(endocrine system) fight & flight response

Question 1

how is adrenaline secreted

Answer 1

in stressful/fear-inducing situations, neurons of the sympathetic nervous system stimulate the adrenal medulla to secrete adrenaline

Question 2

adrenaline

Answer 2

a hormone which prepares the body to deal with fear/stress/exciting-inducing stimulus

Question 3

how is adrenaline transported around the body & what happens at the organs

Answer 3

via the bloodstream where it will bind to receptors on target organs

Question 4

examples of physiological changes caused by fight & flight response

Answer 4

• heart rate increases
• blood pressure increases
• triggers release of blood sugar (glucose) & fats = supplies energy to parts of body associated with fight or flight

Question 5

once fight & flight response has passed, what happens?

Answer 5

• parasympathetic nervous system kicks in
• slow acting

Question 6

what happens when you experience long term (chronic) stress

Answer 6

(as initial surge of adrenaline subsides) the hypothalamus activates a stress response system = HPA axis

Question 7

what does HPA axis stand for

Answer 7

H = hypothalamus
P = pituitary gland
A = adrenal glands

Question 8

1) what does the ‘H’ in HPA axis refer to (during chronic stress)

Answer 8

• hypothalamus releases chemical messenger = CRH
• released into bloodstream in response to stressor

Question 9

CRH

Answer 9

corticotrophin-releasing hormone

Question 10

2) what does the ‘P’ in HPA axis refer to (during chronic stress)

Answer 10

• on arrival at pituitary gland, CRH causes it to produce & release ACTH
• from pituitary, ACTH is transported via bloodstream to target site in adrenal glands

Question 11

ACTH

Answer 11

adrenocorticotrophic hormone

Question 12

3) what does the ‘A’ in HPA axis refer to (during chronic stress)

Answer 12

• ACTH stimulates adrenal cortex to release various stress-related hormones, including cortisol
• cortisol is responsible for several effects in body eg. burst of energy, lower sensitivity to pain

Question 13

how is the HPA axis good at regulating itself

Answer 13

• hypothalamus & pituitary gland have special receptors to monitor circulating cortisol levels
• if rise above normal, they initiate reduction in CRH & ACTH levels which brings cortisol levels back to normal

Question 14

what does too much cortisol cause

Answer 14

suppresses the immune system = shutting down process which fights infection

Question 15

summary of fight/flight response

Answer 15

• hypothalamus activates pituitary gland which triggers activity in sympathetic branch of ANS
• ANS changes from resting state (parasympathetic) to physiologically aroused sympathetic state

Question 16

‘rest & digest’ response

Answer 16

once threat has passed, parasympathetic nervous system returns body to resting state (antagonistic)