Term
| Spinal cord segments that innervate diaphragm |
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Definition
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Term
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Definition
Diaphragm contraction
External intercostal muscles (In strenuous activity) |
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Term
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Definition
1. The diaphragm lengthens and flattens through contraction.
2. This increases the volume in the thoracic cage while reducing pressure, creates negative pressure in relation to atmospheric pressure.
3. Glottis opens in inspiration and air rushes into the negative space. |
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Term
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Definition
1. Diaphragm relaxes, causing in decrease in volume and an increase in pressure in the thoracic cavity.
2. The pressure inside the thoracic cavity is now higher than the outside air (positive to the outside air) and air rushes out. |
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Term
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Definition
| COPD creates labored breathing, patient must use accessory muscles to move air. Also alters the position of the diaphragm. |
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Term
| Factors affecting air conductivity |
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Definition
1. Compliance of the lung
2. Resistance of airways |
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Term
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Definition
(Change in volume in L)/ (change in pressure in cm)
Normal=.2L/cm |
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Term
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Definition
| Measures the rebound of lung after being stretched, inverse of compliance. |
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Term
| Emphysema effects on lung compliance |
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Definition
| Changes the structure of the parenchyma of the lung so that it is more compliant, stretches more. Therefore, it is hard to expel air out during expiration due to low elastance of the lung tissue. Creates a steeper PV curve (indicative of increased compliance). Also creates increased FRC. |
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Term
| Pulmonary fibrosis effects on compliance |
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Definition
| Causes lung to be very stiff, hard to open alveoli. Compliance is lower, creates a flatter PV curve, indicative of decreased compliance. Also decreases the FRC. |
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Term
| Age effects on chest wall compliance |
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Definition
| Chest wall compliance increases with age. |
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Term
| Factors determining compliance of the lung |
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Definition
1. Elastic recoil: Force that causes lung to recoil inwards. Created by collagen and elastin in the parenchyma.
2. Surface forces in the alveoli determined by surfactant (major). |
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Term
| Transpulmonary Pressure (PTP) |
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Definition
| PTP= PA (Alveolar)– PIP (Intrapleural) |
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Term
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Definition
Gap between expiration and inspiration curves. Surface tension in alveoli makes it so that lots of pressure is required to open alveoli initially, and less pressure is needed to open alveoli further once process has been initiated.
Expiratory phase is just relaxation, doesn't have to deal with these surface interactions. |
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Term
| Combined lung and chest pressure at FRC |
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Definition
| 2 pull in equal and opposite ways to create 0 sum pressure at the FRC. Air is not moving in or out. |
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Term
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Definition
| Force of chest wall expansion is greater than force of lung collapse. Pressure is negative and air rushes in. |
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Term
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Definition
| Lung collapsing force is greater than chest expansion force, creates a positive thoracic pressure, air rushes out. |
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Term
| PV Curve at high lung volumes |
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Definition
| Both lung and chest favor collapse to create positive pressure, pushes air out. |
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Term
| Causes of increased compliance |
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Definition
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Term
| Causes of decreased compliance |
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Definition
1. Pulmonary fibrosis
2. Pulmonary edema (alveoli are filled with fluid=harder to inflate)
3. Increased pulmonary venous pressure
4. Acute Respiratory Disease Syndrome (ARDS, creates inflammation) |
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Term
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Definition
| Surface tension is the attractive forces of adjacent molecules, with the forces between liquid molecules greater than between liquid and gas at the alveolar interface: tries to get as small as possible, forms a sphere. |
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Term
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Definition
| P= 2 x surface tension/ radius |
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Term
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Definition
| Alveolar collapse due to surface tension. |
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Term
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Definition
Produced by Type II pneumocyte.
Mixture of lipids: DPPC (Dipalmityl Lecithin) is main component, mixed with proteins
Final assembly takes place in the lamellar bodies. |
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Term
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Definition
| Increases lung compliance through its amphipathic nature, breaks up attracting forces in liquid air interface of alveoli. Keeps alveoli dry. |
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Term
| Effects of loss of surfactant |
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Definition
| Loss of surfactant results in stiff lungs (loss of compliance), areas of atelectasis (collapse due to loss of stability), and “wet” (alveoli filled with fluid)…..collapsed lung does not participate in gas exchange (SHUNT) |
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Term
| Infant Respiratory Distress Syndrome |
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Definition
| Premature babies lack surfactant in the lungs. Inward pull of the alveoli draws interstitial fluid into the lungs and inhibits gas exchange. |
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Term
| Factors governing airflow |
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Definition
Flow=Pressure gradient/resistance
Affected by
1. Airway radius and branching
2. Smooth muscle tone
3. Lung volume
4. Viscosity of gas |
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Term
| Relationship of lung volume and air flow |
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Definition
| Lung is tethered to the airway, amount of tethering is proportional to size of lung. Larger lung is more tethered and pulls open airway, which reduces air flow resistance. |
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Term
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Definition
Takes into account the viscosity(ɲ) of the gas, the “length of the tube” (l), and the radius (r)
R= 8ɲl/ π r 4 |
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Term
| Factors in smooth muscle tone |
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Definition
1. Sympathetic nervous system-beta 2 receptors
2. Parasympathetic/cholinergic nervous system
3. Nonadrenergic, noncholinergic nervous system (NANC) |
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Term
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Definition
With loss of elastic tissue, with forced expiration, airways may collapse
Airway and alveolar P are lower due to loss of elastic tissue
Alveolar P > IP pressure, Tm pressure is +, so alveoli open
Airway P < IP pressure, so Tm – and airway collapses
Clinical correlation: COPD
Expire slowly with pursed lips |
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