Injury, Inflammation, Repair

• 6 structural levels of organisation

  Chemical, cellular, tissue, organ, organ system, organism
• 3 principle parts of a cell

  Nucleus, cytoplasm, plasma membrane
• 4 basic types of tissue

  Epithelial, connective, muscular, nervous
• Covering and lining epithelium

  Simple squamous, simple cuboidal, simple columnar, pseudostratified columnar, stratified, transitional
• Where is Glandular epithelium located?

  Endocrine glands & exorcise glands
• What is Vasodilation?


  Smooth muscle relaxes, widening blood vessels and increasing blood flow to tissue of capillary beds.
• What is Vascular Permeability?

  Endothelial cells no longer adhere to each other allowing fluid and proteins to seep into blood stream.
• What is Exudation?


  Fluid and proteins escape from intravascar space due to increased pressure.
• What is Vascular Stasis?

  Vasodilation and exudation work together to slow blood flow and collect chemical mediators and inflammatory mediators at site of injury.
• Acute vs chronic inflammatory response

  Acute: predominantly polymorphonuclear neutrophils

  Chronic: predominantly macrophages and lymphocytes
• What stages are involved in the reparation process?

  1. Vascular response
  2. Inflammation
  3. Proliferation
  4. Maturation
• Vascular response phase


  Fibrin & Glycoprotein form a clot.

  Leukocyte response - neutrophils migrate to form granulation tissue.
• Inflammation phase (1-3 days)


  Rapid influx of Neutrophils = pus

  Influx of monocytes to phagocytes debris/bacteria & secrete growth factors (TGF, TNF, PDGF, FGF)

  Helps to epithelialise
• Proliferation phase


  Angiohenesis & collagen formation.

  Fibroblasts enter at day 3, proliferate and increase Type III collagen.
• What causes keloids and fibroplasia ?

  Excessive collagen production
• Maturation phase


  Contraction - skin edges move to centre.

  Scar matures (days 5-17) & further collagen remodelling.
• Healing by Primary Intention

  Minimal/no loss of tissue.

  Incision causes trauma but no tissue loss.

  Wound is closed immediately or <6hrs

  Allows faster healing and minimal scarring.
• Healing by Secondary Intention

  Spontaneous healing, wound intentionally left open.

  E.g. large piece of skin removed and wound cannot be closed due to inflammation/infection or trauma.
• Hyperimmune vs Autoimmune response

  Hyper = response is disproportionately high to damage caused.

  Auto = body attacks itself
• What type of WBC indicates an acute inflammatory response?

  Polymorphonuclear Neutrophils (PMN's)
• Which type of WBC indicates a chronic inflammatory response?

  Macrophages & Lymphocytes
• Apoptosis 


  Programmed cell death

  normal cell -> form small blebs -> nucleus breaks apart and DNA breaks. -> cell breaks into several apoptotic bodies (organelles still functional)
• Necrosis


  Normal cell -> small blebs form, nucleus structure changes -> blebs fuse and become larger (no organelles in blebs) -> cell membrane ruptures and releases contents (organelles not functional)
• intrinsic pathway 


  mitochondria can start or delay.

  • start - cytochrome c from mitochondria activates series of caspases which cleave other proteins and cause cell death
  • Delay - Bcl-2 proteins delay apoptosis and are found on outer membrane of mitochondria
• Anaplasia


  Back Formation - Poor differentiation
• Hypoplasia


  Decreased number of cells produced.
• Dysplasia


  Difficulty forming cells - may become cancerous.
• Hyperplasia


  Increased number of cells produced

  Example: Prostatic Hyperplasia & Cushing's Syndrome (Adrenal cortex and gland - excess cells)
• Metaplasia


  Change in cell form, usually in response to a stimuli (Trauma/injury)

  • Example: Smoking irritates the bronchiole epithelium so it changes shape.
• Neoplasia


  New formation - abnormal/excessive cell growth
• Hypertrophy


  Increased size of cells NOT number.
• Human Germinal Layers

  1. Endoderm - Internal layer
  2. Lungs, thyroid, pancreas & digestive tract
  3. Mesoderm - Middle layer
  4. Cardiac/Skeletal?/Smooth muscle (kidney, blood cells and fat)
  5. Ectoderm - Outer Layer
  6. skin, neurons, melanocytes, hair & nails, corneal, tooth etc