HLTH101 Lecture Notes - Lecture 9: Allostatic Load, Autonomic Nervous System, Sympathetic Nervous System

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HLTH 101 – Week Six
What does the concept of “stress” refer to?
-Situations that trigger physical and emotional reactions
-The reactions themselves
What is the difference between, Stressor, Stress Response, and Stress
-Stressor (situation or event that triggers physical and emotional reactions) – ex. writing
an exam, going on a first date
oHow you interpret your stressor is under your conscious control
-Stress response (the reactions to the stressor) – ex. sweaty palms, dry mouth, fast heart
rate + emotional response
-Stress (describes the general physical and emotional state that accompanies the stress
response)
What are the 2 (or 3) main physical responses to stressors?
-Actions of nervous system
-Actions of endocrine system
-The two systems together
CNS VS. PNS?
-CNS - composed of the brain and spinal cord
oDamage to CNS = much more difficult or impossible to repair because nerves in the
PNS can regenerate while the CNS cannot do this as it has much more complex
connections that prevent it from reconnecting so easily
-PNS - composed of neurons and nerves that receive information from the environment
and transmit it to the CNS to give info that initiates responses to the environment
(Often send signals to the same organs, but response being triggered is complete opposite)
What is the nervous system (as a whole) composed of and what does it do?
-CNS = conscious perception and conscious control
-Somatic = important for conscious sensation (ex. seeing, feeling) + controlling signals
-Autonomic = for involuntary actions and sensation (actions that you don’t have control
over)
-Stress response = fight or flight response – ex. during evolution when being attacked by
prey, you either fight or run away (sympathetic)
-Para-sympathetic = going around in background ex. after trying to get away from a
predator, it calms you down
What is the difference between Sympathetic and Parasympathetic Division?
-The parasympathetic division is in control when you are relaxed; it aids in digesting
food, storing energy, and promoting growth.
-The sympathetic division is activated during times of arousal, including exercise, and
when there is an emergency, such as severe pain, anger, or fear.
Norepinephrine
Epinephrine (aka Adrenaline)
oBoth are called catecholamines and are secreted by the adrenal glands
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What does the endocrine system do?
-Glands, tissues, and cells that help control the bodily functions by releasing hormones
-Helps prepare the body to respond to a stressor
How do the 2 systems work together?
oChemical messages and actions of sympathetic nerves cause the release of key
hormones
oHormones trigger physiological changes
oHeart and respiration rates accelerate
oHearing and vision become more acute
oLiver releases extra sugar to boost energy
oPerspiration increases
oBrain releases endorphins
-These changes are called the fight-or-flight reaction
-Actions strive to maintain Homeostasis!
What happens when stress response is undergone too often or at inappropriate times?
-When this stress response is undergone often and at inappropriate times (ex. having
trouble with social interactions, being mad when you see friends had a party without you)
tends to be due to diabetes, hypertension, e.t.c.
What is the HPA Axis?
-Important for autonomic (sympathetic, parasympathetic)
-Amygdala = is primitive in function, important for processing emotions + fear
-Hypothalamus - integrates information, initiate response, memory (ex. from event that
brought you fear)
How is stress response turned on?
-Hypothalamus receives sensory stressors from various nerves.
-The locus coeruleus delivers emotional stressors from amygdala.
-The paraventricular nucleus (PVN) in Hypothalamus releases the hormone
corticotropin-releasing hormone (CRH).
-In the “long-arm” of the stress system, CRH flows through veins to nearby Anterior
Pituitary Gland, to stimulate release of the hormone ACTH into blood stream.
-ACTH flows via blood vessels to Adrenal Cortex gland and stimulates release of
glucocorticoid hormones.
What happens on the “Long Arm” of the stress system?
-In humans the glucocorticoid involved is cortisol
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-Negative Feedback (shown in blue) very important to turn down response:
Glucocorticoids bind to receptors (GCRs) to turn down the response, thereby leading to a
decrease in glucorticoids in the blood
-In addition to turning down the response in the hypothalamus & pituitary, also does so in
the hippocampus
What is accomplished through Allostatic Response?
-Allostatic systems respond to stress by initiating the adaptive response, sustaining it until
the stress ceases, and then shutting it off (recovery).
-Allostatic responses = initiated by an increase in circulating catecholamines from the
autonomic nervous system and glucocorticoids from the adrenal cortex.
-This sets into motion adaptive processes that alter the structure and function of a variety
of cells and tissues.
-These processes are initiated through intracellular receptors for steroid hormones,
plasma-membrane receptors, and second-messenger systems for catecholamines.
-Cross-talk between catecholamines and glucocorticoid-receptor signaling systems can
occur.
What are some emotional and behavioral responses to stressors?
-Cognitive mental appraisal
-Successful prediction
-Perception of control
-Highly individual and strongly related to emotions
-Effective responses to stress:
-Talking, laughing, exercise, and time management
-Time management = predicting/knowing when your stressor will occur (ex. midterms),
and taking action to minimize its impact by being prepared for it
-Ineffective responses to stress:
oPerson receiving a situation that exceeds their ability to successfully perceive,
predict, or control  ineffective response to stress
oOvereating, procrastination, and frustration, self-medicating
How does stress level affect performance and well-being?
-A moderate level of stress challenges individuals in a way that promotes optimal
performance and well-being.
-Too little stress, and people are not challenged enough to improve
-Too much stress, and the challenges become stressors that can impair physical and
emotional health.
How does stress determine personality?
Personality = Sum of cognitive, behavioral, and emotional tendencies
-Type A: Ultracompetitive, controlling, impatient, Higher perceived stress and difficulty
coping with it (tend to have more anger/hostility  CVD, e.t.c.)
-Type B: relaxed, tolerant (don’t have too many health consequences)
-Type C: anger suppression, difficulty expressing emotions, exaggerated response to minor
stressors (suppresses immune system  may get sick easier, ex. get colds, headaches
easier)
-Type D: Distressed, anxious worriers ( increased risk of CVD)
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