Endocrine Glands
--Ductless glands that produce hormones
--Secretions include amino acids, proteins,
glycoproteins, and steroids
--Secreted by exocytosis directly into the extracellular space where the hormones enter the blood and travel to specific target organs

Exocrine Glands
-- More numerous than endocrine glands
--Secrete their products onto body surfaces (skin) or into body cavities either by exocytosis (unicellular glands) or via ducts (multicellular glands)
--Examples include mucous, sweat, oil, and salivary glands

Unicellular Exocrine Glands
--Epithelial lining of the intestinal & respiratory
tracts amid columnar cells
--Produce mucin, a complex glycoprotein that dissolves in water to form mucus
--E.g Goblet Cell

Multicellular Exocrine Glands
-----Classified according to:
-- Simple or compound duct type
--Structure of their secretory units
--Supportive connective tissue surrounds the secretory cells supplying it w/ blood vessels, nerve fibers, forming a fibrous capsule dividing the gland into lobes

---Simple glands have unbranched ducts
---Compound glands have branched ducts
---Multicellular Exocrine Glands are further categorized by their secretory units
1) tubular: secretory cells form tubes
2) alveolar: secretory cells form sacs
3) tubuloalveolar: secretory cells form tubes & sacs