Histology is the study of the tissues of the body and how they are arranged to constitute organs
Cells are the basic structural and functional units of all multicellular organisms
Prokaryotic cells have a cell wall, lack nuclei, and membranous cytoplasmic structures
Eukaryotic cells have cell membranes, nucleus, and cytoplasm
Cell differentiation is a specialization process where cells express sets of genes that mediate specific activities and become efficiently organized in tissues with specialized functions
Cellular components include the cell membrane, cytoplasm, and nucleus
The plasma membrane is a lipid bilayer that functions as a selective barrier regulating the passage of materials into and out of the cell
Biochemical components of the plasma membrane include lipids, proteins, and carbohydrates
Integral Proteins are incorporated directly within the lipid bilayer, while Peripheral Proteins are bound to one of the two membrane surfaces, particularly on the cytoplasmic side
Passive processes involve the movement of substances down a concentration gradient without the expenditure of cellular energy
Active processes involve the movement of substances that require the expenditure of cellular energy
Passive processes include simple diffusion and facilitated diffusion
Osmosis is the diffusion of water across a selectively permeable membrane
Facilitated diffusion can be channel-mediated or carrier-mediated
Active transport involves the transport of ions or small molecules across the membrane against a concentration gradient by transmembrane protein pumps
Vesicular transport includes endocytosis and exocytosis
Endocytosis involves the movement of substances by vesicles forming at the plasma membrane
Major types of endocytosis are Phagocytosis, Pinocytosis, and Receptor-mediated endocytosis
Phagocytosis is the ingestion of particles such as bacteria or dead cell remnants
Pinocytosis involves smaller invaginations of the cell membrane that entrap extracellular fluid and its dissolved contents
Receptor-mediated endocytosis occurs when plasma membrane receptors first bind specific substances and are taken up by the cell
Exocytosis is the bulk movement of substances out of the cell by fusion of secretory vesicles with the plasma membrane
Ribosomes are found free or attached to rough ER
Nucleolus - site of ribosome synthesis
The nucleus is the largest organelle, containing DNA
Free ribosomes synthesize proteins destined for use within the cytoplasm
Bound ribosomes synthesize proteins destined for export from the cell (secreted) or incorporated into organelles
Golgi apparatus - modifies, sorts, packages, and transports proteins and lipids within the cell
The Golgi apparatus modifies, sorts, packages, and transports newly made proteins and lipids
Lysosomes contain hydrolytic enzymes used in digesting food materials and worn-out organelles
Lysosomes contain hydrolytic enzymes used for digestion
Peroxisomes contain oxidative enzymes involved in detoxification reactions
Mitochondria produce ATP through oxidative phosphorylation
Golgi apparatus modifies proteins and lipids produced by RER
Bound ribosomes (rough ER) synthesize proteins that will be transported into the lumen of the ER
Golgi apparatus modifies and packages newly made proteins