HPA axis
This hypothalamic hormone initiates the HPA axis cascade.
CRH: corticotropin-releasing hormone
The SAM axis activates this branch of the autonomic nervous system.
Sympathetic
This brain structure detects psychological stressors and signals the hypothalamus.
Amygdala
Name one cardiovascular and one respiratory symptom caused by stress.
Cardiovascular =increased HR and BP
Respiratory = increased frequency of breathing, shallow breathing
Acute stress is typically adaptive because it promotes this physiological response.
Fight or flight response
The anterior pituitary releases this hormone in response to CRH.
ACTH: adrenocorticotropic hormone
The main catecholamines released by the adrenal medulla are these two.
Epinephrine and norepinephrine
This hypothalamic nucleus is the main control center for initiating the stress response through CRH release.
Paraventricular nucleus (PVN)
CRH gene expression is promoted by the presence of this reproductive hormone.
Oestrogen
Give one cardiovascular disease risk associated with chronic stress.
- Artherosclerosis
- etc
The HPA axis primarily involves which three endocrine glands?
Hypothalamus, pituitary and adrenal glands
Sympathetic and parasympathetic systems often work in balance. Describe briefly how the parasympathetic system can influence sympathetic activity.
Parasympathetic system opposes/ inhibits sympathetic activity when active or increases sympathetic activity when not active
Which brain region integrates autonomic, endocrine, and behavioral stress responses?
Hypothalamus
During stress, blood flow is redistributed: vessels in the gut constrict, and flow increases to this tissue type to support action.
Flow increases to skeletal muscles
Chronic stress can dysregulate which circadian hormone, affecting sleep and metabolism?
Cortisol
Chronic activation of the HPA axis can lead to atrophy in this brain region, which helps regulate negative feedback.
Hippocampus
The main neurotransmitter released from preganglionic sympathetic neurons is this one, while postganglionic sympathetic neurons primarily release this other one.
Preganglionic = Ach (acetylcholine), Postganglionic = NE (norepinephrine)
Where are the two CRH - receptors found?
R1 (central -the brain), R2 (mostly peripheral -skeletal muscles, gastrointestinal tract, and heart, BUT also in subcortical structures of the brain)
Stress affects reproductive health by suppressing the release of these two hypothalamic-pituitary hormones, leading to irregular cycles or reduced fertility.
GnRH -> LH + FSH
The body’s initial alarm phase of stress activates which two major physiological systems?
HPA axis + SAM axis/ sympathetic nervous system
The hypothalamus communicates with the pituitary via this type of portal system.
Hypophyseal portal system
Besides acetylcholine and norepinephrine, name one additional neurotransmitter or neuropeptide that helps modulate autonomic activity in the SAM system.
NPY, nitric oxide (NO), somatostatin, dopamine, adenosine triphosphate (ATP), lipid mediators of inflammation, CRH, galanin
Name one long-term effect of chronic stress on the brain’s structure or function.
Chronic stress can impair thyroid function by decreasing the conversion of this prohormone to its active form.
thyroxine (T4) -> triiodothyronine (T3)
Name 2 psychological disorders that are frequently linked to chronic stress.
Anxiety and depression