Physiological Response.docx

Physiological Response: HPA axis We will now focus on the key physiological reactions that the body generates in response to any stressful stimuli. When we look at the physiological response, we are looking at the hypothalamic – pituitary – adrenal axis commonly referred to as the HPA axis. It is im...

Physiological Response: HPA axis We will now focus on the key physiological reactions that the body generates in response to any stressful stimuli. When we look at the physiological response, we are looking at the hypothalamic – pituitary – adrenal axis commonly referred to as the HPA axis. It is important to note that whatever stimuli or stressor is introduced the response is the same. So, the stressor can be from the external environment or exogenous in origin such as cold, trauma, noise, pain, medical treatment or it can be within us or internal or endogenous in origin such as fear, excitement and anxiety. Whatever the sensory input the output or the response is the same. In turn these real or perceived stressors caused by negative physiological, emotional or cognitive stimuli activate the limbic system and parts of the cerebral cortex, to ultimately simulate the hypothalamus. Acute Stress Feedback We know that acute stress or the short term responses to stress can be beneficial as the body can prepare for the fight or flight response. The increased arousal alertness, vigilance, cognitive functioning and focused attention will facilitate the rapid processing of information, especially during this threatening period. Even a healthy person can experience a pounding headache, cold, moist skin, a stiff neck, but this stress response can be determined for others. If a patient has heart disease, they may not have the cardiac reserve to cope with the catecholamine surge in this situation. The acute stress feedback system occurs at the level of the hypothalamus in the anterior pituitary gland. Normally with the activation of the hypothalamus there is the negative feedback system that decreases further synthesis and release of more cortisol. This increased level of cortisol inhibits the hypothalamus from releasing more CRF and the anterior pituitary from releasing more ACTH. This allows the body to deal with the situation as an acute, self-limited response.