2013 Regional Circulation 2 Cardiovascular adjustment in exercise [isotonic]. Skeletal muscles require more nutrients and produce more wastes and heat. CVS, RS, and other systems has to adjust to meet the needs. The muscles respond to impulses in motor nerves in any exercise: fight of flight. The needs of muscles are met by various mechanisms.
2013 Regional Circulation 3 Nervous adjustments. As the brain perceives the idea of exertion and starts planning appropriate movements, hypothalamus also becomes activated. It activates the sympathetic system and inhibits parasympathetic system. This brings anticipatory changes in heart and circulation. These changes are reinforced when exertion begins through impulses from proprioceptors.
2013 Regional Circulation 4 Anticipatory changes. Heart rate and force increase. Blood pressure increases- systolic. Splanchnic, renal, coetaneous flow reduce. ? Vasodilatation in skeletal muscles. [vaso dilator nerves]. Dilatation in coronary vessels but no change in cerebral flow. Adrenal medulla and cortex increase secretions. [detail after study of endocrines]
2013 Regional Circulation 5 Changes due to muscle action. Muscle pump increases venous return and the cardiac output. Metabolites cause local vasodilatation. Other effects: Increased heat stimulates thermo- regulatory center and causes coetaneous vasodilatation. Respiratory pump. Increased oxygen extraction.
2013 Regional Circulation 6 Net circulatory changes. Increased heart rate and force of contraction. Increased end-diastolic volume. Decreased end-systolic volume. Increased cardiac output. Muscular, skin and coronary vasodilatation. No significant change in cerebral flow. All other places- vasoconstriction. Slightly decreased peripheral resistance. Increased systolic and decreased diastolic pressure