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Anatomy Final: CO2 Transport and Chloride Shift

Why do we need to get rid of CO2?
It is toxic to our body, so we need to remove it completely or break it down into something nontoxic
3 forms of how blood transports CO2 from the tissue cells to the lungs
1. (7-10% efficiency); dissolved in plasma
2. (20% efficiency); binds to hemoglobin
3. (70% efficiency); converted to bicarbonate in plasma or RBC
1. (7-10% efficiency); dissolved in plasma
does not remove a lot of carbon dioxide; it is dissolved in the plasma by passive transport
2. (20% efficiency); binds to hemoglobin
occurs in the RBC;hemoglobin's affinity for CO2 is greater than the affinity of hemoglobin for oxygen; it takes a long time to remove at the level of the respiratory/conducting zone.
3. (70% efficiency); converted to bicarbonate in plasma
occurs in the plasma portion of centrifuged blood or in the RBC;
- bicarbonate is a buffer to acid, so we turn the toxic CO2 into this non toxic substance.
- the plasma is 55% of the blood...the reaction of CO2 + H2O yielding H2CO3 (carbonic acid) and converting it into a hydrogen ion + HCO3- (bicarbonate) is slow
How does the process in the plasma affect pH?
If we have a pH of 7.35, the hydrogen produced has a slight effect and only brings the pH down slightly, to 7.33; there is no risk of destroying globular proteins
3. (70% efficiency); converted to bicarbonate in RBC
- in RBCs, there is an enzyme called CARBONIC ANHYDRASE (lacking in the plasma) that speeds up the production of carbonic is more efficient here
- CO2 + H2O--> carbonic anhydrase-->H2CO2--> hydrogen ion + HCO3- (NONTOXIC)
- this helps move substances in the digestive system, neutralizes hydrogen ions
Levels at which the chloride shift occurs
1. Tissue Level
2. Lung Level
Chloride Shift at Tissue Level
- CO2 is being produced...the interstitial fluid here allows the CO2 to enter the plasma
- hydrogen ion binds to plasma proteins (positive thing because it has no affect on pH)
- RBC transports O2 and releases oxygen as it goes to cellular level; 3 Hgb are left in the RBC
- the free hydrogen and free Hgb yield a reduced Hgb
Calcium chloride can cause what in the body?
Kidney Stones
Chloride works hand in hand with...?
bicarbonate; bicarbonate leaves to perform functions it couldn't otherwise do in the RBC (neutralize acids, etc.) a symbiotic relationship
Chloride shift at the Lung Level
the process is reversed and the shift leaves the RBC and goes to the alveolar sacs; it is never able to produce hydrogen ions
Chronic Bronchitis
affects the conducting zone of the respiratory system
- affects the large bronchi
- there is an excess mucus production that then lays dormant
- if a person is a heavy smoker, they may be affected more by this disease
- a person will produce a large degree of flem (sputum)
not considered a chronic disorder, but this is a secondary stage of chronic bronchitis and can be fatal/severe
Pneuomococcal pneumonia
caused by a variety of viruses, bacteria, and sometimes fungi; Gram positive cells
Klebsiella pneumonia
seen in alcoholic males; sometimes stems from alcoholic cirrhosis; sputum is thick; this pneumonia is more pathogenic
affects respiratory zone
- affects alveolar sacs
- seen with smokers...alveolar surface thickens and once this happens, it loses elasticity and oxygen accumulates and cannot diffuse through the sacs
- blood is drastically impaired and there is a collapse or loss of the alveolar sac