Explain the effects of increased physical activity on the following organ systems

a)Heart.
-Increased physical activity results in increased heart beat rate/ cardiac frequency; increased blood pressure; pumping more blood to the muscles/ peripheral blood vessels; at a faster rate; supplying oxygen; nutrients; for continued oxidation/ respiration; to yield more energy needed to sustain the vigorous contraction and relaxation of muscle;During physical activity carbon (IV) oxide, lactic acid and other nitrogenous/ metabolic wastes produced during the process are also eliminated/ transported to the relevant excretory organs for elimination; the wastes if left to accumulate can also intoxicate/ poison the cells/ cause muscle cramps/ pain/ fatigue;
b)Lungs
-Physical activity increases panting/ increased breathing rate; causing the lungs to expand/ increase in volume to take in more air/ oxygen; and deflate to expel more carbon (IV) oxide; more oxygen is taken in during the exercsise to suatain the process of muscle respiration/ to produce the required energy for constant muscle contraction and relaxation;
c)Kidney
-During exercises, the kidneys filter out more urea releasing more in the urine; maintain the blood plasma pH; osmotic balance; by eliminating excess hydrogen ions that accumulate due to production of lactic acid/ carbon (IV) oxide during exercise; to maintain osmotic balance the kidneys conserve sodium ions; and reabsorb water in the kidney tubules; leading to reduction in the volume of urine produced;
d)Skin
-During physical exercises there is increased muscle activity and one sweats more; eliminating nitrogenous wastes; (through the skin/ sweat pores) which evaporates; cooling the body; the increased internal/ body temperature also leads to vasodilation of superficial blood vessels/ arterioles; more blood flows near the skin surface; leading to loss of excess heat to the atmosphere by radiation/ convection; the hair on the skin surface also lie flat for loss of het to the environment by radiation/ convection;