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
