c2

• Cells are the structural and functional unit of all living things, including humans
• Cell


  • Plasma membrane
  • Cytoplasm containing organelles
  • Nucleus
• Cells are in constant communication with their environment
• Body fluids


  Dynamic, meaning that fluid moves between the compartments of the body, which allows for the movement of solutes and maintains the relative volumes of blood and interstitial fluid
• Body fluids


  • Intracellular (2/3)
  • Extracellular fluid (1/3)
• Intracellular


  Inside the cell
• Intravascular


  Inside blood vessels
• Intercellular


  In between cells
• Selectively permeable membranes


  Membranes that allow only some substances to pass through it
• Selectively permeable membranes separate body fluids into distinct compartments
• Cell membranes of individual cells separate ICF from ECF and blood vessel walls separate blood plasma from interstitial fluid
• Major components of all body fluids

  • Water
  • Solutes (mainly electrolytes)
• Functional characteristics of cells

  • Cell metabolism and energy use
  • Synthesis of molecules
  • Communication
  • Reproduction and inheritance
• Analogy: cell = factory, organelles in the cell work station carrying out different activities
• Plasma membrane


  Also known as the cell membrane, sarcolemma, plasmalemma
• Plasma membrane


  • Encloses and supports cellular contents
  • Controls what goes into the cell and what comes out
  • Regulates intra vs extracellular material
  • Role in inter-cellular (cell-to-cell) communication
  • Production of a charge difference (membrane potential) across the membrane
• Plasma membrane structure


  • Lipid bilayer (phospholipid bilayer and cholesterol) (45-50%)
  • Carbohydrates (4-8%)
  • Proteins (45-50%)
• Fluid mosaic model


  Polar heads facing water in the interior and exterior of the cell (hydrophilic); Nonpolar tails facing each other on the interior of the membrane (hydrophobic)
• Glycocalyx


  Outer surface of cell membrane, composed of glycoproteins (carbohydrates and proteins) and glycolipids (carbohydrates and lipids)
• Cytoplasm


  Cellular fluid material outside the nucleus but within the boundaries of the plasma membrane
• Components of cytoplasm


  • Organelles
  • Cytosol
• Cytosol


  Fluid portion of the cytoplasm (ions and proteins in water)
• Cytoplasmic inclusions


  • Aggregates of chemicals
• Cytoskeleton


  • Supports the cell and its organelles
  • Responsible for changes to the shape of the cell and movement of its organelles
• Microtubules


  Hollow, made of tubulin, internal scaffold, transport, cell division
• Microfilaments


  Actin, structure, support for microvilli, contractility, movement
• Intermediate filaments


  Provide mechanical strength
• Nucleus


  Control centre of the cell, contains DNA which carries the code for the structural and functional characteristics of the cell
• Nuclear envelope


  • A bilayer membrane surrounding the nucleus, porous
• Nucleoplasm


  Fluid portion of the nucleus
• Nucleolus


  Primarily produces ribosomes
• Chromatin


  DNA complexed with proteins (histones)
• Chromosome


  Chromatin condensed into pairs of chromatids joined by a centromere, during cell division
• Ribosomes


  Sites of protein synthesis, composed of 2 subunits: large and small
• Endoplasmic reticulum (ER)


  • Fattened, interconnecting sacs and tubules
  • Rough ER - with ribosomes
  • Smooth ER - without ribosomes
• Rough ER


  Synthesis and modification of proteins
• Smooth ER


  Site of lipid, steroid and carbohydrate synthesis, detoxification of harmful substances, breakdown of glycogen to glucose
• Golgi apparatus


  Flattened membranous sacs, with cisternae, modifies, packages and distributes proteins and lipids that are made in the rough ER
• Lysosomes


  Membrane-bound vesicles that form at the Golgi apparatus, contain enzymes, cell's "demolition crew" that digest molecules no longer needed by the cell
• Mitochondria


  • Outer membrane, intermembrane space, inner membrane, matrix, change shape continuously, have their own genetic material