LQB281 Introduction to cells and tissues.pdf

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Christine Percy

Introduction  to  Cells  and  Tissues   Learning  Objectives  for  this  Lecture:     1. Describe  the  differences  between  apoptosis  and  necrosis.     2. Define  types  of  cellular  adaption  and  their  causes.     3. Memorise  the  factors  that  determine  whether  these  are  reversible   processors.     4. What  is  an  infarct  and  how  do  they  occur?     5. What  determines  whether  a  stimulus  causes  atrophy  or  infarction?       Definitions  by  alphabetical  order:         Active:  Requiring  energy     Aerobic:  with  oxygen       Anaerobic:  Without  oxygen     Chemical  pathology:  the  study  and  diagnosis  of  disease  from  the  chemical   changes  in  the  tissues  and  fluids.     Cytopathology:  The  investigation  and  diagnosis  of  disease  from  examination   of  isolated  cells       Forensic  Pathology:  the  application  of  pathology  to  legal  purposes.     Genetics:  The  study  of  abnormal  chromosomes  and  genes.     Haematology:  The  study  of  disorders  of  the  cellular  and  coagulable   components  of  blood.     Histopathology:  the  investigation  and  diagnosis  of  disease  from  the   examination  of  tissues.       Hypoxia:  lack  of  oxygen       Ischaemia:  lack  of  blood  supply       Immunology:  the  study  of  the  specific  defence  mechanisms  of  the  body     Microbiology:  the  study  of  infectious  diseases  and  the  organisms  responsible   for  them.       Passive:  Does  not  require  energy       Pathology:  Scientific  study  of  disease       Physiology:  scientific  study  of  the  function  of  living  things     Reperfusion:  restoration  of  blood  following  period  of  ischaemia     Toxicology:  the  study  of  the  effects  of  known  or  suspected  poisons.       Reperfusion  Injury:       Introduction  to  Cells  and  Tissues     Histology:  Haematoxylin  and  Eosin   Spaces  may  appear  in  otherwise  solid  tissue  due  to  slight  shrinkage  during   the  dehydration  phase  of  section  preparation.     Fat  is  often  washed  out  during  preparation  and  also  appears  as  clear  spaces.         Haematoxylin  stains  the  nucleus  dark  blue/purple     Eosin  stains  the  proteins  and  therefore  the  cytoplasm  pink         A  tissue  that  is  stained  very  pink  is  said  to  be  ‘pink-­‐loving’  or  Eosinphilic   On  a  practical  level,  tissues  composed  of  cells  with  abundant   cytoplasm  cells  and/or  extracellular  proteins.         Haematoxylin  is  a  common  base  stain.       Nucleic  acids  and  ribosomes  are  attracted  to  bases,  thus  they  are  basophilic.     Tissues  composed  of  cells  that  have  a  large  nuclei  and  scant  cytoplasm  will  be   dark  blue/purple  stain.         Epithelium:     Simple  Squamous  Epithelium     Single  layer  of  cells  whose  cytoplasm  often  appears  thinner  than  their  nuclei   Line  surfaces  that  are  involved  in  exchanges  of  gasses  and  nutrients.     The  endothelial  lining  of  blood  vessels  is  a  specialised  form  of  simple   squamous  epithelium.       Simple  Cuboidal  Epithelium       Cuboidal  cells  are  as  tall  as  they  are  wide  with  central  nuclei     Provide  lining  for  protected  surfaces  including  ducts  of  endocrine  glands,   collecting  tubules  of  the  kidney  and  the  outer  surface  of  the  ovary.       Pseudostratified  Epithelium     Specialised  epithelium  located  in  the  upper  respiratory  tract  and  sections  of   the  male  reproductive  system.     Although  this  epithelium  appears  to  include  multiple  layers  of  cells,    it  is  only   a  single  layer  of  cells  however  the  nuclei  are  located  at  different  levels  of  the   cytoplasm  giving  the  appearance  of  multiple  layers  of  cells.       Stratified  Squamous  Epithelium     Basal  cuboidal-­‐like  cells  that  mature  as  they  migrate  up  towards  the  surface     Keratinised  upper  layer  reduces  absorption  but  increases  strength       Line  surfaces  exposed  to  abrasion,  friction,  and  physical  stress.       Stratified  Cuboidal/Columnar  Epithelium  ★     A  fairly  rare  type  of  epithelium     Some  large  ducts  are  lined  by  columnar  on  top  of  cuboidal  cells  with  cilia   when  located  within  areas  of  the  soft  palate  and  epiglottis.     Introduction  to  Cells  and  Tissues   Stratified  cuboidal  epithelium  lines  the  mammary  glands,  parts  of  the   cochlea,  germ  cells  of  the  seminiferous  tubules  and  granulosa  cells  of  the   ovarian  follicles.       Transitional  Epithelium     Restricted  to  urinary  system.     Allow  stretch  and  retraction  and  are  lined  by  stratified  cells  that  when   relaxed  appear  stratified  columnar  but  when  stretched  look  like  stratified   cuboidal/squamous.           Myocytes  (Muscle  Cells):       Skeletal  Muscle  Fibres     Referred  to  as  striated  muscle  or  voluntary  muscle.      The  cytoplasm  has  alternating  light  and  dark  bands  called  cross  striations.       Cardiac  Myocytes     Individual  cells  with  single,  central  nuclei     Intercalated  discs  connect  cells  end  to  end  allowing  coordinated  contraction     Branching  fibres     Smooth  Muscle     Loose  connective  tissue  with  some  smooth  muscle  cells     Dense  layer  of  smooth  muscle       Connective  Tissue:       Fibroblasts  and  collagen         Fibroblasts  secreting  collagen,  a  long  stringy  protein     Adipocytes  (Fat)       Large  cells  whose  cytoplasm  is  full  of  fat,  which  is  often  lost  in  section.       Nucleus  against  the  edge         Cell  Types:     Red  blood  cells,  neutrophils,  lymphocytes  and  macrophages       Introduction  to  Cells  and  Tissues   Structures:     Vessels,  nerves  and  cartilage.           Structure  and  Function:     Site   Feature   Function   Stratified  Squamous   Skin   Epithelium  Keratinized   External  barrier   hair   Mouth     Oesophagus   Stratified  squamous   Vagina     epithelium   Transit  tubes   Anus   Stomach   Simple  columnar   Secretion  of  enzymes  and   Gastric  glands  and  pits   mucous,  mixing   Simple  columnar  with   Absorption  of  most   Small  Intestine     brush  border  and  villi   nutrients   ñ  Surface  Area   Absorption  of  H O, 2  Large  Intestine   Simple  columnar  with  lots   lubrication  for  faecal   of  goblet  cells   transit     Conductive  respiratory   Ciliated  columnar   Remove  mucous  and   region     epithelium   entrapped  particulate   Simple  squamous   Alveoli   epithelium   Gas  exchange   Simple  cuboidal  with   Secretion  and   Renal  tubules   microvilli  predominately  in   reabsorption   the  proximal  tubules   Renal  Pelvis   Ureter   Transitional  epithelium   Stretch  and  retract   Urinary  Bladder   Cardiac  and  skeletal   Strength,  elastic   Myocytes   Striated  muscle   Concerted  action       3  Types  of  Tissues:       Labile  (continuously  dividing)       Stable  (Quiescent)       Permanent  (non-­‐dividi
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