Cellular adaptations Flashcards
What are the responses to low ATP levels?
inflammation
adaptation
failure to adapt= cell death
abnormal growth= neoplasia
Name types of cell injury (VITAMIN D mnemonic)
Vascular/ischaemia (resp, circulatory disease)
Infection
Trauma (mechanical, thermal, radiation)
Autoimmune/inflammatory (damage by inflammation)
Metabolic (endocrine, electrolytes)
Inherited/congenital (gene, chromosomal disorder)
Neoplasia
Drugs/toxins
What changes in cell growth can you get?
Hyperplasia
Hypertrophy
Atrophy
Metaplasia
Hyperplasia
- cells survive by increasing in number (=enlargement of organ)
- Only occurs in dividing cells
- Hormone driven
- Physiological or pathological
Hypertrophy
- cells survive by increasingin size (overall enlargement of organ)
- more synthesis of structural cell components
- Occurs in non-dividing cells (terminally differentiated cardiac/skeletal muscle, nerve)
- Physiological or pathological
Atrophy
Decreased cell activity
- decrease in cell size and number, hence reduced mass
- reduced cell division, synthesis of structural protein, increased appoptosis
- decreased functional demand or decreased hormonal stimulation
- physiological or pathological
Metaplasia
Alteration in cell morphology
- Change from one mature cell type to another
- Usually epithelial
- Most common: –Columnar –> squamous (squamous metaplasia)
- Also columnar (intestinal) metaplasia
- Metaplastic stimuli, if persistent, may induce malignant change
barrett’s oesophagus
Apoptosis
•Programmed cell death – internal controlled suicide
•Caspase enzymes =>
internally degrade cell
- Individual cells = very pink + small dense nuclei.
- Serves physiological functions: –embryology –menstrual phase endometrial
- Can be pathological: –cell death to DNA-damaging toxins – e.g. chemotherapy, radiotherapy –viral hepatitis
Necrosis
- Spectrum of morphological changes that follow cell death in living tissue
- Always pathological!
- Damage to membrane => lysosomes enter and digest cell => contents leak out
Coagulative necrosis
- Dead tissue appears firm and pale (cooked)
- clinically= gangrene
- Tissue architecture viable histologically
- typically caused by arterial occlusion
Liquefactive Necrosis
Tissue appears cystic and semi-liquid (due to digestion by lysosomes)
No structure histologically
Typically seen in Stroke, bacterial infections
Caseous Necrosis
Dead tissue resembles cream cheese – soft and white
Amorphous granular mess histologically
Associated with TB
Fat necrosis
Hard, yellow material seen in fat
foamy macrophages within fatty tissue
Fibrinoid necrosis
Histological deposition of fibrin in vessel walls (vasculitis)
