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33 Cards in this Set
- Front
- Back
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What are the three key steps of post-mortem examination |
Systematic observation and dissection Sample collection Record and interpretation |
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What are the 6 levels of lesion description |
Location Distribution Size Shape Colour Consistency |
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What are the principles of sample collection? |
1 part sample to 10 parts fixative Samples should be chilled not frozen Samples should be 0.5-1.0cm thick |
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What is the difference between serum and plasma |
Serum = non cellular portion of clotted blood Plasma = non cellular portion of non clotted blood |
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What are red top tube used for |
Serum analysis (clotted blood) and has no anticoagulant. Used for serum biochemistry and endocrinology |
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What are purple top tubes used for? |
Whole blood collection EDTA anticoagulant chelates Ca Used for routine haematology |
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What are green top tubes used for? |
Whole blood collection Heparin anticoagulant inhibits thrombin formation. Used for plasma biochemistry. |
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What are grey top tubes used for? |
Whole blood collection. Na Fluoride anticoagulant prevents glucose use. Used for glucose assessment. |
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What are blue top tubes used for? |
Whole blood collection. Na Citrate anticoagulant binds to Ca. Used for coagulation studies |
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Define aetiology |
Cause of the lesion |
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Describe the characteristics of coagulative necrosis |
Structural detail is maintained while cellular detail is lost (tissue is still recognisable) Commonly caused by ischaemia, burns or caustic chemicals |
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Describe the characteristics of caseous necrosis |
Both structural and cellular detail are lost. Homogeneous, pale, granular mass. Caused by bacterial infection (M.tuberculosis, C.pseudotuberculosis) |
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Describe the characteristics of liquefactive necrosis |
Necrotic mass becomes liquid. All structural and cellular detail is lost. Common in the CNS (malacia) |
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Describe the characteristics of suppurative necrosis |
Liquefaction with pus formation Pus = purulent exudate = necrotic debris + dead neutrophils + tissue fluid |
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Describe the characteristics of fat necrosis |
Death of fat cells, fat splits into glycerol and fatty acids, combine with salt to form soap. Presence of basophils. Firm, white fat. Significant inflammatory response induced. Yellow ceroid pigment may be present. |
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What are the three ways in which necrotic tissue is dealt with |
Liquefaction and removal Sequestration Abscessation Erosion and ulceration |
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Define atrophy and name its three causes |
Normal cell decreases in size. Due to disuse, denervation, or loss of stimulation. Eg. Muscles, prostate after castration |
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Describe hypertrophy |
Normal cell increases in size. Typically in tissue types made up of post mitotic cells (eg heart, skeletal muscle, uterus during pregnancy). |
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Describe hypoplasia |
Incomplete development or cell growth. Aplasia = no development at all. Atresia = failure to develop lumen. Congenital, not a true cell adaptation. |
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Describe hyperplasia |
Increase in the number of cells. Limited to cell types that can divide, eg. Thyroid, prostate, adrenocortical |
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What are the three main substances that can visibly accumulate in the body |
Melanin - yellow/brown - copper dependant enzyme - decreased or increased melanin.
Fat - Accumulation of triglycerides in parenchymal cells - acute = lots of small fat globules - chronic = one large globule
Haemoglobin pigment - haemosiderin from Fe, yellow/brown pigment - bilirubin from haem, orange pigment, causes jaundice |
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Describe normal red blood cell recycling |
Physiological extracellular haemolysis occurs in the spleen in macrophages. Haemoglobin enters the macrophages and splits into Iron, haem and globin |
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Describe the process of intracellular haemolysis |
Always pathological. Occurs in the blood vessel fluid, thus the haemoglobin is released into the plasma, causing a pink colouration. Some haemoglobin molecules are taken up into macrophages, where they are split into haem, iron and globin, and processed into pigments |
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Distinguish between pre-hepatic, hepatic and post-hepatic jaundice |
Pre hepatic Due to increased break down of rbcs Hepatic Due to damage of hepatocytes, causing impaired ability to conjugate and excrete bile. Post hepatic Due to a blockage of the bile system |
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Describe the movement and excretion of bilirubin |
Haem > bilirubin > transported in the blood > liver > conjugated with glucuronic acid > excreted in bile > excreted with digesta |
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Distinguish between intravascular and extravascular haemolysis |
Both result in anaemia and jaundice. Intravascular - always pathological - occurs in vascular space - haemoglibinaemia - haemoglobinuria Extravascular - can be pathological or physiological - occurs in macrophages |
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Define and describe haemorrhage and its effects on the body |
= bleeding from a damaged blood vessel Causes space occupying lesions which may impair organ function. Iron deficiency, or shock. |
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Describe how the body compensates for blood loss and what happens if compensation is insufficient |
Redistribution of blood to vital organs, restores fluid volume from extracellular space (48 hours), replacement of red blood cells (5-6 days) If compensation fails, shock results - hypovolaemic = fluid loss - vasculogenic = vasodilation - cardiogenic = decreased cardiac output |
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Describe thrombosis and the appearance of ante vs post mortem blood clots |
Thrombus = ante mortem blood clot Ante mortem - attached to vessel wall - rough string lying texture - red/grey - layers Post mortem - shaped like vessel - smooth glistening texture - dark red or yellow |
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Define embolism |
Abnormal mass circulating in the blood flow |
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Describe the normal fluid movement in and out of the blood vessel |
Lower protein on the arteriole side, HP > COP Fluid moves out of the vessel Higher protein on venule side HP < COP Fluid moves back into the vessel No net change in fluid volume Any excess fluid is taken up by the lymphatics |
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Describe the different ways in which oedema can arise |
Too much fluid 1. Increased hydrostatic pressure Local = congestion Systemic = heart failure 2. Increased vascular permeability Inflammation Almost always local 3. Decreased osmotic pressure Due to low protein (albumin) conc. Decreased albumin production (liver disease) Increased loss of albumin (inflammation) Always systematic Insufficient fluid removal 1. Impaired lymphatic drainage (almost always local) |
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Distinguish between transudate and exudate |
Transudate - low protein - doesn't clot - low cellular component - clear or straw coloured Exudate - high protein - clots - high cellular component - turbid |
