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162 Cards in this Set
- Front
- Back
What is the difference between gas exchange and breathing?
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gas exchange involves moving O2 into blood and CO2 out of blood, while breathing only refers to moving air in and out of the lung
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What are the requirements for good gas exchange?
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large volumes of gases and blood
limit space reserve for exercise or fright efficient for getting O2 to tissues so they can make energy sterility - lung is the only organ in contact with the outside |
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Where are alveoli located?
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ends of terminal bronchioles
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What is the site of gas exchange?
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alveolar-capillary membrane
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What can an alveoli be described as?
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small bubbles of air surrounded by tissue and blood
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Based on the Fick equation, what is Vgas directly proportional to?
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membrane area
diffusion constant pressure gradient |
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Based on the Fick equation, what is Vgas inversely proportional to?
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membrane thickness
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How does the size of the airway change as it branches?
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shorter, narrow, and more numerous
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How many alveoli are in a human lung?
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2^23 (>8,000,000)
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How does the amount of cartilage in the airway change as it approaches the lung?
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decreases
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How does the amount of smooth muscle in the airway change as it approached the lung?
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increases
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True or False: There is no cartilage in lungs?
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True
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How can asthma be treated?
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relaxing smooth muscle
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What happens in an asthma attack?
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A stimulus causes mast cell degranulation, which releases histamine and other substances that contract smooth muscle and secrete mucus. This causes decreased caliber and air flow, making it harder to breathe.
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Why does the respiratory zone appear pink in color?
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red blood cells
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What makes up the alveolar/capillary membrane?
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projection from an endothelial cell and a type I epithelial cell
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What is important about type I epithelial cells?
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make up part of the alveolar/capillary membrane
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What is important about type II epithelial cells?
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they are loaded with lipids that produce surfactant
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Which type of epithelial cells produce surfactant?
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type II - they begin to develop and mature at about 8 months of fetal life
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What is the diameter of a capillary?
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10 um
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Is pressure higher in the aorta or pulmonary artery?
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aorta
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Is pressure lower in the aorta or pulmonary artery?
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pulmonary artery
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What can high pressure in the pulmonary artery cause?
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physical damage and pulmonary edema
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Does the pulmonary artery contain oxygenated or deoxygenated blood?
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deoxygenated
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Does the pulmonary vein contain oxygenated or deoxygenated blood?
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oxygenated
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Is pulmonary circulation a high pressure or low pressure system?
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low pressure
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What can macrophages not kill or detoxify?
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HIV, TB, asbestos
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Where in the respiratory system are macrophages found?
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lungs (both zones)
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What is the top tacky layer of the mucocilliary escalator that contains antibodies and enzymes?
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gel layer
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What is the bottom watery, ciliated layer of the mucocilliary escalator?
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sol layer
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What does the gel layer of the mucocilliary contain?
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antibodies and enzymes
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What does the sol layer of the mucocilliary escalator contain?
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cilia
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What happens in cystic fibrosis?
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too much mucus
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What is Tidal Volume?
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air moved in a normal breath
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What is Vital Capacity?
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air moved in a maximum inspiration/expiration
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What is Total Lung Capacity?
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vital capacity + residual volume
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What is Functional Residual Volume?
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air remaining after a normal breath
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What is Residual Volume?
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air remaining after a maximum inspiration/expiration
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True or False: The lungs never completely empty.
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True
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What is the term for the air that is moved in a normal breath?
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Tidal Volume
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What is the term for the air that is moved in a maximum inspiration/expiration?
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Vital Capacity
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What is the term for the air remaining after a normal breath?
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Functional Residual Capacity
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What is the term for the air remaining after a maximum inspiration/expiration?
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Residual Volume
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What is the term for the air moved in a maximum inspiration/expiration PLUS the air remaining in the lung?
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Total Lung Capacity
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What is the normal tendency of the lungs?
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to collapse
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What is required for inspiration?
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contraction of the diaphragm to increase the volume of the chest cavity
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True of False: Lungs are not attached to the chest wall or diaphragm.
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True
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What is the intrapleural space?
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space between pleura and chest wall
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How does intrapleural pressure change when the chest expands and what is the result of this change?
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IPP becomes more negative, which creates pressure gradient from mouth to alveoli
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What is IPP when the chest expands?
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-15 cm H2O
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What is the pressure at the mouth?
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0 cm H2O
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What is the significance of functional reserve capacity (FRC)?
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keeps lung partially inflated so it's on the high compliance part of the V/P curve
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What is compliance?
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measure of the ability to deform a system (slope of tangent to V/P curve)
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What happens in emphysema?
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it's very easy to inflate lungs, but expiration is difficult
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At residual volume (RV), is compliance high or low?
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low
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At functional residual capacity (FRC), is compliance high or low?
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high
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After a normal inspiration, is compliance high or low?
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low
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What factors affect compliance?
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elastic recoil
surface tension |
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In general, is pressure greater in a large bubble or a small bubble?
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small
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What is the La Place Law state?
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pressure is inversely proportional to radius
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In lungs, is pressure greater in a large bubble or a small bubble?
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large
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What is the driving force for air flow in a rigid tube?
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pressure gradient
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How is resistance related to radius?
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R is inversely proportional for r^4
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What factors affect resistance?
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smooth muscle (asthma/bronchi)
infections, mucus, foreign particles |
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Describe CNS control regulating ventilation.
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poorly defined groups (no discrete nuclei) in pons and medulla regulate depth and frequency
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Is the response to CO2 or O2 more important in regulating ventilation?
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CO2
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Where are the two types of chemoreceptors located?
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central in pons and medulla
peripheral in aortic arch |
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What do peripheral chemoreceptors sense and what do they do?
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sense increased pCO2, which lowers pH
cause increased ventilation |
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Wheat do central chemoreceptors sense and what do they do?
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sense increased CO2
CO2 reacts with H2O to form H2CO3 carbonic acid separates to H+ and HCO3- |
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What reaction is catalyzed by carbonic anhydrase?
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CO2 + H2O --> H2CO3
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True or False: H+ can cross the blood-brain barrier.
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False
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What is the CNS response to a blow to the head?
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- ventilation decreases, which causes increased pCO2 and [H+]
- chemoreceptors send positive signal to CNS, which leads to increased ventilation - decreased pCO2 and [H+] causes chemoreceptors to send negative signal to CNS |
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How can oxygen delivery be increased?
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increase cardiac output
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Normally, how long are RBCs in a capillary?
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0.75s
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Normally, how long does it take for a RBC to become fully saturated with oxygen?
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0.25s
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How is oxygen uptake changed during exercise?
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cardiac output is increased, so RBC transit time through capillaries decreases to 0.25s and RBCs are still fully saturated with oxygen
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Is carbon dioxide or oxygen more soluble, and how much more soluble is it?
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carbon dioxide 21x more soluble than oxygen
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How can you calculate the volume of each breath?
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volume in conducting zone + volume in respiratory zone
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How can you calculate tital volume?
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Vt = V(dead space) + V(alveolar)
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What is the % composition of O2 in air?
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21%
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What is partial pressure a function of?
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barometric pressure and % composition
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What is the atmospheric pressure at sea level?
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760 mm Hg
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How does an increase in pCO2 affect alveolar ventilation?
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decreases it
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How does an increase in alveolar ventilation affect arterial pCO2?
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decreases it
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What regulates arterial pO2?
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alveolar pCO2 regulates alveolar pO2, which regulates arterial pO2
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How do you calculate alveolar pO2?
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alveolar pO2 = PIO2 - (alveolar pCO2/RQ)
RQ = 0.8 |
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What is the vapor pressure of water?
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47 mm Hg
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What is PIO2 the same as?
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pO2 in conducting zone
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What is the value for PIO2 at sea level?
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150 mm Hg
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Is alveolar pO2 or alterial pO2 greater?
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alveolar pO2
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How does alveolar ventilation change as you move up the lung?
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decreases
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How does alveolar ventilation change as you move down the lung?
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increases
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How do you calculate pulmonary vascular resistance (PVR)?
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R = ΔP/V
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Does an increase in arterial/venous pressure cause an increase or decrease in pulmonary vascular resistance (PVR)?
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decrease
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Does an increase in arterial/venous pressure cause an increase or decrease in systemic vascular resistance (SVR)?
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increase
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What are the two mechmisms for dealing with increased vascular resistance?
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recruitment: all vessels are perfused
distension: vessels that were already being perfused are expanded |
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How does blood flow volume change as you move up the lung?
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flow initially increases a little, then decreases
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What is blood flow proportional to?
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pulmonary arterial pressure - left atrial pressure
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How does pulmonary arterial pressure change as you move up the lung?
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decreases
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How does pulmonary arterial pressure change as you move down the lung?
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increases
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What happens in hypoxic vasoconstriction?
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local mediators cause local decrease in pO2, which leads to local constriction of smooth muscle in blood vessels
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How does pulmonary vascular resistance (PVR) change with a newborn?
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PVR initially high, alveolar pO2 change at first breath causes a decrease in PVR
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What percentage of total blood O2 is bound to hemoglobin?
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98%
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What percentage of total blood O2 is dissolved in plasma?
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2%
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True or False: O2 dissolves in plasma before entering red blood cells.
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True
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What does Henry's Law part I state?
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at equilibrium, partial pressure of a gas is the same as partial pressure of a liquid
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What does Henry's Law part 2 state?
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concentration is proportional to solubility constant and partial pressure
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True or False: O2 only binds to unreduced iron.
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False
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What is O2 binding capacity proportional to?
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[Hb]
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What is the normal concentration of hemoglobin?
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15 g Hb/100 ml blood
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What is the normal O2 binding capacity of hemoglobin?
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1.39 ml O2/g Hb
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What is the maximum bound O2 concentration in blood?
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20.8 ml O2/100 ml blood
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What is the actual bound O2 concentration in blood?
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20.2 ml O2/100 ml blood
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What is the normal concentration of dissolved oxygen in blood?
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0.3 ml/100 ml blood
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What is the normal total O2 concentration in blood?
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20.5 ml O2/100 ml blood
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How do you calculate how much O2 is delivered to tissues?
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total O2 concentration x cardiac output
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How much O2 is normally delivered to tissues per minute?
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2,050 ml O2/min
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In the "lung part" of the oxyhemoglobin dissociation curve, what do big changes in pO2 cause in [O2]?
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small changes in [O2]
this maximizes Hb loading with O2 |
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In the steep part of the oxyhemoglobin dissociation curve, what do big changes in [O2] cause in pO2?
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small changes in pO2
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The Bohr Effect describes changes in what?
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Hb affinity for O2
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In which direction does fetal hemoglobin shift the oxygen saturation curve?
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left
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Does carbon dioxide or oxygen bind more tightly to hemoglobin, and how much more tightly does it bind?
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carbon monoxide binds times more tightly than oxygen
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In which direction does carbon monoxide shift the oxygen saturation curve?
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down (makes person enemic)
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What percentage of expired CO2 is dissolved?
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5-10%
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What percentage of expired CO2 is in bicarbonate?
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60-70%
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What percentage of expired CO2 is in carbamino compunds?
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30%
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True or False: The CO2 concentration vs. pressure curve becomes saturated.
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False
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True or False: The O2 concentration vs. pressure curve becomes saturated.
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True
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Which organs regulate [HCO3]?
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kindeys
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Which organs regulate pCO2?
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lungs
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What is the pKa of carbonic acid?
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6.1
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What is the [HCO3-]/pCO2 ratio equal to when the pH is 7.4?
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20
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What is the Henderson-Hasselback equation?
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pH = pKa + log([HCO3-]/(.03 x pCO2))
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What is hypoxemia?
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decreased pO2 or decreased [O2] in blood
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How does the body compensate for hypoxia?
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increases cardiac output
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What are the mechanisms of hypoxemia?
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hypoventilation
diffusion defect shunted blood ventilation/perfusion mismatch |
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How does hypoventilation affect alveolar pCO2?
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decreased alveolar ventilation increases arterial pCO2, which increases alveolar pOC2
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How does hypoventilation affect arterial pO2?
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decreased alveolar ventilation decreases alveolar pO2, which decreases arterial pO2
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Is arterial pCO2 directly or inversely proportional to alveolar ventilation?
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inversely proportional
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What conditions cause an increase in membrane thickness?
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fibrosis
edema |
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What conditions cause a decrease in surface are of the membrane?
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cancer
infection blood clot |
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What conditions cause a decrease in pressure gradient?
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high altitude (P1 decreases)
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What is shunted blood?
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blood that does not contact air or deal with gas exchange
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What are the two types of shunts?
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anatomical - natural
physiological - bad, ex.) patent ductus arteriosis or foramen ovale |
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What is the treatment for a physiological shunt defect?
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surgery
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What is the pO2 gradient from air to the mitochondria?
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160 mm Hg in air
5 mm Hg in mitochondria |
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What is dye concentration equal to?
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O2 concentration in blood leaving the lungs (g/L)
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If alveolar ventilation is constant, what is dye concentration related to?
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inversely proportional to flow
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If flow is constant, what is dye concentration related to?
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directly proportional to ventilation
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If alveolar concentration and flow are variable, what is dye concentration proportional to?
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V/Q
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Is (Va/Q) ratio greater at the top of the lung or at the bottom, and how many times greater is it?
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3.5 times greater at the top of the lung than at the bottom
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Does flow increase or decrease as you move up the lung?
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decrease
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Is pO2 greater at the top of the lung or at the bottom?
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top
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Is pCO2 greater at the top of the lung or at the bottom?
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bottom
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What is the (Va/Q) ratio equal to when there is great gas exchange?
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1
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What is the (Va/Q) ratio equal to when there is no gas exchange?
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0
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What is the (Va/Q) ratio equal to when there is wasted ventilation?
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infinity
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True or False: Q can compensate for decreased alveolar ventilation.
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True, up to a point
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True of False: Alveolar ventilation can compensate for decreased flow.
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False
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What is O2 delivery equal to when (Va/Q) = 1?
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1,950 ml O2/min
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What is O2 delivery equal to when (Va/Q) = 0.1?
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1,650 ml O2/min
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What is O2 delivery equal to when (Va/Q) = 10?
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200 ml O2/min
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