Physiology II Exam 2
Terms
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- What type of cells secrete surfactant
- Type II Alveolar cells
- What two things make up the pleural cavity?
- Space between the parietal pleura and the visceral pleura
- What is the pressure normally like in the pleural cavity and what is it during inspiration?
-
Normally negative
Inspiration more negative - Where does gas exchange in the lungs occur?
- In the respiratory division, final 7 branchings of the bronchis.
- In the space in the lungs where no gas exchange occurs, what is this called?
- Dead space, for every pound you have 1 mL of dead space.
- How long does it take to get the air out of the lungs normally? Obstructive lung disease?
-
Normally 4-5 sec
Obstructive greater than 5 secs -
What is the normal FEV1/FVC?
What is the FEV1/FVC in obstructive? -
Normal 80%
Obstructive less than 60% - How does obstructive lung disease affect the FEF25-75%?
- It is reduced due to the smaller airways leading to an increased time to expel vital capacity.
- How does TLC, FRC, and RV change in obstructive lung (hard to get air out) disease?
-
TLC increases
FRC increases
RV increases - How does TLC, FRC, and RV change in restrictive (hard to get air in) lung disease?
-
TLC decreases
FRC decreases
RV decreases - Hypoxic Hypoxia
- blood contains abnormallly low PO2 and Hb is poorly saturated. Occurs at high altitudes
- Anemic hypoxia
- PO2 is normal by HB concentration is low. Both oxygen capacity and oxygen content is reduced. CO poisening
- Hypoperfustion hypoxia
- caused by a reduction in blood flow to the tissues.
- Histotoxic hypoxia
- toxic substance (cyanide) interferes with the tissues ability to use O2
- Dissolved CO2
- amount of CO2 physically dissolved in blood. Only 5% of bloods total CO2 is in this dissolved form.
- Carbamino compound
- carbon dioxide binds with the globin portion of Hb to form carbamino hemoglobin. Faciliatates the unloading of CO2 (5% is carried this way)
- Bicarbonate
- 90% carried this way.
- Is V/Q ventilation ratios higher at the apex of the base
- at the apex, however perfusion and ventilation are greater at the base.
- Ventilation and Perfusion must equal what for gas exchange to occur?
- ventilation and perfusion must be equal.
- How are arterial P02 and alveolar PO2 related?
- Arterial PO2 is always less then alveoloar PO2
- What is the most important reason people are hypoxic?
- due to V/Q ventilation inequalities.
- What does the pre Botzinger complex do?
- Causes expiration or inspiration
- If arterial PCO2 increases, which decreases the pH in the brain ECF what kind of receptors are activated and what happens?
- Central Chemoreceptors, ventilation is increased
-
Breathing air with low PO2
Alveolar PO2
Alveolar PCO2 -
Alveolar PO2 decreases
Alveolar PCO2 no change -
Increased alveolar ventilation and unchanged metabolism
Alveolar PO2
Alveolar PCO2 -
Alveolar PO2 increases
Alveolar PCO2 decreases -
Decreased ventilation and unchanged metabolism
Alveolar PO2
Alveolar PCO2 -
Alveolar PO2 decreases
Alveolar PCO2 increases -
Increased metabolism and unchanged alveolar ventilation
Alveolar PO2
Alveolar PCO2 -
Alveolar PO2 decreased
Alveolar PCO2 increased -
Proportional increases in metabolism and alveolar ventilation
Alveolar PO2
Alveolar PCO2 -
Alveolar PO2 no change
Alveolar PCO2 no change - What is the typical value for tidal volume?
- 500 mL
- What is the typical value for TLC?
- 5800 mL
- Three functions of surfactant?
-
1: promotes stability of alveoli (surface tension in large alveoli increases and surface tension in small alveoli decreases.
2: Increases complience of lungs and decreases work for each breath
3: minimizes fluid accumulation in the alveoli because of the reduced surface tension - What is the average PAO2?
- 100 mm Hg
- What does CO2 remain constant at?
- 40 mm Hg
- Describe the tissue differences between the base and the apex of the lung
- Apex of the lung is relatively expanded versus the base that is compressed by the weight of the tissue above it. However this means the alveoli at the apex can expand much less than at the base.
- Describe the pressure changes between the apex and the base
- At the base intrapleural pressure is greater than the apex.
- What is the V/Q ratios at the base and the apex
-
Apex 3.3 (over ventilated)
Base 0.63 (over perfused) - What is the composition of end capillary blood
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O2 100 mmHg
CO2 40 mmHG