Circulation and Gas Exchange

Page
14

O2 unloaded

to tissues

at rest

O2 unloaded

to tissues

during exercise

100

40

0

20

60

80

0

40

80

100

O2 saturation of hemoglobin (%)

20

60

Tissues during

exercise

Tissues

at rest

Lungs

PO2 (mm Hg)

(a) PO2 and hemoglobin dissociation at pH 7.4

O2 saturation of hemoglobin (%)

40

0

20

60

80

0

40

80

100

20

60

100

PO2 (mm Hg)

(b) pH and hemoglobin dissociation

pH 7.4

pH 7.2

Hemoglobin

retains less

O2 at lower pH

(higher CO2

concentration)

Slide 89

Carbon Dioxide Transport

Hemoglobin also helps transport CO2 and assists in buffering.

CO2 from respiring cells diffuses into the blood and is transported either in blood plasma, bound to hemoglobin, or as bicarbonate ions = HCO3–.

Slide 90

Carbon dioxide transport in the blood

Body tissue

CO2 produced

CO2 transport

from tissues

Capillary

wall

Interstitial fluid

Plasma

within capillary

CO2

CO2

CO2

Red

blood

cell

H2O

H2CO3

Hb

Carbonic acid

Hemoglobin

picks up

CO2 and H+

CO2 transport

to lungs

HCO3–

Bicarbonate

H+

+

Hemoglobin

releases

CO2 and H+

To lungs

HCO3–

HCO3–

Hb

H+

+

HCO3–

H2CO3

H2O

CO2

CO2

CO2

CO2

Alveolar space in lung

Slide 91

Elite Animal Athletes

Migratory and diving mammals have evolutionary adaptations that allow them to perform extraordinary feats.

The extreme O2 consumption of the antelope-like pronghorn underlies its ability to run at high speed over long distances.

Deep-diving air breathers stockpile O2 and deplete it slowly.

Weddell seals have a high blood to body volume ratio and can store oxygen in their muscles in myoglobin proteins.

Slide 92

Review

Inhaled air

Exhaled air

Alveolar

epithelial cells

Lungs - Alveolar Air Spaces

GAS EXCHANGE

CO2

O2

CO2

O2

Alveolar

capillaries of

lung

Pulmonary veins

Pulmonary arteries

Systemic veins

Systemic arteries

Heart

Systemic

capillaries

CO2

O2

CO2

O2

Body tissue - GAS EXCHANGE

Slide 93

You should now be able to:

Compare and contrast open and closed circulatory systems.

Compare and contrast the circulatory systems of fish, amphibians, reptiles, and mammals or birds.