Respiratory SystemFunction??????

Lung

Exchangeof gaseswithbodycells

Cell

Capillary

Mitochondria

Breathing

Circulatorysystem

Transportof gases bythe circulatorysystem

CO2

CO2

O2

O21

2

3

Cut

CO2

O2

Cross sectionof respiratorysurface (theouter skin)

Capillaries

• Specialized organs used for gas exchange – Gills in fish and amphibians– Tracheal systems in arthropods– Lungs in tetrapods that live on land

– Amphibians– Reptiles– Birds– Mammals

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• Gills– Increase the surface area for gas exchange

– Oxygen absorbed– Carbon dioxide released

- gas exchange is enhanced by– Ventilation of the gills (moving water past the

gills)– Countercurrent flow of water and blood

Gillarch

Directionof waterflow

Operculum(gill cover)

Gillarch

Bloodvessels

Oxygen-richblood

Oxygen-poorblood

Lamella

Gillfilaments

Water flowbetweenlamellae

Blood flowthroughcapillariesin lamella

Countercurrent exchange

Blood flow insimplified capillary,

showing % O2

Diffusionof O2 fromwater toblood

Water flow, showing % O2

100 70 40 15

5306080

Gillarch

Directionof waterflow

Operculum(gill cover)

Gillarch

Bloodvessels

Oxygen-richblood

Oxygen-poorblood

Lamella

Gillfilaments

Water flowbetweenlamellae

Blood flowthroughcapillariesin lamella

Countercurrent exchange

Blood flow insimplified capillary,

showing % O2

Diffusionof O2 fromwater toblood

Water flow, showing % O2

100 70 40 15

5306080

Gillarch

Directionof waterflow

Operculum(gill cover)

Gillarch

Bloodvessels

Gillfilaments

Gillarch

Bloodvessels

Oxygen-richblood

Oxygen-poorblood

Lamella

Gillfilaments

Water flowbetweenlamellae

Blood flowthroughcapillaries inlamella

Countercurrent exchange

Blood flow insimplified capillary,

showing % O2

Diffusionof O2 fromwater toblood

Water flow, showing % O2

100 70 40 15

5306080

Human Respiratory System

• Trachea– Cilia

• Bronchi• Cartilage• Alveoli• Capillaries• Nasal cavity• larynx

1

5

4

32

8

7

6

9

Alveoli

CO2 O2

CO2-rich,O2-poorblood

O2-rich,CO2-poorblood

Exhaled air Inhaled air

Air spaces

Alveolarcapillaries

Tissuecapillaries

Tissue cellsthroughoutbody

Heart

CO2 O2

CO2 O 2

O2CO 2

Exchange of gases in the alveoli and the tissue cells

Artery from the heart

Vein going to heart

bronchiole

alveoli

capillary

air space

Lung

Diaphragm contracts(moves down)

Diaphragm

Inhalation

Airinhaled

Rib cageexpands asrib musclescontract Volume in thoracic cavity

goes up

Pressure goes down

Low pressure inside, higher outside

air rushes in

Diaphragm relaxes(moves up)

Airexhaled

Rib cage getssmaller asrib musclesrelax

Exhalation

Volume in thoracic cavity goes down

Pressure goes up

higher pressure inside, lower outside

air rushes out

Fig. 22-11

How are the gases carried in the blood?

Oxygen? Carbon dioxide?Most is converted into bicarbonate ions and transported in the blood plasma

CO2 + H2O H2CO3 H+ + HCO3-