Module 5: Coordinated responses

Question 1

State and describe the 5 stages of the fight or flight response mechanism

Answer 1

1)The ANS detects a threat and a signal is passed to the hypothalamus
2)The hypothalamus activates the sympathetic nervous system , sending nerve signals to glands and muscles
3)The sympathetic NS triggers secretion of adrenaline and noradrenaline from the adrenal medulla , resulting in a number of physiological changes
4)The hypothalamus also communicates with the adrenal-cortical system , stimulating the pituitary gland to secrete ACTH
5)ACTH travels via the bloodstream to the adrenal cortex , stimulating secretion of several other hormones to help the body deal with the threat

Question 2

Give the purpose of each of these physiological changes…

-increased heart rate
-dilation of pupils
-constriction of arterioles in skin

Answer 2

increased heart rate=to circulate more oxygenated blood around the body
pupil dilation=improves vision
constriction=diverts more blood to muscles/brain/heart

Question 3

Give the purpose of each of these physiological changes…

-increase in glucose levels
-relaxation of airway muscles
-digestion inhibited

Answer 3

glucose=to allow for increased cellular respiration
airway muscles=allow more oxygen into the lungs
digestion inhibited=preserve energy for prioritised body functions

Question 4

Make 1 point describing the second messenger model of hormone action

Answer 4

a hormone (first messenger) triggers the formation of a second messenger (cAMP) inside the cell , which activates enzymes to carry out a function

Question 5

Describe the first 4/8 points about the cell signalling pathway for adrenaline

Answer 5

1)adrenaline binds to a complementary receptor on the cell surface membrane of a liver cell
2)binding of adrenaline causes the receptor to change shape , activating a G protein
3)this activates the enzyme adenylyl cyclase
4)adenylyl cyclase converts ATP into cAMP

Question 6

Describe the final 4/8 points about the cell signalling pathway for adrenaline

Answer 6

5)cAMP binds to and activates many protein kinases through phosphorylation , amplifying the signal from adrenaline
6)protein kinases activate enzymes which catalyse glycogenolysis
7)glucose moves out liver cells through facilitated diffusion and into blood via channel proteins
8)increases blood glucose concentration to supply body cells with more glucose to sustain increased respiration