Cell Injury and Acute Inflammation (week 2) Flashcards
Increased cellular activity leads to:
1) hyperplasia: more cells produced
2) hypertrophy: cells increase in size
Decreased cell activity leads to:
Cell atrophy: cells decrease in size
Metaplasia definition:
Transformation of one type of differentiated cell into another fully differentiated type
What are the 4 different mechanisms of cell injury
1) Failure of membrane function e.g. ion pump damage
2) Blockage of metabolic pathwyas e.g. iterruption of protein synthesis
3) DNA damage or loss e.g. due to ionising radiation
4) Mechanical trauma e.g. due to osmotic pressure
How does ionising radiation cause damage to cells?
Generation of free radicals, direct damage to thymine dimers in DNA
What is the defence mechanism against ionising radiation?
Exonuxcleases
How do free radicals damage cells?
Remove electrons from molecules and break important bonds
What is apoptosis?
Programmed, planned cell death
Does apoptosis damage adjacent cells?
No
Does apoptosis cost energy?
Yes
What is necrosis?
Unplanned, catastrophic cell death that is always pathological
What causes necrosis?
Cell injury
Does necrosis cost energy?
No
What impact does necrosis have on surrounding cells?
Causes release of harmful substances which damage many cells at once
Name some physiological uses for apoptosis:
embryogenesis
destruction of self-reacting lymphocytes
How can dysfunction of apoptosisbe carcinogenic?
Cells can accumulate e.g. in follicular lymphoma: anti-apoptotic BCL-2 gene is over expressed –> apoptosis is inhibited
Describe coagulative necrosis:
Commonest form - dead tissue becomes firm and swollen and retains microscopic structure. Typical of ischaemic injury.
Describe colliquative necrosis:
Occurs in neural tissues - have little supporting structure therefore liquifies on death. Site becomes marked with a cyst.
Describe caseous necrosis
Granulomatous inflammation. Dead tissue lacks any structure. Characteristic of TB.
What is dry gangrene?
Form of coagulative necrosis that develops in ischaemia. Limited O2 supply limits putrefaction, bacteria cannot survive. Chronic ischaemia without infection.
What is wet gangrene?
Develops rapidly due to blockage of blood. Stagnant blood allows rapid growth of bacteria, which produce toxic products which are then absorbed, causing sepsis. Requires amputation/
What is a neutophil polymorph?
Characteristic cell of acute inflammation - characterised by multi-lobed nuclues
What are the 5 physical characteristics of acute inflammation?
Rubor: redness Calor: heat Tumor: swelling Dolor: pain Functio laesa: loss of function
What are the 3 major components of acute inflammation?
- Changes in vessel calibre
- Increased vascular permeability and fluid exudate formation
- Cellular exudate formation
What is exudate?
extravascular fluid with high protein concentration, contains cellular debris
What is transudate?
Fluid with low protein concetration, no cellular contents
What is oedema?
Excess fluid in interstitial tissue. Can be transudate or exudate
What mediates vasodilation?
Histamine and NO on vascular smooth muscle
What is suppuration?
Pus formation
What is an abscess?
Collection of pus trapped within body
3 types of reaction that make up an acute inflammatory response are vascular, exudative, and?
Cellular
Category of death that must be reported to the coroner?
Unnatural
Necrosis with putrefaction?
Gangrene
The abnormal development or degeneration of a tissue
Dystrophy
Cell type that is able to secrete chemical mediators of acute inflammation
Macrophage
