Impacts of Stress in Our Body

Stress is a common sensation when faced with challenges or overwhelmed. However, stress is not just an emotion, but a physical reaction that affects your entire body.

While short-term stress can be beneficial, chronic activation of the primitive fight or flight response not only alters the brain but also causes harm to various organs and cells in the body. The adrenal gland releases stress hormones, including cortisol, adrenaline (epinephrine), and norepinephrine, which circulate through the bloodstream, affecting the heart and blood vessels.

Adrenaline increases heart rate and raises blood pressure, potentially leading to hypertension. Additionally, cortisol can disrupt the normal functioning of the endothelium, the inner lining of blood vessels. These changes are early indicators of atherosclerosis, the buildup of cholesterol plaque in arteries, which increases the risk of heart attacks and strokes.

When the brain senses stress, it activates the autonomic nervous system, which communicates stress to the enteric nervous system in the gut. This brain-gut connection can disrupt the natural contractions that move food through the digestive system, causing irritable bowel syndrome and increasing sensitivity to acid, resulting in heartburn. Furthermore, stress can alter the composition and function of gut bacteria, affecting digestion and overall health.

Chronic stress can also impact weight. Cortisol, in particular, can increase appetite, leading to cravings for energy-dense foods and carbohydrates. Excessive cortisol levels contribute to the accumulation of visceral fat, deep belly fat that releases hormones and immune system chemicals called cytokines. This type of fat increases the risk of chronic diseases such as heart disease and insulin resistance.

Stress hormones also influence immune cells, initially preparing the body to fight invaders and heal injuries. However, chronic stress weakens immune cell function, making individuals more susceptible to infections and slowing down the healing process. In addition, chronic stress has been associated with shortened telomeres. Telomeres are protective caps at the ends of chromosomes that shorten with each cell division. When telomeres become too short, cells can no longer divide, leading to cell death.

Aside from these effects, chronic stress can also manifest in acne, hair loss, sexual dysfunction, headaches, muscle tension, difficulty concentrating, fatigue, and irritability.

Stress begins with something called the hypothalamus pituitary adrenal axis, a series of interactions between endocrine glands in the brain and on the kidney, which controls your body's reaction to stress. When your brain detects a stressful situation, your HPA axis is instantly activated and releases a hormone called cortisol, which primes your body for instant action. But high levels of cortisol over long periods of time wreak havoc on your brain. For example, chronic stress increases the activity level and number of neural connections in the amygdala, your brain's fear center. And as levels of cortisol rise, electric signals in your hippocampus, the part of the brain associated with learning, memories, and stress control, deteriorate.

The hippocampus also inhibits the activity of the HPA axis, so when it weakens, so does your ability to control your stress. That's not all, though. Cortisol can literally cause your brain to shrink in size. Too much of it results in the loss of synaptic connections between neurons and the shrinking of your prefrontal cortex, the part of your brain the regulates behaviors like concentration, decision-making, judgement, and social interaction. It also leads to fewer new brain cells being made in the hippocampus. This means chronic stress might make it harder for you to learn and remember things, and also set the stage for more serious mental problems, like depression and eventually Alzheimer's disease.

The effects of stress may filter right down to your brain's DNA. An experiment showed that the amount of nurturing a mother rat provides its newborn baby plays a part in determining how that baby responds to stress later in life. The pups of nurturing moms turned out less sensitive to stress because their brains developed more cortisol receptors, which stick to cortisol and dampen the stress response. The pups of negligent moms had the opposite outcome, and so became more sensitive to stress throughout life. These are considered epigenetic changes, meaning that they effect which genes are expressed without directly changing the genetic code. And these changes can be reversed if the moms are swapped. But there's a surprising result. The epigenetic changes caused by one single mother rat were passed down to many generations of rats after her. In other words, the results of these actions were inheritable. It's not all bad news, though. There are many ways to reverse what cortisol does to your stressed brain.

The most powerful weapons are exercise and meditation, which involves breathing deeply and being aware and focused on your surroundings. Both of these activities decrease your stress and increase the size of the hippocampus, thereby improving your memory. So don't feel defeated by the pressures of daily life. Get in control of your stress before it takes control of you.

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