14.5 Coordinated responses Flashcards
(6 cards)
Which part of the nervous system first detects a threat
Autonomic
How does the hypothalamus bring about the fight or flight response
threat detected by autonomic nervous system
Hypothalamus activates SYMPATHETIC NERVOUS SYSTEM
activates glands & smooth muscles
activates adrenal medulla»_space; release of adrenaline & noradrenaline into bloodstream
Hypothalamus releases CRF
causes pituitary gland to secrete ACTH, which causes adrenal cortex to release approx 30 hormones into bloodstream
these changes bring about “fight or flight” responses.
What physiological changes occur during the fight or flight response
￪ HEART RATE
Greater volume of blood travels to cells per unit time, more oxygen & nutrients delivered to cells for respiration
PUPILS DILATE
Take in as much light as possible»_space; better vision & awareness of danger
ARTERIOLES IN SKIN CONSTRICT
Directs blood towards major muscle groups, heart, lungs e.t.c. Other organ systems are not vital for reacting to danger
BLOOD GLUCOSE LEVEL INCREASES
Increase respiration»_space; provide energy for muscle contraction
SMOOTH MUSCLE OF AIRWAYS RELAX
Allow more oxygen into lungs & more diffusion into blood
What’s the role of adrenaline
triggers glycogenolysis in hepatocytes
(to increase blood glucose concentration
for respiration & energy)
Outline the mechanism of action for an adrenaline molecule (secondary messenger model)
1.Adrenaline molecule binds to complementary specific receptor on plasma membrane of target molecule, e.g hepatocyte
2.activates adenylyl cyclase enzyme.
3.adenylyl cyclase catalyses conversion of ATP ⟶ cAMP on inner surface of membrane
4.cAMP activates protein kinases,
5.Each protein kinase molecule activates a number of other enzymes involved in hydrolysis of glycogen to glucose
cascade effect, since number of molecules increases at each step.
Mechanism of action of adrenaline
Adrenaline
Adenylyl cyclase
Auto
cAMP
Protein kinases
Activates hormones
