Purely serous salivary glands secrete which of the following substances?
Serous cells and serous glands are protein secreting. The secretion granules (zymogen granules) that accumulate in the apical cytoplasm before release by exocytosis contain mixtures of digestive enzyme precursors and electrolytes. Mixed salivary glands have both serous and mucous secretory acini, or mucous acini with serous demilunes. Mixed glands secrete both enzyme precursors and mucinogens. The parotid gland is the stereotypic serous salivary gland. Fibrous proteins such as collagen are secreted primarily by the fibroblasts of the connective tissue. Hormones are secreted by endocrine glands and neurosecretory cells. Holocrine secretion of hair follicle-associated sebaceous glands is characterized by the secretion of dead cells and pieces of cells. Ref: Barrett K.E., Barman S.M., Boitano S., Brooks H.L. (2012). Chapter 25. Overview of Gastrointestinal Function & Regulation. In K.E. Barrett, S.M. Barman, S. Boitano, H.L. Brooks (Eds), Ganong's Review of Medical Physiology, 24e.
Mucinogen and other glycoproteins
Enzymes and bicarbonate ions
Fibrous proteins and proteoglycans
Hormones and other regulatory agents