Session 11: Anxiety Flashcards
Purpose of stress response.
Enables us to escape from potentially dangerous situations.
Which is the system primarily responsible for stress response?
Limbic system with neural and endocrine targets.
Explain the hippocampus involvment in stress response.
Inputs from many parts of the cortex to process the emotional content.
Will then project to the thalamus and back to the cortex, but also to the hypothalamus.
The circuit to hypothalamus causes the hypothalamus to send projections down through the cord to autonomic preganglionic neurones via the hypothalamospinal tract in response to the emotional response.
This will lead to sympathetic nervous system activation as well as release of adrenaline from the adrenal medulla leading to an acute stress response.
What is the papez circuit?
Thalamus projecting and communicating with the cortex.
It may be involved in memory consolidation.
Explain the involvment of amygdala in stress response.
Receives many inputs from the sensory system and have major outputs to the cortex, brainstem and hypothalamus.
It is involved, like the hippocampus in behavioural and autonomic emotional responses.
Where can the amygdala be found?
Sitting near the tip of the hippocampus and buried in the roof of lateral ventricle.
Where can the hippocampus be found?
Curved piece of cortex that is folded into medial surface of temporal lobe and occupies the floor of temporal horn of the lateral ventricle.
Three parts of hippocampus.
Subiculum
Hippocampus proper
Dentate gyrus
Explain the prefrontal cortex involvement in stress response.
Modulation of emotional responses like consciously suppressing features of anxiety.
Perception of emotion.
Not classically a part of the limbic system
Functions of the cingulate gyrus in stress response.
Involved in processing of emotions and memory.
Explain the endocrine involvement in stress response.
Limbic system is able to act on the hypothalamus to stimulate the secretion of stress hormones.
This is via the HPA-axis.
There is a realease of cortisole from the adrenal cortex as a part of the chronic stress response.
In general adaptation syndrome the body goes through three stages to the prolonged exposure to a stressor.
Which three stages?
Stage 1 - Alarm reaction
Stage 2 - Resistance
Stage 3 - Exhaustion
Explain stage 1 - alarm reaction.
Release of adrenaline and cortisol as well as sympathetic activation.
Explain stage 2 - resistance.
Resistance starts to build and the effect of adrenaline starts to wear off.
However there is still a prolonged release of cortisol
Explain stage 3 - exhaustion.
This comes into play when you can’t escape an ongoing stressor.
Cortisol levels are still high due to the chronic exposure and patient will start to experience side effects of prolonged elevated levels of cortisol.
Side effects such as muscle wasting, immunosuppression and hyperglycaemia.
When can the stress response become pathological?
When you cannot espace a stressor or when a ‘trivial’ stressor elicits a strong stress response.
Define anxiety.
A term used for a pathological stress response.
Symptoms of anxiety.
Palpitations
Sweating
Trembling or shaking
Dry mouth
Difficulty breathing
Chest pain or discomfort
Nausea or abdominal distress
Dizziness, unsteadiness, faint, light-headed.
Give examples of anxiety disorders.
Social phobia
Specific phobias such as spiders, heights, etc…
Generalised anxiety disorder (GAD)
Panic disorders
Obsessive compulsive disorder (OCD)
Post-traumatic stress disorder (PTSD)
Explain GAD.
Persistent anxiety about a variety of things.
Pathophysiology of anxiety disorders.
Unclear path but might be related to low levels of GABA.
Explain basal ganglia re-entrant circuits.
Cortex -> basal ganglia -> back into cortex via thalamus.
Obsessional thought can re-enter the cortex having entered the basal ganglia and loop.
Why might deep brain stimulation help in OCD?
Because of stimulation of the subthalamic nucleus in order to increase the indirect pathway to inhibit re-entrant.
