Anatomy & Physiology I and II

Anatomy & Physiology Study Guide communicate with the exterior. Hormones, the secretions of endocrine glands, are released by gland cells into the surrounding interstitial fluid. • A glandular epithelial cell may release its secretions by merocrine, apocrine, or holocrine modes. In merocrine secretion, the most common mode, the product is released through exocytosis. Apocrine secretion involves the loss of both the secretory product and cytoplasm. Unlike the other two methods, holocrine secretion destroys the gland cell after it becomes packed with secretions and bursts. • In epithelia that contain scattered gland cells, individual secretory cells are called unicellular glands. Multicellular glands are organs that contain glandular epithelia that produce exocrine or endocrine secretions. • Exocrine glands can be classified by structure as unicellular exocrine glands (mucous cells) or as multicellular exocrine glands. Multicellular exocrine glands can be further classified according to structure. Connective tissue provides a protective structural framework for other tissue types: • Connective tissues are internal tissues with many important functions including: establishing a structural framework; transporting fluids and dissolved materials; protecting delicate organs; supporting, surrounding, and interconnecting tissues; storing energy reserves; and defending the body from microorganisms. • All connective tissues contain specialized cells and a matrix composed of extracellular protein fibers and a ground substance. • Connective tissue proper is connective tissue that contains varied cell populations and fiber types surrounded by a viscous ground substance. • Fluid connective tissues have distinctive populations of cells suspended in a watery matrix that contains dissolved proteins. The two types of fluid connective tissues are blood and lymph. • Connective tissue proper contains fibers, a viscous ground substance, and a varied population of cells, including fibroblasts, fibrocytes, macrophages, adipocytes, mesenchymal cells, melanocytes, mast cells, lymphocytes, and microphages. • Supporting connective tissues have a less diverse cell population than connective tissue proper and a dense matrix with closely packed fibers. The two types of supporting connective tissues are cartilage and bone. • The three fibers in connective tissue are collagen fibers, reticular fibers, and elastic fibers. • The first connective tissue to appear in an embryo is mesenchyme, or embryonic connective tissue. • Connective tissue proper is classified as either loose connective tissue or dense connective tissue. Loose connective tissues are mesenchyme and mucous connective tissues in the embryo; areolar tissue; adipose tissue, i.e., white fat and brown fat; and reticular tissue. Most of the volume in dense connective tissue consists of fibers. The two types of dense connective tissue are dense regular connective tissue and dense irregular connective tissue in the adult. ©2018 Achieve Test Prep Page 45 of 367