Welcome to our first blog series on the physical effects of stress on the body! This is a topic I educate my patients on frequently and thought it would be important to share this with all of you. But before we learn about how stress affects the body, we have to understand the why and how this stress response occurs. Stress is one of those tricky things that we need to survive, but in excess can disrupt our bodily functions. So let’s delve into stress!
What is stress?
Stress is a biological response to an emotional, psychological, or physiological event, known as a stressor. We are hardwired to sense “dangerous” and “threatening” events to improve our likelihood of survival. These events could be anything from being in a car accident, taking a final exam, or speaking publicly. If your body perceives any of these events as threatening it will activate the stress response or the “fight or flight” response. This response involves coordination of the nervous and endocrine systems to make the appropriate changes to the body to deal with the stressor.
The Nervous & Endocrine Systems
Everything starts in the brain. There are a few structures you need to be familiar with to understand how this response is activated. First, the amygdala. This is the area that contributes to emotional processing of images and sounds. When it perceives danger, it sends a distress signal to the hypothalamus. The hypothalamus is the command center for the brain where it communicates with the rest of the body through the autonomic nervous system. I’ll explain what this branch of the nervous system does in a little bit. Next, we have the pituitary glands. These glands regulate other endocrine glands in the release of hormones like estrogen, testosterone, adrenaline, and cortisol. One of the endocrine glands we will be talking about today are adrenal glands. These glands are located above the kidneys, which means you have two of them. Each gland has two layers, where each layer is responsible for the release of different hormones when stimulated by the pituitary gland. The outer layer releases cortisol and the inner layers releases adrenaline. Both of these hormones are heavily involved in the “fight or flight” response.
Now that we’ve covered the hormone side of things, lets talk about the autonomic nervous system. This system is involuntary and controls body functions such as breathing, blood pressure, heart rate, dilation of blood vessels and airways in the lungs. The autonomic nervous system has two components, the sympathetic nervous system and the parasympathetic nervous system. The sympathetic nervous system triggers the “fight or flight” response, providing the body with a burst of energy so that it can respond to perceived dangers. The parasympathetic nervous system promotes the “rest and digest” response that calms the body down after the danger has passed. So how exactly does this happen? Let’s see what the “fight or flight” response actually looks like!
The Fight or Flight Response – Example
You are about to do the most important presentation in your career so far. Your boss has told you this presentation could lead to a major promotion. So, here you are, feeling your heart beat rapidly, your hands, forehead and armpits becoming clammy, you start to breath heavier and heavier. You have this general sense of anxiety throughout your body. This is what your nervous and endocrine systems are doing during this time:
- Your amygdala senses your anxiety and sends a distress signal to your hypothalamus
- Your hypothalamus sends a hormone signal to your pituitary gland to activate the adrenal glands
- The pituitary gland releases a hormone to tell the adrenal glands to release cortisol and adrenaline
- Adrenaline activates your sympathetic nervous system or the “fight or flight” response
- The activation of the sympathetic nervous system causes an increase in your heart rate, breathing rate, sweat production, and blood flow to your legs and arms and less to your digestive and reproductive system
- Cortisol in your system causes an increase in blood sugar, improves your memory and attention, decreases your sensitivity to pain, and reduces your immune response. (Side-note, this is why cortisone (a form of cortisol) is considered to be an effective injection for joint pain and inflammation)
- Once you’ve started to become comfortable with your presentation or you’ve finished your presentation, cortisol and adrenaline levels will start to decrease and signal the activation of your parasympathetic nervous system or the “rest and digest” response.
Now, all of this sounds great, right? So, why do people say stress is bad for the body? Well, these are life-saving responses that are only meant to kick-in in emergency situations, like running from a predator or being in a car accident. This process is very taxing on your body and has a limited reserve. When we constantly activate this stress response, our bodies are working overtime without getting paid time and a half. Our lifestyles promote constant activation of this system for non-life threatening situations like work deadlines, major purchases, relationship troubles, etc.
So, before this blog post becomes a novel, let’s end it here! The next blog post in this series will explain why long-term stress can be detrimental for our health and how it affects the urinary system!
Until next time,
Grecia Alaniz PT, MScPT