Mechanisms of Disease

Question 1

Bacterial meningitis

Answer 1

acute inflammation in the meninges can cause vascular thrombosis and reduce cerebral perfusion

Question 2

abscess

Answer 2

collection of pus in any part of the body, that, in most cases, causes swelling and inflammation around it

happens in solid tiss, the inflamm exudate forces the tiss apart, liquefactive necrosis in centre, may cause high press->PAIN, may cause tiss damage and squash adj structures

Question 3

lobar pneumonia

Answer 3

caused by the bacteria streptococcus pneumoniae

alveoli contain exudate instead of air, lobe becomes consolidated and airless

symptoms: fever, prostration, hypoxaemia over a few days, dry cough, breathlessness

if treated it can generally resolve completely

Question 4

skin blister

Answer 4

caused by heat, sunlight, chemicals

• the collection of fluid strips off the overlying epithelium
• inflammatory cells are relatively few - therefore the exudate is clear unless bacterial infection develops
• resolution/scarring

Question 5

acute inflamm in serous cavity

Answer 5

the exudate pours into the cavity

pleural, pericardial effusion or ascites (peritoneal effusion)

resp/card impairment

localised fibrin deposition

‘bread and butter’ pericarditis

Question 6

acute appendicitis

Answer 6

most commonly caused by bacteria, faecolith (hardening of faeces into various sizes) obstruction, appendicular tumour, or many other ways

appendix begins to swell w/ exudate->oedema, pus develops as neutrophils attempt to deal w/ pathogens and necrotic material, dead neutrophils release lysosomes that begin to digest the cell walls, wall of appendix becomes weakened and may perforate, pus and exudate enters peritoneum, peritonitis (general inflam of peritoneum) and potential septicaemia

Question 7

septicaemia

Answer 7

body’s overrxn to injury causing a widespread immune response that is lifethreatening

eg endothelial damage, over-coagulation

Question 8

hereditary angio-oedema/angioneurotic oedema

Answer 8

deficiency of inhibitor of comp system that leads to excessive production of bradykinin (pain and inc permeability) resulting in the activation of an excessive acute inflam response around the body

Question 9

give 4 defects of collagen synthesis

Answer 9

vitamin C deficiency ie scurvy

ehlers-danlos syndromes

osteogenesis imperfecta

alport syndrome

Question 10

vitamin c deficiency ie scurvy

Answer 10

inadequate vit c dependent hydroxylation -> defective helix formation

this lacks strength and is vulnerable to enz degredation

this particularly affects coll around blood vessels->haemorrhage, skel changes in infants

Question 11

ehlers-danlos syndrome

Answer 11

defective conversion from procollagen -> tropocollagen

Question 12

osteogenesis imperfecta

Answer 12

rare, heritable, often congenital
cellular defect is due to abnormal coll synth by osteoblasts and fibroblasts
events where the disease expression is less severe lead to frag of bones and therefore mult fractures of long bones and bone deformities from incorrect fracture healing
condition is legally important due to occassional confusion with deliberate injury from parents

Question 13

alport syndrome

Answer 13

affects collagen in basement membrane -> renal impairment of kidneys