Respiration

Question 1

Respiration problem

Answer 1

gas exchange necessary to support ATP production in cellular respiration
= O2 must diffuse into the organism from the environment CO2 must diffuse out

Question 2

Diffusion over whole body

Answer 2

no circulation

Capillaries near the surface

Question 3

Gills

Answer 3

• internal or external vascularized membranes
• ventilated by the flow of water over them
• O2 diffusion aided by countercurrent exchange

Question 4

Tracheal systems

Answer 4

• internal network of air tubes
• cells are supplied directly
• system can be ventilated by body movements, which compress and expand the tracheoles

Question 5

Lungs

Answer 5

• localized respiratory organs

- subdivided infolding of body surface

Question 6

Birds lungs

Answer 6

inflatable air sacs associated with rigid lungs

Question 7

Human lungs

Answer 7

-internal sacs, inflatable

Question 8

Human respiratory system

Answer 8

• trachea
• bronchi and alveoli
• trachea branches into two primary bronchi
• bronichi branched repeatedly into bronchioles
• tiniest bronchioles end as alveoli (air sacs)
• alveoli are the site of gas exchange

Question 9

Mechanics of ventilation- negative pressure breathing

Answer 9

• diaphragm contracts, moves down = thoracic volume up
• cohesion of pleural fluid = parietal pleural (lining inside chest) sticks to visceral pleura (lining around lungs)
• lung volume up, pressure down = air rushes in
• exhalation- the reverse of the above processes

Question 10

Respiratory pigments

Answer 10

• bind and transport gases
• help buffer the blood
• special proteins that transport most of the O2 in blood (hemocyanin and hemoglobin)

Question 11

Hemocyanin

Answer 11

• in arthropods and many molluscs

- O2 bound to copper

Question 12

Hemoglobin

Answer 12

• almost all vertebrates
• in red blood cells
• four subunits (for polypeptide chains) each with a heme group = hemoglobin can bind to four O2 molecules
• O2 bound to iron

Question 13

Why do hemoglobin need to carry O2?

Answer 13

• O2 alone has a low solubility in blood

- heme alone would carry Co no O2

Question 14

Hemoglobin also binds to …

Answer 14

• CO2 : bound to amino groups (not O2 binding site)
• H : attached to various sites
• bisphosphoglycerate (BPG) : important regulator for the affinity of hemoglobin for O2

Question 15

Copperative binding and release

Answer 15

• binding of O2 to one hemoglobin subunit = remaining subunits change shape slightly = their affinity for O2 increases
• release of O2 by one subunit = remaining subunits follow suit as confromational change lowers their affinity for O2

Question 16

Bohr shift

Answer 16

a drop in pH lowers the affinity of hemoglobin for O2

Question 17

Composition of dry atmospheric air

Answer 17

Oxygen: 20.95%
Carbon dioxide: 0.03%
Nitrogen: 78.09%
Argon: 0.93%
= 100%

Question 18

Dalton’s law

Answer 18

: In a mixture of gases, the total pressure is the sum of the
pressure each gas would exert if it were present alone.

Question 19

Daltons law example

Answer 19

In dry atmospheric air at standard barometric pressure (760 mm Hg), the partial
pressure of
oxygen (PO2) = 20.95% of 760 mm Hg = 159.2 mm Hg
carbon dioxide (PCO2) = 0.03% of 760 mm Hg = 0.2 mm Hg
At 6000 m, the atmospheric pressure is half that at sea level, or 380 mm Hg,
 PO2 = 80 mm Hg

Question 20

Gas exchange between tissue and blood

Answer 20

• O2 diffuse down the PO2 gradient (alveolar spaces into lung capillaries then from systemic capillaries to tissue)
• CO2 diffuse down to PCO2 gradient (tissue to systemic capillaries then from lung capillaries to alveolar spaces)

Question 21

CO2 transport

Answer 21

- 7% of CO2 transported in solution
• 23% binds to multiple amino groups of
hemoglobin
• 70% transported as bicarbonate ions
• buffering substances in blood:
• carbonic acid – bicarbonate system
• phosphates
• proteins

Question 22

Fetal gas exchange

Answer 22

Fetal hemoglobin is different from adult hemoglobin
• adult: alpha2beta2
• fetal:alpha2gamma2

Question 23

How to hold your breath a long time:

the Weddell seal

Answer 23

• can store large amounts of oxygen, mostly in blood (70%) and
muscles (25%)
– humans: 51% and 13%, respectively
• has huge spleen
• has high [myoglobin]
• has adaptations that conserve oxygen