Biology of stress Flashcards
What does stress cause the activation of
SNS and HPA axis (amygdala, hypothalamus, pituitary gland, pre frontal cortex, hippocampus)
Where is the amygdala and what does it do
ref. notes where
Concerned with emotion, motivation and fear.
• Receives information on events in the world (e.g. threats), assesses danger and the emotional information is conveyed to other brain regions where defensive action is organised (fight or flight).
• There are two amygdale, one on each side of the brain.
• They release Corticotropin Releasing Factor (CRF)
Where is the hypothalamus and what does it do
The hypothalamus is involved in the control of emotional reactions, feeding and drinking. The emotional reactions organised in the hypothalamus trigger hormonal secretions from the pituitary (also called hypophysis) gland like adrenocorticotropic hormone (ACTH)
Where is the hippocampus what does it do
organising memory storage in the cortex and retrieving memories stored in the cortex. There is a hippocampus on each side of the brain.
Where is prefrontal cortex what does it do
Front most region of frontal cortex. Involved with planning and organising behaviour based on use of working memory
Where are the brain areas of the HPA axis linked to
adrenal glands which responds to ACTH and release cortisol.Cortisol binds to glucocorticoid receptor on hypothalamus, hippocampus, pre frontal cortex, pituitary gland.
Draw the feedback mechanism of HPA axis for acute stress
ref. notes
Draw feedback mechanism of HPA axis for chronic stress, how does it differ to acute
ref. notes. Positive feedback, HPA axis constantly activated cortisol constantly released. Cortisol toxic on GR so decrease. This results in less inhibition and CRF and ACTH contniues to be released
Adrenaline function fight or flight
Leads to arousal of SNS and reduced activity in PNS
Decreases digestion, increases sweating, pulse, blood pressure
Effects of ACh and Noradrenaline in ANS
ACh: calm/relaxed/safe
decrease heart rate, decrease BP, iris relaxes so pupil smaller, increase gut motility
Noradrenaline: fight or flight/threat
increase heart rate, increase BP, iris contract to make pupil larger, decrease gut motility, release CRF, ACTH and cortisol
What does cortisol and arenaline+noradrenaline do
Cortisol: decrease inflammation, glucose mobilisation, intravascular volume
Adrenaline and noradrenaline: increase coagulation, increase BP, Insulin resistance, endothelial dysfunction, increase heart rate, decrease heart variability, increase interleukin-6, increase arrhythmias
