Week 1(2) Acute Inflammatory Diseases Flashcards
General Appendix Information
- extends from the interior tip of teh caecum
- no obvious function
- averages 6-7cm in length
- histologic structure is siilar to the colon
Histology of appendix
From outer layer
= Adventitia
=Muscularis externa
=Sub mucosa
Pathogenesis of ACUTE APPENDICITIS (STEPS)
1. LUMINAL OBSTRUCTION (50-80%) - feacal, gallstone, tumour, ball of worms (AHH!)
- Continued secretion of MUCUS (leads to increased pressure)
- Possible ischemia
- Acute musosal inflammation
- Secondary BACTERIAL infection
- spread of inflammation trasmurally
Stages of ACUTE APPENDICITIS
- Early acute appendicitis (mucosal inflammation)
- Acute suppurative appendicitis (transmural inflammation)
- Acute gangrenous appendicitis (necrosis through muscularis propria)
What happens at each STAGE of acute appendicitis
Stage One: EARLY ACUTE -
neutrophilic exudate in mucosa
mild vasodilation
Stage Two: Acute suppuratice appendicitis
- inflammaition spreads
- mucosal ulceration and puralent exudate in lumen
- dialated blood vessels
Stage Three: Acute Gangrenous Appendicitis
- necrosis extending through the muscalaris propia
- followed by RUPTURE and acute peritonitis
What causes NECROSIS and ULCERATION development in acute appendicitis?
- large numbers of NEUTROPHILS releasing enzymes and oxygen free radicals
- also from bacterial toxinsw
What are the MACROSCOPIC features of acute suppurative appendicitis
- the serosa will be covered by pale exudate
- the appendix is likely to have thicker walls
- there may be mucosal ulceration and necrosis/pus
- there may be solid faeces and pus in lumen
What are the CLINICAL features of acute appendicitis?
- abdominal pain (initially vague, crampsm due to stretching of appendix - within hours pain increases difficulty walking and standing)
- low grade fever
- nausea, vomiting
- neutrophilia
- anorexia
A complication of ACUTE APPENDICITIS =
Perforation! (Due to transmural necrosis - spread of faecal organisms into peritoneal cavity)
= REALLY SEVERE PAIN
Generalised Peritonitis: severe pain, high fever, rapid progression to septic shock
Generalised Suppurative Peritonitisis:
- lots of neutrophils, exudate, feacal contents in poeritoneal cavity
- necrosis of appendix wall caused by enzymes and oxygen free radicals released from neutrophils and bacterial infection
What is SEPTIC SHOCK?
Gram negative bacteria entering and proliferating in the blood stream!
Laeds to endothelial injury and the release of cytokines causing widespread vasodilation, permeability and myocardial shock –> decreased BP and shock
Layers of Meningies
Top = Dura Matter
Middle = Arachnoid Matter
Inner = Pia Matter
How are CNS INFECTIONS classified
According to the structures affected by the infection and the nature of the organism.
meningies = meningitis
brain parenchyma = encephalitis
spinal cord = myelitis
brain and spinal = encephalomyelitis
What are the four (4) routes by which infections can enter teh nervous system?
- Harmatogenous spread - msot common (via arterial circulation)
- Direct implantation - very rare e.g. lumbar puncture
- Local extention - infection in sinus, tooth
Meningitis (generally where does it affect?)
Associated with inflammation of
- PIA MATTER, the ARACHNOID MEMBRANE and the CSF and the CSF
- spreads rapidly because of circulation of CSF
Bacterial Meningitis (What bacteria causes?)
- neonates: E coli and streoticocci
normally.
Used to be H influenzae in children but now vaccinated against.
