What happens to the body during stress?

That extreme or chronic stress is harmful seems self-evident. I mean, it feels bad to be stressed out, right? 

But what is it that is actually happening to our body when we are 'stressed out'? How can it be that stress is implicated in the 6 leading causes of death, "heart disease, cancer, lung ailments, accidents, cirrhosis of the liver and suicide" ?

Here's how: 

High blood pressure-Stress hormones  like cortisol and adrenaline cause the heart to beat faster and blood vessels to constrict in an effort to shuttle blood to the core organs. This raises blood pressure. This may lead to chronic hypertension, which can lead to increased risk of stroke, heart damage, damage to arteries, dementia and kidney damage. 

Suppressed immune system-The immune system fights off disease with the help of B-cells and T-cells which are lymphocytes.  The stress hormone corticosteroid can lower the number of lymphocytes, thus rendering the immune system less able to fight off pathogens...disease causing viruses and bacteria. 

Stress also negatively impacts the digestive system, the first line of defense for the immune system. People under stress are more likely to engage in behaviors detrimental to health as well, such as smoking and alcohol consumption. Smoking contributes to heart disease cancer and lung issues, and excessive alcohol consumption damages the liver. 

Lack of sleep-The hyper-aroused state caused by the physiological components of stress outlined above can make sleep elusive. Inadequate sleep can contribute to inattentiveness and poor concentration, which can lead to more accidents. This is not just a problem in situations such as driving...it costs the workplace a substantial amount of money in preventable accidents. 

Depression-Elevated stress hormones like cortisol along with the inhibition neurotransmitters like serotonin and dopamine,  have been linked to depression.  When the fight or flight response is a chronic state of being, it can lead to depression. If lack of sleep and illness from a suppressed immune system are tossed into the mix, or the initial stressor is something like loss of a job that also cuts off a support system, depression may be even more likely. Making matters worse is if lifestyle factors create a downward spiral of stress and deepening depression; nutritional deficiencies, lack of exercise, excessive drinking, etc. In susceptible people, this increases the risk of suicide. 

There are so many easy and inexpensive ways to deal with situational and job related stress that make all of these potential problems less likely!