Answer:
They control body activities by releasing hormones into the blood.
Step-by-step explanation:
The endocrine system produces hormones which maintain our blood sugar level (homeostasis) . The pancreas is the main gland involved.
If our blood sugar level increases the pancreas detects this and insulin is then released which acts on our liver. The excess glucose is then converted to glycogen.
Excessive Glucose → Glycogen
If our blood sugar level decreases , again the pancreas detects it and releases glucagon which act on the liver. The excess glycogen is then converted to glucose.
Excessive Glycogen → Glucose
The reason this system is vital is because our brain needs glucose and if the endocrine system is not working, our brain will cease to work efficiently and will ultimately shut down due to lack of glucose supply.