Antagonistic Muscle

• Antagonistic muscle: a muscle that opposes the action of another; e.g. biceps and triceps are antagonistic muscles or circular and radial muscles in the eye
• Agonist: a muscle that contracts while another relaxes; e.g. when bending the elbow, the biceps are the agonist
• Antagonist: a muscle that relaxes while another contracts; e.g. when bending the elbow, the triceps are the antagonist
• Sense organ: groups of receptor cells responding to specific stimuli: light, sound, touch, temperature and chemicals.