Cheatography
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System in charge of breathing in and out
This is a draft cheat sheet. It is a work in progress and is not finished yet.
Terms:
Respiratory Airways: |
carry air between atmosphere and alveoli |
Nasal Passages: |
nose |
Pharynx: |
passage for lungs and stomach |
Larynx: |
voice box |
Trachea: |
tube where air travels to lungs |
Bronchi: |
two main branches of trachea |
Bronchioles: |
small branches of respiratory airway |
Alveoli: |
small sacs where gas exchange occurs |
4 Pressures in Ventilation
Atmospheric: |
pressure exerted by the weight of gas in the atmosphere on objects on earth |
Intra-alveolar: |
pressure within alveoli |
Intrapleural: |
pressure within the pleural sac |
Transmural: |
pressure gradient across lung wall (intra-alveolar - intrapleural) |
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Conducting Zone
- Top of trachea all the way to respiratory bronchioles |
- Provides low-resistance pathway for airflow |
- Defends against microbes, toxic chemicals, and other foreign objects through mucus, cilia, and macrophages |
- Warms and moistens the air |
- Used in sound production (vocal cords) |
Respiratory Zone
- Where gas exchange occurs |
- Type 1 Cells: form walls of alveoli |
- Type 2 Cells: secrete pulmonary surfactant to reduce surface tension |
- Alveoli are the site of the gas exchange |
- Alveolar surface is large as to allow rapid exchange of oxygen and carbon dioxide through diffusion |
Lungs
- Consists of lower portion of respiratory airways, pulmonary circulation, and connective tissue |
- Pleural sacs: thin fluid-filled sacs that enclose the lungs |
- Pleura produce fluid that lubricates the lungs to prevent friction when breathing |
- Pressure Gradient: air moves from area of high pressure to area of low pressure |
- Respiratory pressures are always relative to atmospheric pressure |
- High altitude = Low atmospheric pressure |
- Low altitude = High atmospheric pressure |
- Boyle's Law: at constant temperature the pressure of a gas varies inversely with its volume |
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During Inspiration
- Diaphragm contracts increasing thoracic cavity vertically |
- External intercostal muscles contract elevating rib cage |
- Intrapleural pressure becomes more subatmospheric |
- Lungs expand |
- Intra-alveolar pressure becomes subatmospheric |
- Air flows into alveoli |
During Expiration
- Diaphragm and intercostals stop contracting |
- Chest wall recoils inward |
- Intrapleural pressure moves back toward preinspiration value |
- Lungs recoil toward preinspiration size |
- Air in alveoli becomes compressed |
- Intra-alveolar pressure becomes greater than atmospheric pressure |
- Air flows out of lungs |
Gas Exchange
Gas exchange: |
- continuous exchange of O2 and CO between environment and body2 |
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- movement of gases occurs by passive diffusion down partial pressure gradient |
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- diffuse from area of high partial pressure to areas of low partial pressure |
Partial Pressures: |
- independent pressure exerted by a particular gas |
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- directly proportional to percentage of gas in that total mixture |
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