What is tachypnea? A rapid rate of breathing normal is 25 or greater.
 80. What is Cheyne strokes breathing? 10 to 30 seconds of apnea followed by a gradual increase in the volume and frequency of breathing followed by a gradual decrease in the volume of breathing until another period of apnea usually in stroke patients.
 81. What is kussmaul’s breathing? Both an increased depth (hypernea) and a rate of breathing, it is as fast and deep as can be, it is usually found in diabetic patients.
 82. What is orthopnea? Condition in which an individual is able to breathe more comfortable in the upright position.
 83. What is Dyspnea? Difficulty in breathing of which the individual is aware.
 84. What is functional residual capacity and it’s importance? Functional Residual Copacity is when the lungs and chest wall recoil/relax the resting volume remaining in the lung.
 85. Why is ventilation more effective when in upright position?
 86. What is alveolar dead space? This is abnormal occurs when an alveolus is ventilated but not perfused with pulmonary blood not effective in terms of gas exchange.
 87. What can change lung compliance? The lung tissue.
Question Answer
What is pH? In Simple terms pH simply refers to the hydrogen ion concentration in the body. Blood pH would be Hydrogen Ion concentration in the blood.
What happens to the pH when the blood becomes more acidic or less alkaline? If the blood becomes less acidic or more alkaline? 1) The pH falls 2) the pH rises
What is an acid? An acid is defined as any compound, which forms hydrogen ions in solution. Acids are sometimes referred to as “proton donors”
What is a hydrogen Ion? The hydrogen ion consists of a single positively charged particle (the proton) that is not orbited by any electrons. The hydrogen ion is, therefore, the smallest ionic particle and is extremely reactive.
What is a base Bases: A base is a compound that combines with hydrogen ions in solution. Therefore, bases can be referred to as “proton acceptors”.
What is a buffer? Buffers: A buffer is a compound that limits the change in hydrogen ion concentration (and so pH) when hydrogen ions are added or removed from the solution.(or in our case, the Blood) Think of it as a sponge.
What is the importance of hydrogen Ion concentration in the blood? Hydrogen ion concentration has a widespread effect on the function of the body’s enzyme systems. As enzymes have a huge number of functions around the body, an abnormal pH can result in disturbances in a wide range of body systems.