Lecture 2 Mitochondria, RER, SER Lecture Notes PDF

Cytology Cytology is the science which deals with the study of cells. The Cytoplasm 1-Cytoplasmic organelles: permanent structures that have important functions & important for life of cell. 2-Cytoplasmic inclusions: products that are stored into the cell & not essential for life of cell. 3- Cytoske...

Cytology Cytology is the science which deals with the study of cells. The Cytoplasm 1-Cytoplasmic organelles: permanent structures that have important functions & important for life of cell. 2-Cytoplasmic inclusions: products that are stored into the cell & not essential for life of cell. 3- Cytoskeleton: formed of tubules & filaments that maintain the shape of cells & help in cell movement. 4- Cytoplasmic matrix (cytosol): a semifluid material inbetween organelles & inclusions. Cytoplasmic organelles * Membranous: surrounded by a membrane 1-Mitochondria. 2-RER. 3-SER. 4-Golgi apparatus. 5- Lysosomes. 6-Secretory vesicles. *Non membranous: not surrounded by membrane 1-Free ribosomes. 2-Microtubules. 3-centrioles, cilia, flagella. 4- Filaments. Mitochondria Definition: membranous cell organelles present in all cells except red blood cells. L.M: granules or rods by special stains as iron haematoxylin. Mitochondria E.M: Rounded or oval vesicle, surrounded by two membranes. outer membrane is smooth. inner membrane is folded (cristae). mitochondria is filled with fluid (matrix) which contains DNA, RNA, calcium, magnesium and ribosomes. Functions: They are the energy house in the cell as they produce ATP needed for metabolism. Due to the presence of DNA, RNA and ribosomes in mitochondria they can synthesize protein & divide by simple fission. RER L/M: localized cytoplasmic basophilia. RER E/M: – network of membranous vesicles & flat tubules [cisternae]. – outer surface is covered with ribosomes. Functions: Synthesis of secretory proteins e.g. pancreatic acinar cells, fibroblasts and plasma cells. Synthesis of lysosomal enzymes. Formation of plasma membrane integral proteins. SER L/M : gives acidophilia to the cytoplasm when present in great amount. E/M : network of anastomosing tubules (no ribosomes). Function: 1- Lipid synthesis as steroid hormones in steroid secreting cells (adrenal). 2- Glycogen synthesis. 3- Detoxification of drugs in liver cells. 4- Ca++ distribution in muscle to regulate contraction & relaxation.