Lecture 12: Stress Flashcards
When is there a higher incidence of heart attacks?
During wars, natural disasters, sporting events
Cardiac and stroke related deaths increased 50% in Dutch men on the day their soccer team was unexpectedly eliminated from the European Championship by France
Pattern not observed in Dutch women, French men or French women
Stressor
Something that disrupts physiological homeostasis (injury, illness, extreme temp, exam)
Stress response
Suite of responses by the body that helps to reestablish homeostasis
Where are the two stress responses in the body? What are their neurotransmitters?
ANS (nor/epinephrine)
HPA (cortisol)
What is an adaptive stress response?
In the short term; helps individuals cope with emergency situations, improves chances of survival
What is a maladaptive stress response?
Long term overactivation
Pathological
What are the two major components of the stress response?
Epinephrine- adrenal medulla- seconds
Glucocorticoids- adrenal cortex- minutes
When is cortisol produced? Where?
In the HPA axis
Under stressful circumstances
When do catecholamine concentrations peak in regards to PhD exam?
On the day of the exam (epinephrine excretion is the highest)
What is the neuroendocrine axis for stress?
Hypothalamus releases CRH to the pituitary gland (anterior) which triggers the release of ACTH to the adrenal gland. Adrenal gland releases cortisol that affects the immune system. There is a negative feedback loop here
Name 4 steroid hormones
Cortisol
Aldosterone
Estradiol
Testosterone
Where are steroids derived? Describe their solubility too.
Derived from cholesterol and are lipid soluble
What are the actions of glucocorticoids (cortisol/corticosterone)?
Turns off bodily systems that are not immediately essential for dealing with the stressor
-shuts down insulin production so liver releases glucose
-shuts down reproductive function
-inhibits immune system
Body’s energy supplies are concentrated on dealing with stress
How is cortisol production regulated?
In a negative feedback system: the production of cortisol by the adrenal gland feeds back to the cortex, hippocampus, hypothalamus and pituitary to inhibit further production
What two brain areas regulate the HPA axis?
Hippocampus
Amygdala
Limbic system regulation of HPA
Amygdala stimulates HPA axis to release cortisol
Hippocampus inhibits the HPA axis and the release of cortisol. The released cortisol excites the hippocampus to increase its inhibition on the HPA axis
What is the relationship between cortisol and cognition?
Inverted U relationship
What do small acute increases in cortisol do?
Enhances hippocampal mediated learning and memory
What do large, prolonged increases in cortisol do?
Impairs memory
What happens if one has chronic stress early in life?
This has enduring effects
What happens if one has chronic stress in adulthood?
It can be reversed after a period of non stress
What does mineralocorticoid receptor (MR) activation do?
Enhances LTP and memory
What does glucocorticoid receptor (GR) activation do?
Suppresses LTP and memory
What five effects do glucocorticoid release have on the body?
- Mobilization of energy
- Suppression of growth
- Suppression of reproduction
- Suppression of digestion
- Suppression of immunity
What happens during acute stress?
Cortisol enhances hippocampal inhibition of HPA axis
What happens during chronic stress?
Cortisol damages hippocampal neurons
- initial effect is loss of dendritic spines
- disrupts negative feedback which further damages hippocampal cells
- loss of neurogenesis in the hippocampus
- neuron death
What happens to dendritic morphology in the hippocampus after chronic stress exposure?
It decreases in the hippocampus
What happens to cells in the hippocampus after chronic stress exposure?
Reduced cell number (due to reduced adult neurogenesis and increased cell death)