Question

1. How does exercise of increasing intensity change HR? What controls this change?
2. What changes are anticipated in an ECG recording in the transition from rest to exercise? What abnormal or pathological changes may occur in the transition from rest to exercise?

Answer 1

* During exercise the body muscles consumes more oxygen due to their increased activity. In order to supply more oxygen, the heart beat should be raised inorder to supply more blood to the body tissues and this process increases with increase in intensity of the exercise. * The sympathetic nervous system( increases heart beat) and parasympathetic nervous system(decreases heart beat) of brain controls the heart beat. The parasympathetic nervous system function got stopped during exercise.

* The changes seen in ECG are:- *RR interval decreases. * the spatial distance between p wave and QRS complex is decreased. * the p wave amplitude increases. * QRS wave altitude increases and space decreases. This all changes are due to increased heart beat.

* The various pathological changes includes, ATP is the main source for the contraction of muscles and can be utilised from the intermediate sources like glucose and fats. The ATP consumed during initial exercise is resynthesized rapidly by various ways. The lactic acid produced during exercise plays an important role in supply of energy. * pulmonary ventilation increases due to increase in tidal volume and respiratory rate to meet required oxygen demands.