Chapter 3 - Muscle Blood Flow and Metabolism Flashcards
What is functional sympatholysis?
Mechanisms are in place to override active muscle vasoconstriction (vasoconstrictor response) in attempt to match blood flow to metabolic demand while maintaining blood pressure.
What impact does muscle pump play on muscle blood flow during exercise?
Blood pump flow is responsible for determining blood flow and matching it to the metabolic demand.
Blood supply is limited and can’t exceed the hearts demand
Long duration & high intensity can undergo vasoconstriction in order to maintain blood pressure.
Explain the role of nitric oxide during exercise.
Nitric Oxide can be released from the vasodilator nerves, the vascular endothelium, or the muscle fiber itself. Nitric Oxide may also originate from red blood cells.
Studies has shown that nitric oxide inhibitors have minimal effect on skeletal muscle blood flow, this effect is mostly present when nitric oxide production is blocking during rather than before exercise.
Explain the role of adenosine during exercise.
During exercise the concentration of the adenosine enzyme can increase via translocation from the cytosol. Adenosine is also released from the endothelial cells and generated from ATP released from the endothelial cells, nerve terminals, or red blood cells and produces vasodilation through stimulation of adenosine receptors. Adenosine is likely responsible for 20% to 40% of the maintained phase of exercise hyperemia.
Explain the role of prostaglandins during exercise.
Produced by factors that increase calcium levels effect smooth muscle results in decreased calcium levels.
Explain the role of potassium during exercise.
During contractile activity, potassium is released from muscle fibers. It then accumulates in the interstitial space where blood flow can be influenced by interacting with the vasculature.
The involvement of the activation of smooth muscle inward-rectifier potassium channels may be the mechanism that cause elevated potassium to increase blood flow.
Explain the role of ATP during exercise
The role of ATP during exercise is that is binds the receptors located on the vascular endothelial cells, thus contributing to exercise hyperemia.
ATP also helps provide energy for muscular locomotion as well as provide energy to the muscles during exercise.
What role does AMPK have on muscle metabolism?
Activated protein kinase serves as a senor molecule that detects the muscle energy state (ie. Thermostat).
The overall effect of AMPK activation is activation of catabolic pathways that generate ATP and inhibition of pathways that consume ATP.
Compare and contrast how insulin promotes glucose uptake versus exercise-induced uptake of insulin.
Insulin promotes glucose uptake by the activated insulin receptor phosphorylates in the insulin receptor substrate and other substrates that bind to other target proteins when phosphorylated.
Exercise-induced increases muscle sensitivity during exercise, type 2 diabetes. AMPK increases glucose uptake.
What is insulin resistance ad what impact does chronic exercise have on it?
Loses ability to clear glucose load in response to insulin. Due to disconnect and fatty acid uptake & oxidation in muscles.
Chronic exercise reduces insulin resistances stimulates gene expression.
