Cellular basis of disease

Question 1

3 forms of necrotic cell death?

Answer 1

1. Coagulative necrosis (ischaemic kidney)
2. Colliquative necrosis (cerebral infarct) - Neutrophils infiltrate tissue and insert their contents, liquifying it. Creamy, yellow, pus.
3. Caseating necrosis (TB granuloma) - Continued influx of macrophages causes soft, white cheesy ‘caseous’ material to form

Question 2

Definition of metaplasia

Answer 2

Replacement of one differentiated cell type with another mature differentiated cell type that is not normally present in that tissue

Question 3

Definition of dysplasia

Answer 3

A condition in which cells have abnormal cellular architecture, with nuclear atypia, nuclear hyperchromasia and loss of cell polarity

Question 4

Definition of neoplasia

Answer 4

New, uncontrolled growth not under physiological control

Question 5

Type 1 (immediate) hypersensitivity:

• Immune reactant
• Effector mechanism
• Example of reaction
• Pathological consequences of the effector mechanism

Answer 5

• IgE
• Mast cell activation
• Allergic rhinitis, asthma, systemic anaphylaxis
• Consequences:
  1. GI tract: Increased fluid secretion & increased peristalsis. Expulsion of GI contents (diarrhoea, vomiting)

2. Airways: Decreased diameter, increased mucus secretion. Expulsion of airway contents (phlegm, coughing)
3. Blood vessels: Increased blood flow, increased permeability. Oedema, inflammation, increased lymph flow and carriage of antigen to lymph nodes

Question 6

Type 2 hypersensitivity:

• Immune reactant
• Effector mechanism
• Example of reaction

Answer 6

• IgG
• Complement or antibody altering signalling
• Drug allergies, chronic urticaria

Question 7

Type 3 hypersensitivity (immune complex):

• Immune reactant
• Effector mechanism
• Example of reaction

Answer 7

• IgG
• Complement phagocytes
• Depends on site of immune complex deposition. Serum sickness, Arthus reaction (perivascular area), nephritis (renal glomeruli), Arthritis (joint spaces), Farmer’s lung (alveolar/capillary interface), Vasculitis (blood vessel walls)

Question 8

Type 4 hypersensitivity:

• Immune reactants
• Effector mechanism
• Example of reaction

Answer 8

• Th1 cells / Th2 cells / CTL
• Macrophage activation (Th1) / Eosinophil activation (Th2) / Cytotoxicity (CTL)
• Contact dermatitis & tuberculin reaction (Th1) / Chronic asthma & Chronic allergic rhinitis (Th2) / Contact dermatitis (CTL)