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Anatomy & Phsyiology
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Chapter 3

Cells : The Living Unit

A.  The Cell Theory
          - base strucural/functional unit of all living things
          - activity of an organism is based on individual/collective activites of cell
          - biochemical activities of cells are determined & made possible by the
             specific subcellular structures of cells (organelles)
          - continuity of life has a cellular basis
B.  Diversity of Cells
          - cells are composed of carbon, hydrogen, oxygen, nitrogen & other
             trace elements
          - size & shape ~ cell diameter (2mm --> 200 mm)
          - length ~ muscle --> 30 cm & nerve --> 1 meter
          - spherical, disc (red blood cell), branching (nerve),cube (kidney tubule)
C.  Cellular anatomy of composite cell
          - nucleus ~ control center
          - cytoplasm ~ organelles found here
          - plasma membrane ~ boundary
          - ribosomes ~ protein synthesis
          - mitochondria ~ powerhouse
          - golgi appareatus ~ packaging
          - smooth/rough er ~ transport
          - lysosome ~ cellular digestion
          - cell membrane ~ boudary, integrity of cell, found in mosaic model -->
             thin bilayer of phospholipids with protein molecules dispersed in it
          - role of proteins ~ specialize function, transport, receptor, marker;
             recognition for immune system; receptors for hormones/chemical
           - protein ~ 2 distinct populations: integral (fully embedded into plasma
             membrane; some face H2O on 1 side; most span the whole width
             of plasma membrane) & peripheral (not embedded; appendage
             to integral protein)
D.  Specialization of plasma membrane
          - microvelli ~ fingerlike projections of plasma membrane
          - found in absorbtive areas --> kidney tubules & intestines   
          - care of actin filaments (contractile proteins)
          - membrane junctions ~ protein molecules in adjacent cells (spot weld)
             fusing cell membranes together
          - desosomes ~ mechanical (physical) junctions along touching cells
          - junction gaps ~ direct passage between adjacent cells
          - connexons ~ hollow cylinders connecting cells
          - smooth muscle & cardiac cells ~ electrically excitable
          - plasma membrane functions ~ membrane transport (selectively
          - interstital fluid ~ extracellular fluid from blood bathing cells; rich in
            nutrients & waste, vitamins, sugars, fatty acids, salts, hormones
          - selectively permeable ~ passive transport (no energy required)
            active transport requires energy
E.  Cytoplasmic Organelles
          - endoplasmic reticulum ~ connective sacs & canal vesicles used for
            transport, lipid synthesis, attachment for ribosomes; next to nucleus
          - ribosomes ~ rRNA; protein synthesis, located on rough ER
          - golgi appaeratus ~ flattened membranous sac; used for packaging
           and modification (example: hormones)
          - mitochondria ~ membrounous sacs used to convert food molecules
           to ATP, then ADP -->ATP; located in cytoplasmic space
          - lysosome ~ membrane bound sac made of enyzmes used for digestion
           of ingested materials & worn away parts; located in cytoplasmic space
          - peroxisome ~ membrane bound vesicle used for enzyme peroxidose
           and fights toxins; located in cytoplasmic space
          - centrosome ~ contains centrioles (rod like filaments); during cell
           division, pulls apart replicated chromosomes and initiates formatoin of
           cilia; located in cytoplasmic space near the nucleus
          - cilia/flagella ~ microfilaments & tubules used for motility and to propel
           substances across the cell membrane; located on cell membrane
          - vesicles ~ membranous sacs that are used for storage of new materials
           in the cell and is located in the cytoplasmic space
          - microfilaments/tubules ~ cytoskeleton used for shape, motility, and
           support; located in cytoplasm
          - inclusion ~ temporary cell structures used to store nutrients; located in
           the cytoplasmm
          - nucleaur envelope ~ porous double membrane that seperates nuclear
           contents from cytoplasm; it maintains the integerity of nucleus and     
           controls passage of materials between nucleus and cytoplasm
          - nucleus ~ dense, nonmembrous body composed of protein & RNA;
           site of ribosome formation
          - chromatin ~ fibers composed of protein & DNA that contain info
           for synthesizing protiens.

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