The Biology of Mind-Body Connections - The Gloss Magazine
4 weeks ago

The Biology of Mind-Body Connections


The RCSI University of Medicine and Health Sciences has established a new Centre for Positive Psychology and Health. In March, it launched a ten-lecture public programme called the Science of Health and Happiness. In the first week, nearly 16,000 people signed up to take the course. The second lecture in the series focused on the connection between mind and body. Dr Pádraic Dunne explains:

We possess immensely complex bodies, with many integrated biological systems that make up who we are as humans, including the brain, nervous, immune, hormone, cardiovascular (heart and blood vessels) and gastro-intestinal systems. In addition, the human body contains approximately 37.2 trillion cells. A cell is usually a round structure that contains the building blocks to replicate itself (DNA). Cells can be grouped together by their specific function. For example, skin cells provide a hydrophobic (waterproof) barrier to protect us from the elements; liver cells help remove toxins from our blood, etc. If we could peek inside a cell, we would see how each individual cell contains thousands of sub-structures that all interact with each other; tasks involving millions of molecules speaking with each other on a second by second basis. This is a spectacularly beautiful and balanced system.

If we zoom out from individual cells and the body in general, we can see that we do not live in bubbles (although it might feel like that these days). We live in a social world, filled with other humans and animals. We also interact with our physical environments on a daily basis; we are exposed to these environments via the food we consume, the air we breathe, clothes we wear and the sights we see. To top it off, as humans, we are the only species that has become consciously aware of its own mortality and an active sense of past, present and future. To summarise, our brains and minds are intimately connected to the rest of the body, as well as our social and physical environments; our happiness is dependent on healthy interactions between all of these systems.

The Brain

The human brain is divided into two hemispheres – although, the reality is more complex, broadly speaking, the right hemisphere is concerned with spatial and tactile awareness as well as creativity: it carries the music of events. The left hemisphere is associated with facts and statistics; it does the talking.

The brain was built from the bottom up (evolutionary and developmentally speaking) – the reptilian brain at the bottom, maintains activities related to survival (breathing, heart rate, etc.). The limbic system (central part of the brain) perceives threat and monitors danger, generates emotions, including fear; monitors danger; defines pleasure and pain; activates fight or flight responses; makes hormones; and regulates immune function. The neocortex (top part of the brain), largest in humans, is dedicated to rational thinking: it perceives time and promotes organisation and goal setting.

What stress can teach us about brain, mind and body connections

Much of what we know about the brain and body comes from studying cases where things go wrong. Stress teaches us a lot about how these complicated systems interact in response to internal and external threats. Humans perceive threat in two basic ways – by neuroception and via the thinking process.

Neuroception can be defined as awareness and sensing of the external environmental via the five senses. Once threat is detected, the limbic system activates immediately, a process that does not require conscious thought or decision-making by the neocortex. Secondly, negative thinking (worry and fear) can activate the limbic system, when humans ruminate over issues from the past or worry about the potential of future threats. In a nutshell, the brain cannot tell the difference between a real external threat, such as hungry wolf at your door, and an abstract (but still very real) threat, such as the fear of not achieving in the future. A number of biological processes are initiated, once threat is perceived as a significant danger from neuroception (sense of the external environment) or via the internal thinking process.

Our brains and minds are intimately connected to the rest of the body, as well as our social and physical environments; our happiness is dependent on healthy interactions between all of these systems.

Once activated, the limbic system subsequently activates a family of nerves (the autonomic nervous system) and the production of chemical messengers (hormones). The autonomic nervous system is divided into the accelerator (sympathetic nerves) and the break (parasympathetic nerves), which are also associated with fight or flight versus rest and digest responses. Sympathetic nerves produce the neurotransmitter and hormone, adrenaline. Adrenaline and other stress-related chemical messengers can cause the following symptoms: accelerated heart rate and breathing, high blood pressure, reduced appetite and digestion, reduced libido, enhanced glucose (sugar) release and increased energy production, dry mouth, sweating, and dilated pupils. The purpose of this response is to help you run for a bus or escape from a dangerous situation. Your body needs energy to catch that bus and does not need to be bothered about digesting your breakfast, solving problems or listening out for friendly voices. Our eardrums become finely tuned for low-frequency predator-like sounds or very high-pitched alarms from prey in trouble. This is why we tune out of conversations when we feel a threat is nearby; it also makes it difficult for us to focus on any other task.

This biological response is very useful to help us escape from, or eliminate a threat. However, when the threat is more abstract or emerges from daily worrying over finances during a pandemic, it becomes less useful and sometimes harmful. The same processes reduce our capacity to focus, inhibit digestion, reduce libido and increase our blood pressure. If this type of stress generated though fear, worry and negative thinking is not addressed, it can cause damage to the body.

Aside from adrenaline, cortisol is another stress hormone and chemical messenger produced by the adrenal glands, which lie on top of your kidneys. The purpose of cortisol is to inhibit the immune response and act as part of a negative feedback loop to limit the stress response in the brain. You might have used creams in the past for a skin rash that contains cortisol, the purpose of which is to dampen down the immune response in the skin.

Stress and the immune system

Stress (specifically adrenaline) can activate the anti-bacterial part of the immune system, while simultaneously dialling down the anti-viral part. Immunologists believe that humans evolved to prime the immune response against bacterial infection in response to stress, as protection against bites from predators and cuts from infected environments. This might prompt the question: what might this bias toward an anti-bacterial immune response (caused by stress) mean during a global pandemic?

Sickness behaviour

Sickness behaviour, caused by the stress response, evolved to protect us from additional danger and allow us to heal and recuperate from injury and/or infection. Symptoms of sickness behaviour include isolation and anti-social behaviour, reduced appetite and libido, fatigue, apathy and disinterest, as well as and a need to sleep. 21st century-related stress can cause sickness behaviour in the absence of an infection or threat from wild animals. These symptoms can often be confused with underlying disease processes and often prompt individuals to visit their GP. When physical causes are ruled out, we must turn to stress management. It is important to realise that our minds can exert a physical effect on our bodies and vice-versa. However, this does not make these symptoms any less real than those cause by infection or other disease processes.

We all possess an exquisitely beautiful and complex mind-brain-body system that is delicately balanced between the internal and external environments. Paying more attention to one over the other might lead to ill health. Whole person health requires that we mind how we think, manage stress and look after our bodies.

Recommended practice for this week

Awesome Breathing (pacer for meditation and stress) from the Apple App Store or Google Play
Alternatively for PC:
Practice breathing for two minutes, twice daily.

Recommended book and online talk

Why Zebras Don’t Get Ulcers by Dr Robert M Sapolsky, St Martins Press; revised and updated edition
Why Zebras Don’t Get Ulcers by Dr Robert Sapolsky. Stanford University – Inaugural Fenton-Rhodes Lecture on Proactive Wellness –

Registration for the RCSI Science of Health and Happiness course is available at The course is free and consists of one pre-recorded lecture per week. Registration is open until the end of May.


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