Cardiovascular Adjustments Prof. K. Sivapalan

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

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

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

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

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 2013 Regional Circulation

Isometric exercise. Sustained muscle contraction. Increase in peripheral resistance. Systolic and diastolic pressure increase. ? Yoga. 2013 Regional Circulation

Effects of training. Inrease in stroke volume. Decrease pulse rate. Quick return to basal valuse after exercise. Reduced coagulability. Healthy vessels. Muscle and bone development. [Feeling better.] 2013 Regional Circulation

Hemorrhage. Loss of blood- reduced blood volume Reduced venous return. Reduced cardiac output. Reduced blood pressure. Heart rate increases before pressure drops. 2013 Regional Circulation

Compensation to hypovolemia. Anxiety and excitement stimulate sympathetics and adrenals. Reduced stretch of baro receptors: Less inhibition to VMC. Less stimulation to CIC. Renal compensation- renin – angeotensin – aldesteron. Tissue fluid dynamics. 2013 Regional Circulation

Severe hemorrhage. Moderate loss- as in blood donation: Effective compensation by mobilizing venous reservoir. If unable to compensate: Circulation mainly to vital organs. Severe peripheral vaso constriction. Tachycardia. Reduced pulse pressure – thready pulse. Reduced tissue fluid. Prolong reduced perfusion – acidosis. 2013 Regional Circulation

Shock. Peripheral circulatory failure. Emergency- if not recovered goes in irreversible shock and death. Causes: Hypovolemic Cardiogenic. Distributive. [anaphylactic or septic] Neurogenic [pain, fear] 2013 Regional Circulation