Pathophysiology Chaptert 9 Stress & Adaptation
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- Define Homeostasis.
- The concept of a stable internal environment, achieved through a system of carfull coordinated physiological processes that oppose change.
- Describe negative feed-back.
- When a function or value decreases below the set point of the system, the feed-back mechanism to increase; and whent it increases above the set point it causes it to decrease.
- Describe an example of negative feed-back.
- increases in blood glucose stimulate the release of insulin that lowers blood sugar, low blood sugar causes inhibits insulin release and stimulates glucose release.
- Describe positive feed-back.
- this mechanism interjects instibility; The initiating stimulus produces more of the same stimulus.
- Give an example of positive feed-back.
- The hormone oxytosin stimulates uterine contractions, which stmulates more contractions: the cycle continues until the baby is born and the cycle is broken.
- Define Stress.
- A state manifested by a specific syndrome of the body developed in response to any stimuli that made an intense systemic demand on it.
- explain the general adaptation syndrome.
- The role of the hypothalamic-pituitary-adrenal axis in the stress response.
- explain the GAS theory.
- general-the effect is a general systemic reaction. adaptive-because the resonse was in reaction to a stressor. syndrone-the physical manistations were coordinated and dependent on each other.
- what are the stages of GAS
-
alarm stage
resistance stage
exhaustion stage - define alarm stage.
- a generalized activation of the HPA axis, resulting in the release of catecholamines and cortisol.
- define resistance stage
- the body selects the most effective and economical channels of defense. The cortisol levels drop because they are no longer needed.
- define exhaustion stage
- if the stressor is prolonged or overwhelms the bodies defenses, resoorces are depleted.
- list the hormones associated with the stress response.
- catecholamine (NE & Epi), CRF, ACTH, Glucocortico hormones(cortisol), Mineralocorticoid hormones (aldosterone), ADH.
-
List the source of these hormones and describe their physiologic effects.
(NE, EPI) -
(NE, EPI)- Locus ceruleus, adrenal medulla.
< insulin, > glucagon resulting in
>glycogenolysis,
gluconeogenisis,lipolysis, proteolysis. > HR, cardiac contractility & bronchiodilation. - Corticotropin releasing factor (CRF)
-
Hypothalamus.
stimulates ACTH release from anterior pituitary and > activity in neurons in locus ceruleus. - Adrenocorticotropic hormone (ACTH)
-
Anterior pituitary.
stimulates the synthesis and release of cortisol. -
Glucocorticoid hormones.
(cortisol) -
adrenal cortex.
potentiates the action of epi and glucagon. inhibits the release and/or actions of reproductive hormones & TSH, & produces a < in immune cells and inflammatory mrdiators. - Mineralcorticod hormones (aldosterone)
-
adrenal cortex.
> sodium absorption by the kidneys. - Antidiuretis hormone (ADH)
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Hypothalamus, posterior pituitary.
> water absorption by the kidneys; produces vasoconstriction of blood vessels: and stimulates the release of ACTH. - discuss neuroendocrine responses.
- It relies on communication along neuronal pathways of the cerebral cortex,limbic system, thalamus, hypothalamus,pituitary gland, and the reticular activating system.
- cerebral cortex
- involved with vigilance, cognition, and focused attention.
- limbic system
- emotional components ( fear, excitement, rage, anger) of the stress response.
- thalamus
- functions as the relay center and is important in recieving, sortingout and distributing sensory input.
- hypothalamus
- coordinates the response of the autonomic nervous system.
- reticular activating system
- modulates mental alertness, ANS activity, and skeletal muscle tone, using input from other neural structures.
- what is the locus ceruleus
- is densly populated with neurons that produce NE and is thought to br the central intergrating site for the ANS response to stress.
- What is corticotropin - releasing factor
- a small peptide hormone that has both an important role as a endrocrine regulator of pituitary and adrenal activity, and a neurotransmitter involved in ANS activity, metabolism and behavior
- how does CRF effect the stress response
- CRF from the hypothalumus induces ACTH from the anterior pituitary gland. ACTH in turn stimulates the adrenal gland to synthesize and secrete cortisol.
- what effects do glucocorticoid hormones have
- they have both direct and indirect effects that mediate the stress response. enhance the actions of other hormones, or suppress other components of the stress system.
- What are some of the effects of cortisol
- maintains blood glucose levels by antagonizind the effects of insulin and enhances the effect of catecholamines on the cardiovascular system.
- Other cortisol functions include
- supress osteoblast activity, hematopoiesis protein and collegen synthesis, and immune responses.
- how can cortisol effect thyroid funtion
- stress induced cortisol also is associated with decreased levels of thyroid hormone and inhibition of conversion of (t4 to the more biologicially active t3)a means to conserve energy.
- What is the role of ADH in the stress response
- ADH is involved in the stress response, particularly in hypotensive stress or stress do to fluid volume loss.
- what role does immune cells play in the stress response.
- monocytes and lymphocytes can penetrate the blood-brain-barrier where the secrete cytokines and other inflammatory mediators that influence the stress response.
- What is the most fully evolved mechanism for copind and adaptation to stress.
- the social responses through which individuals or groups modify their environments, their habits, or both.
- list some factors that affect the ability to adapt.
- physiologic and anatomic reserve, time, genetics, age, health status, nutrition, sleep-wake cycles, hardiness, psychosocial factors.
- define post traumatic stress disorder.
- chronic activation of the stress response as a result of experiencing a potentially life threatening event.
- how is PTSD characterized
- a constellation of symptoms that are experienced as states of intrusion, avoidance, and hyperarousal.
- define Intrusion
- the occurrence of flash backs during waking hours or nightmares in which the event is relived.
- define avoidance.
- the emotional numbing that occompanies this disorder disrupts important personal relationships. (survivor guilt)
- define hyperarousal
- the presence of increased irritability, difficulty in concentration, an exaggerated startle reflex, and concerns over safety.