BMS 108 Ch. 16 Respiratory System Flashcards
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What is ventilation?
Moves air in and out of lungs for gas exchange (external respiration)
What three related functions does respiration encompass?
- ventilation
- gas exchange
- O2 utilization
What is gas exchange?
Exchange of gas between air and blood and blood and tissues.
What is O2 utilization?
cellular respiration
Is gas exchange active or passive?
passive; gas always exchanged down its concentration gradient
How many alveoli in the lungs?
300 million
What is an alveolar type 1 cell? type 2?
alveolar wall; cell that secretes surfactant in the alveoli
What law governs ventilation?
Boyle’s Law (P=1/V)
What is compliance?
- how easy the lungs expand with pressure
- reduced by factors that cause resistance to distention (e.g. pulmonary fibrosis)
What is elasticity?
- the tendency to return to initial size after distention
- elastic tension increases during inspiration and is reduced by recoil during expiration
What is surface tension?
- cohesive forces between liquid molecules that allows them to resist an external force
What causes surface tension in water molecules?
Hydrogen bonds
What are the forces that promote alveolar collapse and resist distention?
surface tension and elasticity
Surface tension acts to ________ the alveoli; thus __________ pressure of air within alveoli.
collapse; increases
Why don’t alveoli normally collapse?
surfactant
What is surfactant secreted by? What is it’s function?
Type II alveolar cells; lowers surface tension by getting between H20 molecules, preventing surface tension from collapsing alveoli
What connects the lungs to the thoracic cavity?
the pleura
What is intrapulmonary pressure?
- pressure inside alveoli (inside lungs)
- must become < atmospheric P for air to enter lungs
- when intrapulmonary P is > than atmospheric P, expiration occurs
What is intrapleural pressure?
- pressure in the intrapleural space (outside the lungs)
- due to thoracic cavity pulling out and the lungs trying to collapse in (elasticity & surface tension)
What is partial pressure of gases?
The pressure that a particular gas in a mixture exerts independently.