Injuries to cells Flashcards
Define hyperplasia
Increase in number of cells = increase in size of organ eg. menstrual cycle
Define hypertrophy
Increase in size of cells = increase in size or organ eg. body builders, heart in hypertension
Define metaplasia
One adult cell type is replaced by another, reversible, may be able to withstand new stress eg. chronic gastro-oesophageal reflux
Define atrophy
Decrease in size of cell by loss of cell substance due to loss of blood, lack of nutrition, loss of hormonal stimulation, ageing
What are the causes of cell injury
Hypoxia, ischaemia, chemical exposure (alcohol, cigs), infection, radiation, lack of nutrition, ageing
What is necrosis?
Cell death which is always pathological
Damage to membrane allows enzymes to digest cell
Causes local inflammation
What are the 4 types of necrosis?
Coagulative
Liquefactive eg stroke
Caseous eg TB
Fat eg breast (mistaken for cancer)
What is apoptosis?
Programmed cell death by Killer T cells- irreparable damage to cells proteins & DNA
Bits of cell break off, rapidly removed by phagocytosis
Can be physiological:
-elimination of cells that have served their purpose & harmful self-reactive lymphocytes
- embryogenesis
Can be pathological:
-DNA damage - accumulation of misfolded proteins
- caused by certain infections, occurs in parenchymal organs after duct obstruction
What is neoplasia?
Mild DNA damage by gene mutation
- damage to genes controlling DNA repair - further change
- damage to genes controlling cell division = excess division
- mutation accumulate = abnormal cells = CANCER
Define inflammation and its aims
Response to tissue damage by a wide range of stimuli
Protective, aims to remove/contain pain, initiates repair and reinstate useful action, essential for wound healing
Vascular reaction of inflammation
Maximises movement of plasma proteins and circulating cells to cite of injury by:
> changing vessel and flow
> increasing vascular permeability
Results in hyperaemia (excess blood in vessels), stasis and fluid exudation
Cellular reaction of inflammation
Leukocyte (neutrophils) extravasation
- margination, rolling, adhesion to endothelium
- transmigration
- migration through tissue
5 cardinal signs of inflammation
Heat, Redness, Swelling, Pain, Loss of function
Signs and symptoms of inflammation
Fever, increase pulse and BP, increase WCC and CRP count
Acute inflammation
Rapid response, short lived
Neutrophils predominant
Aim to complete resolution, healing by fibrosis (scar formation)
Can lead to chronic
