Respiratory system: Exam #2 review Flashcards
Everything below the trachea is _______
Sterile
- ) Name the structures of the conducting zone (7)
2. ) What is their purpose?
- ) Nose, nasopharynx, larynx, trachea, bronchi, bronchioles, terminal bronchioles
- ) Bring air in and out of the respiratory zone for gas exchange, and to warm, humidify, and filter air before it reaches the gas exchange region.
p. 185
The conducting airways are lined with ______ and ______ that function to _______.
Lined with mucus-secreting and ciliated cells that function to remove inhaled particles.
p.185
What are the effects on the smooth muscles of the airways by (and what are their receptors and what are they activated by?)…
- ) Sympathetic innervation
- ) Parasympathetic innervation
1.) Sympathetic adrenergic neurons activate ß2 receptors on bronchial smooth muscle, which leads to RELAXATION and DILATION of the airways. Activated by circulating epinephrine released from the adrenal medulla AND by ß2-adrenergic agonists such as ISOPROTERENOL, EPINEPHRINE, and ALBUTEROL.
- ) Parasympathetic cholinergic neurons activate MUSCARINIC RECEPTORS, which leads to CONTRACTION and CONSTRICTION of the airways
p. 186
- ) What drugs are used to treat asthma?
- ) What do they target?
- ) What is their effect?
- ) ß2-adrenergic agonists (e.g. EPINEPHRINE, ISOPROTERENOL, ALBUTEROL)
- ) ß2-adrenergic receptors (sympathetic)
- ) Dilation of airways
p. 186
Name and describe the structures of the respiratory zone, i.e. participate in gas exchange (3)
- ) Respiratory bronchioles: Transitional structures with cilia, smooth muscle, and occasionally budding ALVEOLI (for gas exchange).
- ) Alveolar ducts: Completely lined with alveoli. No cilia, little smooth muscle. Terminate in the… –>
- ) Alveolar sacs: Also lined with alveoli.
p. 186
Each lung has a total of approx. ______ alveoli
300 million
p.186
Alveoli exchange ____ and _____ between _____ and ______.
O2 and CO2 between alveolar gas and pulmonary capillary blood.
p.186
Alveolar walls are rimmed with ______, and lined with _____ (called _____ and ______).
Rimmed with elastic fibers.
Lined with epithelial cells called TYPE I and TYPE II PNEUMOCYTES (or alveolar cells).
p.186
What are the functions of TYPE II pneumocytes (2)? What is their main purpose?
They regenerative capacity for type I and II pneumocytes.
- **MOST IMPORTANTLY, they synthesize PULMONARY SURFACTANT, which is necessary for the reduction of surface tension of alveoli so they don’t collapse.
p. 187
Alveoli contain phagocytic cells called ______. What do they do?
ALVEOLAR MACROPHAGES, which keep the alveoli free of dust and debris because ALVEOLI HAVE NO CILIA TO PERFORM THIS FUNCTION.
p.187
Alveolar macrophages fill with debris and migrate to the _____. Why?
Migrate to the BRONCHIOLES, where beating cilia carry debris to the UPPER AIRWAYS and PHARYNX where it can be swallowed or expectorated.
pp.186-187
- ) The _____ is the main conducting airway.
- ) Explain its divisions, i.e. how it divides/what it divides into.
- ) Ultimately, how many divisions into smaller airways are there?
- ) Trachea
- ) It divides into two bronchi, one leading to each lung, which divide into two smaller bronchi, which divide again.
- ) 23 such divisions
p. 185
Which structures of the conducting/respiratory tract have cartilage?
Trachea, bronchi (some, patchy). THAT’S IT!!!
p.186
Changes in pulmonary arteriolar resistance are controlled by ______, mainly ______.
Controlled by local factors, mainly O2.
p.187
Because of ______, pulmonary blood is not evenly distributed in the lungs. Explain.
Gravitational forces. When a person is standing, blood flow is lowest AT THE APEX (top) of the lungs, and highest AT THE BASE (bottom) of the lungs. When a person is supine, THESE GRAVITATIONAL EFFECTS DISAPPEAR.
p.187
Regulation of pulmonary blood flow is accomplished by _______
Altering the resistance of the PULMONARY ARTERIES.
p.187
- ) _______ is the blood supply to the conducting airways.
2. ) It is a [large or small?] fraction of the total pulmonary blood flow
- ) Bronchial circulation
- ) VERY SMALL FRACTION
p. 187
_____ volumes of the lung are measured with a spirometer.
Static
p.187
What is tidal volume (Vt). What is the normal value for tidal volume?
Tidal volume (Vt) is the volume of air that fills the alveoli PLUS the volume that fills the airways.
- Normal tidal volume is approx. 500 mL.
p. 187
What is the term for the additional volume that can be inspired ABOVE tidal volume? What is the normal value for this?
Inspiratory reserve volume (IRV).
Normal value is approx. 3000 mL.
p.187
What is the term for the additional volume that can be expired BELOW tidal volume? What is the normal value for this?
Expiratory reserve volume (ERV).
Normal value is approx. 1200 mL.
p.187
What is the term for the volume of gas remaining in the lungs after maximal forced expiration? What is the normal volume recorded by spirometry?
Residual volume (RV).
Normal value is approx. 1200 mL and CANNOT BE MEASURED BY SPIROMETRY.
p.187
Define the four different types of lung capacity…
a. ) What their volumes are composed of, and…
b. ) What their normal values are (e.g. n = #1 + #2)
- ) Inspiratory capacity (IC):
a. ) Composed of TIDAL VOLUME plus the INSPIRATORY RESERVE VOLUME.
b. ) Normal value is approx. 3500 mL (500 mL + 3000 mL). - ) Functional residual capacity (FRC): The volume remaining in the lungs after normal tidal volume is expired (*can be thought of as the EQUILIBRIUM VOLUME).
a. ) Composed of EXPIRATORY RESERVE VOLUME (ERV) plus the RESIDUAL VOLUME.
b. ) Normal value is approx. 2400 mL (1200 mL + 1200 mL). - ) Vital capacity (VC): The volume that can be expired after MAXIMAL INSPIRATION.
a. ) Composed of INSPIRATORY CAPACITY plus the EXPIRATORY RESERVE VOLUME.
b. ) Normal value is approx. 4700 mL (3500 mL + 1200 mL). - ) Total lung capacity (TLC): Includes ALL LUNG VOLUMES.
a. ) It is composed of the vital capacity plus the residual volume.
b. ) Normal value is approx. 5900 mL (4700 mL + 1200 mL).
p.187
What is an analogous term for functional residual capacity (FRC)?
Equilibrium volume
p.187
What factors increase (3) and decrease (1) the value for VITAL CAPACITY?
Increases with BODY SIZE, MALE GENDER, and PHYSICAL CONDITIONING.
Decreases with AGE.
p.187
Lung capacities that include _____ cannot be measured by spirometry, e.g. _____ and _____.
Residual volume: e.g. Functional residual capacity (FRC) and total lung capacity (TLC).
p.187
_____ is the volume remaining in the lungs after normal tidal volume is expired. It can be thought of as ______.
Functional residual capacity (FRC). It can be thought of as the EQUILIBRIUM VOLUME.
p.187
_____ is the volume that can be expired after maximal inspiration.
Vital capacity (VC).
Define anatomic dead space, its volume and its location.
Anatomic dead space is the VOLUME OF THE CONDUCTING AIRWAYS, including the nose (and/or mouth), trachea, bronchi, and bronchioles. The volume is approx. 150 mL.
p.189
If a tidal volume of 500 mL is inspired, how much of that volume fills the alveoli?
350 mL, because 150 mL fills the ANATOMIC DEAD SPACE of the conducting airway.
p.190
To sample alveolar air, one must sample ________.
One must sample END-EXPIRATORY AIR.
p.189
Physiologic dead space includes what?
The anatomic dead space of the conducting airways, PLUS a FUNCTIONAL DEAD SPACE in the ALVEOLI.
p.189
What is the most important reason why some alveoli do not participate in gas exchange (functional dead space)?
Ventilation/perfusion defect: When ventilate alveoli are not perfused by capillary blood.
p.189
What is the physiologic/anatomic manifestation of a ventilation/perfusion dead space?
A pathologic situation in which the PHYSIOLOGIC dead space has become LARGER than the ANATOMIC dead space.
p.190
What provides an estimation of how much ventilation is “wasted,” either in the conducting airways or in nonperfused alveoli?
The ratio of physiologic dead space to tidal volume.
p.190
If physiological dead space is ZERO, then _____ will be equal to ______.
Partial pressure of CO2 in mixed expired air (PeCO2) will be equal to alveolar PCO2 (PaCO2)
p.190
ß2 (dilates or constricts?) bronchioles, and acetylcholine (dilates or constricts?) bronchioles.
ß2 DILATES
Acetylcholine CONSTRICTS
-From lecture 30 slides
What will be the PCO2 discrepancy between PaCO2 and PeCO2 if there is a dead space present?
PeCO2 < PaCO2 because PeCO2 will be “diluted” by dead space air.
p.190
Name and describe the two methods used to measure FRC (also, what does FRC stand for?)
FRC = Functional residual capacity (ERV + RV).
- ) Helium dilution method
- ) Pulmonary plethysmography
p. 187
- ) What is myasthenia gravis?
- ) What types of drugs (give TWO examples) are used to treat it, and…
- ) What is the main side effect of treatment and why?
- ) It is an either autoimmune or congenital neuromuscular disease that leads to fluctuating muscle weakness and fatigue. In the most common cases, muscle weakness is caused by circulating antibodies that block acetylcholine receptors at the postsynaptic neuromuscular junction, inhibiting the excitatory effects of the neurotransmitter acetylcholine on nicotinic receptors at neuromuscular junctions.
- ) Myasthenia is treated medically with *acetylcholinesterase inhibitors (e.g. PYRIDOSTIGMINE and NEOSTIGMINE)
- ) Wheezing, because acetylcholine causes BRONCHOCONSTRICTION.
- ) What is TIOTROPIUM and what is it used for?
2. ) What are possible ADVERSE side effects (7) and why do they occur?
- ) Tiotropium bromide (INN), aka SPIRIVA, is a long-acting, 24 hour, ANTICHOLINERGIC BRONCHODILATOR used in the management of chronic obstructive pulmonary disease (COPD), aka emphysema –> NOT FOR ACUTE EXACERBATIONS
- ) Adverse effects are mainly related to its ANTIMUSCARINIC EFFECTS (acetylcholine blocking). Dry mouth and/or throat irritation. LESS LIKELY –> urinary retention, constipation, acute angle closure glaucoma, palpitations (notably supraventricular tachycardia and atrial fibrillation) and/or allergy (rash, angioedema, anaphylaxis)
- ) What is the effect of ß2 receptor stimulation in bronchial muscle?
- ) What type of innervation do bronchial ß2 receptors receive?
- ) What is their primary neurotransmitter?
- ) What are the effects of the following on the bronchial ß2 receptors:
a. ) Albuterol
b. ) Propranolol
c. ) Exercise
- ) ß2 stimulation DILATES the bronchial smooth muscle
- ) Sympathetic innervation
- ) Epinephrine
- ) –>
a. ) Albuterol dilates (stimulates ß2)
b. ) Propranolol constricts (ß2 blocker)
c. ) Exercise dilates (stimulates sympathetic response, i.e. ß2 stimulation)
- From lecture 30 slides, and p.53 (for receptors)
- ) What type of innervation do the bronchial muscarinic receptors receive?
- ) What is their primary neurotransmitter?
- ) What is the effect of bronchial muscarinic receptor stimulation?
- ) What are the effects of the following on bronchial muscarinic receptors:
a. ) Atropine
b. ) Pyridostimine
c. ) Ach
d. ) Ipratropium
- ) Parasympathetic innervation
- ) Acetylcholine (Ach)
- ) Stimulation CONSTRICTS the bronchial muscle
- ) –>
a. ) Atropine dilates
b. ) Pyridostimine constricts
c. ) Ach increases secretions and causes BRONCHOCONSTRICTION
d. ) Ipratropium (Atrovent) blocks Ach muscarinic receptors and DILATES bronchial muscle.
-From lecture 30 slides, and p.53 (for receptors) and WIKI
What assumption must be made in order to calculate the volume of physiologic dead space?
PCO2 of systemic arteriolar blood (PaCO2) IS EQUAL TO the PCO2 of alveolar air (PACO2)
p.190
What is “the dilution factor” in words, and showed as a mathematical expression.
Dilution factor is the volume of the physiologic dead space.
Dilution factor = (PaCO2 - PeCO2)/PaCO2
p.190
Give the equation for the volume of the physiologic dead space (VD)
VD = VT x [(PaCO2-PeCO2)/PaCO2]
where VT = Tidal volume (mL), and VD = Physiologic dead space (mL)
p.190
- ) What is minute ventilation?
- ) Mathematically?
- ) How does it differ from alveolar ventilation (mathematically)?
- ) The total rate of air movement into and out of the lungs
- ) Minute ventilation = Vt x Breaths/min
- ) Alveolar ventilation (Va) is minute ventilation corrected for dead space –> Va = (Vt - Vd) x Breaths/min
p. 191
Give the alveolar ventilation equation and define its variables
VA = (VCO2 x K)/(PACO2) or rearranged... PACO2 = (VCO2 x K)/VA, where... VA = Alveolar ventilation (mL/min) VCO2 = Rate of CO2 production (mL/min) PACO2 = Alveolar PCO2 (mm Hg) K = Constant (863 mm Hg) p.191
Using the rearranged form of the alveolar ventilation equation, what two variables must be known in order to predict alveolar PCO2?
- ) Rate of CO2 production from aerobic metabolism of the tissues
- ) Alveolar ventilation, which excretes the aforementioned CO2 in expired air
p. 191
Increases in alveolar ventilation cause a(n) (INCREASE or DECREASE?) in PACO2?
Decrease in PACO2
p.191
Decreases in alveolar ventilation cause a(n) (INCREASE or DECREASE?) in PACO2?
Increase in PACO2
p.191
What is alveolar ventilation doing to pulmonary capillary blood?
“Pulling out” CO2
p.191
What happens to the partial pressures of CO2 in the pulmonary arteries (PaCO2) and alveoli (PACO2) when there is DECREASED alveolar ventilation?
There is higher PaCO2 and PACO2
p.192
Give the alveolar gas equation and define its variables
PAO2 = PIO2 – (PACO2 / R) + Correction factor, where…
PAO2 = Alveolar PO2 (mm Hg) PIO2 = PO2 in inspired air (mm Hg) PACO2 = Alveolar PCO2 (mm Hg) R = Respiratory exchange ratio or respiratory quotient (CO2 production/O2 production) p.192
The alveolar gas equation predicts the change in _____ that will occur for a given change in _____.
Predicts the change in PAO2 that will occur for a given change in PACO2.
p.193
- ) What is a mathematical expression for the respiratory exchange ratio or respiratory quotient?
- ) What is the normal value?
- ) CO2 production/O2 consumption
- ) 0.8
p. 192
Which will be greater in a situation of halved alveolar ventilation: The decrease in PAO2, or the increase in PACO2?
Due to the normal respiratory quotient of 0.8 (CO2 production/O2 consumption), the DECREASE IN PAO2 will be greater.
p.192
Explain the effect on FEV1/FVC in the following patients:
- ) Normal patient
- ) Patient with asthma
- ) Patient with fibrosis
- ) Normal FEV1/FVC of approx. 0.8, i.e. 80% of the vital capacity can be expired in the first second of FORCED EXPIRATION.
- ) Asthma (an OBSTRUCTIVE lung disease): Both FEV1 and FVC are decreased, but FEV1 is decreased MORE, so FEV1/FVC is also decreased.
- ) Fibrosis (a RESTRICTIVE lung disease): Both FEV1 and FVC are decreased, but FEV1 is decreased LESS than FVC is. So FEV1/FVC is actually INCREASED.
p. 194
Which two groups of muscles are the EXPIRATORY MUSCLES? What do each do?
- ) Abdominal muscles: Compress the abdominal cavity and push the diaphragm up.
- ) Internal intercostals: Pull the ribs downward and inward.
p. 194
The negative outside pressure that expands the lungs is called an ______.
Expanding pressure
p.194
On a pulmonary pressure-volume loop, why/when does the curve flatten out?
When the alveoli are filled to the limit and have become stiffer and less compliant.
p.195
The slope on a pulmonary pressure-volume loop represents ______.
Compliance
p.195
For a given outside pressure, is compliance greater with inspiration or expiration?
Volume?
Compliance and, thus, volume are greater during EXPIRATION.
p.195
On which limb (inspiration or expiration) of the pressure-volume loop is compliance measured?
Since compliance (and volume) are greater during EXPIRATION, compliance is measured on the EXPIRATION limb of the loop. p.195
Besides reducing surface tension, what other role does surfactant play in the alveoli?
Increases compliance
p.195
When is surfactant added to the alveoli?
During inflation of the lung
p.195
What forces create the negative intrapleural pressure?
Two opposing elastic forces:
- ) The lungs, with their elastic properties, tend to COLLAPSE.
- ) The chest wall, with its elastic properties, tends to SPRING OUT.
p. 196
What is a pneumothorax? What are two consequences of a pneumothorax?
Introduction of air to the intrapleural space.
Consequences are:
1.) Collapse of the lung without negative pressure
2.) Springing out of the chest wall without negative pressure to hold it in.
p.196
Compliance of the chest and lungs together is (less than, greater than, or equal to?) the compliance of the individual structures?
Together, the compliance is LESS than the individual structures.
p.197
Emphysema is a component of COPD, and is associated with a loss of what in the lungs? What happens as a result?
Loss of elastic fibers, this causes the COMPLIANCE of the lungs to INCREASE.
p.199
What effect does emphysema have on FRC?
FRC becomes higher to increase the COLLAPSING FORCE.
p.199 See P/V curves
An emphysema patient is said to breathe at _______, and will have a _______ chest.
Higher lung volumes, and will have a barrel-shaped chest.
p.199
Fibrosis, a so-called ____ disease, is associated with what two lung qualities? Relate these to the P/V curve.
A so-called RESTRICTIVE disease, is associated with…
- ) Stiffening of lung tissue
- ) Decreased lung compliance (decreased slope on P/V curve).
What effect does fibrosis have on FRC?
New, lower FRC because the lungs are less compliant and more elastic.
p.199
What is the Law of Laplace?
Pressure (collapsing pressure on alveolus) = (2 x Surface tension)/Radius
Which has more collapsing pressure, a small or large alveolus?
Small, because collapsing pressure is INVERSELY proportional to radius.
pp.199-200
From a gas exchange standpoint, alveoli need to be ______ in order to increase their surface area relative to volume.
AS SMALL AS POSSIBLE
p.200
- ) What substances would be used to stimulate parasympathetics in the lungs?
- ) What would block parasympathetics?
- ) Musarinic agonists, e.g. muscarine and carbachol
- ) Muscarinic antagonists, e.g. atropine
p. 201
- ) What substances would be used to stimulate sympathetic responses in the lungs?
- ) What effect would they have?
- ) ß2 agonists, e.g. epinephrine, isoproterenol, ALBUTEROL
- ) Relaxation of bronchial smooth muscle
p. 201
High lung volumes are associated with greater _____, and do what to airway resistance?
Greater TRACTION (radial traction exerted by surrounding lung parenchymal tissue) DECREASES AIRWAY RESISTANCE p.201
At rest, pulmonary intrapleural pressure is ______. What does this do to the lungs and chest wall?
Negative –> keeps the lungs expanded, and PREVENTS the chest wall from expanding
p.203
Halfway through inspiration, alveolar pressure ______
Falls below atmospheric pressure.
p.203
What happens to intrapleural pressure during inspiration? How (2 reasons)?
It becomes more negative because:
- ) As lung volume increases, the elastic recoil of the lungs also increases and pulls more forcefully against the intrapleural space, and…
- ) Airway and alveolar pressures become MORE NEGATIVE (How do alveolar pressures become negative?)
p. 203
Why does alveolar pressure become positive during expiration?
Because elastic forces of the lungs compress the greater volume of air in the alveoli.
p.203
Transmural pressure is calculated as…
Alveolar pressure MINUS intrapleural pressure
p.203
Both the airways AND alveoli will remain open as long as….
Transmural pressure remains POSITIVE
p.204
In emphysema, lung compliance (increases or decreases?) because of ______.
Lung compliance INCREASES because of LOSS OF ELASTIC TISSUE.
p.204
Persons with emphysema learn to expire ______, and with _____, raises airway pressure. Why must they do this?
Expire slowly and with pursed lips to prevent large airway collapse.
p.204
- ) In respiratory gas exchange, BTPS refers to gas that is _______.
- ) STPD refers to gas that is ______.
- ) Saturated with WATER VAPOR
- ) Dry
p. 205
Give Boyle’s law
P1 x V1 = P2 x V2
In the developing neonate, surfactant production begins at ____ weeks. Birth <____weeks results in death, after ____ weeks, baby can live.
Begins at 25 weeks. Birth <25 weeks results in death, after 35 weeks baby can live.
-Lecture 32 slides
_____ induce surfactant.
Steroids
-Lecture 32 slides
Give the equation for airflow
Q = ∆P/R
Give equation for airflow resistance
R = (8µL)/(πr^4)
Give Henry’s law and define the variables. What is it used for?
Cx = Px (x) Solubility
-where…
Cx = Concentration of dissolved gas (mL gas/100mL blood)
Px = Partial pressure of gas (mmHg)
Solubility = Solubility of gas in blood (mL gas/100mL blood/mmHg)
- It is used to convert the PARTIAL PRESSURE of a gas in the liquid phase to the CONCENTRATION of gas in the liquid phase.
p. 205
Where is highest airway resistance found?
In MEDIUM SIZED bronchi, the GREATEST DROP occurs across them
-slides lecture 32
What is the driving force in the diffusion of gas across a membrane?
Partial pressure difference, NOT the concentration difference.
p.206
- ) The diffusion coefficient for CO2 is _______ than the diffusion coefficient for O2.
- ) How does this impact diffusion speed?
- ) Diffusion coefficient for CO2 is approximately 20x HIGHER than that of O2.
- ) The result is that CO2 diffuses approximately 20x faster than O2.
p. 206
- ) Henry’s law converts _____ to _____.
2. ) It does not concern _____.
- ) Converts partial pressure to concentration.
- ) It does not concern BOUND GASSES, e.g. O2 in hemoglobin.
- Slides lecture 33
Partial pressure ____ concentration
Partial pressure ≠ concentration
Give Fick’s Law and define variables
Vx = (DA∆P)/∆x -where... Vx = Volume of gas transferred per unit time. D = Diffusion coefficient of the gas. A = Surface area. ∆P = Partial pressure difference of the gas. ∆x = Thickness of membrane. p.206
- ) What is the diffusion coefficient (D) of a gas in Fick’s Law a combination of (2 things)?
- ) Which terms in Fick’s Law can be combined into the “lung diffusing capacity” (DsubL) (3 things)?
- ) What is the last thing DL takes into account?
- )
a. ) Molecular weight
b. ) Solubility of the gas - ) DL combines:
a. ) Diffusion coefficient of the gas
b. ) Surface area of membrane (A)
c. ) Thickness of membrane (∆x) - ) DL also takes into account the time required for the gas to combine with proteins in pulmonary capillary blood (e.g., binding of O2 to hemoglobin in red cells).
p. 206
What effects (and why) do the following have on DL:
- ) Emphysema
- ) Fibrosis or Pulmonary edema
- ) Anemia
- ) Exercise
- ) Emphysema: DL decreases because destruction of the alveoli results in a decreased surface area for gas exchange.
- ) Fibrosis or Pulmonary edema: DL decreases because the diffusion distance (membrane thickness, ∆x, or interstitial volume) INCREASES.
- ) Anemia: DL decreases because the amount of hemoglobin in red blood cells is reduced.
- ) Exercise: DL increases because additional capillaries are perfused with blood, which increases the surface area for gas exchange.
p. 206
What is the temporal element that DL takes into account in Fick’s Law of diffusion?
It takes into account the TIME REQUIRED for GAS TO COMBINE WITH PROTEINS in pulmonary capillary blood, e.g. binding of O2 to hemoglobin in RBCs.
p.206
For gasses in solution, the total gas concentration IN SOLUTION is the sum of…what (3 things)?
- ) Dissolved gas, plus…
- ) Bound gas, plus…
- ) Chemically modified gas
p. 206
Henry’s law gives the relationship between _____ and _______.
Relationship between the partial pressure of a gas and its concentration in solution.
p.206
In solution, only ______ molecules contribute to partial pressure.
Only DISSOLVED GAS MOLECULES contribute to partial pressure. Bound and chemically modified gasses DO NOT contribute to partial pressure
p.206
Of the gases found in inspired air, only _____ is carried exclusively in dissolved form and is never chemically bound or modified.
Nitrogen (N)
p.206
What gasses bind to proteins in the blood?
O2, CO2, and CO.
p.206
Blood leaving the pulmonary capillary is delivered to….
The left heart and becomes systemic arterial blood.
p.207
What is the normal partial pressure value for O2 in the following places:
- ) Dry inspired air
- ) Humidified tracheal air
- ) Alveolar air
- ) Mixed venous blood
- ) Systemic arterial blood
- ) Dry inspired air: 160
- ) Humidified tracheal air: 150
- ) Alveolar air: 100
- ) Mixed venous blood: 40
- ) Systemic arterial blood: 100
p. 208
What is the normal partial pressure value for CO2 in the following places:
- ) Dry inspired air
- ) Humidified tracheal air
- ) Alveolar air
- ) Mixed venous blood
- ) Systemic arterial blood
- ) Dry inspired air: 0
- ) Humidified tracheal air: 0
- ) Alveolar air: 40
- ) Mixed venous blood: 46
- ) Systemic arterial blood: 40
p. 208
- ) O2 transfers FROM alveolar air equals…what?
2. ) CO2 transfer TO alveolar air equals…what?
- ) O2 consumption
- ) CO2 production
p. 207
Blood entering the pulmonary capillaries is _____ blood.
Mixed venous blood.
p.207
- ) The pO2 of mixed venous blood is _____, at what value?
2. ) The pCO2 of mixed venous blood is _____, at what value?
- ) RELATIVELY LOW, at 40mmHg
- ) RELATIVELY HIGH, at 46mmHg
p. 208
Systemic blood has a _____ pO2 than alveolar air. Why?
Systemic blood has a SLIGHTLY LOWER pO2 than alveolar air. This is due to a PHYSIOLOGIC SHUNT that allows a small amount of pulmonary blood flow to bypass the alveoli and not become arterialized.
p.208
What are the two sources of the physiologic shunt?
- ) Bronchial blood flow
- ) Some coronary venous blood that drains directly into the left ventricle, rather than going to the lungs to be oxygenated.
p. 208
When the size of the physiologic shunt increases, what happens?
Equilibration between alveolar gas and pulmonary capillary blood cannot adequately occur, and pulmonary capillary blood is NOT FULLY ARTERIALIZED (i.e. not fully oxygenated)
p.208
What is mixed venous blood?
- Fischer slides –> Any blood “past that has entered the right atrium”
- Medical dictionary –> Blood flowing out to the lungs in the pulmonary artery, which is a mixture of venous blood from the whole of the systemic circulation (i.e. from all parts of the body EXCEPT THE LUNGS).
In a diffusion-limited defect, as long as the ______ for the gas is maintained, diffusion will continue along the length of the capillary.
Partial pressure gradient
p.209
In a perfusion-limited defect, the ______ is not maintained, and the only way to increase the amount of gas transported is by _______.
The PARTIAL PRESSURE GRADIENT is not maintained.
The only way to increase the amount of gas transported is by INCREASING BLOOD FLOW.
p.209
If the value for Pa reaches the value of PA, then ______ has occurred.
COMPLETE equilibration
p.210
Give example(s) of:
- ) Perfusion-limited gas, and…
- ) Diffusion-limited gases (when and why) –> gas, situation, and pathology
- ) Perfusion-limited: Nitrous oxide (N2O)
- ) Diffusion-limited: Carbon monoxide (CO), O2 during strenuous exercise, and with pathological conditions such as EMPHYSEMA and FIBROSIS
p. 210
What maintains the partial pressure gradient for diffusion of CO into the pulmonary capillary?
Binding of CO to hemoglobin
p.210
The only means for increasing the net diffusion of N2O into the pulmonary capillary is by ______
Increasing blood flow
p.210
- ) Under normal physiologic conditions, O2 transport into pulmonary capillary is _____ -limited.
- ) When is it not?
- ) Perfusion-limited
- ) It is diffusion-limited with…
a. ) Fibrosis: Alveolar wall is thickened, increasing diffusion distance and decreasing DL. The increased distance SLOWS rate of diffusion and prevents equilibration…thus rendering it diffusion-limited. MAXIMUM PaO2 IS NEVER HIT!
b. ) Strenuous exercise:
- ) Perfusion-limited _____ exchange.
2. ) Diffusion-limited ______ exchange.
- ) Maximizes exchange
- ) Does not reach maximal exchange.
- Lecture 33 slides
Adult hemoglobin (aka ______) is called ______
aka Hemoglobin A, is called alpha2ß2
p.212
For the hemoglobin subunits to bind O2, iron in the heme moieties must be _______.
In the ferrous state, i.e. Fe2+
p.212
What is the percentage of bound O2 vs non-bound O2 in the bound?
Hemoglobin-bound O2 = 98% Free O2 (dissolved) = 2% p.212
- ) Describe methemoglobin and its causes.
- ) How to treat methemoglobinemia?
- ) What is an outward manifestation?
1.) Methemoglobin has an iron component in the FERRIC (i.e. Fe3+ state) and DOES NOT BIND O2!.
Causes: Oxidation of Fe2+ to Fe3+ by NITRILES and SULFONAMIDES (sulfa drugs)
2.) Methylene blue
3.) Brown blood
p.212
1.) Describe fetal hemoglobin (aka ______) which is given the designation ______.
- ) aka Hemoglobin F, HbF, given the designation alpha2gamma2.
- It has a higher O2 affinity than Hemoglobin A.
p. 212
Where is O2 sat highest in the fetus? What is its sat?
80% O2 sat in UMBILICAL VEIN
p.212
Describe Hemoglobin S:
- ) Abnormalities in structure
- ) Effects on RBCs
- ) Systemic effects
- ) O2 affinity
An abnormal variant of hemoglobin that causes sickle cell disease.
- ) Has normal alpha subunits, but abnormal ß subunits.
- ) In its DEOXYGENATED FORM, Hb S forms sickle-shaped rods in RBCs and distorting them (i.e. sickling them).
- ) This deformation can result in occlusion of small blood vessels.
- ) O2 affinity in Hb S < O2 affinity in Hb A
p. 212
Give the formula for total O2 content in blood and define variables
O2 content = (O2-binding capacity x %sat) + dissolved O2
-where... O2-binding = Amount of blood bound to Hb %sat = % of heme groups bound to O2 DO SAMPLE PROBLEM ON p.213 p.213
Hb S causes pain and infarction of what? (4 things)
- ) Eye
- ) Lung
- ) Penis
- ) Brain
- Lecture 34 slides
The amount of O2 delivered to tissues is determined by what 2 factors?
- ) Blood flow (cardiac output)
- ) O2 content of blood
p. 213
Give formula for O2 delivery
O2 delivery = Cardiac output x O2 content of blood = Cardiac output x (Dissolved O2 + O2-Hb bound)
p.213
What is the normal O2 %sat for:
- ) Arteries
- ) Veins (normal)
- ) Veins (stressed)
- ) 100%
- ) 75%
- ) 50%
- Lecture 34 slide
What is the pO2 at P50 for normal Hb A?
25 mmHg
p.214
Left shifts in O2-Hb curve are associated with _____ P50 and _____ affinity for O2.
Decreased P50 and increased affinity for O2.
p.214
An increase in P50 indicates a ____ in O2 affinity.
DECREASE in O2 affinity.
p.214
- ) Alveolar air, pulmonary capillary blood, and systemic arterial blood all have pO2 of _____.
- ) Mixed venous blood has pO2 of _______.
- ) 100mmHg
- ) 40mmHg
p. 214
Where is pO2 and Hb affinity the highest?
In the LUNGS (for loading of O2)
p.215
In tissues, the PvO2 is approx. ____mmHg, and Hb is ____% saturated, and the affinity is _____.
40mmHg, 75%, decreased affinity to facilitate unloading of O2
p.215
- ) Right shift (aka ____) = _____ affinity, causes (5)?
2. ) Left shift = ____ affinity, causes?
- ) Right shift (aka BOHR effect) = DECREASED affinity. Caused by: a.) increased metabolic activity, and subsequent increased pCO2 and decreases in pH.
b. ) Increases in temp
c. ) Increases in [2,3-DPG]: A byproduct of glycolysis. This binds to ß chains of deoxyHb and reduces affinity for O2.
d. ) SEPTIC SHOCK
e. ) Exercise
2.) Left shift = INCREASED affinity (fetal Hb)
Explain how and why increased [2,3-DPG] affects Hb
-Increases in [2,3-DPG], a byproduct of glycolysis, binds to ß chains of deoxyHb and reduces affinity for O2.
- Increase [2,3-DPG] occurs during HYPOXIA (e.g. HIGH ALTITUDE), when RBCs produce more 2,3-DPG.
p. 216
When do left shifts occur (4)?
- Basically opposite of right shifts, with the addition of Hb F*
- Decreases in pO2 and increases in pH (BOHR effect). DECREASED TISSUE METABOLISM.
- Hb F has more affinity due to less 2,3-DPG bound (2,3-DPG does not bind as avidly to gamma chains of Hb F as it does to ß chains in Hb A).
Explain the left shifted Hb F
- Hb F has more affinity due to less 2,3-DPG bound (2,3-DPG does not bind as avidly to gamma chains of Hb F as it does to ß chains in Hb A).
p. 216
What effect does CO have on the Hb curve and O2 bound and P50?
Decreases O2 bound, left shift, INCREASES affinity, P50 decreased
pp.217-218
- ) What is EPO?
2. ) EPO synthesis is induced in response to what?
- ) Glycoprotein growth factor produce in the KIDNEYS (and liver to a lesser extent) that promote erythropoiesis by promoting differentiation of proerythroblasts into RBCs
- ) Hypoxia
p. 217
What % of blood CO2 is dissolved?
5%
p.219
What percent of CO2 is bound to Hb, what is it called?
approx. 3% –> it is called CARBAMINOHEMOGLOBIN
p. 219
CO2 binding to Hb _____ its affinity for O2 (what kind of shift?)
REDUCES affinity for O2 (right shift)
p.219
When less O2 is bound, the affinity of Hb for CO2 _____
INCREASES
p.219
How is 90% of CO2 carried in the blood?
As bicarbonate (HCO3-) p.219
Carbonic anhydrase is found in high concentrations in _____
RBCs
p.219
How is the H+ created by c.anhydrase buffered in RBCs?
By DEOXYHEMOGLOBIN
p.220
Decreases in PAO2 produce pulmonary _____ (i.e. ______)
Pulmonary VASOCONSTRICTION, i.e. HYPOXIC VASOCONSTRICTION
p.220
O2 is ____ lipid soluble
HIGHLY
p.220
Define the effects of the following:
- ) Thromboxane A2
- ) Prostacyclin (prostaglandin I2)
- ) Leukotrienes
- ) Local VASOCONSTRICTOR of arterioles and veins
- ) Local VASODILATOR, produced by lung epithelial cells
- ) Causes AIRWAY CONSTRICTION
p. 221
Which chemoreceptors are more sensitive, O2 or CO2?
CO2
p.223
What type of shunt can be improved with O2?
Left to right
-Lecture 35 slides
Which is greater at the base of the lung (zone 3), perfusion or ventilation?
BOTH
slides lecture 35
- ) What mathematical expression is used to express ventilation/perfusion ratio?
- ) What vent./perf. is it describing?
- ) What is the normal value?
- ) V/Q –> Normal = 0.8
- ) Alveolar ventilation, pulmonary blood flow (perfusion)
- ) 0.8
p. 224
- ) Where is the inspiratory medullary center located?
- ) innervation? a.) sensory b.) motor
- ) Can be inhibited (i.e. turn off inspiration) by what?
- ) Dorsal.
- ) a.) Glossopharyngeal (IX) and vagus (X) –> both sensory (peripheral chemoreceptors)
b. ) Phrenic nerve - ) Pneumotaxic center in PONS
p. 228
- ) Where is the expiratory medullary center located?
2. ) When are they active?
- ) Ventral respiratory neurons
- ) Inactive during quiet breathing. Active during exercise.
p. 228
A normal breathing rate doesn’t exist without what center? Is breathing rhythm affected?
Pneumotaxic center. Rhythm persists in the absence of this center.
p.228
What nerve does stimulation of the apneustic center affect? How?
Stimulation causes prolonged APs in phrenic nerve, producing long inspiratory gasps and brief expiration. PROLONGS CONTRACTION OF DIAPHRAGM.
p.228
What is role of cerebral cortex in breathing?
Allows temporary alterations in breathing by CONSCIOUS INTENTION
p.228
Brainstem chemoreceptors are sensitive to what?
changes in pH of CSF
p.228
- ) Decreased CSF pH does what?
2. ) Increased pH?
- ) Increases breathing rate
- ) Decreased breathing rate
p. 228
The ___ responds directly to changes in pH of CSF.
Medullary chemoreceptors
p.228
- ) Peripheral chemoreceptors primarily detect ____?
2. ) Max stimulation at pO2 ____
- ) Hypoxia
2. ) <60mmHg
Decreases in arterial pH cause ______, mediated by _____
An increase in ventilation, mediated by PERIPHERAL chemoreceptors for H+, ONLY IN CAROTID BODIES (CN IX), NOT IN AORTA
p.229
What are the effects of the following receptors:
- ) Lung stretch
- ) Joint and muscle
- ) J-receptors (afferent nerve?)
- ) Inhibits breathing by prolonging expiratory time
- ) Increase breathing (exercise)
- ) Juxtacapillary (J): Near capillaries. the major way we sense CHF and fluid overload and become dyspneic. -AFFERENT NERVE IS CN X (vagus)
p. 230
What are the changes in the following during exercise:
- ) O2 consumption
- ) CO2 production
- ) Vent. rate
- ) Arterial pO2 and pCO2
- ) arterial pH
- ) Pulm. blood flow and Cardiac output
- ) V/Q
- ) Phys. dead space
- ) Hb curve
- ) up
- ) up
- ) up
- ) No change in either
- ) no change in moderate exercise
- ) up
- ) more evenly distribute
- ) DECREASED
- ) right shift, increased P50, decreased affinity
p. 230
The respiratory bronchioles are _______ structures, and they have _______ and ________ like the conducting airways.
- transitional structures
- they have cilia and smooth muscle
p. 186
The alveolar ducts are completely lined with _______, but they contain no ______ and little __________.
- alveoli
- no cilia and little smooth muscle.
p. 186
Why are alveolar macrophages necessary?
Alveolar macrophages keep the alveoli free of dust and debris because the alveoli have no cilia to perform this function.
p.186
Changes in pulmonary arteriolar resistance are controlled by ____________, mainly ___.
local factors, mainly O2.
p.187
What is the effect of ACh on the bronchioles?
Constriction of bronchioles, and secretion of the glands. #16
What are the three effects of asthma on the bronchioles?
In asthma, muscles tighten, lining swells, and mucus increases. #17
What is the effect of hypoxia on lung vessels?
CONSTRICTION –To shunt blood flow towards areas with better O2 perfusion. #33
Any CO2 in alveolus was made in our body. Why?
because there is no appreciable CO2 in the air.
Which lung capacity increases with body size, male gender, and physical conditioning and decreases with age? What does this capacity measure?
Vital capacity (VC) –is composed of the inspiratory capacity plus the expiratory reserve volume, or approximately 4700 mL (3500 mL + 1200 mL). Vital capacity is the volume that can be expired after maximal inspiration.
Because __________ cannot be measured by spirometry, lung capacities that include the ________ also cannot be measured by spirometry (i.e. ___, ___ , and ___ ).
- residual volume, residual volume
- i.e. FRC, RV, and TLC.
p. 187
When a tidal volume of 500 mL is inspired, how much of that fills the alveoli? Why?
350mL fills the alveoli because the conducting airways do not participate in gas exchange (i.e. they are dead space), and 150mL fill the conducting zone. Thus, only 350mL fills the alveoli.
p.189
The first air expired is _________ air that has ___________. To sample alveolar air, one must sample __________.
- dead space air that has not undergone gas exchange.
- one must sample end-expiratory air.
p. 189
The functional dead space can be thought of as ______________________.
ventilated alveoli that do not participate in gas exchange.
p.189
The CO2 level at ___________ should equal ________________.
-the end of exhalation
-what is in the artery
#43
When estimating volume of the physiologic dead space, what three assumptions are made?
- All of the CO2 in expired air comes from exchange of CO2 in functioning (ventilated and perfused) alveoli.
- There is essentially no CO2 in inspired air.
- The physiologic dead space (non- functioning alveoli and airways) neither exchanges nor contributes any CO2.
p. 190
If physiologic dead space is zero, then PECO2 will _________ alveolar PCO2 (PACO2). However, if a physiologic dead space is present, then PECO2 will be __________ and PECO2 will be ______ PACO2.
- PECO2 will be equal to alveolar PCO2 (PACO2).
- PECO2 will be “diluted” by dead space air
- PECO2 will be less than PACO2
p. 190
What is the dilution factor?
Volume of physiologic dead space.
p.190
What is a good approximation for anatomical dead space?
≈ 1mL/lb.
Give the normal values for O2 in the following contexts:
- ) Inspired air
- ) Arterial blood
- ) Venous blood
- ) 150
- ) 100
- ) 40
Give the normal values for CO2 in the following contexts:
- ) Inspired air
- ) Arterial blood
- ) Venous blood
- ) 0
- ) 40
- ) 47
Give the normal values for pH in the following contexts:
- ) Inspired air
- ) Arterial blood
- ) Venous blood
- ) n/a
- ) 7.35 – 7.45
- ) 7.32 –7.42
Arterial CO2 always equals ______ CO2. Why?
Alveolar CO2 –because CO2 always equilibrates between pulmonary capillary blood and alveolar gas.
p.191
Define respiratory quotient, what is it for humans?
Respiratory Quotient = 0.8 CO2 produced/O2 consumed –We produce 200mL of CO2 each minute, and consume 250mL of O2 each minute. #15
The lower the alveolar ventilation, the _____ CO2 is pulled out of the blood and the ______ the PaCO2 and PACO2.
- less CO2
- higher the PaCO2 and PACO2
p. 192
When alveolar ventilation is halved, the decrease in PAO2 will be _______ than the increase in PACO2. Why?
-slightly greater
-Because the normal value for the respiratory exchange ratio (R) is 0.8
R = CO2 produced/O2 consumed = 0.8, meaning that more O2 is consumed than CO2 is produced.
p.193
If the rate of CO2 production decreases relative to the rate of O2 consumption (e.g. if the respiratory quotient and respiratory exchange ratio are 0.6 rather than 0.8), then PAO2 would ______ relative to PACO2.
PAO2 would decrease relative to PACO2.
WHY? conceptually speaking.
p.193
- ) What is FVC?
2. ) What does FEV1/FVC tell us?
- ) Forced vital capacity (FVC), p.193: The total volume of air that can be forcibly expired after a maximal inspiration –i.e. Maximum USABLE AIR (#28).
- ) The fraction of the vital capacity that can be expired in the first second, FEV1/FVC.
p. 194
How to determine normal Alveolar-Arterial gradient?
NORMAL = 2.5 plus age x 0.2 #20
- ) What affect does an obstructive disease (e.g. _____ ) have on FEV1?
- ) What is normal FEV1?
1.) Reduces FEV1.
2.) Normal FEV1 > 80%
#28
- ) In which types of lung diseases would FEV1/FVC be decreased? Give three examples.
- ) In which types of lung diseases would FEV1/FVC be normal? Give an example.
1.) Obstructive lung diseases –e.g. COPD, Asthma (reversible in asthma).
2.) Restrictive lung diseases –e.g. Pulmonary fibrosis.
#29
If a bronchodilator makes FEV1 go up, what is the disease?
it is asthma.
At the highest expanding pressures (negative intrathoracic pressure), when the alveoli are filled to the limit, they become _______ and ___________ and the curve flattens.
stiffer and less compliant
p.195
For a given outside pressure, the volume of the lung is greater during ______ than during _______ (i.e. the compliance is higher during _______ than during _______).
- volume greater during expiration than during inspiration
- compliance higher during expiration than during inspiration.
p. 195
Usually, compliance is measured on the ______ limb of the pressure-volume loop. Why?
- expiration limb of the pressure-volume loop.
- because the inspiration limb is complicated by the decrease in compliance at maximal expanding pressures.
p. 195
It is harder to fill the lungs at the _______. Why?
-harder to fill the lungs at the beginning
-because lungs don’t open as easily; therefore, it’s easier to empty lungs than to fill….but here is why, really (p.195) —>
“one begins at low lung volume where the liquid molecules are closest together and intermolecular forces are highest; to inflate the lung, one must first break up these inter- molecular forces.”
What two opposing elastic forces pulling on the intrapleural space create the negative intrapleural pressure?
- ) The lungs, with their elastic properties, tend to collapse. 2.) The chest wall, with its elastic properties, tends to spring out.
p. 196
What keeps the lungs “open”?
5cm H2O keeps lungs open. #42
- ) When the volume is functional residual capacity (FRC), airway pressure is _____ and equal to ________.
- ) At volumes lower than FRC, airway pressures are ______.
- ) At volumes higher than FRC, airway pressures are ______.
- ) airway pressure is zero and equal to atmospheric pressure.
- ) airway pressures are negative (less volume, less pressure).
- ) airway pressures are positive (more volume, more pressure).
p. 197
- ) At what volume (and at what airway pressure) is the airway pressure equal to ATM?
- ) What is the relationship between lung and chest expanding/collapsing pressures?
- ) At FRC –Zero pressure.
- ) Lungs and chest are at equilibrium – Alone, the lungs would collapse and the chest would expand, however…at FRC, the equilibrium position, the collapsing force on the lungs is exactly equal to the expanding force on the chest wall, as shown by the equidistant arrows; the combined lung and chest- wall system neither has a tendency to collapse nor to expand.
p. 197
The exact composition of surfactant remains unknown, but the most important constituent is ___________ (_____).
dipalmitoyl phosphatidylcholine (DPPC) p.200
Without surfactant, the law of Laplace predicts that the _______ alveolus will collapse. What is this called?
- small alveolus will collapse
- atelectasis
p. 200
How does surfactant reduce the collapsing force (i.e. reducing work of expanding force) on the lungs at any given volume?
By reducing surface tension, surfactant effectively INCREASES LUNG COMPLIANCE.
p.200
Between breaths, what is the relationship between alveolar pressure and atmospheric pressure?
alveolar pressure equals atmospheric pressure; there is no pressure gradient, no driving force, and no airflow.
p.200
In Q = ∆P/R for the airways: What is R, and what affects it the most?
R = Resistance
surfactant affects R the most.
p.200 and Fish
If the radius of an airway decreases by a factor of 2, what happens to the airway resistance and airflow?
Resistance does not simply increase twofold, it increases by 24, or 16-fold. When resistance increases by 16-fold, airflow decreases by 16-fold.
- Poiseuilles Law: R = (8ηl)/(πr4)
p. 201
_________ bronchioles have the HIGHEST AIRWAY RESISTANCE.
Medium-Sized bronchioles –analogous to arterioles. #30, p.201
Why do the smallest airways not have the highest collective resistance?
Because of their parallel arrangement, the smallest airways do not have the highest collective resistance.
p.201
- ) By convention, transmural pressure is calculated as _________ pressure minus ________ pressure.
- ) If transmural pressure is positive, it is a(n) _______ pressure on the lung.
- ) If alveolar pressure is zero and intrapleural pressure is −5 cm H2O, there is a(n) _______ pressure on the lungs of _________.
- ) alveolar pressure minus intrapleural pressure.
- ) expanding pressure on the lung
- ) expanding pressure on the lungs of +5 cm H2O (0 − [−5 cm H2O] = +5 cm H2O)
p. 202
Why is there a negative intrapleural pressure at rest?
The opposing forces of the lungs trying to collapse and the chest wall trying to expand create a negative pressure in the intrapleural space between them.
p.203
During inspiration, the diaphragm _______, causing the volume of the thorax to _______.
- contracts, causing the volume of the thorax to increase.
p. 203
The volume present in the lungs at the end of normal inspiration is the ____________ plus _______ ( ___ + __).
functional residual capacity plus one tidal volume (FRC + VT).
p.203
During inspiration, intrapleural pressure becomes __________. Why? (2)
-even more negative than at rest.
There are two explanations for this effect:
1.) As lung volume increases, the elastic recoil of the lungs also increases and pulls more forcefully against the intrapleural space.
2.) airway and alveolar pressures become negative.
p.203 —> I don’t really get this…
What phase of the breathing cycle is prolonged in persons with COPD?
Exhalation is more prolonged in COPD (reduced FEV-1). #38
If intrapleural pressure rises to expel gas in forced expiration, why don’t the lungs collapse?
The ALVEOLAR pressure goes up even more (more positive) –that's why the lungs don't collapse and the airways stay open. #38
Rank the relative diffusion capacities of O2, CO2, and CO in alveoli from lowest to highest.
O2
The diffusion coefficient of a gas depends on which two of its properties?
The diffusion coefficient of a gas (D) is a combination of the usual diffusion coefficient, which depends on molecular weight, and the solubility of the gas.
p.206
________ increases diffusion capacity.
Exercise
- ) In fibrosis or pulmonary edema, DL decreases because of what factor(s)?
- ) Emphysema?
- ) The diffusion distance (membrane thickness or interstitial volume) increases.
- ) In emphysema, DL decreases because destruction of alveoli results in a decreased surface area for gas exchange.
p. 206
What relationship does Henry’s Law give?
Henry’s law gives the relationship between the partial pressure of a gas and its concentration in solution.
p.206
In solution, only _________ contribute to the partial pressure. In other words, ________ and __________ do not contribute to the partial pressure.
- dissolved gas molecules
- bound gas and chemically modified gas
p. 206
The diffusion of Nitrogen in blood is ________-limited. What does this mean?
Perfusion-limited –the only way to increase the amount absorbed is to send more blood through. #23
The diffusion of Nitrogen in blood is ________-limited. What does this mean?
Perfusion-limited –the only way to increase the amount absorbed is to send more blood through. #23
- ) pH for venous and arterial blood are _______ to be ________. Implications?
- ) Is the same true for O2?
- ) -close enough to be clinically identical
- Thus, for DM ketoacidosis testing, you can use either (venous is preferable). - ) The same does NOT apply for O2 because venous and arterial blood gasses are considerably different.
* FROM NOTES*
Describe the pO2 and pCO2 of mixed venous blood.
The composition of this mixed venous blood reflects metabolic activity of the tissues: The PO2 is relatively low, at 40 mm Hg, because the tissues have taken up and consumed O2; the PCO2 is relatively high, at 46 mm Hg, because the tissues have produced CO2 and added it to venous blood.
p.208
- ) There is a small discrepancy between alveolar air and systemic arterial blood. What is it and why?
- ) What is the purpose?
1.) Systemic arterial blood has a slightly lower PO2 than alveolar air. This discrepancy is the result of a physiologic shunt, which describes the small fraction of pulmonary blood flow that bypasses the alveoli and, therefore, is not arterialized (oxygenated).
2.) A shunt feeds lung parenchyma and coronary circulation.
○ Should only account for ≤4%.
p.208
For the subunits to bind O2, iron in the heme moieties must be in the ______ state (i.e. ____ ).
ferrous state (i.e., Fe2+) p.212
- ) How many mL of O2 can ONE GRAM of hemoglobin carry?
2. ) What is the normal concentration of HbA in blood?
1.) 1.34mL O2/gHb
2.) 15g/100mL
MEMORIZE
What is the solubility of O2 in blood?
- 003 mL O2/100 mL
pp. 212-213
- ) Describe the Haldane Effect
2. ) What is the effect of pH buffering implied by this?
1.) O2 bound to hemoglobin changes its affinity for CO2, such that when less O2 is bound, the affinity of hemoglobin for CO2 increases.
2.) Less oxyHb (more deoxyHb) increases the acid neutralizing effect of Hb, i.e. DeoxyHb is a BETTER BUFFER!
#6, p.219
Pulmonary blood flow is directly proportional to the pressure gradient between the ________ and the _________ and is inversely proportional to the ___________ (Q = ΔP/R).
- pulmonary artery and the left atrium
- resistance of the pulmonary vasculature
p. 220
Name two pulmonary vasodilators and where they come from.
-Nitric oxide (NO) –Synthesized in the endothelial cells of the pulmonary vasculature.
-Prostacyclin (Prostaglandin I2) –Produced by lung endothelial cells.
#12, p.221
In chronic hypoxia, the increased ________ pressure causes hypertrophy of the ________, which must pump against an increased afterload.
- increased pulmonary arterial pressure
- hypertrophy of the right ventricle
p. 221
- ) What type of situation would produce global pulmonary vasoconstriction? What is the result?
- ) What is another situation of global pulmonary vasoconstriction?
- ) High altitude –The low PAO2 produces global vasoconstriction of pulmonary arterioles and an increase in pulmonary vascular resistance.
- ) Fetal circulation – This vasoconstriction increases pulmonary vascular resistance and, accordingly, decreases pulmonary blood flow to approximately 15% of the cardiac output.
p. 221
What is a powerful pulmonary vasoconstricting substance?
Thromboxane A2: Product of arachidonic acid metabolism (via the cyclooxygenase pathway) in macrophages, leukocytes, and endothelial cells, is produced in response to certain types of lung injury. Thromboxane A2 is a powerful local vasoconstrictor of both arterioles and veins.
p.221
What are two characteristics of a left-to-right shunt?
• Pulmonary blood flow becomes higher.
• PO2 in blood on the right side of the heart will be elevated.
p.224
What are two characteristics of a left-to-right shunt?
• Pulmonary blood flow becomes higher.
• PO2 in blood on the right side of the heart will be elevated.
p.224
Describe blood flow (perfusion) within the lungs when a person is upright. Why is it like this?
Lowest at the apex (zone 1) and highest at the base (zone 3).
- Gravitational effects increase pulmonary arterial hydrostatic pressure more at the base of the lung than at the apex.
p. 221
- ) _______ exceeds _______ at the lung apex.
- ) _______ exceeds _______ at the lung base.
- ) Where is ventilation and perfusion the highest?
1.) Ventilation exceeds Perfusion at the apex.
2.) Perfusion exceeds Ventilation at the bases.
3.) Both ventilation and perfusion are greater at the BASES.
#24 see fig.5-28 on p.224
Describe the differences in PaO2 and PaCO2 between the bases and the apices. What is the basis for these differences?
-In zone 1 (apex), where V/Q is highest, PaO2
is highest and PaCO2 is lowest – more ventilation than perfusion = more O2.
-In zone 3 (base), where V/Q is lowest, PaO2 is lowest and PaCO2 is highest –more perfusion than ventilation = more CO2.
p.225
What is the spatial arrangement that provides for ideal gas exchange?
Ventilated alveoli are close to perfused capillaries, and this arrangement provides for ideal gas exchange.
p.225
What is the composition of alveolar gas in regions of pulmonary dead space?
Dead space alveolar gas has the same composition as humidified inspired air: PAO2 is 150 mm Hg and PACO2 is 0.
p.225
Describe the pO2 and pCO2 in regions of 1.) Low V/Q, and 2.) High V/Q
- ) Low V/Q: Because ventilation is low relative to perfusion, pulmonary capillary blood from these regions has a low PO2 and high PCO2.
- ) High V/Q: Because ventilation is high relative to perfusion, pulmonary capillary blood from these regions has a high PO2 and a low PCO2.
pp. 225-226
Breathing is ________ process that is controlled by the ______ and _____ of the brain stem.
- an involuntary process
- medulla and pons of the brain stem.
p. 226
What, if any, difference is there between hypoxia and hypoxemia?
Hypoxia: No O2 delivery (blood O2 may be normal).
Hypoxemia: Low pO2 level in blood.
• Hypoxia is not always hypoxemic.
- ) Chemoreceptors are located on the _______ surface of the _______, near the point of exit of the glossopharyngeal (CN IX) and vagus (CN X) nerves and only a short distance from the _________.
- ) Thus, central chemoreceptors communicate directly with the ________.
- ) -ventral surface of the medulla
- DRG in the medulla - ) inspiratory center
p. 228
- ) The peripheral chemoreceptors primarily detect _______, with maximum stimulation at pO2 _____.
- ) What is their responsive measure?
- ) They are less sensitive to ________ and ________.
- ) -HYPOXIA
- pO2
- ) The peripheral chemoreceptors primarily detect _______, with maximum stimulation at pO2 _____.
- ) They are less sensitive to ________ and ________.
- ) -HYPOXIA
- pO2
