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

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  1. 1. Active Processes <ul><li>ATP is necessary to transport substances that are: </li></ul><ul><ul><li>Too large </li></ul></ul><ul><ul><li>Non-soluble </li></ul></ul><ul><ul><li>Unable to move across its concentration gradient </li></ul></ul><ul><li>Active Transport </li></ul><ul><ul><li>Primary & Secondary Active Transport </li></ul></ul><ul><li>Vesicular Transport </li></ul><ul><ul><li>Endocytosis & Exocytosis </li></ul></ul>
  2. 2. Primary Active Transport <ul><li>The energy to do work comes directly from the hydrolysis of ATP </li></ul><ul><li>Example: Sodium-Potassium Pump </li></ul>
  3. 3. The Na + - K + Pump <ul><li>Na + -K + ATPase maintains ↑ [K + ] inside cells & ↑ [Na + ] outside cells </li></ul><ul><li>Binds 3 Na + : 2 K + </li></ul><ul><li>Creates cell membrane’s electrochemical gradient </li></ul><ul><li>Crucial to cardiac & skeletal muscle, and nervous functions </li></ul><ul><li>See video </li></ul>
  4. 4. Resting Membrane Potential <ul><li>Selective permeability allows for the generation of a membrane potential (voltage) </li></ul><ul><li>At rest, the cell membrane has a (-) membrane potential </li></ul><ul><li>Important to excitable tissue like nervous tissue </li></ul>
  5. 5. Secondary Active Transport <ul><li>Indirectly driven by primary active transport through the creation of ionic gradients </li></ul><ul><li>Molecules or ions move from regions of lower concentration to regions of higher concentration </li></ul>
  6. 6. Vesicular Transport <ul><li>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 </li></ul><ul><li>Exocytosis: Out of the cell </li></ul><ul><li>Endocytosis: Into the cell </li></ul>
  7. 7. Exocytosis <ul><li>Secretions within vesicles dock at the membrane and are released as the cell & vesicular membranes fuse </li></ul><ul><li>Used during hormone secretion, neurotransmitter release, mucus secretion & waste elimination </li></ul>
  8. 8. Endocytosis: Clathrin-mediated <ul><li>The main process used for endocytosis </li></ul><ul><li>Clathrin-mediated transport is used during phagocytosis, pinocytosis, and receptor-mediated endocytosis </li></ul><ul><li>Clathrin is a lattice-like protein that cages in cargo for transport into the cell </li></ul>
  9. 9. Endocytosis: Phagocytosis <ul><li>Primarily used by defense cells like WBCs and macrophages </li></ul><ul><li>Large, solid substances such as bacteria and dead cells are engulfed and subsequently destroyed </li></ul>
  10. 10. Endocytosis: Pinocytosis <ul><li>Droplets of extracellular fluid containing dissolved particles are folded into the plasma membrane </li></ul><ul><li>Nutrients dissolved in extracellular fluid are taken into the cell </li></ul><ul><li>Particularly important in the lining of the small intestine </li></ul>
  11. 11. Endocytosis: Receptor-mediated <ul><li>Selective mechanism for bringing specific macromolecules into the cell </li></ul><ul><li>Receptors bind with their specific ligands (enzymes, insulin, hormones) and are endocytosed </li></ul>
  12. 12. The Cytoplasm <ul><li>Gel-like material, consistency of room temperature butter </li></ul><ul><li>Contains the cytosol (viscous, clear liquid), organelles (“cell machinery”), the cytoskeleton (scaffolding & motor units), and inclusion bodies (stored nutrients, pigmentation) </li></ul><ul><li>Most cellular activities take place in the cytoplasm </li></ul>
  13. 13. Mitochondria <ul><li>Organelle whose inner membrane is folded into shelf-like partitions called “cristae” </li></ul><ul><li>Abundance depends on cell type </li></ul><ul><li>Function: &quot;Power plants of the cell” </li></ul>
  14. 14. Ribosomes <ul><li>Small granules dispersed throughout the cytoplasm and on the membranes of Rough ER, composed of ribosomal RNA and protein </li></ul><ul><li>Function: protein synthesis </li></ul>
  15. 15. Endoplasmic Reticulum <ul><li>Network of interconnected parallel membranes that is continuous with the nuclear membrane </li></ul><ul><li>Rough ER : Studded with ribosomes </li></ul><ul><li>Smooth ER : No ribosomes </li></ul>
  16. 16. RER & Protein Synthesis <ul><li>Newly synthesized proteins are taken into the RER cisternae where they undergo modification before they are transported where needed </li></ul><ul><li>RER is also a “membrane factory”. External face is site for phospholipid synthesis </li></ul>
  17. 17. Smooth Endoplasmic Reticulum <ul><li>Contains enzymes that catalyze the synthesis of lipids and steroids </li></ul><ul><li>Plays a role in lipid metabolism and drug detoxification </li></ul><ul><li>Catalyzes the decomposition of glycogen to release glucose </li></ul><ul><li>In muscle, stores Ca +2 </li></ul>
  18. 18. Golgi Apparatus <ul><li>Flattened membranous sacs (&quot;cisternae&quot;) arranged in stacks associated with many vesicles </li></ul><ul><li>Function: modification, packaging, and transport of proteins, the cell’s “traffic director” </li></ul>
  19. 19. Lysosomes <ul><li>Spherical membranous sacs containing digestive enzymes (acid hydrolase) </li></ul><ul><li>Lysosome Function: “demolition crew of the cell“ </li></ul>
  20. 20. Review: Endomembrane System
  21. 21. Peroxisomes <ul><li>Membrane sacs that look like lysosomes abundant in liver and kidney cells containing oxidases </li></ul><ul><li>Oxidases detoxify harmful substances & neutralize free radicals by converting them into hydrogen peroxide and water </li></ul>