Homeostasis and Stress

homeostasis

dynamic maintenance of a relatively constant of stable environment in the face of constantly changing conditions

how is homeostasis maintained

through feedback loops

feedback loop

regulation of the stable conditions of homeostasis in the face of a stressor

control centers of feedback loops

nervous and endocrine systems

feedback loop requirements

receptor, control center, effector

function of receptor

sensor that monitors the environment and responds to stress, provides input to the control center

function of control center

takes the input and sends a signal to the effector to initiate a response

function of effector

produces an action/response

negative feedback loop

response is to reverse the original stimulus effect

positive feedback loop

response that enhances/strengthens the original stimulus to cause an even higher response

definition of stress

any physical, emotional, social, or other factor that acts on the body to respond or change

how is stress mediated in an acute situation

through neuroendocrine systems

how is stress mediated in a chronic situation

through the immune system

HPA axis

feedback loop primarily involved in the stress response to return to homeostasis

compounds secreted by the adrenal gland in an acute situation

catecholamines norepinephrine and epinephrine

compounds secreted by the adrenal gland in a chronic situation

cortisol and glucocorticoids

type of feedback loop the HPA axis operates on

negative feedback

multi-layered feedback loops

the more crucial something is to our health, the more layers of feedback there are in place to protect it

types of stressors

endogenous (internal) and exogenous (external)

categories of stressors

biological, psychological, socioeconomic

characteristics of an acute response to a stressor

most common, short-term, has a total resolution of symptoms, produces an adaptive flight or fight response

characteristics of a subacute response to a stressor

longer than acute but less than 12 weeks, typically total resolution of symptoms, flight or fight response

characteristics of a chronic response to a stressor

dysfunction of the stress response, persistent and recurrent, longer than one year, response has deleterious consequences to the systems

general adaptation syndrome

body’s way of adapting to a stressor by using resources to survive and return to homeostasis

3 stages of general adaptation syndrome

alarm/shock, resistance/adaptation, exhaustion

factors of the stress response

property of the stressor and conditioning of the organism

adaptation

ability to respond to challenges to physical or psychological homeostasis and return to a balanced state

characteristics of cellular adaptation

bodily response to attenuate to return to healthy homeostasis, morphological alteration to tissue, can revert back to normal but chronic stress will be detrimental

factors of individual adaptation to stress

prior experience, adaptive strategies, genetics, age, health status, nutrition, psycho-social

characteristics of eustress

positive, mild, brief, can be a motivator

characteristics of distress

negative, longer, more intense, limited control