Ch. 22 - Oxygen And Carbon Dioxide

Front 1

gas exchange

Back 1

- respiratory gas moves from place to place
- convection/bulk flow
- simple diffusion
- partial pressure determines direction
- materials tend to move in net fashion from regions of high chemical potential to low chemical potential
- rate proportional to difference in chemical potential

Front 2

gas laws of respiratory physiology

Back 2

- boyle's law
- charle's law
- dalton's law
- henry's law

Front 3

boyle's law

Back 3

- pressure of given quantity of gas is inversely proportional to its volume
- constant temperature

Front 4

charle's law

Back 4

- volume of given gas quantity of gas directly proportional to its absolute temperature
- constant pressure
- as temperature of gas increases, the volume occupied by gas increases

Front 5

dalton's law

Back 5

- total pressure of gas mixture is equal to sum of partial pressures of individual gases
- pressure of each gas is proportional to its concentration in mix
- Px=(n/v)RT
-Px is partial pressure
- n is # of moles
- v is volume
- R is universal gas constant
- T is absolute temperature

Front 6

henry's law

Back 6

- at water-air interface
- amount of gas that dissolves in water is determined by its solubility in water and its partial pressure in air
- constant temperature
- solubility of a gas depends on its partial pressure above solution
- partial pressure of a gas in solution is equal to partial pressure of that gas in gas phase with which solution is in equilibrium

Front 7

thoracic cavity and lung volume

Back 7

- when thoracic cavity and lung volume expand, the pressure of air within in lungs drops below atmospheric pressure
- air flows down gradient from the outside into lungs by inhalation
- exhalation is reduction of thoracic cavity and lung volume and increase of intrapulmonary pressure
- aire moves down its gradient from inside lungs to outside

Front 8

partial pressure

Back 8

- influences gas exchange between alveoli and blood
- alveolar air is humidified in nasal cavity and mixes with residual air in alveoli
- alveolar air doesn't have same proportions of gases as inhaled air

Front 9

factors that affect partial pressure

Back 9

- temperature
- solutes dissolved in liquid
- water vapor
- altitude

Front 10

temperature

Back 10

- inflation of lungs is aided by warming of inhaled air in nasal cavity
- gas is cold = condenses
- volume can be changed by temperature

Front 11

solutes dissolved in liquid

Back 11

- solubility is property of solute and solvent
- rise in temperature drives dissolved gases out of solution
- each grain of salt increases salinity in its vicinity, driving dissolved CO2 out of solution

Front 12

solubilities of gases in water

Back 12

- solubilities
- temperature
- presence of other solutes

Front 13

amount of gas dissolved dependent on

Back 13

- nature of gas
- pressure
- temperature
- presence of solutes

Front 14

nature of gas

Back 14

- solubility coefficient = alpha
- volume of a gas in mL at STPD that will dissolve in 1L of water when the pressure of gas is 1 atm
- oxygen: 34.1 mL O2/L water
- nitrogen: 16.0 mL N2/L water
- carbon dioxide: 1019 mL CO2/L water

Front 15

solubility of gas

Back 15

- more soluble the more it will dissolve into pulmonary surfactant
- higher the partial pressure of gas, the more of that gas will dissolve into pulmonary surfactant

Front 16

two factors extremely important in gas exchange

Back 16

- relative concentration gradients of O2 and CO2 contribute to diffusion of O2 into the blood and CO2 out of blood
- concentration of CO2 isn't as great as that for O2
- solubility of CO2 in water is about 20 times that of O2
- amount of gas dissolved in fluid is determined by both its solubility in water and its partial pressure in air

Front 17

effects of pressure and temperature

Back 17

- solubilities of gas in an aqueous solution decreases as temperature increases
- volume is inversely proportional to pressure when at constant temperature

Front 18

gas diffusion

Back 18

- diffuse from areas of high partial pressure to areas of low partial pressure regardless of concentration
- doesn't go down concentration gradient
- greater the area = greater the rate
- greater the distance = slower the rate
- O2 concentration is higher in cold water than warm water
- partial pressure is lover in cold water than warm water
- gas will diffuse from water water where [] is lower but the partial pressure is higher to cold water where [] is higher but partial pressure is lower

Front 19

Fick's law of diffusion

Back 19

- rate of gas diffusion
- Q=KA(P1-P2)/x
- Q is diffusion rate
- K is diffusion constant
- A is cross sectional area
- X is distance separating P1 an dP2

Front 20

diffusion coefficient

Back 20

- contant that expresses physical conditions of the system
- temperature
- molecular weight of the diffusing substance
- nature of the materials through which the substances are diffusing

Front 21

Graham's law

Back 21

- rate at which gas diffuses is inversely proportional to the square root of the molecular mass of the gas

Front 22

O2 diffuses faster than CO2

Back 22

- diffusion occurs faster in air than water
- met rates highest in air breathing animals
- living tissue diffusion is adequate for only about 1mm from exchange site

Front 23

convective transport of gases

Back 23

- ventilation
- bulk movement = convective flow
- cellular diffusion

Front 24

flow

Back 24

- tidal flow moves in and out the same opening
- tidal flow = most mammals
- unidirectional flow goes in one way and out another
- unidirectional flow = fish

Front 25

processes affect partial pressures

Back 25

- gases are exchanged with adjacent regions by diffusion and convection
- usually tend to even out the partial pressures of O2 and CO2
- resident organisms can cause the local partial pressure of O2 and CO2 to be far different from those in neighboring regions

Front 26

alveoli

Back 26

- diffusion space
- sites on the capillaries
- one really thin basement membrane
- short diffusion distance
- O2 goes from alveoli to blood
- CO2 goes from blood to alveoli

Front 27

tissue

Back 27

- opposite flow of O2 and CO2 from alveoli
- higher partial pressure of O2 in blood
- higher partial pressure of CO2 in tissue
- convection carries O2 to tissue
- convection carries CO2 to lungs

Front 28

physiological oxygen cascade

Back 28

- based on analogy with cascade along mountain stream
- only O2 partial pressure that still prevails in systemic capillaries is available to dive O2 diffusion to mitochondria