General Pathology 1.pdf

G Path 1 Wednesday, 2 March 2022 10:02 AM Lesion = any abnormality that we can see - Visible with the naked eye = gross - Visible under a microscope = histological...

G Path 1 Wednesday, 2 March 2022 10:02 AM Lesion = any abnormality that we can see - Visible with the naked eye = gross - Visible under a microscope = histological Pathognomonic means we can immediately tell the disiease since it is the only cause of a specific type of lesion. (this is not common, so need to investigate) Aetiology means the cause of the disease or lesion PATHOGENESIS is the steps between the aetiology ant the outcome (lesions) which is what we need to understand. So we can understand how death occurred, when it happened Also some of the PM changes can resemble lesions that occur during disease in life. So don’t get these mixed up, they arent a disease All bodies once they die cool down to ambient temp, this is a linear relationship and can tell you the time of death. - Depending on initial temp, eg fever or struggle at death elevate temp - The amount of insulation, protected location, lots of wool on sheep makes it take longer - What is the ambient temp?? Eg in the shade, in the sun etc Dead animals can create ATP from store glycogen up to nine hours after death depending on temp of body and ambient temp, enzymes run faster in heat so rigour mortis is quicker. Also body condition effects this, how much glycogen is stored?? Begins and breaks down in the same order, stops as muscle fibres rot Hypostatic congestion, the sheep died lying down and the heart is stopped. Blood is therefore effected by gravity and sinks to the down side of the body and then it clots so it stays there. So we can tell the position of the body at death PM clots form a jelly like mould of the vessel it is in and is easily removed Life clots are granular, stuck and hard to remove. Decomposition is the tissues breaking down or rotting Self dissolving from the enzymes in your own cells. As the cells die the membranes break down releasing enzymes that the do autolysis Putrefaction is breakdown from bacterial enzymes Rate of decay - Enzymes work quicker at higher temps - Bacteria = more enzymes at work, these can come from in body eg GIT, or from the environment of the death  What does an organ look like after death Red is a fresh liver recently removed from an animal And brown is normal autolysis of red blood cells, it becomes friable/breakable/crumbly due to destruction of fibrous tissues. Black areas is because of what the tissue is sitting against, in this case staining from contact with blood filled structures like the kidney or from touching the gall bladder PM colour changes Hb and bile are really good at staining stuff Dark parts where the blood dropped in gravity, pale areas from laying on a hard surface which pressure dosent allow the blood in Patches of liver look necrotic but are just decomposing Particularly with anaerobic bacteria and particularly with ruminants due to having a lot of anaerobic bacteria in rumen This means there is no way to know anything about how it died Sometimes there is so much decay you cant tell how it died We need to understand all the steps between the aetiology and the outcome Draw a diagram or mind map between them to practise So to diagnose the disease we need to collect info from the body that relates to all these diff stages of the pathogenesis: - Iodine in environment? - Iodine in blood? - T4 in blood? Low? - TSH in blood high? - Biopsy of gland to look at epithelial cell numbers - Gross lesion location/appearance And this understanding leads into generation of treatment plans, where is the best point of intervention in the pathogenesis timeline? T4 lack can cause caridac issues in utero PRACTICE using path diagrams when I see a new disease or sysndrome in this course and others Reversible can progress to irreversible Cellular degeneration = reversible cell damage Cellular necrosis = cell death  Use lab test to look at whole blood or serum looking for enzymes mostly If there's no ATP the pump doesn't remove Na+ to maintain osmotic balance If there's no ATP or the pump is damaged (membrane damage) then Na+ accumulates and osmotic pressure in cell draws in water and makes the cell swell (first sign of cell damage) Also fluid globules begin to build up, as the cell stretches the organelles also swell and will not function normally The MAIN cause is O2 lack, so no ATP, so Na+ pump fails… So loss of enzymes into ECM the condition or process of deterioration with age. loss of a cell's power of division and growth. Bilurubin normally processed in hepatocytes and excreted into bile ducts If the liver has hypoxia then all the cells will swell So the entire liver will swell - Hepatomegaly So this indicates widespread damage to the entire liver. This is painful, can trigger a systemic response of nausea, vomiting and loss of appetite, and JAUNDICE In this case due to cholestasis (bile not moving) So the bilirubin accumulates in the cells of the liver and cant get out. So jaundice is staining of body tissues with bile pigments And it builds up in the blood stream Seen earliest and easiest in the whites of the eyes - Dosen't build up in eyes first, just more obvious