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Spring 2010 chapter 3b PowerPoint for BIOL2401 (Human Anatomy & Physiology) at San Antonio College with Alba

Spring 2010 chapter 3b PowerPoint for BIOL2401 (Human Anatomy & Physiology) at San Antonio College with Alba



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    Chapter3b Chapter3b Presentation Transcript

    • Active Processes
      • ATP is necessary to transport substances that are:
        • Too large
        • Non-soluble
        • Unable to move across its concentration gradient
      • Active Transport
        • Primary & Secondary Active Transport
      • Vesicular Transport
        • Endocytosis & Exocytosis
    • Primary Active Transport
      • The energy to do work comes directly from the hydrolysis of ATP
      • Example: Sodium-Potassium Pump
    • The Na + - K + Pump
      • Na + -K + ATPase maintains ↑ [K + ] inside cells & ↑ [Na + ] outside cells
      • Binds 3 Na + : 2 K +
      • Creates cell membrane’s electrochemical gradient
      • Crucial to cardiac & skeletal muscle, and nervous functions
      • See video
    • Resting Membrane Potential
      • Selective permeability allows for the generation of a membrane potential (voltage)
      • At rest, the cell membrane has a (-) membrane potential
      • Important to excitable tissue like nervous tissue
    • Secondary Active Transport
      • Indirectly driven by primary active transport through the creation of ionic gradients
      • Molecules or ions move from regions of lower concentration to regions of higher concentration
    • Vesicular Transport
      • Large particles, macromolecules, and larger volumes of fluids do not fit through channels of protein pumps and must be transported in and out of the cell through vesicles
      • Exocytosis: Out of the cell
      • Endocytosis: Into the cell
    • Exocytosis
      • Secretions within vesicles dock at the membrane and are released as the cell & vesicular membranes fuse
      • Used during hormone secretion, neurotransmitter release, mucus secretion & waste elimination
    • Endocytosis: Clathrin-mediated
      • The main process used for endocytosis
      • Clathrin-mediated transport is used during phagocytosis, pinocytosis, and receptor-mediated endocytosis
      • Clathrin is a lattice-like protein that cages in cargo for transport into the cell
    • Endocytosis: Phagocytosis
      • Primarily used by defense cells like WBCs and macrophages
      • Large, solid substances such as bacteria and dead cells are engulfed and subsequently destroyed
    • Endocytosis: Pinocytosis
      • Droplets of extracellular fluid containing dissolved particles are folded into the plasma membrane
      • Nutrients dissolved in extracellular fluid are taken into the cell
      • Particularly important in the lining of the small intestine
    • Endocytosis: Receptor-mediated
      • Selective mechanism for bringing specific macromolecules into the cell
      • Receptors bind with their specific ligands (enzymes, insulin, hormones) and are endocytosed
    • The Cytoplasm
      • Gel-like material, consistency of room temperature butter
      • Contains the cytosol (viscous, clear liquid), organelles (“cell machinery”), the cytoskeleton (scaffolding & motor units), and inclusion bodies (stored nutrients, pigmentation)
      • Most cellular activities take place in the cytoplasm
    • Mitochondria
      • Organelle whose inner membrane is folded into shelf-like partitions called “cristae”
      • Abundance depends on cell type
      • Function: "Power plants of the cell”
    • Ribosomes
      • Small granules dispersed throughout the cytoplasm and on the membranes of Rough ER, composed of ribosomal RNA and protein
      • Function: protein synthesis
    • Endoplasmic Reticulum
      • Network of interconnected parallel membranes that is continuous with the nuclear membrane
      • Rough ER : Studded with ribosomes
      • Smooth ER : No ribosomes
    • RER & Protein Synthesis
      • Newly synthesized proteins are taken into the RER cisternae where they undergo modification before they are transported where needed
      • RER is also a “membrane factory”. External face is site for phospholipid synthesis
    • Smooth Endoplasmic Reticulum
      • Contains enzymes that catalyze the synthesis of lipids and steroids
      • Plays a role in lipid metabolism and drug detoxification
      • Catalyzes the decomposition of glycogen to release glucose
      • In muscle, stores Ca +2
    • Golgi Apparatus
      • Flattened membranous sacs ("cisternae") arranged in stacks associated with many vesicles
      • Function: modification, packaging, and transport of proteins, the cell’s “traffic director”
    • Lysosomes
      • Spherical membranous sacs containing digestive enzymes (acid hydrolase)
      • Lysosome Function: “demolition crew of the cell“
    • Review: Endomembrane System
    • Peroxisomes
      • Membrane sacs that look like lysosomes abundant in liver and kidney cells containing oxidases
      • Oxidases detoxify harmful substances & neutralize free radicals by converting them into hydrogen peroxide and water