Term
| What is the basic function of the respiratory system? |
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Definition
| To provide oxygen to cells, and to remove carbon dioxide. |
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Term
| Where does the CO2 in the body come from? |
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Definition
| Metabolic activity in the body. Virtually no CO2 is inspired. |
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Term
| How does breathing relate to hydration? |
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Definition
| By breathing we lose water (200-300 mL per day) |
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Term
| How does cross sectional area relate to different parts of the respiratory system? |
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Definition
| As one moves down the respiratory system from the conductive zone to the respiratory zone, cross sectional area increases (highest at alveoli) |
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Term
| What lung volume cannot be measured directly? How is it measured? |
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Definition
| Residual Volume. By having a person breath in a marker and measuring the concentration of the marker in subsequent breaths. |
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Term
| How do the lung volumes change when moving from standing to supine? Why do they change? |
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Definition
Expiratory reserve volume decreases, and Inspiratory reserve volume increases accordingly. When upright, the diaphragm is lower in the chest compared to when supine. |
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Term
| Why do premature babies have trouble breathing? |
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Definition
| Lack of pulmonary surfactant causes difficulty in breathing and unstable lungs. |
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Term
| What are the major parts of the human airways leading from the conducting zone to the respiratory zone? |
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Definition
| Trachea => bronchi => bronchioles => terminal bronchioles => respiratory bronchioles => alveolar duct => alveolar sacs |
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Term
| During normal breathing how does expiration work? During forceful exhale? |
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Definition
Regular exhalation is completely passive - the lungs and chest wall return to equilibrium position based on their own elasticity. During forceful exhalation the abdominal wall pushes the diaphragm upward. The internal intercostal muscles pull the ribs down and in decreasing thoracic volume. Causes a positive intrapleural pressure, forcing air out. |
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Term
| Describe the sequence of changes during breathing. |
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Definition
- Phrenic nerves innervate diaphragm and intercostal nerves innervate external intercostal muscles.
- Diaphragm pushes abdominal contents down, intercostal muscles lift ribs up and out.
- Thoracic cavity expands, chestwall pulled up and out pulling lung along with it, increasing lung volume.
- Intrapleural Pressure becomes more negative, transpulmonary pressure increases. Alveolar pressure become more negative
- Air drawn in until alveolar pressure equals atmospheric
- Recoil property of the lung causes alveolar pressure to become positive.
- Air is forced out of the lung, decreasing volume, and causing intrapleural pressure to become less negative.
- As expiration ends, alveolar pressure returns to atmospheric
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Term
| What generates the pressure in the pleural space? |
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Definition
| The opposite forces between the chest wall (want to expand) and the lungs (want to collapse). |
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Term
| How is optimal gas exchange maintained? |
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Definition
| By matching ventilation with perfusion. (Directing blood flow from lower ventilated areas to higher venitlated areas) |
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Term
| How does the carbon dioxide soluability compare to that of oxygen? |
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Definition
| Carbon Dioxide is much more soluable than Oxygen in the lungs. |
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Term
| How does the autonomic nervous system affect respiratory resistance? |
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Definition
Parasympathetic: increases resistance to airflow by constricting airways Sympathetic: decreases resistance to airflow by dilating airways. |
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Term
| How can more oxygen be transported in the blood? |
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Definition
| Force more blood through alveolar capilaries per unit time. |
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Term
| Under normal conditions, what would happen if you were to increase partial pressure of oxygen above 100 mmHg in the blood? |
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Definition
| Not much. At 100 mmHg the hemoglobin are 97% full of oxygen. Increasing beyond this will slightly alter the amount of oxygen diffused in the blood, but this is relatively small. |
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Term
| How does the P50 of adult blood compare to than of a fetus? |
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Definition
| An adult has a much higher P50 that a fetus. |
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Term
| What factors can shift the oxy-hemoglobin saturation curve? How does this affect the P50? |
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Definition
| Increasing temperature, increasing DPG, increasing PCO2, decreasing pH (increasing H+). All shift to the right. This increases the P50, requiring higher partial pressures of oxygen to achieve a similar % concentration of hemoglobin. |
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Term
| How would anemia affect an otherwise healthy individual's PO2, O2 Capacity, O2 Content, and O2 Saturation? |
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Definition
PO2 would remain the same - alveolar ventiation has remained constant. O2 Capacity would be lower as hemoglobin concentration is lower. O2 Content would be lower, due to the decreased hemoglobin concentration. O2 Saturation would be normal because hemoglobin binding is still working normally, we just have less hemoglobin, which does not affect % saturation. |
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Term
| What two organs are the primary regulators of acid/base balance? Which is the major one? |
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Definition
Lungs: Regulate amount of CO2. Major regulator, ~10,000 mEq/day. Able to react quickly.
Kidneys: Produce and reabsorb bicarbonate. Minor regulator, ~70 mEq/day. React slowly over time.
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Term
| How does PCO2 affect blood pH and why? |
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Definition
Increasing PCO2 will decrease blood pH and vice versa. Comes from the equation: CO2 + H2O <==> H2CO3 <==> H+ + HCO3 |
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Term
| How does the Acid excretion of the kidney relate to that of the lungs? |
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Definition
| Lungs excrete vastly more acid (~10000 mEq/day) than the kidneys (~70 mEq/day) |
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Term
| What is effort independence in relation to breathing? Why does it occur? |
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Definition
During an expiratory effort, beyond a certain lung volume, expiratoration is automatic and independent of effort. Two main pressures affect expiration - alveolar and intrapleural. As the amount of air pushed through the airways increases, the alveloar pressure drops. When the alveolar pressure drops below intrapleural pressure, any increase in intrapleural pressure will only serve to constrict the airways - flow becomes independent of effort. |
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Term
| What is the Alveolar Ventilation Equation, and what does it relate? |
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Definition
PACO2 = 0.863 * (VCO2 / VA ) Increases in alveolar ventilation will reduce the partial pressure of CO2 in the alveoli. |
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Term
| What is the Alveolar Gas Equation and what does it relate? |
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Definition
PAO2 = PIO2 - (PACO2 / R) PI is O2 in inspired air. R is the respiratory quotient (volume of CO2 expired / volume of O2 inspired), about 0.8. Relates PO2 to PCO2, shows they are inversely related. |
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Term
| Where is blood flow greatest in the lung? Airflow? |
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Definition
Both are greater at the bottom of the lung. Alveoli at the bottom of the lung tend to be more compliant, allowing them to inflate easier during inspiration. |
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Term
| When the V/Q ratio is low what does the blood look like? When its high? Where is it high/low in the lung? |
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Definition
When low, there is low ventilation, high perfusion, causing the blood to look like venous blood. When high, there is high ventilation, low perfusion, causing the blood to look like inspired air. Its low at the bottom of the lung, high at the top. |
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Term
| How can you tell the difference between a V/Q mismatch and a shunt? |
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Definition
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Term
| How do the left and right heart differ in terms of flow/pressure/etc. |
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Definition
Right heart (systemic) is high pressure, high flow, high resistance. Left Heart (pulmonary) is low pressure, high flow, low resistance. |
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Term
| How does pulmonary edema affect the respiratory system? |
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Definition
| Interferes with the diffusion of oxygen and gas exchange. |
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Term
| How does CO2 diffuse across the aveoli to the capillary? |
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Definition
| CO2 is much more soluble than oxygen, allowing it to diffuse with a relatively low partial pressure gradient (~5 mmHg) |
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Term
| What three ways can CO2 be transported? How is CO2 transported mostly? |
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Definition
| Dissolved in blood, as carbamino CO2, and (mostly) as bicarbonate ions. |
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Term
| Where/how is bicarbonate formed? |
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Definition
| CO2 diffuses from the tissue into the plasma, and into the red blood cells, where there is carbonic and hydrase. CO2 is hydrated to form bicarbonate, which diffuses back into the plasma. The bicarbonate has a negative charge, to compensate for the loss of charge in the blood cell, chloride moves in. |
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Term
| What is the center for rythmic breathing? |
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Definition
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Term
| How does alveolar ventilation compare when you're asleep to when you're awake. |
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Definition
| When asleep, receptors are desensitized. It takes a greater PCO2 to trigger inspiration. |
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Term
| Where does the output of the right heart of a fetus go? |
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Definition
| 10-15% to the lungs, remainder to the ductus arterius shunt. |
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Term
| What are the two respiratory control centers? |
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Definition
- Medullary Respiratory Center
- Pontine Respiratory Center
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Term
| From what areas does the Respiratory Center of the body receive inputs? |
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Definition
- Chemoreceptors
- Mechanoreceptors
- Cerebral Cortex
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