During your morning walk, a large dog barks at you. How do you respond?
Most likely you perceive that dog as some type of threat, so your hypothalamus, a tiny region at the base of your brain, sets off an alarm system in your body. Through a combination of nerve and hormonal signals, this system prompts your adrenal glands, located atop your kidneys, to release a surge of hormones, including adrenaline and cortisol.
Adrenaline increases your heart rate, elevates your blood pressure and boosts energy supplies. Cortisol, the primary stress hormone, increases sugars (glucose) in the bloodstream, enhances your brain’s use of glucose and increases the availability of substances that repair tissues.
Cortisol also curbs functions that would be nonessential or detrimental in a fight-or-flight situation. It alters immune system responses and suppresses the digestive system, the reproductive system and growth processes. This complex natural alarm system also communicates with regions of your brain that control mood, motivation and fear.
Understanding the Stress Response – if your mind and body are constantly on edge because of excessive stress in your life, you may face serious health problems. That’s because your body’s “fight-or-flight reaction” – its natural alarm system – is constantly on.