(13) Gas Exchange Flashcards
An understanding of the general gas laws helps us clinically in… four things… what are they?
- Interpretation of arterial blood gas conc
- Interpretation of throacic radiographic findings
- integration - clinical signs, radiography, and blood gases
- Knowing when to ventiliate, and when not to ventilate
(Facts, Figure, and Definitions)
- Body temp = assume ?
- Ambient pressure = _____ pressure
- atm pressure at sea level = ___ mmHg = air pressure in airways
- Fractional Concentrations of gases in air: O2 = ?, N2 = ?, CO2 = ?
- Water vapor pressure in conducting airways at 37 C = ___ mmHg
- Airways –> ____ inspired air
- 37 C
- barometric
- 760
- 21%, 79%, 0%
(Boyle’s Law)
- What is it?
- The Equation?
- Example - Diaphragmatic contraction to increase lung volume —> to sustain P*V, gas pressure in the lungs must ____ as lung volume increases
- At a given temp, the product of pressure and volume for a gas is constant
- P1*V1 = P2*V2
- decrease
(Dalton’s Law of Partial Pressires)
What does it say?
Then just look at the figure and figure it out (if you can’t read it is on your ipad)
- The partial pressure of a gas in a mixture of gases is the total pressure mutliplied by the fractional concentration of gas
(Henry’s Law for Concentrations of Dissolved Gases)
what does it say?
What is the equation?
- and then just read the thing (it is also on your ipad)
- the concentration of a dissolved gas is related to its partial pressure and solubility
- C = P * solubility
(Fick’s Law of Diffusion of Gases)
- what does it say?
- an then just look at picture
- Transfer of gases across cell membranes or capillary walls occurs by simple diffusion
(The Ideal or General gas law)
- What do Boyle’s Law, Charles’ Law, and Avogadro’s Law combine to form?
- What is the equation and what does each term stand for?
- THE IDEAL GAS LAW
(Forms of Gas in the Circulation)
What are the three types?
- Dissolved Gas
- Bound Gas
- Chemically Modified Gas
(Forms of Gas in the Circulation)
- Dissolved Gas - what three gases? Which of the 3 is only carried in the circulation in dissolved form?
- Bound Form - what three? What do they bind to?
- Chemically Modified Gas - what is the example of this?
- The total concentration of each gas in the blood will be equal to what?
- O2, CO2, N2 – N2
- O2, CO2, CO – bind to plasma proteins and/or hemoglobin
- CO2 carried in blood as HCO3- in RBC
- the dissolved gas concentration, bound gas concentration, and chemically modified gas concentration
(Overview of Gas Exchange)
- What two types of circulation is this figure involved with (also learn the figure)
- pulmonary circulation, systemic circulation
(Overview of Gas Exchange)
(Mixed Venous Blood)
Give me the order of blood flow - starting with tissue…
What are the pressures of O2 and CO2 in this blood?
Tissue –> Veins –> Caudal Vena Cava –> Right Atrium –> Right Ventricle –> Pulmonary Artery –> Pulmonary Capillaries
O2 = 40 mmHg, PCO2 = 46 mmHg
Give me the Pressures of C02 and O2 in the following circumstances….
- Dry Inspired Air
- Humidified Air
- Alveolar Air
- Capillaries (venous and arterial)
- What occurs is diffusion-limited gas exchange?
- What occurs in Perfusion-limited gas exchange?
- total amount of gas transported across the alveolar-capillary barrier is limited by diffusion process (ex fibrosis - in westies alot - increases membrane thickness)
- The total amount of gas transported across the alveolar-capillary barrier is limited by blood flow (perfusion) (ex thromboamblism)
Look at this picture - it is on your ipad
