Homeostasis, Response to stress

Topics: Nervous system, Sympathetic nervous system, Parasympathetic nervous system Pages: 3 (1027 words) Published: April 12, 2014
All living organisms maintain a complex dynamic equilibrium, or homeostasis, which is constantly challenged by internal or external adverse effects, termed stressors.[4,5] Thus, stress is defined as a state in which homeostasis is actually threatened or perceived to be so; homeostasis is re-established by a complex repertoire of behavioral and physiological adaptive responses of the organism Our biological stress response was designed for survival and is regulated by both the neural and endocrine (hormonal) systems. Fundamentally, both systems are communication systems that receive sensory information from various sources (eyes, ears, skin, blood, etc.) and transmit appropriate responses to specific targets once information has been processed to re-establish balance. The nervous system is a rapid-acting, but short-lived communication system that functions by transmitting nerve impulses – it reacts very quickly to stimuli, but its effects do not last very long (e.g., the sudden, short-lasting elevation of heart rate when startled). The endocrine system is a slower-acting, but longer-lasting communication system that functions by hormonal action – it is activated more slowly (sometimes by nerve activity) and its effects may last longer (e.g., the sustained elevation of heart rate during a 60-minute run). - his "alarm", carried by chemical messengers like adrenalin, causes several changes to occur in your body. Stress and Cardiovascular Responses The cardiovascular system is affected by the sympathetic stimulation of increased heart rate by firing of SA nodes. Each time we respond to stress, the release of epinephrine increases platelet adhesiveness to help blood clot.  Likewise, under stress the body aims to increase blood volume to offset any potential loss of blood volume from sweating or bleeding by increasing the release of antidiuretic hormone (ADH) from the anterior pituitary gland that re-absorbs fluid from the kidneys. However, without any loss of blood...
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