Anatomy And Physiology

• Cells are the building blocks of all organisms
• All cells come from the division of preexisting cells
• Cells are the smallest living units that perform all vital physiological functions
• Each cell maintains homeostasis at the cellular level
• Cytology


  The study of cells
• 2 major types of cells

  • Sex cells (germ cells or reproductive cells)
  • Somatic cells (all body cells except sex cells)
• Plasma membrane


  • Isolation
  • Protection
  • Sensitivity
  • Support
  • Controls entry and exit of materials
• Cytoskeleton


  • Proteins organized in fine filaments or slender tubes
  • Functions: Strength and support; movement of cellular structures and materials
• Microvilli


  • Extensions of the plasma membrane containing microfilaments
  • Function: Increase surface area to facilitate absorption of extracellular materials
• Cilia


  • Long extensions of the plasma membrane containing microtubules
  • Functions: Primary cilia act as sensors, motile cilia move materials over cell surfaces
• Proteasomes


  • Hollow cylinders of proteolytic enzymes with regulatory proteins at their ends
  • Function: Breakdown and recycling of damaged or abnormal intracellular proteins
• Ribosomes


  • RNA + proteins; fixed ribosomes bound to rough endoplasmic reticulum; free ribosomes scattered in cytoplasm
  • Function: Protein synthesis
• Golgi apparatus


  • Stacks of flattened membranes (cisternae) containing chambers
  • Functions: Storage, alteration, and packaging of secretory products and lysosomal enzymes
• Mitochondria


  • Double membrane, with inner membrane folds (cristae) enclosing important metabolic enzymes
  • Function: Produce 95% of the ATP required by the cell
• Endoplasmic reticulum (ER)


  • Network of membranous channels extending throughout the cytoplasm
  • Functions: Synthesis of secretory products; intracellular storage and transport; detoxification of drugs or toxins
• Peroxisomes


  • Vesicles containing degradative enzymes
  • Functions: Catabolism of fats and other organic compounds; neutralization of toxic compounds generated in the process
• Lysosomes


  • Vesicles containing digestive enzymes
  • Function: Intracellular removal of damaged organelles or pathogens
• Nucleus


  Control of metabolism; storage and processing of genetic information; control of protein synthesis
• Extracellular fluid (interstitial fluid)


  Watery medium that surrounds a cell
• Plasma membrane (cell membrane)


  Separates cytoplasm from the extracellular fluid
• Functions of the plasma membrane

  • Physical isolation
  • Barrier
  • Regulation of exchange with the environment
  • Sensitivity to the environment
  • Structural support
• Plasma membrane lipids


  • Phospholipid bilayer containing hydrophilic heads and hydrophobic fatty-acid tails
  • Barrier to ions and water-soluble compounds
• Plasma membrane proteins


  • Integral proteins
  • Peripheral proteins
  • Anchoring proteins
  • Recognition proteins
  • Enzymes
  • Receptor proteins
  • Carrier proteins
  • Channels
• Plasma membrane carbohydrates


  • Proteoglycans, glycoproteins, and glycolipids
  • Form sticky "sugar coat" (glycocalyx)
  • Functions: Lubrication and protection, Anchoring and locomotion, Specificity in binding, Recognition (immune response)
• The cytoplasm contains the cytosol (intracellular fluid) with dissolved materials
• Organelles


  • Nonmembranous organelles
  • Membranous organelles
• Cytoskeleton


  • Structural proteins for support, shape and strength
  • Contains: Microfilaments, Intermediate filaments, Microtubules
• Microfilaments


  • Thin filaments composed of the protein actin
  • Provide mechanical strength, Interact with other proteins to adjust consistency of cytosol, Interact with thick filaments of myosin for muscle contraction
• Intermediate filaments


  • Mid-sized between microfilaments and microtubules
  • Durable, Strengthen the cell and maintain its shape, Stabilize position of organelles, Stabilize cell position
• Microtubules


  • Large, hollow tubes of tubulin proteins
  • Attach to centrosome, Strengthen cell and anchor organelles, Change cell shape, Move organelles within the cell with the help of motor proteins, Form spindle apparatus to distribute chromosomes, Form centrioles and cilia of organelles
• Microvilli


  Increase surface area for absorption, Attach to cytoskeleton
• Centrioles


  • Form spindle apparatus (cell shape changer) during cell division
  • Centrosome—cytoplasm next to the nucleus that surrounds centrioles
• Ovillus


  • Microfilaments
  • Plasma membrane
  • Terminal web
  • Mitochondrion
  • Intermediate filaments
  • Endoplasmic reticulum
  • Secretory vesicle
• Cytoskeleton


  • Provides strength and structural support for the cell and its organelles
  • Interactions between cytoskeletal components are also important in moving organelles and in changing the shape of the cell
• Microvilli


  • Increase surface area for absorption
  • Attach to cytoskeleton
• Centrioles


  • Form spindle apparatus (cell shape changer) during cell division
  • Centrosome—cytoplasm next to the nucleus that surrounds centrioles
• Microfilaments and microvilli


  • SEM × 30,000
• Microtubules (yellow) in living cells


  • LM × 3200
• Cilia (singular, cilium)


  • Slender extensions of plasma membrane
  • Move fluids across the cell surface
  • A primary cilium is nonmotile
  • Found on a variety of cells
  • Senses environmental stimuli
  • Motile cilia are found on cells lining the respiratory and reproductive tracts
  • Microtubules in cilia are anchored to a basal body
• Flagellum


  Whip-like extension of cell membrane