Over the past week, I've been reading this very interesting (for me) book. In order not to misrepresent the author, I'm going to quote some paragraphs from the opening chapter.
For animals like zebras, the most upsetting things in life are acute physical crises. You are that zebra, a lion has just leapt out and ripped your stomach open, you’ve managed to get away, and now you have to spend the next hour evading the lion as it continues to stalk you. Or, perhaps just as stressfully, you are that lion, half-starved, and you had better be able to sprint across the savanna at top speed and grab something to eat or you won’t survive. These are extremely stressful events, and they demand immediate physiological adaptations if you are going to live. Your body’s responses are brilliantly adapted for handling this sort of emergency.
The half of the autonomic nervous system that is turned on is called the sympathetic nervous system. Originating in the brain, sympathetic projections exit your spine and branch out to nearly every organ, every blood vessel, and every sweat gland in your body. They even project to the scads of tiny little muscles attached to hairs on your body. If you are truly terrified by something and activate those projections, your hair stands on end; gooseflesh results when the parts of your body are activated where those muscles exist but lack hairs attached to them. The sympathetic nervous system kicks into action during emergencies, or what you think are emergencies. It helps mediate vigilance, arousal, activation, mobilization. To generations of first-year medical students, it is described through the obligatory lame joke about the sympathetic nervous system mediating the four F’s of behavior—flight, fight, fright, and sex. It is the archetypal system that is turned on at times when life gets exciting or alarming, such as during stress. The nerve endings of this system release adrenaline. When someone jumps out from behind a door and startles you, it’s your sympathetic nervous system releasing adrenaline that causes your stomach to clutch.
The other half of the autonomic nervous system plays an opposing role. This parasympathetic component mediates calm, vegetative activities—everything but the four F’s. Sprint for your life across the savanna, gasping and trying to control the panic, and you’ve turned the parasympathetic component down. Thus, the autonomic system works in opposition: sympathetic and parasympathetic projections from the brain course their way out to a particular organ where, when activated, they bring about opposite results. The sympathetic system speeds up the heart; the parasympathetic system slows it down.
Another important class of hormones in the response to stress are called glucocorticoids.
The body synthesizes these glucocorticoids, but we can also be given synthetic glucocorticoids, a good example being Prednisone that is a potent synthetic corticosteroid used to quickly reduce inflammation, suppress an overactive immune system, or replace natural cortisol. It is prescribed for a wide variety of conditions, including severe allergies, asthma, arthritis, and autoimmune diseases like lupus.
The connection between this scan (which was done yesterday) and the glucocorticoids is that I had to undergo a 'preparation protocol' that involved taking prednisone three times at various hours of the day along with another medicine an hour before the test. Everyone at the hospital checked that I had taken the medicines although obviously they had to rely on my answer.
I am going to go into detail about what I felt from the scan onwards, primarily so that I will have it documented. During the test itself, the only abnormal thing that I felt was as if part of my testicles had been lowered into warm water; the rest of the body felt fine. My hands were shaking slightly but that's something that I've noticed over the past few weeks. After I got home, I took the dog for a walk then had a light supper. I felt slightly warm but I thought that this was due to walking the dog. By the time I came to measure my blood pressure at 9 pm, I was surprised to see that it was high (relatively for me) at 125/82 with a pulse of 102. For comparison, the readings on Sunday evening were 103/78 and pulse 77. When I got into bed, I felt quite warm, despite the air conditioner, and slept for some time uncovered.
Obviously the prednisone had activated the sympathetic nervous system, and the iodine was having its effect.
Going back to zebras and why they don't have ulcers: humans have both external sources of stress and internal souces, or psychological stresses. Unfortunately, the body can't distinguish between the two sources and so the sympathetic nervous system gets unnecessarily mobilised, moving blood to our arms and legs and taking it away from other areas of the body. One familiar source of psychological stress is how much control we feel we have over our lives, otherwise known as locus of control. Those with a low locus of control have more stress than those with a high locus.
My job affords me with a very high locus of control, but I remember that when I was in the army (compulsory service and reserve duty) I had a very low locus, and I used to say that if something were about to happen and I could think of two alternatives, the army would always choose a third option which would be worse than anything that I could think of.
Internal links
[1] 2095
| Title | Tags | ||
|---|---|---|---|
| 952 | Dave Swarbrick, RIP | Obituary, Fairport Convention | |
| 1505 | Italy 2022: pre-flight check | Holiday, Italy, Bari | |
| 1771 | Cruise log #2: Rodos | Holiday, Rodos, Greece | |
| 1943 | A cheap source of Erythritol | Erythritol |
