EXAM #1: RESPIRATORY PATHOPHYSIOLOGY Flashcards
What is the major factor that controls breathing?
1) PCO2
+
2) PO2
3) pH
Outline the neuro-anatomic pathway that controls breathing.
1) Increased PCo2
2) Central chemoreceptors
3) Central Pattern Generator
4) Spinal cord or cranial nerves
5) Respiratory muscles, chest wall/ diaphragm
6) Increased ventilation
At what generation does cartilage stop?
11
What generation marks the conducting airway/ anatomic dead space?
16
Where is smooth muscle most abundant in the airway?
Bronchioles
What two regions of the airway confer the greatest resistance to air flow?
Bronchus and bronchioles
List four factors that will increase airflow resistance.
1) Inflammation of bronchial epithelium
2) Secretions
3) Constriction
4) Physical blockade
Write the equation for resistance.
N/A
What is the resistance of airflow inversely proportional to?
r^4
What type of ANS receptors will increase airway resistance?
M3
What type of ANS receptors will decrease airway resistance?
B2
What are the obstructive pulmonary disorders?
1) Asthma
2) Bronchitis
3) Emphysema
4) Obstruction of the airway lumen (physical)
List some of the disorders that will obstruct the airway.
Asthma Bronchitis Bronchiectasis Bronchiolitis CF Acute FB obstruction Epiglottitis Croup
Describe the blood flow around an alveoli.
Capillaries form a SHEET of flow around the alveoli
Describe the composition of the respiratory membrane from the alveolar side to the capillary side.
1) Surfactant
2) Alveolar epithelium
3) Epithelial basement membrane
4) Interstitial space*
5) Capillary basement membrane
6) Capillary endothelial cell membrane
This space is INCREASED in CHF
What are the major components of the lung interstitial space?
1) Connective tissue–elastin (like a balloon)
2) Smooth muscle
3) Lymphatics
4) Capillaries
5) Cells
*Under normal conditions this space needs to be v. small
Write the equation for the diffusion of a gas across a membrane.
D= Diffusion of gas dP= difference in partial pressure A= surface area d= distance S= solubility
Which is more soluble, oxygen or carbon dioxide?
Co2
What factors will alter dP?
1) High altitude
2) Restrictive lung disease
*Note that you can control this will an oxygen mask
What factors will alter d?
1) Pulmonary edema
2) Pneumonia
What are the major components of the parietal pleura?
1) Parietal lymphatics
2) Stoma opening into the pleura space
3) Systemic capillaries
What are the components of the visceral pleura?
Pulmonary capillaries
What causes pleural effusion?
1) CHF i.e. increased pulmonary venous hydrostatic pressure
2) Decreased oncotic pressure
- Liver disease
- Nephrotic syndrome
3) Decreased pleural pressure from atelectasis
4) Blockade of lymphatic drainage (e.g. tumor at the stoma)
What is the definition of a restrictive lung disorder?
Disorders that cause decreased expansion of the lungs
What is lung compliance?
Extent to which the lungs will expand with an increase in transpulmonary pressure
*Note that this is the inverse of elasticity
What are the primary intrinsic determinants of lung compliance?
Elastin and collagen
- Increased elastin/collagen= decreased compliance
- Decreased= increased compliance
*Note that things like CHF and pneumonia will also decreased lung compliance
What are the types of restrictive lung disorders?
1) Fibrotic interstitial lung diseases
2) Atelectatic disorders (ARDS)
3) Pleural space disorders
4) NM disorders
5) Chest wall deformities
6) Infection/inflammation
How does the pulmonary circulation differ from the systemic circulation?
1) Shorter
2) Thinner/more COMPLIANT
- Accommodate more volume in a shorter amount of space
What artery is responsible for bronchial circulation? Where does the blood go after the bronchial capillaries?
Bronchial a. - broncial capillaries - pulmonary vein
*Note that this is deoxygenated blood going to the left heart and accounts for a lower oxygen saturation of arterial blood–this is “physiological shunting”
What is hypoxic pulmonary vasoconstriction (HPV)?
- Low oxygen content to alveoli
- Surrounding vessels VASOCONSTRICT
*Avoids perfusing hypoxic areas
What is the normal V/Q ratio? What is the normal V/Q ratio at the apex? Base? Why?
Normal= 0.8
Apex= 3, b/c there is wasted oxygen with less perfusion Base= 0.6 b/c there is wasted perfusion
What is a V/Q of infinity? What causes it?
Blood flow obstruction
- Think PE
- OR, physiologic dead space where there is normally no gas exchange
What is a V/Q of 0?
Airway obstruction, also called “shunt”
*Bronchial circulation is a physiologic shunt
What volume cannot be measured by spirometry?
Residual volume
What is the normal tidal volume?
500 mL
What is the total amount of air that can go in and out in a single breath?
Vital capacity
What is FVC?
Forced Vital Capacity
Draw the Flow-Volume curve.
N/A
After one second of expiration, where are you on you the flow-volume curve?
FEF75
*75% of the Forced Expiratory Flow
How will the Flow-Volume curve change in obstructive lung disease?
See ppt.
How will the Flow-Volume curve change in upper airway obstuction?
See ppt.
How will the Flow-Volume curve change in restrictive lung disease?
See ppt.
What is a normal FEV1/FVC?
0.8
What is the FEV1/FVC in obstructive lung disease?
Decreased i.e. less than 0.7
*Both decreased, but FEV1 more so
What is the FEV1/FVC in restrictive lung disease?
Increased i.e. greater than 0.8
*Decreased FVC
