Anxiety and Stress unit Flashcards
(25 cards)
What does stress refer to?
The physiological reaction caused by aversive or threatening situations. It comes from engineering: the action of physical forces on physical structures. Saying that someone is stressed means that they were exposed to a situation that elicits a stress response
What do emotional responses consist of?
Behaviour (fight/flight), autonomic (increased HR), and endocrine responses (increased adrenaline). Autonomic and endocrine responses to stress are adversive to our health.
What are the main two systems that control the release of stress-related hormones?
The sympathetic adrenal-medullary system and the hypothalamic pituitary adrenal axis
How does the sympathetic adrenal-medullary system work?
In response to a stressful stimulus, the nerves of the sympathetic nervous system (under the control of the hypothalamus), stimulate the adrenal medulla (inner part of the adrenal glands that sit on top of the kidneys), causing it to release catecholamine hormones: adrenaline and noradrenaline. Catecholamines produce sympathetic response (glucose metabolism speeds up to provide energy for physical activity) (also to increase cardiovascular disease).
How does the hypothalamic pituitary adrenal (HPA) axis work?
When we are stressed, the hypothalamys also communicates with the adrenal glands via hormones, rather than just via sympathetic nerves. Neurones in the paraventicular nucleus of the hypothalamus secrete corticotropin-releasing hormone (CRH) into capillaries that lead to the anterior pituitary gland. This causes the anterior pituitary to secrete adrenocorticotropic hormone (ACTH) into the general blood cirucilation, stimulating the adrenal cortex to secrete cortisol (a type of gluchocorticoid hormone)
What does Glucocorticoids do?
They are released by adrenal glands in response to stress in order to increase blood glucose concentrations.
They cause
1) The liver to release gluscose into the blood.
2) The breakdown of muscles proteins to be used by the liver to create glucose.
3) The breakdown of fatty acids into a usable source of energy (lipolysis). Despite its long term exposure is harmful, its necessary for survival.
What is the long-term effect to exposure to cortisol?
Long-term exposure to glucocorticoids can be damaging: it increases blood pressure (a risk factor for heart attacks and stroke), damages muscle tissue, infertility, inhibition of growth (when stressor occurs during critical phases of development). It can also inhibit inflammatory response. It also can supress the immune system.
What is the long-term effect on the brain to exposure to cortisol?
Research on animals show, long-term exposure to glucocorticoids damages neurones in the CA1 area of the hippocampus by decreasing the entry of glucose into the neurones, and decearing their reuptake of glutamate. Too much extracellular glutamate causes too much calcium to enter neurone, which kill them.
What is the effect of decreased entry of glucose on the brain?
Decreased entry of glucose into neurones in the hippocampus also damages them, which causes them to be more susceptible to potentially harmful events such as decreases in blood flow, which happens during aging. This means that persistant stress responses during our lives may increase the likelihood of memory in old age.
What does short-term stress affect in the brain and prenatal rats?
It affects the hippocampus functioning and prenatalstress in rat mothers can disrupt hippocampus development in the offspring.
How to individuals that were exposed to stress early on have healthy brains?
It’s possible that because of protective hormones like testosterone, neuropoptide-Y and DHEA (DHEA mediates the negative effects of excess cortisol) hormone protected the brain. However, severe stress like torture has shown to cause degeneration of brain cells. Maltreatment in childhood has been related to reduced volume of the dorsomedial prefrontal cortex. Chronic back pain = loss of 1.3cm^3 of cortical grey matter
What does PSTD consists of developing what?
Certain symptoms after a traumatic event that persist long after the termination of the event. PTSD is more likely to develop after events involving some form of violence and women are more likely to develop PTSD than man.
What are the symptoms of PTSD?
Recurrect dreams or recollections; the feeling that the event is recurring and intense psychological distress.
Lead to avoiding to think about the event, which can cause them to participate less in social events, detachment from others and suppressed emotions.
Aside from poor physical health, patients may also experience poor sleep, irritability, outbursts of anger, difficulty concentrating and heightened reactions to sudden noises or movements
What is PTSD due to?
It is partily due to genetic factors. Suvivors of the genocide in were found to be more likely to have PTSD if they were subjected to a higher number of traumatic events.
Those that were more likely to develop PTSD also have a particular allele of the gene that produces COMT.
COMT: an enzyme that desrtoys interstitial catecholamines. People with this allele destroy COMT relatively slowly, meaning COMT would be present in interstitial fluid
What area of the brain does PTSD affect?
PTSD affects the same brain regions as long-term stress: the hippocampus and PFC. Hippo. volume reduces by 20% in veterans with combat-related PTSD. With reductions being proportional to the duration of exposure to combat.
Reduced hippocampus volume may be a consequence of PTSD and…?
a rick factor for developing PTSD. Individuals with small hippocampus may be more likely to develop PTSD
What roles does the hippocampus play in PTSD?
The hippocampus helps form memories of the context in which an event took place. In the case that when PTSD patients are confronted with a context similar to the one in which the traumatic event occurred they may misrecofnise the context, causing the amygdala to activate and trigger an emotional response. A normally functioning hippocampus would detect the difference between the present context and the one associated with the traumatic event.
What other part other than the hipocampus that is affected by PTSD?
The Ventromedial PFC, it also appears to be affected in PTSD. The amygdala underlies the creation of conditioned emotional responses, and the ventral PFC plays an inhibitory role in extinguishing these emotional responses. this suppresion of emotional responses by the PFC appears to be disrupted in PTSD: individuals with PTSD show greater activity in the amygdala and lower in the PFC.
What is anxiety disorder characterised by?
Fear and anxiety, which would be considered excessive for the circumstances. They also contrubute to the occurrence of depressive and substance abuse disorders. There are many types of anxiety disorder, which involve some form of fear accompanied by physical symptoms of anxiety.
What protein appears to be related to anxiety?
BDNF, it appears to be related to anxiety disorders. It plays a role in neuronal survival during development, but also plays a role in forming long-term memories. An allele of the gene that produces BDNF seems to be related to the development of anxiety disorders. Having this allele results in atypical connections between the ventromedial PFC and amygdala, which impaits the extinction of conditioned emotional responses.
What do anxiety disorders involve alterations in connections structures?
They involve the alterations in the connections between the limbic structures and the PFC, and also involve the alteractions in the structures themselves. resulting in: panic attacks experianced during neuroimaging recordings have shown decreased activity in the ventromedial PFC and anterior cingulate cortex, and increased activity in the amygdala.
What do people with social anxiety disorder show?
An increased amygdala activity when viewing emotional faces compared to control subjects, and the activity in the amygdala was positively correlated with the severity of symptoms.
What is social anxiety disorder (SAD)?
excessive fear of being exposed to scrutiny of other people and avoidance of social situations, especially in which the individual must perform
What do people with generalised anxiety disorder show?
they also showed increased amygdala activity to angry faces, and reduced activity in the ventromedial PFC: when control subjects viewed the angry faces they increased acitivity in the ventromedial PFC that suppressed activity in the amygdala, which the GAD subejct failed to show.
