Flashcards in Lecture 9: Stress & the Endocrine System Deck (45):
What is the role of the cerebral cortex?
Conscious thinking and executive functioning
What is the main role of the hypothalamus?
Regulate/maintain our body's homeostasis
How does the cerebral cortex send information to the temporal lobe of the brain?
1. Gathers information and processes it
2. Projects information via hard-wired neuronal projection pathways in the cingulate gyrus
What are the 2 structures of the temporal lobe?
What is the role of the hippocampus in response to the information sent by the cerebral cortex?
Attach a memory to the information sent by the cerebral cortex
What is the role of the amygdala in response to the information sent by the cerebral cortex?
Attach as emotion to the information sent by the cerebral cortex
Where does the info sent by the cerebral cortex go once it is process by the temporal lobe? What happens there?
Hypothalamus: mammillary bodies that distribute the info to the appropriate nuclei
What happens once the hypothalamus responds to the info sent by the cerebral cortex?
It sends info back to the cerebral cortex so that it can be aware of the body's reaction and can regulate the amount of information it will send to the HT in the future (either quiet or stimulate it)
What does the sympathetic nervous system correspond to?
Fight or flight
What does the parasympathetic nervous system correspond to?
Rest and digest
How is the SNS regulated during stress?
CRH HT neurons project down to spinal cord and make synaptic contact with SNS centers
What is the pathway from stress to cortisol?
Stressors --> HT --> CRH --> Pit ---> ACTH --> Adrenal cortex --> Cortisol
How does the autonomic nervous system (SNS) regulate the stress response?
Adrenal medulla produces norepi and epi in response to SNS and high cortisol which act on tissues to increase blood flow, skeletal muscle strength/contraction, heart rate, and respiration rate
How do the SNS and HPA axis provide an integrated response to stress?
SNS acts on tissues while HPA axis provides cortisol to provide energy (glucose) for the SNS response
What are the 7 effects of CRH as an NT in the brain?
1. Increase locomotor activity in familiar photocell environments
2. Acoustic startle response
3. Increase responsiveness to stress in open field test
4. Axiogenic-like effects (anxiety for focus)
5. Enhanced suppression of responding to conditioned emotional response test
6. Dose-dependent facilitation of stress induced fighting (defense to offense switch)
7. Dose-dependent place and taste aversion
What is the acoustic startle response?
Immediately orienting our head toward loud noise source
How does stress affect your appetite?
Short acute CRH levels: increase
Consistently high CRH levels: CRH becomes an anorexigenic agent
How is CRH related to clinical depression?
Constant high CRH levels drive clinical depression
What types of symptoms can inappropriately high levels of CRH cause?
Cushing's like symptoms
What is a common treatment option for inflammatory diseases or organ transplants causing excess levels of CRH? What can be the side effects of this treatment?
Exogenous glucocorticoids to increase appetite and cause negative long feedback loop to hypo
Side effects: elevated glucose can lead to hyperinsulemia and potentially Type 2 diabetes and excessive feeding can lead to increase in fat mass
How does administering exogenous glucocorticoids cause an increase in appetite?
1. Negative feedback on CRH
2. Decrease of POMC
3. Decrease of alpha-melanocyte secreting hormone
4. Increase in neuropeptideY (NPY) = stimulates appetite and feeding
Other than stress, what other 5 states are associated with an increase in the HPA axis?
1. Anorexia nervosa
2. Excessive exercise
3. Type 2 diabetes
5. Cushing's syndrome
What happens when chronic HPA axis activation is left untreated? Why? 4 steps
It morphs into decreased HPA axis associated diseased states:
1. Adrenal cortex cannot meet the high demands
2. The body views itself as having a relative deficiency in cortisol
3. Increase CRH levels
4. Clinical depression
What are 5 disorders associated with a decreased HPA activation?
1. Chronic fatigue syndrome
2. Post-partum depression
5. Rheumatoid arthritis
What is the "young pattern" of resiliency?
Cortisol levels return to baseline after stress
What does a loss of resiliency mean? What does this lead to?
Cortisol levels do not return to baseline after stress
Leads to impaired memory because high levels of cortisol damage hippocampus neurons
How does cortisol affect the immune system? Overall and 2 detailed way?
Overall: ongoing high levels of cortisol will impair every aspect or function of the immune system
How can high cortisol levels affect the ovaries?
Increased cortisol --> increased glucose --> increased insulin --> targets thecal and stromal cells of the ovary --> increase in androgen production --> virilization and potential cessation of menstrual cycle
What is polysystic ovarian disease? Most common symptom? Cause?
Most common reproductive disorder among women of reproductive age.
Most common symtom: infertility
Cause: increase in stress/obesity = increase in cortisol = increase in insulin/IGF-1 = ovaries secrete elevated androgens
How does chronic stress affect the GI tract? (stomach and colon)
SNS takes over PSNS:
1. Stomach: decreases contractility and emptying ability (bloating)
2. Colon: increased gut motility, contraction, material transit and urge/frequency of defecation AND even potential sloughing of inner cell lining leading to diarrhea leading to new food allergies because antigens can now pass through and interact with immune system
How does stress affect arterial vessels? Short term and long term?
Short term: cortisol causes increased SNS outflow causing smooth muscle cells in arterial vessels to contract leading to vasoconstriction
Long-term: smooth muscle cell hypertrophy = more narrow lumen of blood vessels = increased BP
How can stress increase risk for heart attack in middle-aged men?
They already have atherosclerotic plaques in the lumen of their vessels so a stressful event or chronic stress can cause even more vasoconstriction in coronary arteries leading to heart attack
What are telomeres?
Repeating DNA sequences that help protect chromosomes
When do telomeres shorten?
How can one prevent telomere shortening? 3 ways. How does this work?
1. Stress management
2. Low fat diet
3. Aerobic exercise
=>increases telomerase activity, which helps lengthen telomeres
How does stress affect the aging process?
It shortens telomeres leading to aging
Does stress cause cancer?
How does stress affect cancer?
Chronic stress has been shown to cause a tumor to metastatize in mice studies
What role do cytokines play in the stress response?
Chronic stress leads to the production of pro-inflammatory cytokines (eg: IL-1 and TNF alpha) in the hypo which stimulate CRH neurons leading to increased cortisol and SNS outflow
What is another name for cytokines?
How does stress affect the release of other hypo neurohormones?
+ SS = -TSH/-GH
What part of the HPA axis stimulates catecholamine synthesis?
CRH and cortisol!
What kind of foods are preferred when hunger is stimulated by NPY?
Sugary and fatty foods
What cells are cytokines made by in the brain?