the fight or flight response

Question 1

What is the fight or flight response?

Answer 1

The way an animal responds to stress as it becomes physiologically aroused to fight an aggressor or to run away.

Question 2

What are the two main stress response systems?

Answer 2

Acute (sudden) stressors.
Chronic (ongoing) stressors.
They are both co-ordinated by the hypothalamus.

Question 3

Outline the sympathomedullary pathway.

Answer 3

Acute stressors = arousal of the ANS.
ANS - SNS - fight/flight - sympathetic adrenal medullary system.

Question 4

What are the effects of the SNS?

Answer 4

increases heart rate, contracts rectum, dilates pupils, inhibits saliva production, inhibits digestion, increases breathing rate.

Question 5

What are the effects of the PSNS?

Answer 5

Decreases heart rate, relaxes rectum, constricts pupils, stimulates saliva production, stimulates digestion, decreases breathing rate.

Question 6

How does the body initiate fight or flight?

Answer 6

1. When a stressor is perceived, the hypothalamus activates the sympathetic branch of the ANS.
2. The ANS changes from its resting state (parasympathetic) to a psychologically aroused sympathetic state.
3. The stress hormone is released from the adrenal gland (from the adrenal medulla) into the bloodstream.
4. This hormone triggers physiological changes into the body which produces the necessary arousal for fight or flight.
5. This is an acute response - automatic.
6. Once the threat is gone, the PSNS returns to its resting state. This puts a break on all of the physiological changes, known as the ‘rest and digest’ response.
7. The two nervous systems are antagonistic - they work in opposition to eachother.