Physiological Stress Response - Case Study Example

Case Study of Physiological Stress Response Case history A 56 year old gentle man by Hien Ng was admitted with a 2-day history of vomiting,diarrhea and abdominal cramping. On the day of admission, the patient was noticed to have dark and offensive stools. His urine output was significantly decreased in the past 24 hours. His past history was significant. He suffered from rheumatic fever as a child, as a consequence of which he developed atrial fibrillation 5 years ago. Since then he has been on 125mcg of digoxin and 3 mg of warfarin. Recently, he was also diagnosed to have arthritis. He was taking anti-inflammatory drugs on his own to relieve arthritis pain. His personal history was also significant. He was a chronic smoker and had smoked 20 cigarettes per day for many years. On admission, general examination of the patient revealed that he was anxious and agitated, but orientated to time and place. His skin was pale and cool to touch. Heart rate was 116 beats per minute and irregular, blood pressure was 140/95mmHg, temperature was 37.8 C (cool peripheries), respiratory rate was 28 per minute, abdominal pain score was 6/10 and approximate weight was 68kg and height 163cm. Introduction Disruption of homeostasis through physical or physiological stimuli is known as stress. The normal homeostasis is defined by the range of certain blood parameters. These include pH of 7.36 to 7.45, bicarbonate of 21- 27.5 m mol per liter, oxygen saturation of >97% and glucose concentration of 3.6 to 6.8 m mol per liter. During a stressful condition, the body takes some measures to restore normal homeostasis and these are called the physiological effects of stress (Tortora & Derrickson, 2006). There are many stimuli which can cause physiological stress in a person. These can be either physical (trauma, pain, extremes of temperature, disease, dehydration, infection and excessive physical activity), psychological (deep emotions, anxiety, apprehension and fear) or physiological (pregnancy, delivery, post-partum, lactation, sexual activity, menstruation and pre-menstrual tension) or chemical (excessive intake of alcohol, drug abuse and drug over-dose). These stimuli can either cause immediate effects, or delayed effects or even chronic effects on the body. When the body is exposed to a stressful condition, the hypothalamus situated in the brain secretes adrenocorticotrophic releasing hormone (CRH). Hypothalamus is concerned with the secretion and control of the different hormones of the body. The CRH which is released is a peptide and is produced by the neurons in the paraventricular nuclei in the median eminence after being triggered by the afferent nerve pathways which come from many parts of the brain and converge in to the paraventricular nuclei. There are other pathways which carry impulses of stress to these nuclei. Fibers from the amygdaloid nucleus mediate responses to intense emotions, anxiety, apprehension and fear. Pain, trauma and suffering are mediated via nociceptive pathways and reticular formation. From paraventricular nuclei, CRH is transported in the portal hypophysial vessels to the anterior pituitary causing stimulation of gland to release ACTH. This hormone in turn stimulates the adrenal or the suprarenal glands situated at the apex of the kidneys to secrete the ‘stress hormones’ namely, the catecholamines and the cortisol which cause physiological effects of stress. ACTH also stimulates the production of aldosterone from adrenal glands (Ganong, 2003). Blood is diverted from the less vital to more vital organs like brain, heart and kidneys, heart rate increases to supply more blood quickly, blood pressure increases to supply blood efficiently, respiratory rate increases to get more oxygen from the atmosphere, glycogen stores in the liver and muscle are broken down to get more glucose (glycogenolysis) and beyond a certain level, glucose is formed from non-carbohydrate sources like fats and proteins (gluconeogenesis). These effects are mediated through two distinct nuclear receptors, the mineralocorticoid receptors and the glucocorticoid receptors. These mediate the steroid control of hypothalamus-pituitary-adrenal activity and behavior in a coordinate manner (Ron de Kloet, 2000). Effects of stress on individual organs In the brain, the stress hormones act on the limbic system, situated in the temporal lobe of the brain. Since limbic system is mainly concerned with emotions, emotional symptoms like anxiety, apprehension, mood swings and depression are manifested. Effects of these hormones on the frontal lobe result in memory disturbances. The bad experience due to stress gets stored due to the effect of these hormones on hippocampus, which is also in the temporal lobe and is related to long term memory. The person may recall this bad experience repeatedly in the future. In genetically predisposed individuals, an imbalance in this binary control mechanism can introduce a bias towards stress-related brain disease after adverse experiences (Ron de Kloet, 2005). In the heart, adrenaline acts on the B1 receptors of the heart resulting in increase in the heart rate (positive chronotropic effect of adrenaline) and also the force of contraction (positive ionotropic effect of adrenaline) leading to increased cardiac output. Adrenaline also stimulates the alpha receptors of the blood vessels, thus increasing the blood pressure (Ganong, 2003). All these result in effective delivery of blood to various tissues of the body, especially the vital organs. The blood supply to less vital organs like spleen, gastrointestinal tract and skin is decreased for conservation of energy. Spleen, being a reservoir of blood, shrinks to expel blood in to the main blood vessels, so that blood is diverted to the vital organs. Gastrointestinal tract is deprived of blood supply resulting in poor digestion. Also, decreased blood supply to the stomach results in worsening of the ulcers. The transit time of the colon is increased resulting in loose stools. Oral mucosa and conjunctiva dry up, giving a dehydration appearance. Skin becomes cold and clammy and the blood refill time becomes more than 2 seconds. The erector pilae muscle which is attached to the hair follicles contracts resulting in goose flesh appearance. Adrenaline acts indirectly on the lungs resulting in increased respiratory rate. This allows more oxygenation of tissues. Cortisol, being a steroid, is immunosuppressant and hence increased levels of this hormone may result in increased susceptibility to infections. Also, if secreted continuously due to persistent stress, there may be flaring up of the allergic disorders, because in the long run, steroids derange the immune system. Prolonged rise of aldosterone leads to potassium diuresis. Both sodium and water are retained; the concentrations of sodium hence remain to be almost normal. Consequently the extra cellular volume rises and this further increases the blood pressure. Stages of Stress Response to stress goes through 3 main stages: First is the stage of alarm, followed by stage of resistance and then stage of exhaustion. When a person comes across or realizes or faces a situation of stress, the bodys stress response is a state of alarm. During this stage, adrenaline will be produced in order to bring about a fight response. Some amounts of cortisol also may be produced. If the stress stimuli continue to persist, the body begins to try to adapt to local and environmental needs. In the process, the body’s reserves of energy gradually start getting depleted. Also, catecholamines and glucocorticoids are secreted in increased quantities to replenish the reserves. Heart rate, blood pressure and respiratory rate increases. This is the stage of resistance. If the stress situation continues, all the bodys resources eventually get depleted and the body becomes unable to maintain normal function. The capacity of the glands, especially the adrenal glands, and that of the immune system gets exhausted. Their function also gets impaired resulting in decompensation. The person may develop severe tachycardia and sweating. Blood pressure which increases initially may go down and lead to hypotension and shock. Exacerbation of chronic problems like ulcers and cardiovascular related events can occur. The person may go in to depression. This model of stages of stress was proposed by Hans Selye. He described this universal response to the stress stimuli as the General Adaption Syndrome (Seyle, 1950) Chronic Stress It is important to discuss about chronic stress because this can go unnoticed until the ill effects of health have already ensued. The stimuli in chronic stress are mainly psychological related. The stress could be either due to marital discord, financial burden, incurable disease of a dear one, employment issues or chronic disease and medication. Chronic stress impairs the immune system’s capacity to respond to hormonal signals. It down regulates glucocorticoid expression and diminishes glucocorticoid sensitivity of interleukin-6 (Miller, 2002). Inflammation plays a role in the pathogenesis of allergic, autoimmune, rheumatologic, and cardiovascular diseases and contributes to the symptomatology of many infectious diseases. These conditions are exacerbated in chronic stress. Also, these people tend to develop infections more frequently and may need severe treatment. Chronic stress also leads to depression. Case discussion This 56 year old gentle man was brought to the hospital with symptoms of acute gastro-enteritis, probably infectious in origin. He was vomiting everything he was taking and hence there was no scope for rehydration of lost fluids. His urine output was significantly decreased, pointing towards dehydration. However, on the third day of illness, the day when he was brought to the hospital, he developed foul-smelling tarry stools suggestive of gastro-intestinal bleeding. Why should bleeding occur in a simple gastroenteritis case? When we go into the past history, this gentle man had suffered many health insults- rheumatic fever, atrial fibrillation, arthritis and chronic smoking. He had also been self-medicating with anti-inflammatory agents. Probably, the smoking and anti-inflammatory drugs must have caused a silent ulcer in the stomach which must have got exacerbated during this acute stressful situation and caused gastrointestinal bleeding. This is consistent with his abdominal scores. The gentleman’s general physical examination revealed increased heart rate, increased blood pressure and mildly increased respiratory rate. Also, his peripheries were cold and clammy despite normal core body temperature. All these are signs of response to acute stress. During dehydration, the homeostasis of the body is altered and the hypothalamus-pituitary-adrenal axis gets activated to bring back the homeostasis to normal. The catecholamines increase the heart rate, the respiratory rate and the blood pressure. Decreased urine out-put is probably due to aldosterone secretion, and further adds to increase blood pressure. The peripherals are cold and clammy because these stress hormones react in such a way so as to increase blood supply to vital organs and thus decrease blood supply to non-vital organs (skin being one of them). Due his chronic disease state, this gentle man is at risk of frequent infections, exacerbation of arthritis, worsening of heart ailment and psychological depression as discussed above. Conclusion The patient under study was subjected to both acute stress and chronic stress. His arthritis (immunological impairment) and ulcer were probably a manifestation of chronic stress. His decision to come to the hospital was due to alarm response for acute stress. At the time of admission, he was in the second stage of stress (resistance) when there were signs suggestive of upsurge of catecholamines and cortisol. Appropriate treatment must be initiated before he goes in to the exhaustion phase of stress. References Ganong, W.F. 2003, Review of Medical Physiology, Mc Graw Hill, United States. Miller, G.E., Ritchey, A.M., & Cohen, S. 2002. Chronic Psychological Stress and the Regulation of Pro-inflammatory Cytokines: A Glucocorticoid –Resistance Model. Health Psychology, 21 (6), pp.531-541. Ron de Kloet. 2000. Stress in Brain. Eur J Pharmacol 29, pp.187-98. Ron de Kloet, E., Joels, M. & Holsboer, F. 2005. Stress and the brain: from adaptation to disease. Nature Reviews Neuroscience 6 (6), pp. 463-475. Seyle, Hans. 1950. Diseases of adaptation. Wisconsin Medical Journal 49 (6).  Tortora, G.J., & Derrickson, B.H. 2006, Principles of Anatomy and Physiology, 11th edition, John Wiley & Sons Inc. Read More