Patho ch 2 Homeostasis
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a state of being in which all systems are in balance around a particular ideal "set point"
_______ occurs when the body does not respond appropriately to maintain internal stability when threatened by perceived or actual events.
______ loops are used to tell the body when there is a deviation from a "set point" in the body.
______ responses refer to systems whose purpose is specifically to normalize slelected physiologic variables.
Through the processes of ______ the body's parameters are continuously reevaluated and readjusted in order to match resources to the needs dictated by the situation.
______ is the way the body maintains and returns to stability, and ______ is concerned with the process of achieving this balance.
overall process of adaptive change necessary to maintain survival and well-being
______ may involve altering multiple physiologic variables in order to match the resources of the body to environmental demands. It helps the body achieve _____.
physical, chemical, or emotional factor that produces tension in the body or the mind
anything that throws the body out of allostatic balance
the body's effort to try to restore the balance
Is the stress response considered a positive or negative response for the body?
can have a positive effect short-term, but becomes damaging when repeatedly activated or when it does not cease
General Adaptation Syndrome - idea that all stressors cause similar physical responses in the body - a general "stress" response
When stress is generated by extreme psychological or environmental demands, ______ reactions are initiated to restore balance.
3 physiologic stages of GAS?
- 1. alarm stage
- 2. resistance or adaptation stage
- 3. exhaustion stage
The alarm stage is AKA the ______ response.
fight or flight
5 physiologic responses in the body that occur during the alarm stage of GAS?
- 1. increased secretion of blucocorticoids and responses
- 2. increased sympathetic NS activity
- 3. increased secretion of EPI & NE from adrenal medulla
- 4. fight-or-flight manifestations
- 5. reduced resistance to stressors
What causes the alarm stage of GAS to begin?
the hypothalamus senses a need to activate the GAS in response to a stimulus that places homeostasis at risk
When the alarm response is triggered, the hypothalamus secretes _______.
CRH - corticotropin releasing hormone
What are the 2 effects of the release of CRH during the alarm response?
1. activates the sympathetic NS which stimulates the adrenal medulla to release NE & EPI
2. stimulates the anterior pituitary gland to release ACTH
The 2 catecholemines are _____ & _____.
EPI & NE
What 5 hormones are released during the alarm stage of GAS?
What is the function of each?
CRH, EPI, NE, ACTH, glucocorticoids
- CRH- stimulates release of EPI, NE, and ACTH
- EPI & NE- enable body to rapidly take action
- ACTH - stimulates the secretion of cortisol & aldosterone
- glucocorticoids - diverse responses
Which 2 glucocorticoids are specifically secreted during the alarm stage of GAS?
cortisol and aldosterone
hypothalamic-pituitary- adrenal axis - chemical responses that occur in the body in response to a stressor
At what point does the alarm stage progress to the stage of resistance?
when the pituitary gland is activiated
3 chemicals in the body that mediate allostasis in the body?
hormones, neurotransmitters, cytokines from the immune system
What is the purpose of the alarm stage and its release of hormones?
overcome the stressor
7 stress responses of body tissues in response to the release of catecholamines?
- 1. elevation of cardiac output due to increased force and rate of heart
- 2. vasoconstriction
- 3. lipolysis = increased lipids in the blood
- 4. elevates blood glucose levels by glycogenolysis of hepatic and skeletal mus
- 5. insulin suppression
- 6. increased respiration
- 7. enhanced blood coagulation
6 responses of body tissues stimulated by corticosteroid release?
- 1. gluconeogenesis - generation of glucose from non-carbs
- 2. protein catabolism
- 3. inhibition of glucose uptake
- 4. suppression of protein synthesis
- 5. stabilization of vascular reactivity
- 6. immune response suppression
What is the purpose of the body moving from the alarm stage to the resistance/adaptation stage?
the body cannot maintain the changes that occur during the alarm stage without suffering damage or death
What is the purpose of the resistance/adaptation stage of GAS?
return to homeostasis
What 3 structures in the body are functioning to mobilize resources to manage the stressor when the adaptation/resistance stage of GAS begins?
These resources include ____, ____, & ____.
the sympathetic NS, the adrenal medulla, and the adrenal cortex
glucose, amino acids, and fatty acids
Why do the catecholemines and glucocorticoids release glucose, fatty acids, and amino acids during the alarm response
they are used for energy & for later growth and repair
What are the 2 possibilities during resistance phase for attaining homeostasis?
1. allostatic changes will return the organism to its earlier state
- 2. allostatic changes occur that causes the organism to have to function at a new baseline for different physiologic variables
- (EX: COPD pt baseline O2 sat is <normal)
When does the exhaustion stage of GAS occur?
when the body is unable to return to homeostasis following prolonged exposure to agents
Why do exhaustion and stress-related diseases occur?
What are 2 stress-related diseases?
1. actual stress response itself can be harmful when repeatedly activated
2. resources become depleted
hypertension and heart disease
wear and tear on the body and brain due to the accumulation of various mediators produced by the systems during allostatic mechanisms of every day life
cost to the body's organs and tissues for an allostatic response that is excessive or ineffectively regulated and unable to deactivate
agents or conditions that are capable of producing stress and endangering homeostasis
Stressors may be due to what 6 types of factors?
- 1. physical - conditions of the environment
- 2. chemical - EX: pollution
- 3. biological - bacteria and viruses
- 4. social - overcrowding/relationships/etc
- 5. cultural - behavioral norms
- 6. psychological - feelings
When does a stressor of low intensity become a danger?
when it is prolonged
What 2 factors allow for a great deal of variation in the way humans perceive and respond to stressors and the type of stress response produced?
personal characteristics and the psychological context of the situation
The HPA axis/glucocorticoid release is more prominent in what ppl?
ppl with depression and PTSD and when a person has low self-esteem or lacks a sense of control
Do men or women have a larger increase in EPI release in response to stressors?
What differences occur in the stress response of adolescents?
variations in HPA axis function due to sex hormone secretion being elevated during this time
conditions or situations that increase the likelihood of encountering or experiencing a stressor
Perception of a stressor depends on what 4 factors?
- past experiences and conditioning
- cultural influences,
Once the challenges contributing to allostatic load have been resolved what should happen to chemicals released to aid allostasis?
they should go back to their normal levels
What chemicals are considered responsible for the fight or flight response?
catecholamines- NE & EPI
Release of catecholamines is initiated through the activation of the ______ which sends info about stressors to the ____ ____ & _____ ______ which determine whether or not something is harmful then relay the information back to the ______.
- cerebral cortex
- limbic system
3 effects of catecholamines on the heart?
What is the result of this?
- 1. increases rate
- 2. increases speed of impulse conduction
- 3. increases contractility
increased cardiac output
____ is a the primary constrictor of smooth muscle in BV making it important in the maintenance of BP and blood flow regulation.
NE role in GI and functioning of the eyes?
reduces gastric secretion
innervates the iris and ciliary muscles of the eyes - dilates the pupils and increases night and far vision
EPI effects on cardiovascular system?
enhances myocardial conractility and increases heart rate and venous return to the heart = increased CO
EPI effect on respiratory system?
relaxes bronchial smooth muscle which dilates the airway to enable better oxygenstion
EPI effects on the metabolic system?
increases glycogenolysis and the release of glucose from the liver and inhibits insulin secretion (all of this increases blood glucose levels)
What are the results in the brain of the increased blood flow and blood glucose levels produced by EPI?
increased mental attention and alertness
How do EPI and NE exert immune system effects?
affect the production of cytokines by immune cells and adipose cells
Catecholamines' effect on the respiratory tract?
relaxes bronchial smooth muscle to dilate airway
Catecholamine effects on the vascular smooth muscles of the skin, mesenteric bed, and kidneys?
constricts to reduce perfusion
Catecholamines effects on the vasculature of skeletal muscle, lungs, and heart
dilates to increase perfusion
Catecholamines effect on the peripheral vasculature?
constricts to increase blood pressure
3 Catecholamine effects on the gastrointestinal tract?
- 1. decreases peristalsis
- 2. constracts sphincters
- 3. decreases gastric secretions
2 catecholamine effects on the eyes?
1. contracts radial muscle to dilate iris and pupil to control light
2. relaxes ciliary muscle for far vision
Catecholamine effect on liver?
glycogenolysis and gluconeogenesis for increased glucose levels = energy
Catecholamine effect on CNS?
promotes arousal, attention, and vigilance
4 major effects of glucocorticoids in the stress response on metabolism?
- 1. catabolism of muscle, fat, lymphoid tissue, skin, and bone
- 2. liver gluconeogenesis
- 3. opposes insulin in transport of glucose into cells
- 4. increased appetite
Major effect of glucocorticoids in the stress response on fluid balance?
Na & water retention
4 major effects of glucocorticoids in the stress response on inflammation and infection?
- 1. suppressed inflammatory response
- 2. increased neutrophil release
- 3. decreased new antibody release
- 4. decreased production of certain WBC's
2 ways that glucocorticoids support catecholamines in the stress response?
- 1. increased EPI synthesis
- 2. enhanced vasoconstriction
Why may excessive stress inhibit female reproduction?
cortisol suppresses the release of gonadotropin-releasing hormone, LH, estradiol, and progesterone
What effect does estradiol have on glucocorticoids?
down-regulates glucocorticoid receptor binding in the brain and alters regulatory feedback control
The androgens ____ & _____ may inhibit the effects of glucocorticoids.
testosterone & DHEA (dehydroepiandosterone)
How does DHEA affect glucocorticoid functions?
interacts with neurotransmitters in the brain and counteracts depressive tendencies caused by glucocorticoids
Numerous stressful stimuli may result in a significant reduction in circulating levels of ____ which works with vasopressin to enhance BP & heart rate and augments the fight or flight response.
Effects of oxytocin on the fight or flight response?
has a calming effect
What are the 4 functions of growth hormone?
- 1. increases protein synthesis
- 2. increases bone and muscle mass growth
- 3. increases fat mobilization (lipolysis)
- 4. decreases rate of carb utilization by peripheral tissues
Growth hormone secretion is highest during ____ and then gradually declines during _____.
Why may children who experience prolonged chronic stress have stunted growth?
continued activation of the stress response = decreased secretion of growth hormone
_____ is secreted from the anterior pituitary gland in response to stress, sexual activity, suckling, and breast feeding.
What hormone interferes with ovulation?
______ is produced during childbirth, lactation, and sexual behavior and has been associated with promoting bonding and social attachment.
What is the primary role of the sympathetic NS?
appraisal of a stressful stimulus and release of NE
5 effects of NE on the body?
- 1. increases heart rate and contractility
- 2. constricts BV to decrease blood flow to less essential tissues and raise BP
- 3. reduces gastrointestinal motility and gastric acid secretion
- 4. dilates the pupils
- 5. inhibits insulin secretion
Epinephrine's actions are similar to those of NEand are particularly important for what 3 functions?
- 1. increasing cardiac performance (rate/contractility/CO)
- 2. promoting the release of glucose from the liver
- 3. enhancing bronchodilation
What are the 2 main functions of aldosterone?
- fluid volume expansion
- increases BP
ineffective, inadequate, or inappropriate change in response to new or altered circumstances
What will determine what coping mechanisms a person uses?
circumstances and culture
It's effect on the stress response?
the experience of perceiving an inability to cope with a stressor
activates the HPA axis and escalates levels of circulating mediators that will exacerbate existing allostatic load
A person with asthma with acute SOB is likely to become even more SOB when discovering an inhaler is not available. This is an example of _____.
4 ways that allostatic load can become allostatic overload?
What is the end result?
- 1. repeated exposures to multiple stressors
- 2. inability to habituate or adapt to the stressor
- 3. unnecessarily prolonged stress response or stress response that continues after the stressor is removed
- 4. inadequate response to the stressor that causes other stress response mediators to attempt to compensate
homeostasis is not attained
8 effects of allostatic overload on the NS?
neuropsychological manifestations, neervous tic, fatigue, loss of motivation, anxiety, overeating, depression, insomnia
4 effects of allostatic overload on the cardiovascular system?
disturbances of heart rate and rhythm, hypertension, stroke, coronary artery disease
5 effects of allostatic overload on the GI system?
- 1. gastritis
- 2. irritable bowel syndrome
- 3. diarrhea
- 4. N&V
- 5. ulcerative colitis
4 effects of allostatic overload on the GU system?
- 1. diuresis
- 2. irritable bladder
- 3. sexual dysfunction
- 4. menstrual irregularity
5 effects of allostatic overload on the integumentary system?
- 1. eczema
- 2 psoriasis
- 3. neurodermatitis
- 4. acne
- 5. hair loss
3 effects of allostatic overload on the respiratory system?
- 1. increased respiration
- 2. asthma
- 3. hay fever
3 effects of allostatic overload on the immune system?
- 1. immunodeficiency
- 2. immnosuppression
- 3. autoimmune disease
2 effects of allostatic overload on the endocrine system?
- 1. hyperglycemia
- 2. diabetes mellitus
4 effects of allostatic overload on the musculoskeletal system?
- 1. tension HA
- 2. muscle contraction backache
- 3. rheumatoid arthritis
- 4. inflammatory diseases of connective tissue
How does excessive catecholamine levels effect the body?
cardiovascular pathologies - hypertension, stroke, and MI
How does excessive secretion of cortisol increase the risk for cardiovascular problems?
causes increased circulating fatty acids and increased blood pressure which leads to artherosclerosis
How do stress hormones in the brain affect the CNS?
facilitate learning, memory, and neuroendocrine and autonomic regulation
How can allostatic overload affect cognitive functioning?
because stress hormones function in learning and memory allostatic overload can cause altered and impaired cognitive function
____ & _____ stress hormones help promote long-term memory consolidation and retention of traumatic and fearful events and may contribute to PTSD.
cortisol and NE
Why can allostatic overload cause diabetes, obesity, artherosclerosis and insulin resistance?
causes increased appetite and increased blood glucose levels and the release of fatty acids into the bloodstream
How does the immune system respond to immediate and chronic stress?
What can result from chronic stress?
immune system functioning increases with immediate stress but immunosuppression occurs with chronic stress
How may chronic physical or psychological stress affect disease processes, wound healing, and risk for infection?
may allow for progression of disease processes such as AIDS, delay wound healing, and increase risk for infection due to immunosuppression
tail ends of chromosomes that get shaved down with repeated cell division
What happens to the telomeres of older cells?
Why is this a problem?
they are shorter than younger cells'
more susceptible to death
How are telomeres linked to stress?
the stress hormones may cause telomeres to shorten
________ is an enzyme capable of lengthening telomeres and is inversely related to ______ of stress.
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