Respiration Flashcards
Respiration problem
gas exchange necessary to support ATP production in cellular respiration
= O2 must diffuse into the organism from the environment CO2 must diffuse out
Diffusion over whole body
no circulation
Capillaries near the surface
Gills
- internal or external vascularized membranes
- ventilated by the flow of water over them
- O2 diffusion aided by countercurrent exchange
Tracheal systems
- internal network of air tubes
- cells are supplied directly
- system can be ventilated by body movements, which compress and expand the tracheoles
Lungs
- localized respiratory organs
- subdivided infolding of body surface
Birds lungs
inflatable air sacs associated with rigid lungs
Human lungs
-internal sacs, inflatable
Human respiratory system
- 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
Mechanics of ventilation- negative pressure breathing
- 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
Respiratory pigments
- bind and transport gases
- help buffer the blood
- special proteins that transport most of the O2 in blood (hemocyanin and hemoglobin)
Hemocyanin
- in arthropods and many molluscs
- O2 bound to copper
Hemoglobin
- 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
Why do hemoglobin need to carry O2?
- O2 alone has a low solubility in blood
- heme alone would carry Co no O2
Hemoglobin also binds to …
- 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
Copperative binding and release
- 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
Bohr shift
a drop in pH lowers the affinity of hemoglobin for O2
Composition of dry atmospheric air
Oxygen: 20.95% Carbon dioxide: 0.03% Nitrogen: 78.09% Argon: 0.93% = 100%
Dalton’s law
: In a mixture of gases, the total pressure is the sum of the
pressure each gas would exert if it were present alone.
Daltons law example
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
Gas exchange between tissue and blood
- 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)
CO2 transport
- 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
Fetal gas exchange
Fetal hemoglobin is different from adult hemoglobin
• adult: alpha2beta2
• fetal:alpha2gamma2
How to hold your breath a long time:
the Weddell seal
• 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
