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Transcript
Essentials of Anatomy & Physiology, 4th Edition Martini / Bartholomew 3 Cell Structure and Function PowerPoint® Lecture Outlines prepared by Alan Magid, Duke University Slides 1 to 102 Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings The Cell Membrane Key Note Things tend to even out, unless something—like a cell membrane— prevents this from happening. Across a freely permeable or water permeable membrane, diffusion and osmosis will quickly eliminate concentration gradients. Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings The Cell Membrane Membrane Transport • Permeability – property that determines which substances can enter/leave the cytoplasm • Freely – any substance crosses • Selective – certain substances cross • Permeability factors • Molecular size/shape • Electrical charge • Lipid solubility Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings The Cell Membrane Membrane Transport Processes • Passive Transport – no energy expended • Diffusion (includes osmosis) • Filtration • Facilitated Transport (carrier-mediated) • Active Transport – energy expended • Carrier-Mediated • Vesicular Transport • Endocytosis • Exocytosis Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings The Cell Membrane Membrane Transport Definitions • Diffusion Random movement down a concentration gradient (higher to lower [C]) • Osmosis Movement of water across a membrane down a gradient in osmotic pressure (lower to higher osmotic pressure) Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings The Cell Membrane Diffusion Figure 3-4 The Cell Membrane Diffusion Across Cell Membranes Figure 3-5 The Cell Membrane Osmosis Figure 3-6 The Cell Membrane Osmotic Effects of Solutions on Cells • Isotonic—Cells maintain normal size and shape • Hypertonic—Cells lose water osmotically and shrink and shrivel • Hypotonic—Cells gain water osmotically and swell and may burst. Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings The Cell Membrane Osmotic Flow across a Cell Membrane Figure 3-7 The Cell Membrane Passive Membrane Transport • Filtration • Hydrostatic pressure pushes on water • Water crosses membrane • Small solutes follow water through pores • Examples: blood pressure and urine formation Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings The Cell Membrane Carrier-Mediated Transport - Passive • Membrane proteins as carriers • Facilitated Diffusion (no ATP required) • Co-transport • Counter-transport Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings The Cell Membrane Facilitated Diffusion Figure 3-8 Carrier-Mediated Transport – Active • Active transport (ATP consumed) • Independent of concentration gradients • Ion pumps - Na+/K+ Exchange Pump The Cell Membrane The SodiumPotassium Exchange Pump Figure 3-9 The Cell Membrane Vesicular Transport • Active Transport • Membranous vesicles move material into/out of cell • Types: • Endocytosis - movement into cell • Receptor-Mediated • Pinocytosis – cell drinking • Phagocytosis – cell eating • Exocytosis - Movement out of cell Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Ligands EXTRACELLULAR Ligands binding FLUID to receptors Receptor-Mediated Endocytosis Target molecules (ligands) bind to receptors in cell membrane. Endocytosis Exocytosis Ligand receptors Areas coated with ligands form deep pockets in membrane surface. Pockets pinch off, forming vesicles. CYTOPLASM Coated vesicle Vesicles fuse with lysosomes. Ligands are removed and absorbed into the cytoplasm. Lysosome Ligands removed Fused vesicle and lysosome Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings The membrane containing the receptor molecules separates from the lysosome. The vesicle returns to the surface. Figure 3-10 1 of 8 EXTRACELLULAR Ligands binding FLUID to receptors Ligands Receptor-Mediated Endocytosis Target molecules (ligands) bind to receptors in cell membrane. Ligand receptors CYTOPLASM Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 3-10 2 of 8 EXTRACELLULAR Ligands binding FLUID to receptors Ligands Receptor-Mediated Endocytosis Target molecules (ligands) bind to receptors in cell membrane. Endocytosis Ligand receptors Areas coated with ligands form deep pockets in membrane surface. CYTOPLASM Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 3-10 3 of 8 Ligands EXTRACELLULAR Ligands binding FLUID to receptors Receptor-Mediated Endocytosis Target molecules (ligands) bind to receptors in cell membrane. Endocytosis Ligand receptors Areas coated with ligands form deep pockets in membrane surface. Pockets pinch off, forming vesicles. CYTOPLASM Coated vesicle Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 3-10 4 of 8 Ligands EXTRACELLULAR Ligands binding FLUID to receptors Receptor-Mediated Endocytosis Target molecules (ligands) bind to receptors in cell membrane. Endocytosis Ligand receptors Areas coated with ligands form deep pockets in membrane surface. Pockets pinch off, forming vesicles. CYTOPLASM Coated vesicle Vesicles fuse with lysosomes. Lysosome Fused vesicle and lysosome Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 3-10 5 of 8 Ligands EXTRACELLULAR Ligands binding FLUID to receptors Receptor-Mediated Endocytosis Target molecules (ligands) bind to receptors in cell membrane. Endocytosis Ligand receptors Areas coated with ligands form deep pockets in membrane surface. Pockets pinch off, forming vesicles. CYTOPLASM Coated vesicle Vesicles fuse with lysosomes. Ligands are removed and absorbed into the cytoplasm. Lysosome Fused vesicle and lysosome Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 3-10 6 of 8 Ligands EXTRACELLULAR Ligands binding FLUID to receptors Receptor-Mediated Endocytosis Target molecules (ligands) bind to receptors in cell membrane. Endocytosis Ligand receptors Areas coated with ligands form deep pockets in membrane surface. Pockets pinch off, forming vesicles. CYTOPLASM Coated vesicle Vesicles fuse with lysosomes. Ligands are removed and absorbed into the cytoplasm. Lysosome Ligands removed The membrane containing the receptor molecules separates from the lysosome. Fused vesicle and lysosome Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 3-10 7 of 8 Ligands EXTRACELLULAR Ligands binding FLUID to receptors Receptor-Mediated Endocytosis Target molecules (ligands) bind to receptors in cell membrane. Endocytosis Exocytosis Ligand receptors Areas coated with ligands form deep pockets in membrane surface. Pockets pinch off, forming vesicles. CYTOPLASM Coated vesicle Vesicles fuse with lysosomes. Ligands are removed and absorbed into the cytoplasm. Lysosome Ligands removed Fused vesicle and lysosome Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings The membrane containing the receptor molecules separates from the lysosome. The vesicle returns to the surface. Figure 3-10 8 of 8 Phagocytosis Cell membrane of phagocytic cell Lysosomes A phagocytic cell comes in contact with the foreign object and sends pseudopodia (cytoplasmic extensions) around it. The pseudopodia approach one another and fuse to trap the material within the vesicle. The vesicle moves into the cytoplasm. Vesicle Lysosomes fuse with the vesicle. Foreign object Pseudopodium (cytoplasmic extension) This fusion activates digestive enzymes. CYTOPLASM EXTRACELLULAR FLUID Undissolved residue The enzymes break down the structure of the phagocytized material. Residue is then ejected from the cell by exocytosis. Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 3-11 1 of 8 Phagocytosis Cell membrane of phagocytic cell A phagocytic cell comes in contact with the foreign object and sends pseudopodia (cytoplasmic extensions) around it. Foreign object Pseudopodium (cytoplasmic extension) CYTOPLASM EXTRACELLULAR FLUID Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 3-11 2 of 8 Phagocytosis Cell membrane of phagocytic cell A phagocytic cell comes in contact with the foreign object and sends pseudopodia (cytoplasmic extensions) around it. The pseudopodia approach one another and fuse to trap the material within the vesicle. Foreign object Pseudopodium (cytoplasmic extension) CYTOPLASM EXTRACELLULAR FLUID Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 3-11 3 of 8 Phagocytosis Cell membrane of phagocytic cell A phagocytic cell comes in contact with the foreign object and sends pseudopodia (cytoplasmic extensions) around it. The pseudopodia approach one another and fuse to trap the material within the vesicle. The vesicle moves into the cytoplasm. Vesicle Foreign object Pseudopodium (cytoplasmic extension) CYTOPLASM EXTRACELLULAR FLUID Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 3-11 4 of 8 Phagocytosis Cell membrane of phagocytic cell Lysosomes A phagocytic cell comes in contact with the foreign object and sends pseudopodia (cytoplasmic extensions) around it. The pseudopodia approach one another and fuse to trap the material within the vesicle. The vesicle moves into the cytoplasm. Vesicle Lysosomes fuse with the vesicle. Foreign object Pseudopodium (cytoplasmic extension) CYTOPLASM EXTRACELLULAR FLUID Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 3-11 5 of 8 Phagocytosis Cell membrane of phagocytic cell Lysosomes A phagocytic cell comes in contact with the foreign object and sends pseudopodia (cytoplasmic extensions) around it. The pseudopodia approach one another and fuse to trap the material within the vesicle. The vesicle moves into the cytoplasm. Vesicle Lysosomes fuse with the vesicle. Foreign object Pseudopodium (cytoplasmic extension) CYTOPLASM This fusion activates digestive enzymes. EXTRACELLULAR FLUID Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 3-11 6 of 8 Phagocytosis Cell membrane of phagocytic cell Lysosomes A phagocytic cell comes in contact with the foreign object and sends pseudopodia (cytoplasmic extensions) around it. The pseudopodia approach one another and fuse to trap the material within the vesicle. The vesicle moves into the cytoplasm. Vesicle Lysosomes fuse with the vesicle. Foreign object Pseudopodium (cytoplasmic extension) CYTOPLASM EXTRACELLULAR FLUID Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings This fusion activates digestive enzymes. The enzymes break down the structure of the phagocytized material. Figure 3-11 7 of 8 Phagocytosis Cell membrane of phagocytic cell Lysosomes A phagocytic cell comes in contact with the foreign object and sends pseudopodia (cytoplasmic extensions) around it. The pseudopodia approach one another and fuse to trap the material within the vesicle. The vesicle moves into the cytoplasm. Vesicle Lysosomes fuse with the vesicle. Foreign object Pseudopodium (cytoplasmic extension) This fusion activates digestive enzymes. CYTOPLASM EXTRACELLULAR FLUID Undissolved residue The enzymes break down the structure of the phagocytized material. Residue is then ejected from the cell by exocytosis. Copyright © 2007 Pearson Education, Inc., publishing as Benjamin Cummings Figure 3-11 8 of 8 Coloring Workbook The packet will be due the day before the test. You can now complete numbers 8, 9, 10 and 11.
