Akademik Veri Yönetim Sistemi
STRESS AND HEALTH, cilt.22, sa.2, ss.71-80, 2006 (SCI-Expanded)
An organism's ability to respond to the external and internal environments is explained in terms of the concept of biological stress. The causes of these responses are called stressors. They may be physical, chemical, emotional, or traumatic. With continued exposure to the stressor the organism enters the stage of resistance and defense. After prolonged exposure to the same stressor the organism may enter the stage of exhaustion. Catecholamines have an important role in maintaining biological homeostasis to stress. Catecholamine biosynthesis starts from tyrosine and in the first step DOPA is synthesized from tyrosine and catalyzed by the enzyme tyrosine hydroxylase (TH). In rats this enzyme activity varies depending on cold stress, exercise and age. The production of adrenomedullin in adrenal medulla, heart and brain also suggest a role for this peptide in the physiological control of homeostasis.