1.84 Stress Flashcards
When the senses pick up a threat, what is the first route it takes to the brain?
When danger is perceived, senses (e.g. olfaction, sight) send the information to the amygdala
• The amygdala interprets the information
When it perceives danger, it instantly sends a distress signal to the hypothalamus
What are the results of a classic fear response?
○ Sweaty palms ○ Rapid heartbeat ○ Increased blood pressure ○ Burst of adrenaline Occurs before you are conscious of the threat
What is the second step to a perceived threat brain pathway?
Only after the fear response has activated does the conscious mind engage
• Some sensory information travels through the thalamus to the cortex
• The cortex analyses the raw data coming from the senses and decides whether a fear response is needed
• If a fear response is needed the cortex signals to the amygdala to maintain activation of the system
• Amygdala signals to the hypothalamus to coordinate and maintain the stress response
The hypothalamus is the most important brain region for coordination of the SNS stress response
Which is the most important brain in region in coordinating SNS stress response?
The hypothalamus
Where does the hypothalamus signal to?
Various brain regions - amygdala, hippocampus, septal area and prefrontal cortex
Interomedial lateral cord of the spine
Where is the intermediolateral cell column and what is its function?
T1 - L2
Mediates entire sympathetic system of the body
Which other structure is an extension of the SNS and what is its function?
Adrenal medulla
Some pre-ganglionic neurons directly synapse on the secretory portion of the adrenal medulla
Adrenaline 80%, noradrenaline 20% released
List some of the body function to which an activation of the SNS can lead to? (cardiac &BP, glucose, blood, and others)
- Increased heart rate
2. Increased cardiac contractility
3. Increased blood pressure
4. Bronchodilation
5. Liberation of glucose into the blood
6. Inhibition of insulin secretion
7. Reduction in blood clotting time
8. Mobilisation of blood cells by contraction of the spleen
9. Decreased gastrointestinal activity
10. Sweating
Pupillary dilation
Why is bronchodilation important in the stress response?
Extra oxygen sent to the brain - increasing alertness
Sight and hearing become sharper
What other symptoms could present with stress induced tachycardia?
Many acute stress symptoms (palpitations, shaking, couldn’t breathe, felt faint) cause further anxiety, and mimic more serious health problems
What are the two types of tachycardia present with anxiety?
Sinus and supra ventricular tachycardia
What can stress induced hypertension present as?
In 95% of cases the cause is unknown and are categorized as ‘essential’ hypertension but stress is a major contributory factor
Elevated sympathetic tone contributes to the development of hypertension
What can long lasting elevated levels of catecholamine’s contribute towards?
Long lasting elevated catecholamine levels are considered to contribute to the development of atherosclerosis and predispose to myocardial ischemia (angina)
Elevated catecholamine levels make the blood more prone to clotting, increasing the risk of arterial obstruction (stroke) and myocardial infarction
Which SNS action can lead to tissue wasting?
Catecholamines - Altered metabolism
Increased breakdown of glycogen and fat can lead to tissue wasting
What else could lead to CHD?
Raised cholesterol can contribute to vascular disease, particularly coronary heart disease
What stress actions could lead to type II diabetes and kidney damage?
Raised glucose levels can contribute to the development of type II diabetes
Probably arising from chronically raised glucose due to metabolic effects and insulin resistance
How is stressed linked to kidney disease?
Increased sympathetic nervous system activity is linked to kidney disease probably arising from chronic hypertension
Elevated renal sympathetic activity increases vascular tone while altering renal sodium and water homeostasis, thus contributing to excessive fluid volume, oedema formation and increases in BP
What are the two major psychiatric disorders linked with hyperactivation of the SNS?
Panic disroders and Post traumatic stress disorder
What is a panic disorder and what symptoms can it present with?
Panic = sudden onset of intense apprehension/fear • tachycardia • palpitation • sweating • tremor • hyperventilation dry mouth
What is post traumatic stress disorder?
• The most severe of the stress-related psychiatric illnesses
• Triggered by (single) intense stressful (traumatic) experience, e.g. sexual assault, witness or involvement in accident/violence
• Onset is delayed weeks to months and may persist for years
Cognitive dysfunction means PTSD patients constantly re-experience the memory (flashbacks) or have it triggered by sensory cues associated with the event (e.g. smell)
What are the symptoms of PTSD?
Symptoms also include nightmares, autonomic hyperarousal with hypervigilance, anxiety, depression, guilt
What is hyperarousal?
Higher baseline level of NE
Why does skin conductance reflect sympathetic activation?
Skin conductance response (SCR) reflects sympathetic activation because palmar sweat glands are innervated by the sympathetic chain of the autonomic nervous system
Which part of the brain is more active in PTSD patients when fearful images are shown to them?
Amygdala
