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Anatomy Final: CO2 Transport and Chloride Shift

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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 acids..it 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.)...like 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)
- CAN LEAD TO PNEUMONIA
Pneumonia
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
emphysema
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