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