Unit 9: Gas Exchange
Video #1: Gas Exchange Overview
Respiration: involves 2 systems: circulatory and respiratory
1. Ventilation = air or water flow through specialized tissue
2. Gas exchange = across respiratory membrane (gas diffusion)
3. Circulation = Oxygen diffused to cells which need it; Carbon dioxide is removed (this
occurs because of a diffusion gradient which is due to partial pressures of oxygen and
carbon dioxide)
4. Cellular respiration = cell breathes Oxygen and removes carbon dioxide (waste) in order
to generate ATP
Video #2: Oxygen and Carbon Dioxide in Air and Water
Pressure:
- Atmospheric pressure (at level) = 760mmHg
- Dalton’s Law = total atmospheric pressure determined by partial pressures of N2, O2,
CO2…(Partial pressure = total pressureXpercentage)
- Pressure decreases as elevation increases but percent composition does not change
(density decrease)
Partial pressure gradient = difference in pressure between two regions allows for movement
- Oxygen moves from lungs to blood
- Carbon dioxide moves from blood into lungs
,Water versus air:
- Water holds less oxygen than air
- Water is much more dense than air.
Characteristics of O2 and CO2 in water and air:
1. Gases vary in their solubility in water
a. CO2>O2>N2
b. Oxygen is bound to hemoglobin
c. Henry’s Law = solubility of gas in a liquid is directly proportional to partial
pressure of that gas above the liquid (higher partial pressure, more soluble)
2. Temperature:
a. Warmer water holds less dissolved gas
3. Dissolved Solutes:
a. Water with more solutes can hold less dissolved gas
Video #3: Aquatic Respiration
Ventilation occurs across gills or through lungs:
- Internal gills = protected by external environment by operculum
- External gills = exposed to environment
Countercurrent Exchange System:
- Fluid flowing in opposite directions of parallel running tubes
- Exchange if there is a difference in solute or temperature, moves down tubes
- Testes: blood from testicular artery is warmer and transfers heat to venous blood
- Fish Gill:
- Water ventalites across gill bringing oxygen
, - Gill contains gill arch and gill filament (highly vascularized tissue where gas
exchange occurs)
- Blood flows in opposite direction of the water
- Blood is at lower concentration of oxygen than water establishing a partial
pressure gradient: higher partial pressure of oxygen in water than blood causing
oxygen to flow from water into blood.
Video #1: Gas Exchange Overview
Respiration: involves 2 systems: circulatory and respiratory
1. Ventilation = air or water flow through specialized tissue
2. Gas exchange = across respiratory membrane (gas diffusion)
3. Circulation = Oxygen diffused to cells which need it; Carbon dioxide is removed (this
occurs because of a diffusion gradient which is due to partial pressures of oxygen and
carbon dioxide)
4. Cellular respiration = cell breathes Oxygen and removes carbon dioxide (waste) in order
to generate ATP
Video #2: Oxygen and Carbon Dioxide in Air and Water
Pressure:
- Atmospheric pressure (at level) = 760mmHg
- Dalton’s Law = total atmospheric pressure determined by partial pressures of N2, O2,
CO2…(Partial pressure = total pressureXpercentage)
- Pressure decreases as elevation increases but percent composition does not change
(density decrease)
Partial pressure gradient = difference in pressure between two regions allows for movement
- Oxygen moves from lungs to blood
- Carbon dioxide moves from blood into lungs
,Water versus air:
- Water holds less oxygen than air
- Water is much more dense than air.
Characteristics of O2 and CO2 in water and air:
1. Gases vary in their solubility in water
a. CO2>O2>N2
b. Oxygen is bound to hemoglobin
c. Henry’s Law = solubility of gas in a liquid is directly proportional to partial
pressure of that gas above the liquid (higher partial pressure, more soluble)
2. Temperature:
a. Warmer water holds less dissolved gas
3. Dissolved Solutes:
a. Water with more solutes can hold less dissolved gas
Video #3: Aquatic Respiration
Ventilation occurs across gills or through lungs:
- Internal gills = protected by external environment by operculum
- External gills = exposed to environment
Countercurrent Exchange System:
- Fluid flowing in opposite directions of parallel running tubes
- Exchange if there is a difference in solute or temperature, moves down tubes
- Testes: blood from testicular artery is warmer and transfers heat to venous blood
- Fish Gill:
- Water ventalites across gill bringing oxygen
, - Gill contains gill arch and gill filament (highly vascularized tissue where gas
exchange occurs)
- Blood flows in opposite direction of the water
- Blood is at lower concentration of oxygen than water establishing a partial
pressure gradient: higher partial pressure of oxygen in water than blood causing
oxygen to flow from water into blood.
