Histology and Human Development Lecture 2 PDF

Unified Lecture 2 EPITHELIUM PART- 2 HIHD-211 TERM-3 Basic Science Department COSHP, KSAU-HS, KSA Learning Outcomes By the end of this lecture the student must be able to: 4. Classification of Glandular epithelium Glandular Epithelia ▪ Primary function of glandular epithelium is secretion, and is or...

Unified Lecture 2 EPITHELIUM PART- 2 HIHD-211 TERM-3 Basic Science Department COSHP, KSAU-HS, KSA Learning Outcomes By the end of this lecture the student must be able to: 4. Classification of Glandular epithelium Glandular Epithelia ▪ Primary function of glandular epithelium is secretion, and is organized into specialized structures called glands Types of Glands 1. Exocrine glands, which release their secretions on epithelial surface directly or through ducts e.g. Salivary glands 2. Endocrine glands are ductless glands which release their secretion into blood and reach to target organs through blood e.g. Thyroid gland LO-4 EXOCRINE GLANDS Most glands of the body are exocrine types which have ducts connecting to anatomical surfaces e.g. salivary glands and sweat glands. Exocrine glands can be classified according to: 1- Mode of secretion 2- Morphology of the glands LO-4 1- Types of exocrine glands according to the mode of secretion: 1- Merocrine (eccrine) In the glandular cell, membrane-bound secretory vesicles are formed and released from the apical surface of the cell e.g. large intestine glands 2- Apocrine The secretory vesicles aggregate in the apical part of the glandular cells then a portion of the cells is pinched off and lost during the secretory e.g. Mammary glands 3- Holocrine The secretory cell, as whole is released from the gland into the duct e.g sebaceous glands LO-4 2- Types of exocrine glands depending on the morphology of secretory parts and ducts ▪ The exocrine glands consist of two parts the duct and the secretory component ▪ If the duct system is unbranched, it forms simple gland, and if the duct system is branched it forms compound gland ▪ The secretory component may be tubular forming tubular gland or acinar forming acinar gland or mixed forming tubulo-acinar gland LO-4 Simple tubular glands: A single, straight tube with secretory cells which secrete and drain the products as in large intestine Simple branched tubular glands: Each gland consists of several tubular secretory portions which converge on to a single unbranched duct as in stomach Simple coiled tubular glands: A single coiled tube with cuboidal cells which secrete and drain the products as in sweat glands Simple acinar glands: lobes or pockets of epithelial secretory cells secrete and drain in single duct as in penile urethra Compound tubular: Each gland consists of several secretory ducts that empty into a branched excretory duct as in Brunner’s glands in the duodenum The feature unique to the duodenum is the extensive mass of coiled, branched tubular glands, G, in the submucosa, SM, called Brunner’s glands. Simple branched acinar: Each gland consists of several secretory acini that empty into a single excretory duct as in sebaceous glands Compound acinar: Each gland consists of several secretory acini that empty into a branched excretory duct as in mammary gland Compound tubulo acinar: Compound tubulo-acinar glands have three types of secretory units; namely branched tubular, branched acinar and branched tubular with acinar end-pieces called the demilunes as submandibular glands Thank you 15