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Hello, From reading about smooth muscle relaxation, I understood that MLCP enzyme (myosin light chain phosphatase) dephosphorylates the myosin. This leads to relaxation because dephosphorylated myosin is unable to bind actin in smooth muscle cells. However, some smooth muscle cells have 'latch state' where myosin heads remain attached to the actin even after dephosphorylation. I don't really understand what causes the difference between the two cases. In one, dephos. causes relaxation while in the other it causes prolong binding. Anyone knows the explanation?

Hello, When reading about the physiology of maintaining blood pressure I came across something that confused me a bit. In the book the example was of hemorrhage: Loss of blood results in low RBC (erythrocytes) and low blood pressure --> fluid moves from interstitial fluid into blood stream --> increased blood plasma volume --> normal blood pressure. What confuses me is how this is helpful. I understood that blood pressure is important to maintain so all tissues/organs receive adequet supply of oxygen and dispose of CO2. Since this autotransfusion will not return RBC count to normal levels, how does it help the body? In other words: I understood that the importance of blood pressure is its role in supplying the organs with erythrocytes. If this is so, how does normal blood pressure with low RBC is helpful?