tissue types and structure

• 4 tissue types

  1. epithelial
  2. connective
  3. muscle
  4. nervous
• origins of body tissue

  labels

  A) endoderm

  B) ectoderm

  C) mesoderm

  
• 5 types of cell junctions

  1. tight
  2. adherens
  3. desmosomes
  4. hemidesmosomes
  5. gap
• cell junction

  labels

  A) tight

  B) adherens

  C) desmosome

  D) hemidesmosome

  E) gap

  
• cell junctions function


  joining cells in tissues
• tight junction structure

  • strands of transmembrane proteins (for impermeable seal between adjacent cells
• tight junctions are found

  in epithelium
• tight junction function

  • barrier to molecules or pathogens
  • first line of defence (as skin)
• adherens junction structure

  • cadherins (transmembrane protein) connect to microfilaments or actin filaments
  • part of cytoskeleton
  • on adhesion belt
• adheren junction function

  • mechanical
  • help cell resist strains and stress
  • holds cells together
• desmosomes structure

  • have cadherins
  • connected internally to plaque
  • connected to keratin
• desmosome function

  • found at spots or small regions between adjacent cells
  • keratin filaments connect to other desmosome junctions, stress spread throughout tissue, allows cell to resist mechanical trauma
• hemidesmosome structure

  • plaque
  • connect basement membrane and transmembrane proteins with integrins
• hemidesmosome function

  • whole sheet of cells firmly attaches to basement membrane
  • cells are resistant to being pulled apart and off the basement membrane
• gap junction structure

  • connexins (individual protein components) 6 each, which form pore between adjacent cells
  • pores are 1.5nm in diameter
• gap junction function

  • cell communication
  • allow passage of small ions, molecules and electrical signals between adjacent cells
• nervous tissue cell types

  neurons, neuroglia
• neurons function 


  generate and conduct nerve impulses
• neuron cell body contains

  nucleus and other organelles
• neuron dendrites receive signals
• neuron axons conduct signal over


  long distances
• neuroglia function 


  non-conducting, insulate, support and protect neurons
• types of neurons

  labels

  A) multipolar

  B) bipolar

  C) unipolar

  
• brain

  labels

  A) motor cortex

  B) sensory cortex

  
• somatic and autonomic nervous system


  motor output
• sensory input 


  somatic senses e.g. touch, pain

  special sense e.g. hearing and vision
• 3 types of muscle

  skeletal, cardiac and smooth
• skeletal muscle is under conscious control (99% connected to the skeleton), what muscle isn't

  tongue, bladder, anal sphincters
• cardiac muscle is not under conscious control
• smooth muscle lines our GI tract, parts of respiratory system, blood vessels is not under conscious control
• skeletal muscle structure

  • long cylindrical cells, many peripheral nuclei
  • myofilament arrangement (striated)
  • attach bone to skeleton
  • parallel fibres
• cardiac muscle structure

  • walls of the heart
  • central nuclei
  • cells joined end to end by intercalated discs
  • striated and involuntary
• smooth muscle structure

  • no striations
  • cells thick in middle, taper either end
  • central nucleus
  • found in walls of hollow structures
• smooth muscles are connected via gap junctions in the intestines
• epithelial tissue function

  • covers body surfaces
  • lines hollow organs
  • forms glands
• epithelial tissue structure

  • forms continuous sheets
  • avascular
  • innervated
  • high proliferative potential (high cell division rate)
• avascular means


  have no blood vessels running through them
• innervated means


  when touch, can feel extremely sensitively (lots of nerves)
• epithelium structure

  labels

  A) basement membrane

  
• simple epithelium has 


  one layer