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What is Daltons Law of Partial Pressures (the equation)?
Partial Pressure = Total Pressure x Fractional Gas Coefficient
What factors affect the diffusion of gases according to Fick's Law?
The diffusion of gases is directly proportional to: 1) The driving force 2) A diffusion coefficient 3) Surface area available for diffusion
The diffusion of gases is inversely proportional to: 1) Thickness of the membrane
What does Lung Diffusion Capacity (DL) take into account? How is it measured?
DL combines the diffusion coefficient of the gases, the surface area of the membrane, and the thickness of the membrane. It also takes into account the time required for the gas to combine with proteins in the pulmonary capillary blood
DL can be measured with carbon monoxide as CO transfer cross the alveolar/pulmonary capillary barrier is limited exclusively by the diffusion process
How does Lung Diffusion Capacity change in response to the following conditions?
2) Fibrosis or Pulmonary Edema
4) Rigorous Exercise
- 1) DL Decreases due to destruction of the alveoli resulting in decreased surface area for gas exchange
- 2) DL decreases because the diffusion distance increases (either by increased membrane thickness or increases interstitial volume)
- 3) DL decreases because the amount of hemoglobin in RBCs is reduced
- 4) DL increases because additional capillaries are perfused with the blood, which increases the surface area for gas exchange
The diffusion rate of O2 and CO2 depend on ______ and _____
The diffusion rate of O2 and CO2 depend on the partial pressure differences across the membrane and the area available for diffusion
How is Diffusion-Limited Exchange effected in conditions such as:
- 1) The diffusion of O2 is restricted due to thickening of the alveolar membrane increasing the diffusion distance
- 2) Diffusion of O2 is decreased due to the surface area available for gas diffusion is decreased
Define: Tidal Volume
Volume inspired or expired with each normal breath
Define: Inspiratory Reserve Volume (IRV)
The volume that can be inspired over and above the TV and is used during exercise
Define: Expiratory Reserve Volume
The volume that can be expired after the expiration of a Tidal Volume
Define: Residual Volume
The volume that remains in the lungs after a maximal expiration. It cannot be measured by spirometry
Define: Inspiratory Capacity
The sum of TV and IRV
Define: Functional Residual Capacity
- The sum of ERV and RV
- It is the volume remaining in the lungs after a TV is expired
- It includes the RV, and thus cannot be measured by spirometry
Define: Vital Capacity (or Forced Vital Capacity)
- The sum of TV, IRV, and ERV
- It is the volume of air that can be forcible expired after a maximal inspiration
Define: Total Lung Capactiy
- The sum of all four lung volumes (IRV, TV, ERV, and RV)
- It is the volume in the lungs after a maximal inspiration
- As it includes RV, it cannot be measured by spirometry
What is the Forced Expiratory Volume (FEV1)?
- It is the volume of air that can be expired in the first second of a forced maximal expiration
- It is normally 80% if FVC, and expressed as (FEV1/FVC = 0.8)
In obstructive lung disease (such as ______), FEV1 is ____ more than FVC so that FEV1/FVC is _____.
In obstructive lung disease (such as Asthma), FEV1 is reduced more than FVC so that FEV1/FVC is decreased.
In restrictive lung disease (such as ______), both FEV1 and FVC are _____.
In restrictive lung disease (such as Fibrosis), both FEV1 and FVC are reduced
When the diaphragm contracts, the abdominal contents are pushed ______ and the ribs are _______, thus causing the volume of the thoracic cavity to ______.
When the diaphragm contracts, the abdominal contents are pushed downward and the ribs are lifted upward, thus causing the volume of the thoracic cavity to increase.
True or False: The external intercostals and accessory respiratory muscles are often used during normal quiet breathing
FALSE: Neither groups of muscles are actively participating in Inspiration during normal quiet breathing, they only play a role during exercise or when airway resistance is increased due to disease (e.g., Asthma)
What effect to the Abdominal Muscles and Internal Intercostal Muscles have?
Abdominal Muscles: Compress the abdominal cavity, push the diaphragm up, and push air out of the lungs
Internal Intercostals: Pull the ribs down and inward
An FEV1 that is significantly less that 80% of FVC suggests the presence of an ______ disease
An FEV1 that is significantly less that 80% of FVC suggests the presence of an obstructive pulmonary disease (such as Asthma, where VC is usually normal but expiration is more difficult and takes longer because bronchoconstriction increases the resistance to air flow)
Explain the Surface Tension of Alveoli (what it results from, what it creates, how it relates to Large and Small Alveoli)
The Surface Tension of Alveoli is the result from attractive forces between molecules of liquid lining the alveoli. This creates a collapsing pressure that is directly proportional
to surface tension, and indirectly proportional
to Alveolar Radius
Pressure to keep Alveoli Open = (SurfaceTension/AlveoliRadius)
- Large Alveoli = low collapsing pressure; easy to keep open
- Small Alveoli = high collapsing pressure; more difficult to keep open
The condition characterized by small alveolar collapse in the absence of surfactant to reduce surface tension
Airflow is directly proportional to ______, and inversely proportional to _____.
Airflow is directly proportional to the pressure difference between the mouth (or nose) and the alveoli, and inversely proportional to airway resistance.
Airflow = (PressureGradient/AirwayResistance)
Briefly describe Asthma
2) Caused by
Condition: Obstructive lung disease where expiration is impaired; Airway occasionally constricts, inflamed, lined with excess mucus
Caused By: Environmental stimulants or allergens such as cold or warm air, exertion, emotional stress, pollens, etc.. .In children most common trigger is viral illnesses (common cold).
Symptoms: Wheezing, shortness of breath, chest tightness, coughing
Treatment: Bronchodialators; Beta2 Antagonist such as Albuterol
Briefly describe COPD
2) Caused by
Condition: Combination of Chronic Bronchitis and Emphysema; An obstructive lung disease where expiration is impaired
Symptoms: Decreased FEV1 and FVC, Barrel-shaped chest
Describe Pink-Puffers and Blue-Bloaters as they relate to COPD
Pink Puffers: Have primarily emphysema; present with mild hypoexmia, and due to maintained alveolar ventilation have normocapnia (normal CO2 partial pressure)
Blue Bloaters: Primarily have Bronchitis, severe hypoxemia with Cyanosis (blue-ish discoloration of skin), due to inability to maintain alveolar ventilation will present with Hypercapnia (increased CO2 partial pressure). May lead to Right Ventricular Failure and Systemic Edema
Breifly describe Firbosis
A restrictive disease in which inspiration is impaired
Characterized by a decrease in all lung volumes
FEV1 is actually decreased less than FVC, thus FEV1/FVC may end up increasing or presenting as normal.
How is most CO2 carried in the blood?