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MP - Lecture 23
Mechanics of Breathing I
| Question | Answer |
|---|---|
| Medical Physiology – Lecture 23 | Mechanics of Breathing I |
| Total lung capacity is made of what respiratory volumes? | IRV, TV, ERV, and RV |
| Vital capacity is made of what lung volumes? | IRV, TV, and ERV |
| Inspiratory capacity is made of what volumes? | IRV and TV |
| All respiratory muscles are relaxed at: | Functional Residual Capacity |
| Muscles of inspiration are: | Diaphragm, External Intercostals, Sternocleidomastoid, and Scalene |
| The main muscle for normal quiet breathing is: | Diaphragm |
| Muscles used for active breathing (inspiration) are: | External Intercostals, Sternocleidomastoid, and Scalene |
| Muscles of expiration are: | Abdominals and Internal Intercostals |
| At the end of expiration, lung volume equals: | FRC |
| At the end of inspiration, lung volume equals: | FRC + TV |
| Contracting external intercostals causes: | Increase in A-P diameter of ribcage (elevate ribcage) |
| Contracting internal intercostals causes: | Decrease in A-P diameter of ribcage (depress ribcage) |
| Breathing is impossible when: | Both ribcage and abdomen are prevented from contracting (i.e. surrounded by rigid barrier) |
| At the end of inspiration, vertical and horizontal diameters are: | Increased |
| Law of Laplace | P = 2T/r (P = Pressure required to keep alveolus inflated) |
| Small alveoli require ___ pressure to stay inflated. | high (Law of Laplace) |
| Collapse tendency of lung is caused by: | Elastic Fibers and Surface Tension |
| Surfactant is secreted by: | Type II Alveolar Epithelial Cells |
| Surfactant decreases: | Surface Tension |
| How does surfactant prevent alveoli from collapsing? | Reducing surface tension reduces required pressure to keep alveoli inflated (Laplace) |
| Insufficient surfactant secretion in newborns (especially premature) can cause: | Infant Respiratory Distress Syndrome (IRDS) |
| Driving force of bulk air movement is: | Pressure Difference (Between two points) |
| Pulmonary pressures are taken respectively to: | Atmospheric Pressure |
| Atmospheric Pressure = ? | P = 0 |
| Subatmospheric Pressure = ? | P < 0 |
| Pleural pressure is between the: | Visceral Pleura and Parietal Pleura |
| Pleural pressure is generally: | Subatmospheric (Ppl = -5 cm H2O) |
| Changes in pleural pressure can be measured by: | Esophageal Balloon |
| Driving force for airflow in and out of lungs is: | Alveolar Pressure (PA) |
| Alveolar pressure during inspiration is: | PA < 0 (Subatmospheric pressure) |
| Alveolar pressure during expiration is: | PA > 0 |
| Alveolar pressure with no airflow is: | PA = 0 (Atmospheric pressure) |
| Pressure difference between inside and outside lungs is: | Transpulmonary Pressure (PL) |
| PL = ? | PL = PA – Ppl |
| Transpulmonary pressure determines: | Degree of Inflation in the Lung |
| Pleural pressure equals ___ when the thorax or lung is punctured. | atmospheric |
| During pneumothorax: | Lung collapses, hemi-thorax expands, and other lung decreases because of mediastinum shift |
| What are the PA, Ppl, and PL after a normal expiration? | PA = 0, Ppl = -5, PL = +5 |
| What are the PA, Ppl, and PL after a normal inspiration? | PA = 0, Ppl = -10, PL = +10 |
Created by:
emyang
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