Histo

• Human Histology (MLS 10 7) Lecture 1 is titled "Cells are the basic structural and functional units of all multicellular organisms and are the smallest living parts of the body.
• Prokaryotic cells have a cell wall and lack nuclei and membranous cytoplasmic structures.
• Eukaryotic cells have cell membranes, nucleus, and cytoplasm.
• Lipofuscin is a pale brown granule found in many cells, especially in stable nondividing cells such as neurons and cardiac muscle.
• Cell differentiation is a specialization process where predominantly expressed sets of genes that mediate specific cytoplasmic activities become efficiently organized in tissues with specialized functions and usually change shapes accordingly.
• Hemosiderin is a dense brown aggregate of denatured ferritin proteins with many atoms of bound iron, prominent in phagocytic cells of the liver and spleen.
• Lipofuscin contains a complex mix of material partly derived from residual bodies after lysosomal digestion.
• Pigment deposits include melanin, which are dark brown granules that protect cells from ultraviolet radiation.
• Stem cells can give rise to muscle, intestinal, liver, cardiac, nerve, and blood cells.
• Cellular components include the Cell Membrane, Cytoplasm, and Nucleus.
• Zymogen granules contain digestive enzymes.
• Lysosomes are spherical-shaped membrane-bound organelles formed from the Golgi apparatus, contain about 40 different hydrolytic enzymes and are particularly abundant in cells with great phagocytic activity.
• Secretory granules are formed as vesicles in the Golgi apparatus, are surrounded by membrane and contain a concentrated form of the secretory product.
• Mitochondria synthesize most ATP during aerobic cellular respiration by digestion of fuel molecules (glucose) in the presence of oxygen.
• The mitochondrial matrix contains enzymes that oxidize pyruvate and fatty acids to form acetyl coenzyme A (CoA) and those of the citric acid cycle that oxidize acetyl CoA, releasing CO2 as waste and small energy rich molecules that provide electrons for transport along the electron-transport chain.
• Inclusions are temporary structures in the cell that contain accumulated metabolites or other substances, and include fat droplets, glycogen granules, zymogen granules, pigment granules, crystals and dust particles.
• Mitochondria are double membrane-bound organelles containing a circular strand of DNA (genes for producing mitochondrial proteins), with an outer membrane that is sieve-like and contains many porins, and an inner membrane that has many long folds called cristae.
• Peroxisomes are smaller, spherical-shaped membrane-bound organelles formed from the ER or through fission, contain oxidative enzymes.
• The Golgi apparatus consists of a series of several elongated, flattened saclike membranous structures that modify, package, and sort materials that arrive from the ER in transport vesicles, form secretory vesicles and lysosomes.
• Nucleus PLASMA MEMBRANE • cell membrane / plasmalemma • a lipid bilayer that functions as a selective barrier regulating the passage of materials into and out of the cell and facilitating the transport of specific molecules.
• PLASMA MEMBRANE • Biochemical components include Lipids, Proteins, and Carbohydrates.
• Osmosis is the diffusion of water across a selectively permeable membrane, with the direction determined by relative solute concentrations and continuing until equilibrium is reached.
• Endocytosis is the movement of substances by vesicles forming at the plasma membrane, with major types including Phagocytosis, Pinocytosis, and Receptor-mediated endocytosis.
• Vesicular transport involves vesicles formed or lost as material is brought into a cell or released from a cell.
• Peripheral proteins are bound to one of the two membrane surfaces, particularly on the cytoplasmic side.
• Integral proteins are incorporated directly within the lipid bilayer of the plasma membrane.
• Transmembrane proteins and membrane transport involve passive processes such as Simple Diffusion and Facilitated Diffusion, and active processes like Active Transport and Vesicular Transport.
• Lipids in the plasma membrane are amphipathic, hydrophobic, and hydrophilic.
• Phagocytosis, or "cell eating", involves the ingestion of particles such as bacteria or dead cell remnants, with the fusion of the membranous folds enclosing the bacterium in an intracellular vacuole called a phagosome, which then merges with a lysosome for degradation of its contents.
• Pinocytosis, or "cell drinking", involves smaller invaginations of the cell membrane which fuse and entrap extra-cellular fluid and its dissolved contents.
• Active transport involves the transport of ions or small molecules across the membrane against a concentration gradient by transmembrane protein pumps.
• The ER detoxifies potentially harmful exogenous molecules.
• The Smooth Endoplasmic Reticulum (SER) is a region of the ER that lacks bound polyribosomes, with ER cisternae being more tubular or saclike, with interconnected channels of various shapes and sizes rather than stacks of flattened cisternae.
• Organelles include Ribosomes, Endoplasmic Reticulum, Golgi Apparatus, Secretory Granules, Lysosomes, Mitochondria, and Peroxisomes.
• Ribosomes are composed of two subunits of different sizes bound to a strand of mRNA, and are formed in the nucleus (nucleolus) and exported to the cytoplasm.
• Cytosol is the fluid cytoplasm, while formed elements include organelles, inclusions, and fibrillar elements.
• Pinocytic vesicles pinch off inwardly from the cell surface and either fuse with lysosomes or move to the opposite cell surface where they fuse with the membrane and release their contents outside the cell.
• Free ribosomes produce proteins used within the cell.
• The large subunit of ribosomes has three other rRNA molecules and 50 other basic proteins.
• Exocytosis is the bulk movement of substance out of the cell by fusion of secretory vesicles with the plasma membrane.