(a) When sugar levels in the blood rise, they are detected by the cells of the pancreas which respond by producing more insulin. As the blood sugar level falls, insulin secretion is reduced. The timing and amount of hormones to be secreted are regulated by the feedback mechanism.
(b) (i) Adrenaline hormone is secreted into the blood when you are under stress, Adrenal gland that secretes this hormone.
(ii) It acts on heart. Heart beats faster, resulting in more supply of oxygen to skeletal muscles. · Breathing rate also increases because of contraction of diaphragm and the rib muscles.