Stress Flashcards
What are the different types of stress?
Psychological and physical
What has molecules evolved to do?
Provide a series of emergency systems that protect key cellular functions from unexpected external challenges and internal consequences
What do heat-shock proteins do?
Guide damaged proteins to where they can be repaired or harmlessly degraded, protecting cells from toxicity or dysfunction
What has our stress systems evolved to be and do?
It has evolved as highly sophisticated processed to help deal with out of the ordinary challenges that might afflict us, they use cellular protection mechanisms as building blocks in a larger network of stress protection
Who is neuroendocrinology?
Study of how the brain regulates the hormones in our body
What is the first response to stress?
Immediate activation of sympathetic nervous system
How is the fight or flight response formed?
During stress, the brain rapidly activates nerves originating from control centres in the brain stem which causes the release of noradrenaline in a variety of structures and adrenaline from the adrenal glands
What happens to your body during fight or flight response?
Initial tingling sensation, sweating, heightened awareness, rapid pulse rate, higher blood pressure and general feelings of fear
Why do we have rapid pulse rate during stress?
Receptors are found on blood vessels, causing them to constrict and blood pressure to shoot up and causing the heart to accelerate and produce pounding sensations in the chest known as palpitations
What are goosebumps causes by?
Receptors in the skin causing hairs to erect
WhAt are the changes during stress used to do?
Prepare us to fight or free and to concentrate blood flow to vital organs, muscles and the brain
What is the second major neuroendocrine response to stress?
Activation of a circuit linking the body and the brain called the HPA axis
What does HPA axis link together?
Hypothalamus, pituitary, gland, adrenal cortex and hippocampus by a bloodstream highway carrying specialised hormones
What is the hypothalamus?
A key brain area regulating many of our hormones
What does the hypothalamus have?
Strong inputs from areas of the brain processing emotional information, including amygdala and from regions of the brain stem controlling sympathetic nervous responses
What does the hypothalamus do?
It integrates areas of the brain processing emotional information to produce a coordinated hormonal output that stimulates the next part of the circuit, the pituitary gland
What happens at the pituitary gland?
It releases a hormone called adrenocorticotrophin (ACTH) into the blood
What does ACTH do?
Is stimulates part of the adrenal gland to secrete cortisol
What is cortisol?
Steroid hormone that raises blood sugar and other metabolic fuels such as fatty acids, help adrenaline to raise blood sugar and make you feel good and turns off growth, digestion, inflammation and even wound healing
When do cortisol raise blood sugar and other metabolic fuels such as fatty acids?
It occurs at the expense of proteins that are broken down into fuels required immediately
Where is the highest density of cortisol receptors located at?
Hippocampus
What does hippocampus do?
A key structure of learning and memory
Where does cortisol act on besides the hippocampus?
Amygdala
What does amygdala do?
Process fear and anxiety
What does the cortisol feedback to the brain do?
Turn on the amygdala to allow learning of fear related information and to turn off the hippocampus to ensure that resources are not wasted in more complex but unnecessary part of learning
What kind of receptors are in high levels in the hippocampus for cortisol?
low MR and high GR receptor
How is low MR receptor activated?
Normally circulating levels of cortisol in the bloodstream highway of the HPA axis
What does low MR receptor do?
Keep our general metabolism and brain processing ticking over nicely
What happens when cortisol levels begin to rise?
High GR receptor becomes progressively more occupied
What happens when we are stressed?
Cortisol levels become very high and activation of high GR is sustained and the hippocampus is shit down by a genetically controlled program
What is the curve for stress called?
Bell-shaped curve
What happens in severe depression?
Cortisol is over-produced and hippocampus shrinks
How can patients with severe depression be helped?
Blocking the production of action of cortisol, particularly those in whom classical anti-depressant drugs do not work
What does anti-depressant drugs do?
Help to normalise the overactive HPA axis, by adjusting the density of MR and GR receptors in the brain, particularly in the hippocampus
What is the implication of cortisol levels in ageing?
Cortisol levels are higher in unsuccessful than in successful ageing, the rise precedes the fall in mental abilities and the associated decline in the size of hippocampus seen in brain scans
How to prevent the emergence of memory defects?
By keeping stress hormones level low from birth or from middle age onwards
Who gets more memory loss and cognitive disorders in the later years?
Those who make the greatest responses to stressors
