Certain physical manifestations occur when I am stressed such as increased heart rate, sweating, and trembling. All of these occur in response to the release of various hormones designed to help us react faster and protect ourselves from dangerous situations. This sequence of bodily changes is called the stress response which is controlled mainly by the hypothalamus and occurs in three stages. The first stage is the fight or flight response initiated by nerve impulses from the hypothalamus to the sympathetic division of the autonomic nervous system (ANS) which quickly mobilizes the body’s resources in preparation for physical activity. Increased amounts of oxygen and glucose are brought to the organs that can help in warding off danger such as the brain, the skeletal muscles, and the heart. The second stage is known as the resistance reaction which helps the body continue fighting a stressor after the fight or flight response has dissipated. CRH stimulates the anterior pituitary to secrete ACTH, which in turn stimulates the adrenal cortex to increase the release of cortisol which stimulates glucogenesis, the breakdown of triglycerides into fatty acids, and catabolism of proteins into amino acids, all of which help in repairing damaged cells throughout the body. GHRH, causes the anterior pituitary to secrete growth hormone (GH). Acting via insulin-like growth factors, GH stimulates lipolysis and glycogenolysis, the breakdown of glycogen to glucose, in the liver. The third hypothalamic-releasing hormone is the TRH which stimulates the anterior pituitary to secrete thyroid-stimulating hormone (TSH). TSH promotes the secretion of thyroid hormones, which stimulate the increased use of glucose for ATP production. The last stage of the stress response is exhaustion wherein the body’s resources are depleted, and the resistance stage cannot be sustained. Prolonged exposure to stress may lead to suppression of the immune system, leaving the body more susceptible to diseases.