Stress- bodily response to stress
Stress- a physiological response when a person perceives thats a social, physical or environmental pressure/demand exceeds their ability to cope/ threatens or challanges resources.
Stressor- a stimulus or situation imposing demands on an individual (poses a threat).
When a stressor is perceived and is considered to be threatening and demanding on our coping resources signals are sent to the hypothalamous. The hypothalamous then activates the HPA axis and SAM pathway.
Hypothalamous- located above the brain cells it is responsible for metabolic processes and other autonomic nervous system (ANS) activities. It is linked to the nerous system via the pituitary gland.
Pituitary gland- master gland of the body located at the base of the hypothalamous, it is responsible for releasing 9 hormones regulating processes.
Autonomic nervous system (ANS)
ANS regulates the internal body environment (homeostasis) and fuctions largely below levels of consciousness. It is responsible for the bodily arousal assosiated with stress. It is divided into 2 subsystems:-
sypathetic nervous system- increases physiological arousal/ sets off stress response eg.pupils dilate.inhibits saliva flow- less friction on roof of mouth so can take in more air.increases heart rate- oxygen pumped to work muscles.increases respiration- more air.inhibits peristalsis- non essensial function of digestion.coverts glucogen to glucose- instant energy.secrets adrenaline and non adrenaline.inhibits bladder- wet yourself to loose water weight.
parasymathetic nervous system- reduces physiological arousal and creates calm/ switches off stress responses. eg.pupils constrict.stimulates saliva flow.decreases heart rate.decreases respiration.stimulates peristalsis and secretion.stimulates release of bile.contracts bladder.
(Hypothalamic) pituitary adrenal system (HPA axis)
HPA axis is a chain of reactions which occur as part of the energy response.
CRF (chemical message)
ACTH (into blood stream)
Adrenal cortex (outer part of adrenal gland)
corticosteroids- regulates metablism of glucose and has anti inflammatory effect
energy and immune suppression
sympatho- medullary pathway (SAM)
SAM pathway is a chain of reactions which result in physiological, bodily changes to prepare for fight or flight
SNS (sympathetic nervous system)-sympathetic arousal
adrenaline - hormone in the circulatory system, and nor adrenaline- increases rate of oxygen to muscles
HPA axis and SAM pathway
Together HPA and SAM ensure we have sufficient energy resources available to deal with stressors and prepare our body for any action that might be needed to cope.