Superbodies by Greg Wells

Author:Greg Wells [Wells, Greg]
Language: eng
Format: epub
ISBN: 9781443405959
Publisher: HarperCollins Canada
Published: 2012-04-13T04:00:00+00:00

Sources: Borek, 2004; Clarke and Armitage, 2002; Reynolds, 2006; Huang et al., 2006.

THE MIND–BODY CONNECTION

Can you imagine that your brain influences your immune system? Amazingly, this is true and has major implications for both health and disease. Psychological events that are perceived as negative and stressful by the brain can have a physical effect on the immune system because there are sympathetic nerve connections between the brain and the bone marrow, the thymus, the spleen and the lymph nodes.48 When electrical signals from the brain descend through these nerves and connect with the various immune system organs, neurotransmitters are released from these nerve endings and circulate through the immune system tissues. The cells of the immune system such as lymphocytes and natural killer cells have receptors on their surface that are sensitive to these neurotransmitters. Therefore, signals from the brain and the nervous system can have a direct impact on the immune system cells, increasing or decreasing their activity levels.

In addition to direct nerve connections between the brain and the immune system, there are also chemical signal connections. Endocrine system organs such as the hypothalamus and the pituitary glands in the brain, or the adrenal glands above the kidneys, release chemical-signalling hormones, including epinephrine (also known as adrenaline), norepinephrine and cortisol, which circulate throughout the body. These hormones produce wide-ranging effects on most body tissues and also affect the white blood cells of the immune system. Just as immune system cells have receptors for neurotransmitters, they also have receptors for hormones. When the hormones bind to the surface of the white blood cells, they have wide-ranging effects on the distribution and function of the cells.

People typically think that the mind and body are separate. Our thoughts don’t affect our bodies—how could they? They are just thoughts and don’t really even physically exist, right? Actually, this is wrong. Thoughts exist as electrical currents passing through the neurons of our brains. Sometimes those electrical currents pass through areas of the brain that are part of the endocrine system. (For more information, see Chapter 5 on the endocrine system.) When these passages happen, hormones leave the endocrine organs to circulate through the body. We perceive this response as emotions or physical feelings. Imagine you are lying in bed, thinking about something that happened at work. You tense up, your heart rate increases and your breathing rate goes up. These changes are the mind–body stress response. I’ll talk about this response in detail in Chapter 7 and provide tips on how to combat the negative effects that go along with it, but it is an important concept to deal with here because psychological stress causes a decrease in the effectiveness of your immune system.

Think back to your high school or university exams. I was one of many people who crammed for finals; perhaps you did so as well. I remember the sleepless nights, the anxiety, the constant memorization, the focusing for hours on end, and the mental fatigue—not to mention overdosing on caffeine and poor food.

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