During stressful, frightening and challenging situations, the hypothalamic-pituitary-adrenal (HPA) axis stimulates the endocrine stress response which causes adrenaline rush. The part of brain called as amygdala processes the information about stressful condition and stimulates the hypothalamus which in turn establishes a contact with rest of the body through sympathetic nervous system. A hypothalamus transmits signal to adrenal glands via adrenal medulla which releases adrenaline into the bloodstream. This entire process takes some time and hence the adrenal rush is created after the stressful condition is over and hence maintains the dynamic equilibrium
As light intensity increases, the rate of photosynthesis will increase as long as other factors are in adequate supply. As the rate increases, eventually another factor will come into short supply.
