Your fellow classmate usually does not eat breakfast nor lunch before lecture at

Question

Your fellow classmate usually does not eat breakfast nor lunch before lecture at 1:30 PM. His last meal is typically dinner the night before. As a result of his fast, his blood sugar is low. However, he has not passed out yet during class because his pancreatic alpha cells produce the protein glucagon which raises his blood sugar level for utilization by his cells. Explain which feedback mechanism this is a part of and how this is an example for how your body is trying to maintain homeostasis: Write the equation for the carbonic acid/bicarbonate ring system and indicate which side of the equation is acid and basic. Now explain what's occurring when you're holding your breath for 90 seconds and what is occurring with CO_2 levels, [H^+] and blood pH. Then explain how the carbonic acid-bicarbonate buffering will correct for this change in restoring your blood pH back into the 7.4 plusminus 0.05 range. Also include the specific type of feedback mechanism that's involved for maintaining homeostasis.

Explanation / Answer

If a person has not eaten for quite some time , blood glucose levels decrease in the body. This is recognised by certain cells in pancreas and glucagon is released, causing blood glucose level to increase. This glucose level increase causes special cells in pancreas to release insulin hormone. But after some time blood glucose levels get lowered in the body and the insulin hormone release is stopped by negative feedback.

Homeostasis is maintaining the equilibrium and regulation of internal environment, in an organism by using feedback controls. This is maintained by negative feed back in the above case.Excess insulin production is cutoff due to lowered glucose levels.

2 Bicarbonate buffering system is most important as it is the only one that is coupled to respiratory system. This buffer will neutralise any acidic or alkaline condition in blood. Changes in blood ph is v dangerous.Anybuffer will contain a weak acid and a conjugate base.

CO2 +H2O-----> H2CO3------->HCO3-+H+

carbonic acid is the acid and bicarbonate ion is its base.The above equation is reversible

H2CO3 + H2O -------------->     H3O++HCO3-

When we hold our breath for more time,CO2 will be more in our blood , that makes the blood ph drop. H+ ions increase.The bicarbonate ions neutralise H+ ions forming carbonic acid and water.This way ph is brought back to normal. The relative concentrations of carbonic acid and bicarbonate ions fluctuate in the blood stream, But this slight change in concentration of these 2 components, doesnt have adverse effect.This buffering system prevents blood from becoming acidic or basic

This change is neutralised by bicarbonate ion, thus minimising changes in ph.

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