An agonist exhibit a positive biological effect similar to the receptor it stimulates. For instance, beta agonists (i.e. Salbutamol) stimulate the beta receptors in the bronchial system therefore leading to bronchodialtion. A competitive antagonist negates the function of the specific receptor by binding to the receptor binding site before the biological ligand. A non-competitive agonist negates the function of the specific receptor by binding to an allosteric site leading to a conformational change of the receptor site.
Both aristotle and ptolemy models stated that the planets rotate on their axis. Both models stated that the planets and objects in the solar system have small orbits called epicycles. The both persons are stated that the sun is the center of the system around which objects have elliptical orbits.
reas on the Equator have a constant 12 hours of day light all year round. As latitude increases to 80° (polar circles - north or south) day length can be seen to increase to 24 hours or decrease to zero (depending on time of year). Land of the Midnight Sun and Polar Winters where the sun never rises.
