Mechanisms Of Disease Flashcards
Give four differences between the processes of oncosis+necrosis and apoptosis.
Oncosis - blebbing
Apoptosis - budding
Oncosis - inflammation
Apoptosis - no inflammation
Oncosis - swelling
Apoptosis - no swelling
Oncosis no membranes maintained
Apoptosis - membranes maintained
Name four types of necrosis and give an example of where each might be found.
Coagulative - heart in MI. Caused by protein denaturation
Liquefactive - brain. Caused by enzyme digestion in areas of little stromal support
Caseous - lungs in TB
Fat - pancreas
Which type of necrosis is associated with granulomas?
Caseous
What happens to the nucleus after cell death (necrosis)?
Pyknosis - shrinks
Karyorrhexis - breaks apart
Karyolysis - completely dissipates
Give one example of apoptosis occurring in a useful way and one example of it occurring in a pathological way.
Sculpting during embryogenesis eg the interdigitation of the fingers.
Graft vs host disease or cancer
What is the difference between hypoxia and ischaemia?
Hypoxia is the lack of oxygen to the tissues due to a number of reasons eg anaemia, reduced respiration rate. Another reason for hypoxia might be ischaemia which is the blockage of the blood supply to the tissues. Ischaemic tissue is not only missing oxygen but the other plasma contents.
What is the difference between blood plasma and serum?
Plasma contains platelets
Describe 3 physiological processes which occur during reversible hypoxia injury.
- Na/k ATPase stops working. Gradient no longer upheld and Ca+ and Na+ enter the cell. Water follows and it swells.
- Glycolysis is unregulated to try to produce more ATP. This makes the pH more acidic and chromatin clumps together.
- Without ATP ribosomes detach from the ER and protein production reduces.
When hypoxic injury is irreversible, what happens to the cell?
The membrane becomes leaky and there is a huge influx of calcium. This activates a number of enzymes eg ATPase, phospholipase, protease, endonuclease which digest the cell. ATPase makes it happen even faster.
What pigment builds up in the cell to form a bruise?
Haemosiderin
What five classic symptoms are observable during acute inflammation?
Rubor, tumor, calor, dolor and loss of function.
What is the mechanism of acute inflammation?
- Changes in blood flow
- (constrict) dilation
- increase permeability
- increase viscosity (rbcs) - Exudate
- Infiltration of neutrophils and fibrin
In acute inflammation what four changes occur to the blood flow?
- Transient vasoconstriction
- Vasodilation
- Increased permeability
- Increased viscosity/stasis
What are the two key differences between an exudate and a transudate? When might each of them be found?
Exudate - 1. protein rich fluid loss 2. due to both osmotic pressure and oncotic pressure in the interstitium. Found in acute inflammation.
Transudate - 1. Low in protein 2. due to osmotic pressure only. Found in heart failure.
Name four key chemical mediators of acute inflammation.
Histamine
Cytokines - bradykinin
Leukotrines
Complement - C3a, C5a, IL-1
Give 4 systemic effects of acute inflammation.
Fever
Leukocytosis
Increase in c reactive protein
Possible shock
What is the main white blood cell type involved in acute inflammation?
Neutrophils/polymorphs (same thing)
Describe how neutrophils leave the blood vessel and enter the tissue. Is it an active or passive process?
- Chemotaxis - attracted along chemical gradient
- Rolling along the sides of the vessel.
- Adhesion by integrins
- Aggregation
- Diapedesis - force their way between cell junctions and digest the basement membrane
Passive
When might a chronic inflammation arise in relation to an acute inflammation?
- After an unresolved acute inflammation
- Alongside a severe acute inflammation
- Without an acute inflammation eg TB, autoimmune arthritis
What are the key features of chronic inflammation?
Fibrosis
Macrophages
Lymphocytes
Can have - pus, granuloma, giant cells
What is the major white blood cell involved with chronic inflammation?
Macrophages
Give three functions of a macrophage.
- Phagocytosis
- Present antigens to T lymphocytes to trigger production of antibodies
- Secrete substances such as cytokines to further immune response
What are antigens and antibodies?
Antigens are signal proteins on bacteria cell walls which are recognised by lymphocytes. The T lymphocytes then produce antibodies to specifically attack that bacteria.
How is fibrosis caused? Give an example.
Overstimulation of fibroblasts by cytokines during chronic inflammation leads to excessive scar tissue and shrinkage. Eg cirrhosis of the liver.
What is a granuloma? Give two situations which might cause a granulomatous inflammation.
The body’s response to insoluble particles.
- Foreign body eg a splinter
- Hypersensitivity to a molecule eg. TB, sarcoidosis, crohns
What is a giant cell? Give three specific types of giant cell and describe their nuclei.
When macrophages fuse together.
- Langhans - nuclei in a peripheral ring
- Touton - nuclei in a central ring
- Foreign body - nuclei randomly spaced
In what type of inflammation would you find a giant cell?
Chronic granulomatous inflammation.
Describe the type of inflammatory response you would expect to see with a TB infection.
Caseous necrosis
Granulomatous inflammation with Langhans giant cells
What kind of protein can build up in an alcoholic liver?
Malory’s hyaline from altered keratin
What causes reperfusion injury?
When blood is returned to an area after ischaemia, endothelial cells produce more reactive oxygen species, causing damage to the reperfused tissue.
What are free radicals? Give 4 ways they can be produced in the body.
Highly reactive ions which cause damage to tissue. Eg. OH, 1/2o2, ONOO, H2O2
Can be produced by Fenton reaction, Haber Weiss reaction, radiation, escape from electron transport chain.
What is the difference between a red and white infarct? Where math they occur?
A White infarct is simple occlusion of blood and tissue death.
Red infarct haemorrhages after death.
White occur where there is solid stroma eg heart, kidney, spleen
Red occur where there is loose stroma eg lungs, gonads, colon
What are the body’s natural defences against reactive oxygen species?
SOD enzyme plus catalase
NADPH keeps up stores of glutathione
ACE vitamins
Describe the mechanism of apoptosis.
Intrinsic - activation of p53 increases permeability of mitochondria, cytochrome c is released which creates an apoptosome and interacts with caspases
Extrinsic - ligand such as TRAIL activates caspases
Caspases cleave up the cytoskeleton
What is the function of heat shock proteins? Give an example.
After cell damage, they collect up damaged proteins, unfold them and take them back to the endoplasmic reticulum to be re folded.
Eg chaperonins
What is granulation tissue? Name some of its contents.
Early scar tissue - proud flesh
Fibroblasts
Type 3 collagen (later replaced by type 1)
Macrophages and neutrophils
Lots of new blood vessels
Define haemostasis
The collection of processes which maintain blood volume by preventing excess bleeding.
Requires vessel wall, platelets, coagulation and afterwards fibrinolysis
What is virchow’s triad?
Triad of risk factors for thrombosis:
Blood components
Blood flow
Vessel wall
Define thrombosis
Formation of a solid mass of blood in the circulation
Give three differences between the appearances of venous and arterial thrombosis.
Venous - dark red - lots of cells - soft Arterial - pale - not many cells - lines of zahn form striped between cells and fibrin - hard -
What are the 5 possible outcomes of a thrombus?
- Lysis
- Propagation - progressive spread towards the heart because of stagnant blood. (Backwards in arteries and forwards in veins.)
- Organisation - granulation tissue then scar
- Re canalisation - channels form through the scar
- Ischaemia - eg DVT, MI, stroke depending on location
Define an embolus and give 4 substances which can form one.
Obstruction of a blood vessel at a distant site. Can be formed by- 1. Thrombus (thrombo embolus) 2. Air 3. Fat 4. Nitrogen 5. Amniotic fluid
What are the contents of granulomatous inflammation? (Granulomas)
Epithelioid cells and macrophages
Plus sometimes fibroblasts and giant cells
What happens during the vascular phase of the clotting cascade?
Vessels transiently dilate then constrict
Tissue factors from endothelium activate extrinsic pathway
Collagen activates the intrinsic pathway
Von willebrand factor activates platelets
What happens during the platelet phase of the clotting cascade?
Platelets are released from megakaryocytes
Formation of the primary plug
Gla residues attract the clotting factors
What happens during the coagulation phase of the clotting cascade?
Extrinsic pathway and intrinsic pathway meet at factor 10 - prothrombin
Activate thrombin which activates fibrin which attaches to the primary plug and forms a clot
What is measured by 1. Bleeding time 2. Prothrombin time 3. PTTK?
- Platelet activation and formation of primary plug
- Extrinsic pathway of clotting cascade
- Intrinsic pathway of clotting cascade
What tissue factors are absent in Haemophilia? What measure will increase?
8 and 9
Increase in PTTK
What is missing in Von Willebrands disease? What measure will increase?
Von willebrand factor which activates platelets
Bleeding time will increase
What measure will increase in a vitamin k deficiency?
INR (prothrombin time)
Name 4 substances which help fibrinolysis and name the substance they act on.
Anti thrombin c - clotting factors
Plasminogen - fibrin
Protein c and thrombomodulin - thrombin
Prostacyclin - platelets
When would each of the following drugs be used to break down a clot? Aspirin Streptokinase Heparin Warfarin
- Chronic - platelet action
- Emergency - clotting factor action
- Acute - clotting factor action
- Chronic - clotting factor action
What is the difference between atheroma and atherosclerosis?
Atheroma is the accumulation of intra and extra cellular lipid in the intima of arteries.
Atherosclerosis is the hardening of the arterial wall as a consequence.
How does atheroma develop macroscopically?
Fatty streak
Simple plaque - fibrosis/necrosis
Complicated plaque - extends to media
How does atheroma develop microscopically?
Smooth muscle proliferation
Macrophages, Foam cells and extra cellular lipid
Fibrosis/necrosis
Extends to the intima