Flashcards in MOD Deck (42)
Describe the 4 categories of hypoxia
-Hypoxaemic -> low pO2
-Anaemic -> reduced ability of Hb to carry O2
-Ischaemic -> interruption to blood supply
-Histiocytic/cytotoxic -> inability to utilise oxygen
What are the 4 target areas of cellular injury?
Describe the consequences of hypoxia on a cellular level and how it leads to cell death
-Decreased oxidative phosphorylation = decreased ATP = decreased NaKATPase = imbalance of electrolytes = oncosis
-Anaerobic metabolism produces lactic acid = lower pH = enzymes begin to denature and ribosomes fall of rER causing decreased protein synthesis
-Increased cytosolic Ca from mitochondria, endoplasmic reticulum and increased pm permeability = activation of cellular enzymes such as phospholipase and endonuclease = cell death
What is a free radical and why are they so dangerous?
Name 3 in the body
-Molecule with single unpaired electron
-highly reactive, often producing more free radicals and result in damage to DNA and other cellular components -> apoptosis
-OH-, O2*, H2O2
How does the body defend against free radicals?
-Enzymes such as superoxide dismutase and catalase
-Free radical scavengers such as vitamins ACE
-Reducing molecules such as glutathione
What is ischaemic reperfusion injury?
-When blood vessels undergo ischaemia they continue to produce vasodilator metabolites such as adenosine/H+ which causes a high bloodflow to return. The returning flow can damage cells as it contains a high amount of free radicals, neutrophils and complement
Decribe the nuclear changes which occur in necrosis
-Pyknosis -> chromosome clumping
-Karryohexis -> chromosome lysis
-Karyolysis -> disintegration
Describe the main differences morphologically between apoptosis and necrosis
-Apoptosis -> single cell death with shrinkage and organised degradation and disintergration of cells forming budding apoptotic bodies -> cell membrane preserved
-Necrosis -> cell death with swelling -> loss of integrity of pm causing blebbing and release of proteolytic enzymes
Describe the 4 types of necrosis and when they are seen
-Coagulative -> proteins coagulate and clump and outline preserved, associated with ischaemia
-Liquefactive -> proteins autolysed and dissolved, associated with abscesses and bacterial infections and tissues with little support
-Caseous -> TB
-Fat -> acute pancreatitis or direct trauma to fatty tissue
Describe the different types of gangrene
-Dry -> Necrosis which has been modified by the air
-Wet -> necrosis which has been modified by bacteria (septecaemia)
- Gas -> tissue infected with anaerobic bacteria producing bubbles under the skin
What is infaction and describe its types and when they occur
-White -> solid organs as limits haemorrahage from adjacent capillaries, occulsion of end arteries
-Red -> dual blood supply with one vessel not being sufficient to maintain perfusion, loose tissue with poor stromal support as adjacent capillaries burst
In which two ways is apoptosis initiated?
-Intrinsic by leakage of Cytochrome C
-Extrinsic by binding of death ligand
List 3 abnormal accumulations which can occur in cells and a disease associated with it
-Fat -> steatosis in fatty liver disease
-a1-antitrypsin produced in liver -> misfolded proteins accumulate -> liver failure
-Carbon -> coal worker's pneumoconiosis
-Haemosiderin -> Hereditary haemochromotosis (increased intestinal absorption of iron which gets deposited in liver, skin, pancreas and heart - bronze diabetes)
-bilirubin -> jaundice
What are the two types of pathological calcification and their causes?
-Dystrophic -> local deposition due to local disease
-Metastatic -> systemic deposition, often due to hyperpatathyroidism
Define acute inflammation and name its 4 cardinal signs
- Response of living tissue to injury which is immediate, innate and stereotyped with a short duration
-rubor -> redness
-tumor -> swelling
-calor -> heat
-dolor -> pain
Describe the changes in vessels which occurs in acute inflammation
-Vasodilatation of arterioles/capillaries causing increased blood flow (rubor and calor)
-Increased vascular permeability resulting i exudation of fluid into tissues and vascular stasis (tumor)
Describe the role of histamine in acute inflammation
-Early responder as it is presynthesised and stored. released from mast cells, basophils and platelets in response to many stimuli to cause vascular dilatation, increase in vascular permeability and pain
What causes exudation of fluid in inflammation?
-Increased vascular permeability
-Vasodilation -> increased bf -> increased hydrostatic pressure
-Increased oncotic pressure of interstitium
Give 3 generic causes of exudative oedema
What is the primary wbc involved in acute inflammation? Describe its infiltration into tissues
1)Margination (stasis causes neutrophils to line up along endothelium)
3)Adhesion (ICAMs, Integrins)
What are the 2 killing mechanisms used by neutrophils and what immunodeficiency is associated with one of them?
-O2 independant -> Lysozyme and hydrolases
-O2 dependant -> produces superoxide and H2O2 -> most efficient mechanism -> inability to do this produces Chronic Granulomatous Disease
What is the purpose of exudation of fluid in acute inflammation?
-Deliver plasma proteins to site of injury -> Igs, inflam mediators
-Increases lymphatic drainage -> increase delivery of microorganisms to lymph nodes
What is the acute phase response and what proteins are involved in it? Why are the proteins useful?
-Decreased appetite, raised HR, altered sleep etc
-Can be used as a marker of inflammation
What separates acute inflammation from chronic inflammation?
-Chronic inflammation involves granulation tissue, fibrosis and healing by scarring in addition to the resolution occuring with a degree of dysfunction
-Macrophage is dominant in chronic vs neutrophil in acute
Describe the different types of giant cell and when they are seen
-Langhan -> nuclei around the periphery -> seen in TB
-Foreign body -> Random nuclei -> hard to digest material -> frustrated phagocytosis
-Touton -> nuclei arranged in a ring towards centre -> fatty tissues
Why does fibrosis occur in chronic inflammation? Why is it damaging?
-Prolonged or excessive cytokine stimulation of fibroblasts produces excessive collegen leading to fibrosis as the excess CT goes beyond healing a scar to replacing normal parenchyma and impair function
Liver cirrhosis is a form of chronic inflammation. What are the most common causes of liver cirrhosis
What is a granuloma?
-Localised collection of cells characterised by the presence of epithelioid histiocytes, giant cells and lymphocytes which have formed in response to hard to clear infections/material
Name 4 diseases associated with granulomas
-Granulomatosis with polyangitis