Blood Gas Exchange Flashcards
What is principle of gas exchange?
Gas molecules move randomly in a net direction from high conc to low conc
What is partial pressure?
AP is 760mmhg - total pressure exerted by each type of gas as % of total pressure of air
What is dry air made from?
Nitrogen, oxygen and co2
What happens to air when it enters respiratory tract?
Humidifies then o2 diffuses from alveoli into blood and co2 from blood to alveoli , air is partially replaced by next inspiration
Gases dissolve into liquids until they reach what?
Equilibrium - gases partial pressure and solubility in liquid determine this
What is solubility coefficient for o2 and co2?
O2 in water - 0.024
co2 in watwe - 0.57
co2 more soluble in water
What is nitrogen narcosis?
AA has 70 - low solubility coefficient, nitrogen diffusion induced in high pressure enviroments e.g as deep diver PP or nitrogen increase and diffuse across respiratory membrane cause hallucinations
WHat is decompression sickness?
Rapid changes from high to low pressure cause dissolved gases such as nitrogen out of solution causing bubbles forming in tissue
Dizziness, SOB, fatigue, paralysis- severity depends on number of bubbles formed - diver spend time in decompression chamber
What is hyperbaric oxygenation?
If o2 pp increase then diffusion to blood increase - bacteria for disease for gangrene and tetanus anaerobic, individual who surfer placing in chamber of o2 with 3-4 atmospheres
Whar are hyperbaric chambers?
Used to treat carbon monoxide poisen, gas embolism, smoke, near drowning
What is Respiratory membrane made up of?
thin layer fluid lining alveoli, thin squamous epithelial, epithelial basement, interstitial space, capillary endothelium
What 4 factors effect diffusion of gas across respiratory membrane?
Thickness of membrane 0.5mm thick
Diffusion of coefficient - o2 is 1 cos is 20
Surface area - larger better 70m2
PP difference of membrane - po2 high in alveoli low in capillaries - increased ventilation changes
What is blood flow and RR used for?
Insure maximal gas exchange, 2 main factors
What are 2 factors for blood flow and RR?
When ventilation exceeds blood to take up o2 heart failure
When blood supply to lungs exceeds ventilation lung not enough o2 - partially oxygenated blood is shunted blood
Where does deoxygenated blood arised from?
Bronchial arteries called physiological shunt
