Actions of cortisol

Let us take another example. Blood samples were taken from two experienced male motor rally drivers before each attempted a rally circuit and again when they had finished. The blood samples were analysed for levels of noradrenaline, adrenaline and cortisol. Below are the results of the blood analysis of the winner and loser driver. The levels of hormones shown are those after the rally, compared with those before the start of the competition.

Can you pick the winner by looking at these blood analysis results?

Rally driving is not a race against other competitors but against time. At the end of the race, each driver will have judged how well he has performed and whether he feels he has mastered the course. The winner’s blood chemistry should indicate that he felt he had mastered the circuit and performed well, so his noradrenaline levels should be higher than those of the loser. Also the winner’s adrenaline and cortisol levels should be lower than those of the loser, who would be likely to feel he had not mastered the circuit and therefore did not expect to win. So looking at the test results, driver B should be the winner. In fact he was. It is interesting to learn that the noradrenaline levels were higher at the end of the race for both drivers, reflecting the increased alertness and physical effort required for the race.

The chemical messenger league table on page 56 and Figure 11 on page 57 summarize the relationship between how we feel and the release of the stress response hormones.

The power of the alarm response

The stress response allows us to produce extremes of human performance; speed, strength and stamina. There are numerous stories describing tremendous feats of power during activation of the alarm reaction. A woman achieved the strength to lift a car releasing her trapped child. A man racing for cover during an air raid did not realize that he scaled a ten foot wall in his dash for safety. If there had not been an emergency, neither the man nor the woman would have had the physical strength to perform these feats.

Athletes and sportsmen use the fight response to psych’ themselves up before races and events. Observe Olympic weightlifters. Notice how they pace up and down preparing to attack the weights as though it were a sabre-toothed tiger that they are about to take on in battle. Look at the aggression and hostility in their faces and behaviour. Ready for action, they grasp the bar, attack’, and lift.

Athletes often drive themselves to the limits of human performance. To achieve this, they must reduce the pain that arises during intense muscle activity. When they continue to perform even though they should really stop, a group of chemicals called endorphins are released in the brain to suppress the pain associated with the body’s efforts. Joggers and long distance runners owe their sustained activity to endorphins which produce a euphoric feeling. This may be one reason why joggers say they feel so good after a run when in fact they often look terrible! Being able to pass through the pain barrier is essential for survival if we are in a life or death situation and need to continue our effort until we are safe.

Chemical messenger league table

Appraisal of situation Dominant part of stress response Chemical messenger(s) order of dominance

1 can cope’ 1 am in control’ 1 have mastered this’ Alarm Fight’ aspect 1 Noradrenaline 2 Adrenaline

This is too demanding’ Can 1 cope?’ 1 fear failure’ Alarm Flight’ aspect leading to resistance 1 Adrenaline 2 Cortisol 3 Noradrenaline

1 feel helpless’ 1 am not in control’ ‘1 have failed’ Resistance 1 Cortisol 2 Adrenaline

Recognizing the signs of activity in your stress response and identifying the position of your stress balance are essential if you are to reduce distress, avoid ugly stress and make stress work for you. Your knowledge of the biology of the stress response can now be put to the test.

Linking the physiology of the stress response to the signs of stress

Most signs of stress can be explained by looking at the physiological actions of the stress response in the body. For O example, a sign of stress is cold hands and feet. Why? The skin temperature of the hands and feet is determined by the amount of blood flowing into these areas, and when the flow is significantly reduced, the hands and feet will feel cold. There are a number of factors that can change skin blood flow, such as environmental temperature, but the stress response certainly does so. If you remember, there is a redistribution of blood flow in the body during the alarm response, taking blood away from non-essential areas and diverting it to the muscles and other essential regions. The skin is a non-essential area so the sympathetic nervous system sends messages to the blood vessels of the skin instructing them to constrict. This leads to reduced blood flow and therefore reduced heat, which results in cold hands and feet. Using this as an example, it is possible to explain how and why the signs of stress arise. By referring to the actions of adrenaline, noradrenaline and cortisol, described in the previous chapter, we show the effects on the body of stress response activation. It then becomes possible to explain what happens to the body when the stress response is overactivated and the stress balance tips out of the normal zone, giving rise to distress or eustress.

Actions of cortisol Photo Gallery



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