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 SystemIII. Immune System

Stress

• 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 homeostasis1. thalamus= regulator of sensory information, also

controls sleep and awake states of consciousness2. pituitary gland = master endocrine gland3. amygdala = conscious memories of emotions (fear)4. hypothalamus = the place of all emotions

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:3. 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

**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?????

B.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:C.Sympathetic B. Parasympathetic

-responsible for “flight or fight” -responsible for energy conservationresponses. and relaxation which is-Norepinephrine (noradrenaline)-Epinephrine (adrenaline)(these are released at various -dominated by the vagus nerve (which isneural synapses to prepare the influenced by the brain stem).body for rapid metabolic changeand physical movement.)

A.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 organtissue, the effects of the sympathetic nervoussystem 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

Glands involved in the stress response:

1) pituitary gland = master gland which manufactures severalimportant 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.

b.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.)