In the heart and groundbreaking work of Otto Loewi, the heart of a donor frog was stimulated to beat more rapidly than the normal basal rate. When an extract of fluid from the donor frog's heart was administered to the heart of a recipient frog, its heart rate also accelerated. Loewi concluded that :

more words for this could be abiotic and biotic

abiotic: living organisms within an ecosystem

biotic: non-living organisms within an ecosystem

the wetland preservation movement began in the u.s. in earnest with the clean water act (cwa) of 1972. although not specifically written to protect wetlands, the cwa is comprised of a series of regulations designed to prevent pollutants from contaminating u.s. waters.

answer increasing the intensity, duration,and frequency of exercise progressively;