Flashcards in Session 1 Deck (24):
What are the different branches of pathology?
Medical microbiology- virology, chemical pathology, haematology, immunology, cellular pathology- paediatric, forensic and neuro
Why is cytology worse than histology?
Higher error rate
Why is examination of tissue microscopically useful?
Ensure surgery is needed and guides type and extent
What are the different stages of tissue preparation?
Fixation, trimming, embedding, blocking, staining, mounting, microscopy, report writing
What are the different types of hypoxia?
Why is ischaemic reperfusion injury damaging?
Free radical production
Increased number of neutrophils
Delivery of complement proteins and activation of complement pathway
What is a free radical?
A species with an unpaired electron in its outer orbit
What enzymes are used as defence against free radicals?
Superoxide dismutase converts superoxide to hydrogen peroxide
Hydrogen peroxide is much less harmful and is broken down by catalase and peroxidase into water and oxygen.
What are the defences of cells against cell injury and free radicals?
Free radical enzymes
Iron and copper sequestration- transferrin
Heat shock proteins
What are light microscope changes of an injured cell?
Cytoplasmic changes-Hyperchromasia- stains darker
Nuclear changes-Pyknosis if reversible, karyolysis or karyhorexis if not
What do injured cells look like under an electron microscope?
Blebbing, swelling, chromatin clumping, swelling of cell organelles, dispersion of ribosomes
If irreversible injury
Autophagy by lysosomes, cell components lyse, cells membrane integrity fails. Karyolysis/ karyhorexis.
What kinds of things can accumulate in cells?
Lipids- TAGs and cholesterol
Water and electrolytes
What accumulates in cells in liver cell damage commonly due to alcohol?
What is necrosis?
The morphologic changes which take place in a cell after it has been dead for some time.
How does hypoxaemic cell injury occur?
Cell deprived of oxygen
Aerobic respiration stops
Glycolysis continues but produces lactic acid. pH drops
Cell membrane pumps stop working. Sodium leaks into cell and into organelles. These swell. Calcium enters- activates endonucleases which cause chromatin clumping, proteases which damage cytoskeleton, phospholipases which cause cell membrane to lose lipid. Cell responds by producing heat shock proteins in stress response. These cant do enough and eventually cell dies.
What is coagulative necrosis?
Increased protein denaturation and decreased protease activity
What is liquefactive necrosis?
Increased protease activity and decreased denaturation
What is gangrene?
What is wet gangrene?
Necrosis visible to the naked eye
Is called wet if it is modified by infection
Where do white infarcts occur?
In solid organs where there is good stromal support and occlusion of an end artery
What do apoptotic cells look like under the microscope?
Formation of apoptotic bodies
Chromatin condensation, pyknosis, karryhorexis
Why is there no inflammation in apoptosis?
Everything is divided into apoptotic bodies so cell components are not exposed to immune system
What are the three phases of apoptosis?
Initiation, execution and degradation
What is dystrophic calcification
Occurs in dying tissue/ atherosclerotic plaque, damaged heart valves
Is deposition of hydroxyapatite crystals due to local change in the tissue.