stress and mood disorders Flashcards
(37 cards)
what does stress stimulate
sympathetic nervous system
what does stress inhibit
parasympathetic nervous system
how are the release of adrenal hormones stimulated
pre-ganglionic neurons in sympathetic nervous system stimulate adrenal medulla to release adrenaline and noradrenaline into the blood
what are adrenal medulla cells also a form of
modified post-ganglionic sympathetic neurons
where is cortisol stored and released
the adrenal cortex
what stimulates the adrenal cortex to make and release cortisol
Adrenocorticotropic hormone (ACTH)
released by pituitary gland
what releases ACTH from the pituitary gland
corticotropin-releasing hormone (CRH)
released by hypothalamus
what two parts of the amygdala are involved in stress response activation
central nucleus - in response to homeostatic challenges
medial nucleus - in response to psychogenic challenges
what happens after amygdala has been activated
activates the sympathetic nervous system (via lateral hypothalamus) and the HPA axis (via disinhibition)
what brain area is involved in indirect activation of stress
Subgenual Anterior Cingulate Cortex
why is the HPA in the stress response considered a negative feedback system
hypothalamus - releases CRH
Pituitary gland - ACTH
Adrenal gland - cortisol
cortisol levels signal hypothalamus and pituitary to reduce CRH and ACTH
central effects of cortisol
increases glucose production
raises blood pressure
increases alertness
reduces non-essential bodily functions
how is the hippocampus involved in stress response
Indirect inhibition
: returns psychogenic stress response back to baseline
how may depression be related to the HPA axis
dysregulated HPA is common
Increases and decreases in cortisol can lead to depressive symptoms
how is chronic stress a positive feedback system
Amygdala stimulates the HPA axis
Glucocorticoids activate the Locus Coeruleus
Locus Coeruleus has noradrenergic projections which activate (among other brain areas) the Amygdala
how does chronic stress reduce negative feedback
repeated stimulation by glucocorticoids reduces receptor sensitivity in the hippocampus
also damage hippocampal neurons
what do most treatments for depression target
attempt to reduce stress response
how is MJD related to sleep
REM sleep entered too early
REM sleep deprivation has long term effects
effects of chronic stress on monoamines
Depletion of noradrenaline from Locus Coeruleus
Depletion of serotonin from Raphe Nuclei
Depletion of dopamine from Ventral Tegmental Area to n. Accumbens and prefrontal Cortex
how are monoamines related to depression
reserpine (mono-amine antagonist) induces depression
what are SSRIs
Selective serotonin reuptake inhibitors
lipohilic
usually ingested
target monoamines
mechanism of adaptation of autoreceptors in SSRIs
initially SSRIS INCREASES 5HT levels in the synapse
autoreceptors respond by reducing 5HT through negative feedback
Takes approx 2 weeks for autoreceptors to adapt to the higher levels of 5HT - resulting in reduced negative feedback
5HT reuptake is still blocked so 5HT levels at the synapse increase, leading to more binding to the post synaptic receptor
what is ketamine
Dissociative anaesthetic and analgesic
effects of low doses of ketamine
Lightness & euphoria
Disconnection of thoughts and from the world
Strange perceptions
