We all experience stress at one time or another. There are different kinds of stress, and not all stress is negative. Acute stress is more immediate stress that we deal with in everyday life. Eustress, positive acute stress, provides us with energy when running a race or completing a deadline. It also causes the exhilarating feeling we get when doing things like riding a roller coaster or skiing down a steep slope.
Negative acute stressful situations are those we tend to associate the word stress with: forgetting to study for a test, arguing with a friend or co-worker, or having a flight delayed due to bad weather. We may be stressed for a few minutes, hours, or a day or two, but eventually the problem is resolved and we return to a peaceful state.
The physiologic response to stress is controlled by the autonomic nervous system, the involuntary part of our nervous system that controls heart rate, blood pressure, and digestion. There are two branches to the autonomic nervous system: sympathetic and parasympathetic. The sympathetic nervous system prepares our body to react to stress (“fight or flight”) and the parasympathetic helps us recover from stress (“rest and digest”). When we are stressed, our body releases chemicals that temporarily improve performance.
Cortisol, adrenaline, and other stress hormones increase heart rate, slow digestion, and increase blood pressure, all to allow greater blood flow to our muscles, heart, and brain to be able to think or act quickly in the face of immediate or acute stress. The body is able to recover from acute from stress via a natural feedback loop with the brain. High levels of stress hormones in the blood signal to the brain to stop producing the stress hormones so we can rest and recover from the stressful event.
Sometimes stress can seem more like a way of life. Chronic stress is ongoing stress that seems endless, such as a demanding job, difficult family life, or experiencing ongoing hardship. This type of stress is the most damaging to our health. With acute stress, once the perceived threat has passed, the parasympathetic nervous system takes over, allowing us to relax and recover from the stressful event. But during chronic stress, the body is continually exposed to the hormones that regulate stress.
The system’s natural feedback loop is interrupted. The relaxation response is not activated, and the pathway that regulates cortisol is shut down, rendering it unable stop the effects of the stress. It is the constant activation of the stress response that leads to the negative health outcomes seen with chronic stress.
The primary stress hormones are cortisol, epinephrine (also called adrenaline), and norepinephine. Cortisol is a steroid hormone released from the adrenal glands, which sit above the kidneys. Epinephrine is also released from the adrenal glands. Norepinephrine is a neurotransmitter that helps the body and brain communicate with each other about stress and about how the body should react physiologically to stress. When cortisol is released in response to stress, it works with the other stress hormones to prepare the body to react to the stressful event.
The breakdown of fat leads to increased blood sugar, helping to provide energy for the essential organs – brain, heart, and lungs (more on this later). Cortisol makes blood vessels more responsive to epinephrine and norepinephrine, and in turn these hormones constrict blood vessels to increase blood pressure. In addition, epinephrine acts to increase heart rate. Increased blood pressure and heart rate help deliver nutrients and oxygen faster to the organs that need them most. Acting together, stress hormones ensure that we can think and act quickly and clearly in stressful situations.
In addition to creating the emergency response, stress hormones also divert energy away from non-emergency functions like digestion, reproduction, and maintaining the immune system. For example, cortisol inhibits the immune system by preventing the production of T-cells, important players in the immune system, and by interrupting the distribution of other immune cells to the lymph nodes and bone marrow.
Because stress hormones suppress non-emergency functions, such as maintaining the immune system, chronic stress can leave many bodily systems at risk. Constant suppression of the immune system, for example, leaves us vulnerable to infections. Additionally, as mentioned above, to provide the body with extra energy to deal with stress, stress hormones stimulate the breakdown of stored fat into smaller fatty acids that we can use for short-term energy.
These fatty acids, called triglycerides, enter the blood stream waiting to be taken up by our muscles to be used for quick energy if we need flee a stressful situation. This is likely an evolutionarily advantageous response to stress: earlier in time, stress probably meant running from a dangerous situation, and the free fatty acids gave our muscles energy. But if we don’t use the fatty acids for energy through a physical outlet, the fatty acids remain in the blood, eventually causing high cholesterol. Thus, chronic stress leads to high blood pressure and cardiovascular disease, especially in combination with the stress hormones’ direct effects on increasing blood pressure. When we have high blood pressure, our heart rate increases and blood flows more vigorously through our veins and arteries.
Branch points in arteries can receive small injuries from the quicker flow of blood. The immune system then repairs arteries, but this process can lead to the deposition of plaque in the damaged areas. These little clots in our arteries block the free flow of blood, causing heart disease. Exercise is a great way to prevent this negative series of events: in addition to providing endorphins that makes us feel better, exercise uses the triglycerides in our blood stream so there are less to become trapped in our vessels as plaque.
As we can see, chronic activation of the stress response can lead to host of health problems. De-stressing and activating a resting state is important for maintaining proper balance between the sympathetic and parasympathetic nervous systems. Transcendental meditation may help to achieve this relaxation response.
Look out for my next post about Transcendental Meditation and how much that can help reduce stress and it's effects on the body.
Yours in health,
Coach Anthony Kassis