Provide definitions/explanations for the following terms:
$(1)$ Hormone
$(2)$ Endocrine glands
$(3)$ Exocrine glands
$(4)$ Acromegaly

(N/A) $(1)$ Hormones are non-nutrient chemicals which act as intercellular messengers and are produced in trace amounts. They are synthesized by ductless glands,secreted into the blood,and transported to target organs.
$(2)$ Endocrine glands are ductless glands that synthesize hormones and pour their secretions directly into the blood to reach specific target organs.
$(3)$ Exocrine glands are glands that possess ducts. Their secretions (e.g.,enzymes,mucus,saliva) are transported through these ducts to the specific target sites or surfaces.
$(4)$ Acromegaly is a condition in adults caused by the excessive secretion of growth hormone $(GH)$. It is characterized by the abnormal enlargement of bones,particularly in the lower jaw,limbs,and facial features.