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Physiology of Stress: I. Nervous System a. CNS (central nervous system)

Stress. Psychophysiology = the body’s physiological reaction to perceived stressors suggesting that stress response is a body-mind phenomenon. Physiology of Stress: I. Nervous System a. CNS (central nervous system) **brain and spinal cord b. PNS (peripheral nervous system)

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Physiology of Stress: I. Nervous System a. CNS (central nervous system)

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  1. Stress Psychophysiology = the body’s physiological reaction to perceived stressors suggesting that stress response is a body-mind phenomenon. Physiology of Stress: I. Nervous System a. CNS (central nervous system) **brain and spinal cord b. PNS (peripheral nervous system) **all neural pathways II. Endocrine System III. Immune System

  2. Central Nervous System:Brain = has three levels 1) Vegetative Level = the lowest level of the brain**stress physiologists believe that this is: - the bridge joining the mind and body. -communications link between mind and body. 2) Limbic Level = (mid level) the emotional control center. **several tissue centers are directly responsible for the biochemical chain of events that make up the stress response. **Has four parts: they work together to create homeostasis 1. thalamus= regulator of sensory information, also controls sleep and awake states of consciousness 2. pituitary gland = master endocrine gland 3. amygdala = conscious memories of emotions (fear) 4. hypothalamus = the place of all emotions

  3. Hypothalamus= appetite and body-core temperature center that registers pain and pleasure (the seat of emotions). **when a threat is encountered the hypothalamus carries out four specific functions: 1) activates autonomic nervous system 2) stimulates production of stress hormones (2 of them) 3) stimulates thyroid gland to produce thyroxine(increase the rate of cell metabolism) Brain continued: Neocortical Level = (highest level and most sophisticated level of brain) this is where sensory information is processed as a threat or non- threat AND thought processes take place. **highly developed area of brain tissue that separates humans from all other species. **decodes all stimuli **housed here are the neural mechanisms allowing a person to: -analytical -imaginative -creative -intuitive -logical -have memory -organizational skills

  4. **the positions of these structures are such that a higher level can override a lower level of the brain. ** Therefore: -conscious thought can influence emotional response. -conscious thought can intercede in the involuntary control of the vegetative functions to control heart rate, ventilation and blood flow. ***These are important when learning coping skills and relaxation techniques designed to override the stress response and facilitate physiological homeostasis. HOW?????

  5. Peripheral Nervous System = neural fibers that feed into the central nervous system. • Two networks: • 1) Somatic Nervous System = responsible for transmission of sensory messages between the five senses and higher brain centers. (Voluntary) • 2) Autonomic Nervous System = functions without conscious thought (circulation, digestion, respiration and temperature regulation). • **most important in regards to the stress response. • Peripheral Nervous System has two parts: • Sympathetic B. Parasympathetic • -responsible for “flight or fight” -responsible for energy conservation • responses. and relaxation which is • -Norepinephrine (noradrenaline) • -Epinephrine (adrenaline) • (these are released at various -dominated by the vagus nerve (which is • neural synapses to prepare the influenced by the brain stem). • body for rapid metabolic change • and physical movement.)

  6. Sympathetic • -the effects of epinephrine and norepinephrine • are very short, lasting only seconds. • -because of rapid release from neural endings as • well as their rapid influence on targeted organ • tissue, the effects of the sympathetic nervous • system are categorized as immediate. • Release of Epinephrine and Norepinephrine cause: • *acceleration of heart rate *increase force of myocardial contraction • *increases ventilation *reduction of digestive activity • *released glucose from liver *dilation of pupils and bronchi • *vasodilation of arteries throughout working muscles • *vasoconstriction of arteries to non-working muscles

  7. Glands involved in the stress response: 1) pituitary gland = master gland which manufactures several important hormones. a. Hypothalamus = has a direct influence over the pituitary. 2) thyroid gland = increases the metabolic rate (thyroxine) 3) adrenal gland = (sits on top of each kidney) has two parts: a. adrenal cortex = (exterior of the adrenal gland) manufactures and releases hormones called corticosteroids. **has a direct impact on the stress response **is the major stress gland.

  8. Adrenal medulla (inside of the adrenal gland) = secretes epinephrine and norepinephrine thru the bloodstream which act like those secreted at the neural synapses. • **80% = epinephrine • **20% = norepinephrine • **These are intermediate stress effects (takes 20-30 seconds to get into system and can last up to 2 hours.)

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