Question

What is the function of the glands that make up the endocrine system?

Answer 1

To produce substances, mainly hormones, that coordinate our systems.

Explanation:

The endocrine system, also called neuro-endocrine system is the second way most biological systems, e.g. humans, use to coordinate their physiological systems.

The second way being neurotransmitters, e.g. in the brain. The glands in general are clusters of cells with specialized function (s), but not being the only way to communicate, e.g. the fat tissues and the stomach are example of non-gland systems that accomplish similar tasks. Some are quite specialized that makes up an organ, e.g. pancreas.

One practical example is when we are hurt, or close to get sick, some glands, for instance close to the neck, grows and you can feel them with your hand. Other can even cause diseases such as the thyroid that grows more than normal in some conditions, producing too much hormones, effects being for instance excess gain of weight.

So, to conclude, glands are clusters of specialized cells whose function (s) is "long-distance," e.g. bloodstream, communication. See schematic view below.