Читать книгу Understanding Anatomy and Physiology in Nursing - John Knight - Страница 17

The Golgi apparatus is a specialised region of smooth ER resembling a series of crescent-shaped stacked membranes (Figure 1.1). The Golgi is frequently referred to as the cell’s ‘packaging and export’ region since it is involved in preparing material for release from cells. Its key role is refining proteins from the rough ER; this usually involves adding sugar residues to the crude amino acid sequences via a process termed glycosylation. The refined proteins may be used within the cell or may leave the Golgi in membranous sacs called secretory vesicles which travel to the cell membrane before their contents are discharged out of the cell. Cells that have a secretory role such as those within endocrine glands may each have several well-developed regions of Golgi apparatus; a good example would be the insulin-producing beta cells of the pancreas. The Golgi is also responsible for packaging digestive enzymes required for intracellular digestion into small membrane-bound sacs called lysosomes (see below).