The fight or flight response including the role of adrenaline.

Question 1

Define fight or flight response

Answer 1

A sequence of activity within the body that is triggered when the body prepares itself for defending or attacking (fight) or running away to safety (flight). This activity involves changes in the nervous system and the secretion of hormones that are necessary to sustain arousal.

Question 2

Define adrenaline

Answer 2

A hormone produced by the adrenal glands which is part of the human body’s immediate stress response system. Adrenaline has a strong effect on the cells of the cardiovascular system - stimulating the heart rate, contracting blood vessels and dilating air passages.

Question 3

Which 2 parts of the brain do we look at?

Answer 3

The amygdala and hypothalamus

Question 4

What happens when someone is faced with a threat?

Answer 4

The amygdala is mobilised.

Question 5

What does the amygdala do?

Answer 5

The amygdala associates sensory signals (what we see, hear or smell) with emotions associated with fight or flight, such as fear and anger. The amygdala then sends a distress signal to the hypothalamus.

Question 6

What does the amygdala then send?

Answer 6

The amygdala then sends a distress signal to the hypothalamus, which functions like a command centre in the brain, communicating with the rest of the body through the sympathetic nervous system.

Question 7

What 2 major systems does the body’s response to stressors involve?

Answer 7

one for acute (i.e. sudden) stressors such as an attack, and the second for chronic (i.e. ongoing) stressors such as a stressful job.

Question 8

What are the 3 main responses to acute stressors

Answer 8

• The sympathetic nervous system
• Adrenaline
• The parasympathetic nervous system

Question 9

Explain the sympathetic nervous system as a response to acute stressors

Answer 9

When the SNS is triggered, it begins the process of preparing the body for action necessary to fight or flight. The SNS sends a signal to the adrenal medulla, which responds by releasing the hormone adrenaline into the bloodstream.

Question 10

Explain adrenaline as a response to acute stressors

Answer 10

As adrenaline circulates through the body, it causes a number of physiological changes. The heart beats faster, pushing blood to the muscles, heart and other vital organs and blood pressure increases. Breathing becomes rapid in order to take in as much oxygen as possible. Adrenaline also triggers the release of blood sugar (glucose) and fats, which flood into the bloodstream, supplying energy to parts of the body associated with fight or flight.

Question 11

Explain the parasympathetic nervous system as a response to acute stressors

Answer 11

When the threat has passed, the parasympathetic branch dampens down the stress response. This branch will slow the heart down again and reduce blood pressure. Another benefit of the parasympathetic action is that digestion begins again after the SNS has inhibited.

Question 12

Describe some of the physiological changes in the body which are a result of the sympathetic state

Answer 12

• Increases heart rate
• Increases breathing rate
• Dilates pupils
• Inhibits digestion
• Inhibits saliva production

Question 13

Describe some of the physiological changes in the body which are a result of the parasympathetic state

Answer 13

• Decreases heart rate
• Decreases breathing
• Constricts pupils
• Stimulates digestion
• Stimulates saliva production

Question 14

What is the response to chronic stressors?

Answer 14

If the brain continues to perceive something as threatening the second system kicks in. As the initial surge of adrenaline subsides, the hypothalamus activates a stress response system called the HPA axis.

Question 15

What does the HPA axis consist of?

Answer 15

Hypothalamus
Pituitary
Adrenal glands

Question 16

Define the HPA axis

Answer 16

describes the sequence of bodily activity in response to stress that involves the hypothalamus, pituitary and adrenal cortex.

Question 17

Describe the role of the Hypothalamus in the HPA axis

Answer 17

The HPA axis relies on a series of hormonal signals to keep the SNS working. In response to continued threat, the hypothalamus releases a chemical messenger, corticotropin-releasing hormone (CRH), which is released into the bloodstream in response to the stressor.

Question 18

Describe the role of the Pituitary Gland in the HPA axis

Answer 18

On arrival at the pituitary gland, CRH causes the pituitary to produce and release adrenocorticotropic hormone (ACTH). From the pituitary, ACTH is transported in the bloodstream to its target site in the adrenal glands.

Question 19

Describe the role of the Adrenal Glands in the HPA axis

Answer 19

ACTH stimulates the adrenal cortex to release various stress-related hormones, including cortisol. Cortisol is responsible for several effects in the body that are important in the fight or flight response. Some of these are positive (e.g. a quick burst of energy and lower sensitivity to pain) whereas others are negative (e.g. impaired cognitive performance and a lowered immune system).

Question 20

What is the system very good at? (feedback)

Answer 20

The system is also very efficient at regulating itself. Both the hypothalamus and pituitary gland have special receptors that monitor circulating cortisol levels. If these rise above normal, they initiate a reduction in CRH and ACTH levels, thus bringing cortisol levels back to normal.

Question 21

Describe the pituitary gland’s role in the fight or flight response

Answer 21

The pituitary gland releases ACTH into the bloodstream, and from there to its target sites.

Question 22

Describe the hypothalamus’s role in the fight or flight response

Answer 22

The hypothalamus in response to continued threat, releases CRH into the bloodstream

Question 23

Describe the amygdala’s role in the fight or flight response

Answer 23

The amygdala associates sensory signals with emotions such as anger or fear and sends a ‘distress signal’ to the hypothalamus.

Question 24

Describe the Sympathetic nervous systems’s role in the fight or flight response

Answer 24

The SNS prepares the body for rapid action associated with fight or flight

Question 25

Describe the Parasympathetic nervous systems’s role in the fight or flight response

Answer 25

The PNS dampens down the stress response when the threat has passed

Question 26

Describe the Adrenal medulla’s role in the fight or flight response

Answer 26

The adrenal medulla releases adrenaline into the bloodstream, causing physiological changes such as increased heart rate and release of blood sugar.

Question 27

Describe the Adrenal cortex’s role in the fight or flight response

Answer 27

The adrenal cortex releases stress hormones, including cortisol, in response to stress.

Question 28

Describe the feedback system’s role in the fight or flight response

Answer 28

The feedback system. Cortisol levels are monitored so that CRH and ACTH production is inhibited if cortisol is too high