gas exchange from ch. 42 08 april 20151gas-exchange.ppt

Gas Exchange

From Ch. 42

08 April 2015 1Gas-Exchange.ppt

08 April 2015 Gas-Exchange.ppt 2

Animal Life

• Four critical processes• Obtain energy and material• Ingest, digest, absorb

• Obtain oxygen

• Dispose of nitrogenous waste• NH3, urea, uric acid

• Dispose of CO2

Animal Life

• Multicellular organisms• Internal circulation

• Coordination, information transfer

• Structural maintenance

• Movement

• Maintenance of homeostatic internal environment



Gas Exchange

• Exchange of O2 for CO2 occurs by diffusion

• Structure of gas exchange organs facilitates diffusion


Gas Exchange

• To, temperature

• S, solubility

• mol. wt., molecular weight of diffusing gas

• r, rate of diffusion

• P, difference in partial pressure (O2 or CO2)

• A, area of exchange membrane

• d, distance

Gas Exchange Systems• Gills in aquatic & marine animals

Large area Hemoglobin & other oxygen transporters pO2 variable in water


Gas Exchange Systems


• Fish gill• Filaments with large area

• Countercurrent flow maintains ΔP



• Fish gillCountercurrent flow maintains ΔP



• Tracheal systems of arthropods• large area

• Ventilation (?) to maintain ΔP



• Lungs in mammals• Diaphragm & other muscles for ventilation



• Lungs in mammals• Enclosed, protected by ribs


• Lungs• Thin, delicate

membrane between air and blood



Gas Exchange

• To, temperature

• S, solubility

• mol. wt., molecular weight of diffusing gas




• d, distance


Gas Exchange

• Constantso temperature (= body temperature)

o solubility (property of O2 or CO2)

o molecular weight (property of O2 or CO2)

• These don’t change. Disregard.


Gas Exchange




• d, distance


Gas Exchange

• To maximize diffusion rate:• Maximize P

• Maximize Area

• Minimize distance.

• These result from evolutionary and physiological adaptation.


Gas Transport

• Ventilation of alveoli

• O2 diffusion from alveoli to hemoglobin in RBC’s • Equilibrium pO2 = 100 mmHg

• Diffusion from hemoglobin to body tissues• Equilibrium pO2 = 40 mmHg


Gas Transport

• CO2 diffusion from body tissues to hemoglobin• Equilibrium pCO2 = 45 mmHg

• Diffusion from hemoglobin in RBC’s to alveoli• Equilibrium pCO2 = 40 mmHg

• Ventilation of alveoli


Gas Transport

• Hemoglobin• Oxygen-hemoglobin

dissociation curve

• Hb binds O2 at high pO2

• Hb releases O2 at low pO2


Gas Transport

• Hemoglobin• Oxygen-hemoglobin

dissociation curve

• Exercise lowers pO2 and pH in muscles, higher temperature

• Hb releases more O2 at low pO2 , low pH, and high temperature

gas exchange from ch. 42 08 april 20151gas-exchange.ppt

Documents

gas exchange r

gas exchange t o

gas exchange systems

gas exchange systems

diffusion slide

p slide

mmhg slide

ventilation slide