Respiratory System Flashcards
Pathway
Nasal cavity -> trachea -> bronchi -> bronchioles -> alveolar ducts + alveoli -> pulmonary capillaries (0.5 um)
Epithelial surfaces are made of ___ cells
Pseudostratified ciliated columnar cells
Mucus beats towards ____
pharynx
Phagocytes + simple cuboidal cells are in
Lower airway
Functions
- O2/CO2
- Speech sounds in humans
- Defend against microbes
- Traps and dissolves blood clots
- Metabolic
Metabolic functions
- Dipalmitoyl lecithin synthesis
- Prostacyclin release (lung injury)
- Angiotensin 1 -> angiotensin 2 (vasoconstrictor)
- Inactivation and removal of toxic substances
Inspiration
- Inrapleural pressure must be elastic recoil lung and chest wall
- When inspiratory muscles increase, thoracic dimensions of lungs increase because change in intrapleural pressure
Boyle’s law
Pressure within alveoli drops below atmosphere
Expiration
Completely passive at rest -> depends on relaxation of inspiratory muscles and recoil of stretched lungs
Under certain conditions expiratory intercostal muscles…
contract with abdominal muscles to actively decrease thoracic dimensions
VT
Tidal volume - volume of gas passing into and out of respiratory tract
FRC
Functional residual capacity - volume of gas remaining in lungs + airways following normal expiration
TLC
Total lung capacity - volume of gas after max inspiration
RV
Residual volume - volume of gas after max expiration
VC
Vital capacity - volume of gas exhaled between points of max inspiration and max expiration
Largest possible volume =
TLC - RV
IC =
Inspiratory capacity = TLC - FRC
IRV =
Inspiratory reserve volume = TLC - (VT + FRC)
ERV =
Expiratory reserve volume = FRC - RV
Dynamic lung volume
FVC = VC, FEV1
Compliance is the measure
of ease at which lungs can be inflated, the smaller the delta P to produce a given delta P
Compliance depends on
- elasticity
2. surface tension forces at the gas/ liquid interface
Laplace’s equation
P = 2T/r
transpulmonary pressure = 2 tension of alveolus wall / radius of alveolus
Surfactant
Produced by type 2 alveolar cells : a phospholipid which reduces cohesive forces on alveolar surface
How does surfactant reduce surface tension?
Surface tension is at the air/water interface with alveoli. Expansion requires energy to overcome surface tension of water lining of alveoli. Surfactant increases lung compliance and prevents lung collapse.
