Why do Zebras don’t get ulcer!!

Imagine sitting in your examination centre and writing for admission in your most preferred institute. While you are in the middle of your examination, you realise that your mother was ill at home and your little brother was sleeping when you left. While, the scenario mentioned till now seems absolutely normal, the next thought triggers your senses. You abruptly realised that while preparing for your breakfast, you had left the stove on. You also realise that the kitchen platform is not at a safe height and thus can be contacted by your little brother. The thought spreads with the hypothetical intuition of him touching the stove and making it fall on the ground. The fire spreading at your house and harming your loved ones will be the next thought capturing your mind. I don’t intend to continue with this intuition as it would definitely induce negative hormones in you while reading. But, what I tried to mention was how a single stress elevated dramatically and formed a chain of stresses that were actually completely non related.
The initiator of the scenario was the stress induced because of you sitting in the exam hall and attempting the question paper. The mere thought of failing in your most preferred exam was enough to create a run of stressful thoughts. Your brain started configuring every possible stress that you might have in your life.

Yet another way of beginning is with the story of a glass of water which very precisely would clear the topic for today’s blog. It starts with a lecturer who in a class of 100 students raised a glass of water and asked his students- “How heavy do you think this glass of water is?” Every student tried to present their knowledge, some even said the range could be 20-500g. Apparently the question was answered by the lecturer himself who tried to show them a different perspective of the raised glass of water. He said- “The absoulte weight of this glass of water hardly matters, what matters is how long you could hold it. If I hold it for a minute, it won’t be inducing a noticeable effect. If I hold it for an hour, I will surely have an ache in my arm. But if I hold it for a day, you will have to call an ambulance.
It is exact the same weight, but the longer I hold it, the heavier it becomes. If we carry our burdens all the time, sooner or later, we will not be able to carry on the burden becoming increasingly heavier. The burden here, metaphorically refers to the stress in life.

Why zebras don’t get ulcer!

Far away in the middle of tall grasses of Savanna, a zebra is running for his life. A lion with all his strength and tremendous speed is behind its prey. This starving predator is just few steps away from his lunch. But, very soon he plunges this beautifully striped mammal down to the ground and tears his stomach half open. Interestingly, the zebra manages to escape the big jaws, however, the injury is enough for him to succumb against the pain. These extreme events inducing stress in life demand immediate physiological adaptations for the survival. For animals like zebra, the most upsetting stress in life are acute physical crisis.

What do you think zebras have stress in life about
Dazzle of Zebras

If you were asked to make a mental list of all the things you find stressful, you would immediately come up with some obvious examples like deadlines, family issues, money worries, relationships, traffic, etc. But the zebra won’t be worried for any of your issues mentioned in the list. It can never undergo stress about relationships, obviously, not about deadlines, or traffic, or for most of the other issues that were prioritised in your list. For the zebra, the top of the list is bulleted with concerns like serious physical injury during its escape, predators, starvation, etc. Its important to acknowledge that while stress can be induced in both, you as well as the zebra, its dimensions would definitely not be same. It can therefore be concluded that the term ‘stress’ should not be perceived in a speciocentric manner.

This illustration was made for something critical- You and I are more likely to get an ulcer than a zebra. Zebra running for life or lion sprinting for its meal, all these conditions demand a quick physiological response and our body is superbly adapted for dealing with such short term physical emergencies. For almost every beast on this planet, stress is about short term crisis, after which, either the stress is over or the beast is. But in case of humans, who are supposed to have the most sophisticated cognitive power, the same physiological response becomes a potential disaster. A major chunk of evidence suggests that unlike wild animals, humans have evolved the short term stress into a long term “chronic stress”.

We humans can be stressed by things that simply make no sense to zebras and lions. The activation of stress response in humans for something hypothetical that actually turns out to be real, leads us to congratulating our cognitive skills which allowed us to mobilise our defences early. These anticipatory defences can be quite protective in preparing us for the expected stressful conditions. This defence can thus be effective to manage stress in life.

History of Stress

In the 1930s, Hans Selye, one of the godfathers in the field of stress physiology was just beginning his work in endocrinology, the study of hormonal communication in the body. Naturally, as a young, unheard and budding scientist, he was fishing around for something with which to start his research career. A biochemist down the hall had just isolated some sort of extract from the ovary, and colleagues were wondering what this ovarian extract did to the body. So Selye obtained some of the stuff from the biochemist and set about studying its effects. As a initiator to the experiment, he attempted to inject his rats daily, but apparently not with a great display of dexterity. Selye would try to inject the rats, miss them, drop them, spend half the morning chasing the rats around the room or vice versa, swiping with a broom to get them out from behind the sink, and so on. After a number of months, Selye examined the rats and discovered something extraordinary. The rats had peptic ulcers, greatly enlarged adrenal glands (the source of two important stress hormones), and shrunken immune tissues. He was delighted; he had discovered the effects of the mysterious ovarian extract.

Dr. Hans Selye. Source: ncbi 
His contributions have made it easier to understand impacts stress in life.
Dr. Hans Selye. Source: NCBI

Being a good scientist, he ran a control group where the rats were injected daily with saline alone, instead of the ovarian extract. And, thus, every day they too were injected, dropped, chased, and chased back. At the end however, the control rats had the same peptic ulcers, enlarged adrenal glands, and atrophy of tissues of the immune system. It was evident by then that the physiological changes couldn’t be due to the ovarian extract after all, since the same observations in both, the control as well as the experimental groups were reported.

What did the two groups of rats have in common? Selye reasoned that it was his less-than-trauma-free injections. Perhaps, he thought, these changes in the rats’ bodies were some sort of nonspecific responses of the body to generic unpleasantness. To test this idea, he put some rats on the roof of the research building in the winter, others down in the boiler room. Still others were exposed to forced exercise, or to surgical procedures. In all cases, he found increased incidences of peptic ulcers, adrenal enlargement, and atrophy of immune tissues.
We know now exactly what Selye was observing. He had just discovered the tip of the iceberg of stress-related disease. Selye apparently was the person who, searching for a way to describe the nonspecificity of the unpleasantness to which the rats were responding, borrowed a term from physics and proclaimed that the rats were undergoing “stress.” In fact, by the 1920s the term had already been introduced to medicine by a physiologist named Walter Cannon. What Selye did was to formalize the concept with two ideas:

  1. The body has a surprisingly similar set of responses (which he called the general adaptation syndrome, but which we now call the stress-response) to a broad array of stressors.
  2. If stressors go on for too long, they can make you sick.

Diversity in responses to stress:

Various organisms respond to different stress in life via diverse array of responses. If you are a bacterium stressed by food shortage you will probably prefer to remain in a suspended dormant state. But, if you’re a starving lion, you would have to predate after your prey. However, if you are a zebra being chased by that lion, you will have to run for your life. For almost every vertebrate, the core of the stress response is built around the fact that our muscles will have a heavy mechanical load and thus the muscles need energy in the most readily utilisable form rather than being stored in our fat cells. This is one of the most important hallmark of stress response – ‘rapid mobilisation of energy from storage sites and the inhibition of further storage’. While channelising this energy from glucose to the critical muscles, our heart rate, blood pressure and breathing rate increases for the supply of nutrients and oxygen at greater rates. Another marking feature of stress response is when our body senses any emergency, it halts the long term expensive building projects. Thus, during stress, digestion is inhibited. Digestion being a slow process and not a reliable source of energy for an emergency is inhibited. The same thing goes for growth and reproduction which are yet another expensive processes in our body. The situation of being chased by a lion would never prioritise ovulating or growing antlers or making sperm. Similarly, during stress, growth and tissue repair is curtailed, sexual drive decreases in both sexes; females are less likely to ovulate or to carry pregnancies to term, while males begin to have trouble with erections and secrete less testosterone.

Compromised Immunity in Stress:

Immune system is another such area which remains compromised during stressful conditions. Our body handles diverse variety of stress in life very wisely by expending energy in only those areas which need immediate response. Thus the complete immune system remains suppressed during stress in order to save energy.

With sufficiently sustained stress another interesting sensation is blunted which is PAIN. Lets take an insight of battlefield for our better understanding. In between the heavy gun firing of the battle, a soldier is shot, grievously injured but rarely notices it. He can see blood on his clothes but the worries of his friends in danger makes him unaware of his own injury. Such stress-induced analgesics are highly adaptive and well documented. Imagine being that zebra whose innards are dragging in the dust but still has to run to evade its predator for the survival. Now this is a clever move adapted by our body. Because the Zebra doesn’t have enough time to go into shock from extreme pain, but needs loads of energy into his muscles to manage his escape from the predator still stalking him.

Finally, during stress a shift occurs in cognitive and sensory skills. Suddenly, certain aspects of memory improve which proves to be helpful in figuring out how to get out of an emergency. The brain questions- Has this happened before? Is there a good hiding place? Moreover our senses become sharper. So we may clearly conclude here that- stress curtails growth and tissue repair; reduction in sexual drive of both sexes leading to reproductive complications; compromised immune system; blunted pain reception and sharpened cognitive and sensory skills.

How can stress in life make us sick?

You can very well recall the ulcerated rats of Dr. Selye for the referral. His observations though puzzled him, showed good outcomes in future for understanding stressors and stress.
According to Selye the last stage of stress should be termed- “Exhaustion” where stress related disease emerges. He believed that one becomes sick because their is depletion of stress-responsive hormones like an army that runs out of ammunition. However, this rarely happens that any of the crucial hormones are actually depleted during stress. The army does not run out of bullets, instead the body spends so much on health budgets that it neglects the defense and education. This is something which you can correlate with our current pandemic situation.
When we imagine things that happen during stress, it certainly makes sense that these responses are short-sighted, inefficient and the most costliest ones for our body to adopt in emergency.

But if we start experiencing everyday as an emergency, we will surely have to pay the price. If we constantly mobilize energy at the cost of energy storage, we will never store any surplus energy. This will fatigue us more rapidly, and also increase our risk of developing a form of diabetes. The consequences of chronically activating our cardiovascular system are similarly damaging. As an example- if your blood pressure rises to 180/100 when you are sprinting away from a dog, you are being adaptive; but if it remains 180/ 100 irrespective of an emergency situation, it means you could be heading for a cardiovascular disease. If you are constantly under stress, a variety of reproductive disorders may ensue. In females, menstrual cycles can become irregular or cease entirely whereas in males, sperm count and testosterone levels may decline. In both sexes, interest in sexual behavior decreases.

This however is merely an initiation of your body’s response to chronic or repealed stressors. If you suppress immune function for too long and too much, you are more likely to fall victim to a number of infectious diseases, and be less capable of combating them once you have them. Finally, the same systems of the brain that function more cleverly during stress can also be damaged in prolonged cases.

Working of the brain!

There is something unique about the working of the brain that must be appreciated. The principle way in which the brain guides the body is via transmitting messages which are biologically called as impulses. The autonomic nervous system has two components, the sympathetic nervous system and the parasympathetic nervous system. The sympathetic nervous system functions like a gas pedal in a car. It 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 acts like a brake. It promotes the “rest and digest” response that calms the body down after the danger has passed. When someone jumps out from behind a door and startles us, its our sympathetic nervous system which releases adrenaline causing our stomach to clutch. Sympathetic nervous system also releases a closely related substance called noradrenaline. These two chemical messengers are responsible for reacting differently in different situations of stress in life.

Short term vs Long term stress:

Stress can dominantly be classified into two types: short term and long term. As the name itself suggests, the short term stresses remain for a less duration of time, whereas those perceiving for a rather greater duration are grouped as long term stresses.

Machinery of long term stress.
Machinery of long term stress.

When presented with a situation of stress in life, the body responds by releasing hormones that provide a burst of energy. The hormones epinephrine and nor-epinephrine released by sympathetic nerve endings increase the blood glucose level by stimulating the liver and skeletal muscles to break down the stored glycogen. These hormones prioritise body function by increasing blood supply to essential organs such as heart, brain and skeletal muscles. Long term stress response differs from short term stress response, where the hypothalamus triggers the release of ACTH from the anterior pituitary gland. The adrenal cortex is stimulated by ACTH to release steroid hormones called corticosteroids which backs the activities of epinephrine and nor-epinephrine for long term stress response.

Take your Call!

While stress is an inevitable feature of our society, it definitely needs to be moderated. As the society progresses towards advancement, we have observed the complexity of stress in life to elevate exponentially. While our ancestors were only worried about surviving, the future is worried about surviving, killing and competing. Surviving, because everyone expects a better and longer survival rate than their precursors. Killing, because the chances of your survival increase when you eliminate your competitors. And competing, because life is a race, if you don’t run fast, you’ll be the chick of the broken egg which falls from the tree. Though we use the term almost exclusively in a negative sense, but a little bit of stress in life, keeps it exciting and ongoing. Finding the right balance must be the foremost priority for any kind of stress in life.
It has been truly said“Our anxiety doesn’t come from thinking about future, but from the desire to control it.”

Reference: Why zebras don’t get ulcer by Robert M Sapolsky. Click here to get the book.
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