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528 E4 L5
528 E4 L5 Gas Exchange
| Question | Answer |
|---|---|
| Functions of the Respiratory System | Provide surface area for gas exchange; Moves air to and from gas exchange areas; Protection of respiratory surfaces, defense against apthogens; Producing sounds; Facilitating detection of olfactory stimuli |
| Parts of the Upper Respiratory System | Nose, Nasal Cavity, Paranasal Sinuses, Pharynx |
| Parts of the Lower Respiratory System | Larynx (voice box), Trachea, Bronchi, Bronchioles, Alveoli |
| What are Alveoli? | Gas exchange region; Extensive capillary network |
| What are the cells that make up Alveoli? | Simple Squamous Epithelium (Type I Cells); Septal Cells (Type II Cells); and Alveolar Macrophages |
| What is the function of Simple Squamous Epithelial Cells? (Type I Alveolar Cells) | Diffusion |
| What is the function of Septal Cells? (Type II Alveolar Cells) | Surfactant production, which relieves surface tension |
| What is Diffusion dependent on? | 1. Size of concentration gradient 2. Temperature 3. Distance 4. Molecule size 5. Electrical forces |
| Dalton’s Law | In a mixture of gases, each gas will contribute to the total pressure relative to its abundance |
| Partial Pressure | Pressure contributed by a single gas in a mixture of gases |
| Partial Pressure Equation | 760 mmHg (atm) = P(N2) + P(O2) + P(H2O) + P(CO2) |
| What percentage of the air does N2 make up? | 78.6% |
| What percentage of the air does O2 make up? | 20.9% |
| What percentage of the air does H2O make up? | 0.5% |
| What percentage of the air does CO2 make up? | 0.04% |
| What causes air pressure? | Gravity pulling on molecules |
| Why is there no air pressure in outer space? | Because air pressure is caused by gravity and there is no gravity in outer space |
| What is the air pressure in Mt Everest? | 226 mmHg (10,000 m above sea level) |
| What is the air pressure 20 meters underwater? | 2280 mmHg (due to 20 meters of water above) |
| Henry’s Law | At a gien temperature, the amount of a gas in solution is directly proportional to the partial pressure of that gas |
| What can happen to gas under pressure? | Can dissolve into a liquid |
| What happens to gas under pressure that has reached equilibrium? | Gas molecules will diffuse out of the liquid as quickly as they enter it |
| What does the actual amount of gas in the body depend on? | The solubility of the specific gas |
| Specific Solubility of gases in the body | CO2: highly soluble; O2: less solube; N2:very limited solubility |
| What happens if there is a sudden increase in pressure on our body? | At normal atmospheric pressures, there are few nitrogen molecules in blood. Increased pressure forces more nitrogen into blood and tissues |
| How do you avoid Decompression Sickness? | A slow decrease in atmospheric pressure allows nitrogen to diffuse out of tissues into blood, out via lungs |
| How does Decompression Sickness happen? | A sudden decrease in atmospheric pressure will cause nitrogen to move out of solution and form bubbles of nitrogen gas in blood, tissues, and body fluids |
| Where do the nitrogen bubbles accumulate first during Decompression Sickness? | Joint Capsules (called “The Bends”) |
| What can nitrogen bubbles in your blood/tissues cause? | Infarctions, strokes, paralysis, respiratory arrest |
| What is the treatment for Decompression Sickness? | Recompression in hyperbaric chamber |
| How is Alveolar air different than the inhaled air? | It’s warmer, humidified, contains less oxygen, and contains more CO2 |
| Why does the Alveolar air contain more CO2? | Because there’s always some air left in your lungs (residual volume) and that is always CO2, so you’ll always have a higher concentration of CO2 because you’re not getting rid of all of your air in one breath |
| Why is gas exchange at respiratory membrane very efficient? | Large differences in partial pressures across respiratory membrane; Distances involved in gas exchange are minimal (0.5 micrometers related to thickness of membrane); Gases are lipid soluble; Large suface area (140 m2); Blood/air flow are coordinated |
| What can cause increased thickness of the gas exchange membrane? | Fibrosis and Edema – makes it take longer for gas exchange to occur |
| What does Emphysema do? | Decreases surface area – makes gas exchange less efficient |
| How does a Pulmonary Embolism affect gas exchange? | Pulmonary Embolism affects blood flow, and since blood flow and air flow are coordinated, it lowers the efficiency of gas exchange |
| Coordination of Ventilation and Perfusion Ratio | V(A)/Q [V(A) = ventilation; Q = blood flow] |
| What happens when V(A)/Q is above normal? | Increase in physiologic dead space – More ventilation than blood flow; Work of ventilation is then wasted effort (wasted air) |
| What happens when V(A)/Q is below normal? | Physiologic Shunt – Not enough ventilation to match blood flow; Some blood fails to be oxygenated (wasted blood) |
| What is V(A)/Q in the TOP of a normal lung? | V(A)/Q is increased due to not much blood flow = physiologic dead space (except during exercise); Pulmonary Embolism can also increase V(A)/Q |
| What is V(A)/Q in the BOTTOM of a normal lung? | V(A)/Q is decreased due to not enough ventilation = physiologic shunt; Can also occur from chronic obstructive lung disease – Emphysema, COPD |
| Where does the partial pressure for External Respiration come from? | Pulmonary Circuit (getting air into the respiratory pathway) |
| Where does the partial pressure for Internal Respiration come from? | Systemic Circuit (what happens at the cellular level) |
| What is the partial pressure of O2 in the Alveolus? | P(O2) = 100 mmHg |
| What is the partial pressure of CO2 in the Alveolus? | P(CO2) = 40 mmHg |
| What is the partial pressure of O2 in the Pulmonary Capillary end closest to the Pulmonary Vein? | P(O2) = 100 mmHg |
| What is the partial pressure of CO2 in the Pulmonary Capillary end closest to the Pulmonary Vein? | P(CO2) = 40 mmHg |
| What is the partial pressure of O2 in the Pulmonary Capillary end closest to the Pulmonary Artery? | P(O2) = 40 mmHg |
| What is the partial pressure of CO2 in the Pulmonary Capillary end closest to the Pulmonary Artery? | P(CO2) = 45 mmHg |
| What is the partial pressure of O2 in Systemic Arteries? | P(O2) = 95 mmHg |
| Why is the partial pressure of O2 in Systemic Arteries dropped from 100 mmHg to 95 mmHg? | Because blood flow is going to other tissue regions of the lungs that don’t participate in gas exchange |
| What is the partial pressure of CO2 in Systemic Arteries? | P(CO2) = 40 mmHg |
| What is the partial pressure of O2 in Tissues? | P(O2) = 40 mmHg |
| What is the partial pressure of CO2 in Tissues? | P(CO2) = 45 mmHg |
| What is the partial pressure of O2 in Systemic Veins? | P(O2) = 40 mmHg |
| What is the partial pressure of CO2 in Systemic Veins? | P(CO2) = 45 mmHg |
| What is the concentration gradient for CO2 so small in Internal Respiration? | Because CO2 has a higher solubility than O2 (so you don’t need as large as a partial pressure gradient) |
| Oxygen and Carbon Dioxide have __________________ solubility in blood plasma | Limited (RBCs are the solution) |
| Hemoglobin (in RBCs) is responsible for ____% of Oxygen transport | 98.5% |
| ___% of Oxygen dissolves in plasma | 1.5% |
| Oxygen binds to Hemoglobin _______________ and _______________ (specifically associates with _______________ molecules) | Loosely and Reversibly; Associates with Iron molecules |
| Hemoglobin Saturation | Percent of heme units containing bound O2 (if each O2 molecule is carrying 3 O2s, 75%, etc) |
| Why is the Oxygen-Hemoglobin Saturation (Dissociation) Curve not a straight line? | Because having one Oxygen bound makes it more likely that a second Oxygen will bind which makes it more likely that a third Oxygen will bind, etc |
| Why is the P(O2) in active tissues lower? | Because the Oxygen is being released to the tissues if they are active and require the Oxygen |
| What is Cooperative Binding of Oxygen? | 1 Oxygen binds to Hemoglobin, changes the conformation, it’s easier for 2nd Oxygen to bind which changes conformation & makes it easier for the 3rd, etc (explains why the Oxygen-Hemoglobin Saturation (Dissociation) Curve is a curve, not a straight line) |
| What factors affect Hemoglobin saturation? | P(O2) of blood; Blood pH; Temperature; Metabolic activity within RBCs |
| What happens to O2 binding to Hemoglobin when P(O2) is high? | O2 binds to Hemoglobin (Pulmonary Capillaries, for example) |
| What happens to O2 binding to Hemoglobin when P(O2) is low? | O2 is released from Hemoglobin (Tissues Capillaries, for example) |
| Bohr Effect | Tissues generate acids that will decrease the pH; This makes it easier for Oxygen to release from Hemoglobin (CO2 is mostly responsible for Bohr effect) |
| Does a high or low pH make it easier for Oxygen to be released from Hemoglobin (lower Hemoglobin saturation)? | Lower pH |
| What is mostly responsible for the Bohr Effect? (and equation) | CO2 is most responsible (CO2 + H2O ←→ H2CO3 ←→ H+ + HCO3-) |
| What happens to the Bohr Effect if you increase CO2? | The equation will shift to the right (more H2CO3, H+, and HCO3-) – more hydrogen ions, which will lower the pH and cause Oxygen release from Hemoglobin |
| What happens to the Bohr Effect if you decrease CO2? | The equation will shift to the left (more H2CO3, H2O, and CO2) |
| What does an increase in temperature do to Hemoglobin Binding? | Less Oxygen will bind / More Oxygen will be released from Hemoglobin |
| What would cause an increase in temperature in tissues? | Increase in metabolic activity (increase muscle activity) – means they need more Oxygen |
| What is the by-product of ATP production in RBCs? | BPG (2,3-bisphosphoglycerate) |
| What does an increase in BPG cause? | An increase in the amount of O2 released from Hemoglobin |
| What can cause an increase in BPG? | Thyroid hormones, growth hormone, epinephrine, androgens, and increased blood pH |
| What happens to BPG production as RBCs age? | BPG production decreases |
| What happens if BPG levels are too low? | O2 will be permanently bound to Hemoglobin and O2 won’t be released to tissues (determines how long a blood bank can store fresh whole blood) |
| Factors that promote Oxygen release from Hemoglobin | Increase temp, decrease pH, increase CO2, decrease P(O2), increase BPG in RBCs |
| Where in the body does the Bohr Effect shift to the left? | (means decrease in pH and increase in CO2) – occurs in the lungs – CO2 diffuses out of blood, increased Oxygen binding to Hemoglobin |
| Where in the body does the Bohr Effect shift to the right? | (means increase in pH and decrease in CO2) – occurs as blood passes through tissues – Forces O2 away from Hemoglobin and into tissues |
| Fetal Hemoglobin has a __________________ affinity for O2 than adult Hemoglobin | Higher |
| What chains does Fetal Hemoglobin contain? | 2 Alpha chains and 2 Gamma chains |
| At the same P(O2), Fetal Hemoglobin will have a ______________ percent Hemoglobin saturation | Higher |
| ABG | Arterial Blood Gas Samples (Concentrations of dissolved gases can be determined by this) |
| Normal ABG ranges | P(O2): 80-100 mmHg; P(CO2): 35-45 mmHg; pH: 7.35 - 7.45 |
| What is Oxygen saturation measured by and what is the normal range? | Measured by Pulse Oximetry (normal: 95-99%) |
| If someone has low oxygen-Hemoglobin saturation and are placed on 100% oxygen, what would happen? | The saturation would go up |
| If you put someone on 100% oxygen and the O2-Hb saturation didn’t increase, what might be the problem? | Something is wrong with the lungs where you don’t have efficient gas exchange (Fibrosis, Edema) |
| ___% of CO2 is dissolved in plasma | 7% |
| ___% of CO2 is converted to HCO3- | 70% |
| What functions as a buffer for H+ (pH)? | Hemoglobin |
| ___% of CO2 binds to Hemoglobin | 23% (carbaminohemoglobin; binds to protein protion of Hemogloblin) |
| What is Hemoglobin called when it has CO2 bound to it? | Carbaminohemoglobin |
| Chloride Shift | HCO3- is released from a RBC in exchange for a Cl- from the tissues |
| ___% of Hemoglobin are bound to CO in CO poisoning | 50% |
| What happens to Hemoglobin during Carbon Monoxide poisoning? | 50% of Hb are bound to CO and the other 50% of Hb have an increased affinity for O2 so it is more difficult for O2 to be released to the tissues |
| What part of the body is most sensitive to decreased O2? | Brain – so people may become disoriented or unconscious without knowing the cause if they have Carbon Monoxide Poisoning |
| What happens to atmospheric pressure at increased altitudes? | Decreased atmospheric pressure – results in P(O2) in air decreased |
| What are the immediate adjustments made for high altitudes? | Increased respiratory rate; Increased heart rate; Bronchodilation |
| What are the long-term adjustments made for high altitudes? | EPO secretion which causes increase in the amount of RBCs |
| What is it called when your body fails to adjust to high altitudes? | Mountain sickness |
| Symptoms of Mountain Sickness | Headache, insomnia, fatigue, shortness of breath, light-headedness, nausea |
| What are the symptoms of Mountain Sickness a result of? | Hypoxia |
| Mountain Sickness may develop after rapid ascent to how many feet? | 8,000 – 11,500 feet |
Created by:
Cyndi1087