respiration lec 1

Question 1

How do the various laws of physics affect transportation of oxygen and carbon dioxide within the respiratory system?

Answer 1

fick equation-diffusion rates
ideal gas law - gas pressure
dalton's law of partial pressures
henry's law - dissolving gases in liquid
graham's law - rate of diffusion
boyle's law - volume vs pressure
resistance to bulk flow
surface area geometry - SA:volume ratios

Question 2

How does an animal’s size affect its mode of gas transport?

Answer 2

larger cannot rely on diffusion, due to volume increasing more than SA, so must rely on bulk flow aswell via systems

Question 3

What are the 4 general types/models of respiration?

Answer 3

way of the small
embracing the environment
way of the skin
mass transit

Question 4

Why is measurement of partial pressure important when discussing gas transport?

Answer 4

because air is not pure oxygen

Question 5

What physical factors affect diffusion rates, and how does this relate to respiratory organs/systems?

Answer 5

.increases with diffusion coefficient of medium
surface area
pressure gradient
solubility
decreases withdiffusion distance and molecular weight

Question 6

 What are some of the important physical differences between air and water as they relate to gas exchange?

Answer 6

-O2 must dissolve and then diffuse when travelling from air to water of the cell

Question 7

What are the three main physical processes that govern transportation of gases to and from the mitochondria?

Answer 7

dissolution: from environment to body
diffusion: body to cell
bulk flow: environ into trachea (ie in bugs)

Question 8

respiratory system summary

Answer 8

one goal
two mediums
three processes
four systems

Question 9

way of the small

Answer 9

• diffusion over small area

- ie. cellular respiration

Question 10

embracing the environment

Answer 10

flow of external medium (air or water) through the body

ie. water flowing out of a sponge, or air into an insect through spiracles; oxygen bathes/bulk flows over the cells

Question 11

way of the skin

Answer 11

aka cutaneous respiration/diffusion, followed by internal circulation which distributes O2 to the cells via bulk flow

Question 12

mass transit

Answer 12

bulk flow into specialized system, then bulk flow in internal circulation distributes O2

Question 13

diffusion

Answer 13

movement of molecules from high conc to low conc

-slow over long distances but fast over short distances

Question 14

Fick equation

Answer 14

• diffusion rate of gases is proportional to diffusion coefficient, area of the membrane, and diff in pressure over distance
• to max diffusion respiratory surface are THIN with LARGE SA and rely on high diffusion gradients

Question 15

ideal gas law

Answer 15

pressure of a gas is equal to the number of moles of gas and the volume the occupy (PV=nRT)

Question 16

dalton’s law of partial pressure

Answer 16

air does not equal oxygen

• in a gas mixture each gas exerts its own partial pressure
• sum of all partial pressures is equal to the total of the mix
• Ptotal= Po2+Pco2

Question 17

henry’s law

Answer 17

• gas molecules in the air must first dissolve in liquid to diffuse into cells
• concentration of gas in a liquid is proportial to its partial pressure and solubility
• henrys law= [G]= Pgas*Sgas

Question 18

diffusion rates: grahams law

Answer 18

solubility of a substance is the amount of that substance that will dissolve in a given amount of solvent

Question 19

rate of diffusion at specific temp in specific medium increases with

Answer 19

diffusion coefficient of medium
surface area
pressure gradient
solubility

Question 20

rate of diffusion at specific temp decreases with

Answer 20

diffusion distance and molecular weight

Question 21

boyles law/bulk flow of gases

Answer 21

PV=PV

• initial pressure and volume=final pressure and volume
• for respiration that means liquids and gases both move from an area of higher pressure to an area of lower pressure
• in bulk flow think of a pump filling with water when area available expands

Question 22

resistance of bulk flow

Answer 22

rate of flow determind by diff in pressure and resistance: Q=P/R
-resistance decreases with radius, and increases with length and viscosity

Question 23

surface area geometry

Answer 23

higher sa-vol ratio the better

• as radius increases, volume increases faster than SA, and as organisms grow, the ratio decreases
• bigger means limited surface area available for diffusion and increases diffusion distance/time: t=x^2/4D
• thus only small organisms can rely only on diffusion of oxygen

Question 24

other problems with diffusion

Answer 24

surface must be moist and requires a boundary layer

-larger organisms rely on bulk flow and diffusion, and thus need a proper respiratory system