Respiratory System Flashcards
Which structures are involved in pulmonary defense systems?
Olfaction, filtration (cilia and mucus), alveolar macrophages and neutrophil recruitment
Regions of the tracheobronchial tree NOT involved in gas exchange
Trachea, bronchi, bronchioles, terminal bronchioles
Regions of the tracheobronchial tree that ARE involved in gas exchange
Respiratory bronchioles, alveolar ducts, alveolar sacs
Layers to pass through for gas exchange
Thin epithelium of alveoli, parenchyma and blood vessel wall (goes through via diffusion)
Factors that affect rate of gas diffusion
Diffusion coefficient of the gas, membrane thickness, surface area of membrane, partial pressure difference between sides of membrane
What is shunt flow?
The flow of blood to supply the pulmonary system (lungs and alveoli). It is not exposed to gas exchange.
It is also the act of shifting where blood flow goes in result to lack of gas exchange
What is Dalton’s Law (state and describe in cases of dry and humid)
Px = (Pb) * Fx ---- Dry Px = (Pb - 47mmH [water vapor pressure]) * Fx ----- Humid
Know that PO2 in humid environment (during inspiration) is less than in the dry environment
Draw the lung volume and capacity chart describing volumes of air in lungs
Should include: inspiratory reserve volume, expiratory reserve volume, residual volume, tidal volume, inspiratory capacity, vital capacity, functional residual capacity, and total lung capacity
Intrapulmonary pressure
Pressure within the pleural cavity (where gas exchange occurs)
Intrapleural pressure
Pressure within pleural cavity (between lung and thoracic wall)
Transpulmonary pressure
Difference between Intrapulmonary and Intrapleural pressure
Pressure balances at rest
Pressure along tracheobronchial tree is atmospheric
Recoil of lung and chest are equal but opposite (wall wants expansion, lung wants contraction)
Intrapleural pressure is negative
Transpulmonary pressure = 0
Pressure balance during inspiration
Alveolar pressure (intrapulmonary pressure) becomes lower, forcing chest to expand (but increases during inhalation)
Transpulmonary pressure is more negative
Intrapleural pressure is more negative
Pressure balance during exhalation
Recoil of lung causes alveolar pressure to increase
Transpulmonary pressure is less negative
Intrapulmonary pressure increases but begins to decrease
Intrapleural pressure increases (less negative)
Define compliance and give equation
Measure of lung expandability
C = dV/dP
More compliant = easier to inhale, more difficult to exhale (emphysema)
Less compliant = more difficult to inhale, easier to exhale (fibrosis)
What is surfactant and what is its purpose?
Produced by alveolar type II cells
Decreases surface tension and prevents collapse at the end of expiration
Allows for structural dependence
Describe structural independence
Surfactant allows the local reduction of surface tension to allow an alveolus that may have a smaller radius (and therefore increased pressure and harder to inflate) to be easier to inflate. Allows a sort of equilibrium between alveoli with each one maintaining its size and ability to participate in gas exchange.
Pressures during forced expiration
Intrapulmonary pressure decreases
Intrapleural pressure increases (less negative and becomes positive)
Transpulmonary pressure increases to force air out
Chance of collapse where intrapleural pressure = intrapulmonary pressure
(when transpulmonary pressure = 0)
Describe COPD
Chronic obstructive pulmonary disorder
Loss of alveolar wall = decreased elastic recoil and increased compliance
Increased chance of collapse during expiration
Series of events that occur during airway obstruction concerning ventilation-perfusion relationships
In response to reduced ventilation without change in perfusion (hypoxia), hypoxic vasoconstriction reduces the local blood flow. The local reduced blood flow shunts more blood to areas of lungs that can still participate in gas exchange.
What are the primary causes of hypoxia
- Reduced inspired O2
- Reduced diffusion through alveolar membrane (asbestosis)
- CO (greater affinity to Hb than O2)
- Anemia (tissue hypoxia)
- Anemia + CO
- Physiologic shunt
How does anemia result in tissue hypoxia?
The saturation of Hb is the same – arterial PO2 does not decrease
Volume of O2 held and therefore transferred to tissue lowers – not as much oxygen is being given to tissue = tissue hypoxia
How are levels of breathing controlled under normal conditions?
Controllers: neural circuitry required to generate each breath
Effectors: muscles of respiration
Sensors: regulate rate of ventilation
Example of breathing controllers
Cerebrum, brainstem, spinal cord, reflexes
Examples of breathing effectors
Diaphragm, lungs
Example of breathing sensors
Central medullary (CO2 - brainstem neurons) and peripheral (O2 - carotid and aortic bodies)
