PHTY208 Lecture Notes - Lecture 15: Arthralgia, Sensory Deprivation, Vasodilation
Stress and adaption, activity tolerance and fatigue:!
Stress and adaption:!
-Stress is a term in psychology and biology!
-It refers to the consequence of the failure of an organism to responda appropriately !
-Signs of stress may be cognitive, emotional, physical or behavioural!
Activity tolerance and fatigue:!
-Physical activity- process of energy expenditure for the purpose of accomplishing an effect!
-Rest- inactivity!
-Fatigue- perceived lack of sufficient energy!
Concept 1: The Stress response:!
Homeostasis:!
-The purposeful maintenance of a stable internal environment !
-A condition of equilibrium (balance) in the body’s internal environment!
-Physiologic processes opposing change- dynamic condition, narrow range is compatible with
maintaining life !
Stress:!
-Anything that disrupts equilibrium or demands that exceed the body’s ability to cope!
-Requires psychological, behavioural and physiologic adjustment!
-Can have negative health consequences!
-A state manifested by symptoms that arise from the coordinated activation of the
neuroendocrine and immune systems (general adaption syndrome: GAS)!
Adaption:!
-The ability to respond to challenged of physical or psychological haemostats and to return to a
balanced state!
Stressors:!
-Events or environmental agents responsible for initiating the stress response!
-Can be endogenous or exogenous or mix of both!
-Eustress: as stress that is healthy or gives one a feeling of fulfilment or other positive feelings!
-Distress: aversive state in which an animal is unstable to adapt completely to stressors and
their resulting stress and shows maladaptive behaviours !
Stages of the general adaption syndrome:!
-Alarm stage- a generalised stimulation of the sympathetic nervous system and the HPA axis
resulting in release of catecholamines and cortisol!
-Resistance stage- the body selects the most effective and economical changes of defence!
-Exhaustion stage- resources are deleted and signs of wear and tear appear!
Allostasis:!
-Physiological changes in the neuroendocrine, autonomic and immune system that occurs in
response to real or perceived challenges to homeostasis!
-CNS: neuronal pathways!
-Cerebral cortex, limibic system, thalamus, hypothalamus, pituitary gland, reticular activating
system!
Neuroendocrine responses:!
-Stress response is strongly influenced by the nervous (sympathetic) and endocrine system!
-Mobilisation of energy, ^ cerebral blood flow and glucose usage, enhanced cardio/respiratory
function, redistribution of blood from to brain and muscles, modulation of immune response,
inhibition of reproductive function, decrease appetite!
-Designed to be a short term fix to insults to homeostasis!
Hormone response to stress:!
-Corticotropin-releasing factor- found in hypothalamus, limbic system and brain stem!
-Important in ANS activity, adrenal activity, metabolism and behaviour!
-Induces the secretion of aCTH which stimulates adrenal gland to secrete glucocorticoid
hormones (e.g. cortisol)!
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-Other important hormone responses to stress!
-About 10+ other hormones!
Adaption to stress:!
-Mechanisms that evolved for organisms to respond to or modify their environments, habits, or
both to achieve a way of life that is best suited to their need!
-Feedback mechanisms- negative feedback!
Adaptive capacity:!
-Stressors tend to produce different responses in different persons or in the same person at
different times!
-Conditioning factors- internal, external !
-Relative risk for development of a stress-related pathologic process is partially dependent on
these factors!
Factors affecting ability to adapt:!
-Previous learning/exposure and physiologic reverse, time, internal: genetic endowment, age,
sex, health status, nutrition, sleep-wake
cycles, hardiness, psychological factors!
Failure to adapt:!
-Failure to adapt to a stressor can result in!
-Emotional disturbances, headaches,
insomnia, upset stomach, fastric and
duodenal ulcers, rheumatic disorders,
cardiovascular disease, kidney disease!
Concept 2: Effects of Stress:$
Effects of stress:!
-Stress is meant to last only a short time
(response is beneficial)!
-Stress can also for long periods
(disruptive to physical and mental health)!
-Acute (time-limited and do not recur)!
-Chronic (sustained stress, an fatigue and
impair)!
Reactions to acute stress:!
-Associated with fight or flight!
-Facilitation of neural pathways mediating!
-Arousal, alertness, vigilance, cognition, focused attention, appropriate aggression!
Acute stress:!
-Results from psychologically or physiologically threatening events!
-May be life saving (divert blood away from less essential areas, enable rapid processing of
information)!
-In a health person: redirect attention from behaviours that promote health (eating and sleeping)!
-In unhealthy people: can lead to arrhythmias and other problems!
Effects of chronic stress:!
-Pathophysiologic changes occur!
-Altered physiological function- component of a system fails, neural and hormonal connections
fail, overwhelms ability of system to respond: overactive or underactive !
-Chronic activation of the stress response can result in illness and long term health problems!
-Chronic stress has been linked to other disorder (cardiovascular, gastrointestinal, immune,
neurologic systems, oral disease, common cold, delays in wound healing)!
-Altered psychological factors (depression, accidents, suicide, chronic alcoholism, drug abuse,
eating disorders)!
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Stress is a term in psychology and biology. It refers to the consequence of the failure of an organism to responda appropriately. Signs of stress may be cognitive, emotional, physical or behavioural. Physical activity- process of energy expenditure for the purpose of accomplishing an e ect. The purposeful maintenance of a stable internal environment. A condition of equilibrium (balance) in the body"s internal environment. Physiologic processes opposing change- dynamic condition, narrow range is compatible with maintaining life. Anything that disrupts equilibrium or demands that exceed the body"s ability to cope. A state manifested by symptoms that arise from the coordinated activation of the neuroendocrine and immune systems (general adaption syndrome: gas) The ability to respond to challenged of physical or psychological haemostats and to return to a balanced state. Events or environmental agents responsible for initiating the stress response. Can be endogenous or exogenous or mix of both.
