Hey everyone, welcome to my new article. In my previous article, I talked about the mechanism of childbirth. Well, this article is going to be different. Today, I will discuss stress and its impact on our bodies. A pretty common word but with much larger impact. But is it really that bad? believe it or not, stress to some extent is very important. That helps you to give a quick response to the situation you are in. Stress is a basic natural phenomenon. Everyone in their life expresses it. But what if stress becomes your daily routine?
From family responsibilities, the workload and much more serious issues like you got a deadly disease, violence, death of someone, etc triggers stress. In the short term, it actually beneficial. Your mind starts throwing different ideas to get out of that situation and calm yourself. Also known as "Fight or flight" response. But, due to some reason, you start expressing stress daily. what will be the consequences now?
To answer that, we need to know, how the stress mechanism works in our body and the different changes that occur during this mechanism.
Stress Physiology
We need to look at stress from a different perspective. Specifically, from the perspective of Endocrine activity(Hormones) and our central nervous system. Stress is a well-co-ordinated response between these two systems. Also, we need to review different hormones that play a role. Let's get right into the topic now.
The hormones that play a major role are "Epinephrine (Adrenaline)", "nor-Epihenephrine (nor-adrenaline)" and cortisol. These hormones are produced by the adrenal gland. Adrenaline and nor-adrenaline are for short term responses whereas cortisol is for the long term. Cortisol is of our main concern in this article as we are discussing the long term effects of stress.
There is something called basic stressors or stimuli that helps in the production of these hormones;
- Extreme Temperature (either high or low)
- Surgery
- Emotional stress
- heavy exercise
- fear
There are many more, but these are more common. But who gives the order to release those hormones? Well, it's our central nervous system. Adrenal gland functions under the pituitary gland, which is furthermore controlled by the hypothalamus. Therefore, the hypothalamus is the prime controller or the ultimate boss in any stressful situation.
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Anatomy of Adrenal Glands
The adrenal glands sit on the upper pole of both kidneys and consists of three parts. Outer connective tissue is known as the capsule, cortex below the capsule, and inner part known as the medulla. The cortex and medulla are the functional part and actively secrets different hormones.
Cortex: If we look at the cut section, it's will be slightly yellowish in color and is divided into 3 functional parts;
- Zona glomerulosa: secrets aldosterone
- Zona fasiculata: secrets cortisol
- Zona reticularis; secrets androgens.
Medulla: This is the innermost part and is seen dark brown on the cut section. The medulla contains chromatin cells, which secrets catecholamine such as adrenaline and nor-adrenaline in into the blood. These hormones are responsible for short term response to stress or "fight or flight" response.
Release of hormones
The stressors or stimuli stimulate our nervous system triggering the hypothalamus. The hypothalamus is a small structure that is situated just above the brain stem that controls the release of hormones from the pituitary gland. The pituitary gland sits right below the hypothalamus and is no bigger than a "pea". This gland can release hormones directly into the bloodstream that can reach very specific targets. A triggered hypothalamus sends signals to the pituitary. Hormones are now released from the pituitary gland and travel to the kidneys. This hormone is called adrenocorticotropic hormone or ACTH. This in-turn influences the secretion from the adrenal glands. The location and anatomy of the adrenal gland are mentioned in the above heading.
The ACTH specifically targets the Adrenal cortex. It stimulates all three layers of the adrenal cortex ( Zona glomerulosa, fasciculate, and reticularis) to release aldosterone, cortisol, and androgens.
Effects of hormones to the body
As, we are looking for the long term effects, which is controlled by the adrenal cortex rather than adrenal medulla. We will mainly talk about the hormones released by the adrenal cortex. ie, aldosterone, cortisol, and androgens.
Effect of Aldosterone: Aldosterone is a mineralocorticoid whose primary function is to act on the kidneys. To understand this, you must know the functions of kidneys and their functional unit. A nephron is a functional unit. Millions of them collectively form a functioning kidney. Nephrons are responsible for filtering and reabsorbing things from our bodies. And also, it has a very big role in controlling our blood pressure.
Whenever there is a decrease in the blood pressure, nephrons act and reabsorbed Sodium ions and water back into the blood, making the urine more concentrated. This is important because an increase in sodium ions helps in bringing the blood pressure back to normal.
Now, if aldosterone is secreted in response to stressful situations, it actually, stimulates the process of reabsorption and retention of sodium and water. Which in turn, increases blood pressure to very high levels. Also, Potassium ions are exchanged with sodium ions, therefore, potassium is excreted which also leads to hypokalemia.
Effect of Cortisol: Cortisol is a glucocorticoid. And this hormone has many functions. The first and major function of cortisol is, it causes Hyperglycemia. Hyperglycemia means excess glucose in the bloodstream. Of course, in a stressful situation, our body needs more energy to show a quick response. Therefore, more glucose is needed in the blood. Cortisol actually does this, by stimulation the liver to make more glycogen stores and more glucose from non-glucose sources(gluconeogenesis). It also promotes protein break down and stimulates insulin resistance.
All this will, ultimately result in too much glucose in the bloodstream and due to temporary insulin resistance, cells won't be able to utilize them, thus leading to hyperglycemia.
This also increases blood pressure and suppresses our immune system. Suppressing the immune system increases the risk of infection. Finally, this also promotes osteoclastic activity in the bones. It basically means, dissolving of bones slowly. Thus increasing the risk of osteoporosis and bone fractures in the long term.
Also, we now know, excess cortisol interferes with the endothelial(inner lining of the blood vessel) to functions abnormally, which can be a precursor for plaque deposition and thus leading to a risk of heart attack.
Effect of Andrgones: Now, in stress, these hormones are actually decreased in production. In males, androgens give thems secondary sexual characteristics. Such as hair growth, masculine look, beard, deep voice, etc. In females, androgens have a role in increasing libido. When the androgens are decreased over time, a decrease in libido is also observed over time in females and can also cause infertility in males over time.
The long term effects of stress on a human body due to stress hormones can be better understood by this table:
| Hormones | Effects |
|---|---|
| Aldosterone | ↑ Blood pressure Hypokalemia (Loss of potassium) |
| Cortisol | ↑ Blood pressure Hyperglycemia Diabetes over time Insulin resistance Fat deposition Suppressed immune system Brittle bones over time Osteoporosis Risk of heart attack |
| Androgen | ↓ Libido Infertility in males. |
This is how our body is affected by stress in the long term. So, does this affect all of us? Of course not. We all have stressful situations in our life, what our matters most to our brain is if you take those situations as a threat or a challenge.
Hope you liked it.
*All the images used are copyright free and are provided with appropriate credits*
References;
https://teachmeanatomy.info/abdomen/viscera/adrenal-glands/
https://www.health.harvard.edu/staying-healthy/understanding-the-stress-response
https://en.wikipedia.org/wiki/Stress_(biology)
https://www.huffpost.com/entry/adrenaline-cortisol-stress-hormones_n_3112800
https://www.apa.org/helpcenter/stress/effects-endocrine