Flashcards in Cell Injury Deck (61):
What 7 situations can cause cell injury?
Hypoxia, Chemical agents and drugs, Infections, Immunological agents, Dietary imbalance, Genetic derangement + Physical agents
What are the 2 types of cell death and define them
Necrosis - a pathological form of cell death due to disease, injury or inadequate blood supply
Apoptosis - programmed cell death
What are the types of necrosis and which one is the most common?
Coagulative, liquefactive, fat, caseous and fibrinoid
Coagulative is the most common
What is an infract, what are the different types and where can they be seen?
An infract is a lesion that can be seen as a result of an infarction.
There can be white infarcts which occur in solid organs like the heart, spleen and kidney
There can be red infarcts which occur in organs with a dual blood supply, loose stromal support or numerous anastomoses like the liver and lungs
What are the differences between necrosis and apoptosis?
Necrosis affects groups of cells, causes swell enlargement, disrupted plasma membrane and is frequently associated with inflammation
Apoptosis affects single cells, caused cell shrinkage, keeps the plasma membrane intact and is not associated with inflammation
What proteins are released from myocardiocytes during myocardial infarction and which one is the best clinical marker and why?
Troponin - best marker because it lasts the longest ~120 hours after heart attack
What are some causes of acute inflammation?
Microbial infection, hypersensitive reactions, physical agents,chemicals, tissue necrosis and anything that can cause trauma to the tissue
What are the 5 clinical features of acute inflammation?
Redness, swelling, heat, pain and loss of function
What is the main leukocyte involved in acute inflammation and what is its function?
Produce growth factors for repair
What is the difference between a transudate and exudate? Describe the formation of an exudate
Both are fluids that fill extra vascular spaces and serous cavities
Transudate - has low protein content
Exudate - has high protein content
Give examples of some chemical mediators
Histamine, prostaglandin, serotonin and bradykinin
What are the 4 systemic effects of acute inflammation?
Pyrexia, leukocytosis, acute phase response in liver and shock
What is alpha-1 antitrypsin deficiency?
An autosomal recessive disorder caused by low levels of alpha-1 antitrypsin resulting in unchecked inflammation which can lead to emphysema and cirrhosis
What is chronic inflammation?
A chronic response to cell injury which is usually associated with fibrosis
Which leukocyte is mainly involved in chronic inflammation and what are its functions?
Antigen presenting to immune system
Synthesis of cytokines
Fibrosis and angiogenesis
Release of growth factors
What are giant cells and what are the 3 types?
Giants cells - multinucleated cells made by fusion of macrophages due to frustrated phagocytosis
3 types are: langerhans giant cell, foreign body type and touton type giant cell
What are the main effects of chronic inflammation?
Fibrosis, impaired function and atrophy
What is granulomatous inflammation and what are the 3 main causes?
Chronic inflammation with granulomas
3 main causes: mildly irritant foreign material, infections and other unknown causes
What can cause reduced blood supply to tissue?
Thrombosis, embolism, twisting of blood supply and external compression of blood vessel
What is a gangrene and what are the different types?
A clinical term used to describe visible necrosis
3 different types: wet, dry and gas
What are the 5 groups of intracellular accumulations?
Water and electrolytes
What are the 3 different tissue types in terms of regeneration, give an example of each.
Labile tissue - surface epithelia, bone marrow
Stabile tissue - fibrous tissue, liver parenchyma, bone osteoblasts
Permanent tissue - neural tissue, cardiac muscle, skeletal muscle
What are the processes of wound healing?
What is granulation tissue and what does it consist of?
Tissue that has a granular appearance and texture
Consists of developing capillaries, fibroblasts, myofibroblasts and chronic inflammatory cells
What are the different types of cell signalling mechanisms?
Autocrine - cells respond to signalling molecules that they produce themselves
Paracrine - cells produce signalling molecules that act on adjacent cells
Endocrine - hormones are made by cells and travel through the blood stream to any organ/tissue of choice
Why are growth factors important in healing?
They are polypeptides that act on cell surface receptors by binding to them and stimulating transcription of genes that regulate entry of genes into the cell cycle
What are some local factors in healing?
Size of wound
Location of wound
What are some systemic factors of healing?
Diseases like diabetes
Vitamin deficiency (vitamin c)
What is a keloid scar?
A complication of fibrous repair where there is overproduction of fibrous scar tissue due to overproduction of collagen
What is haemostasis and what are the steps involved?
The complex process that stops bleeding, representing a balance between procoagulant and anticoagulant factors
3 stages include: primary haemostasis, secondary haemostasis and fibrinolysis
What 4 components does successful haemostasis depends upon?
Describe the process of haemostasis
Injury occurs > vessel wall constricts > endothelial cells secrete Von willebrand factor > platelets adhere to subendothelial structures via Von willebrand factor > platelets adhere to each other > fibrinogen holds platelets together forming a primary platelet plug > fibrin surrounds platelet plug making it insoluble > after a while, plasminogen is activated into plasmin > plasmin breaks down fibrin into fragments following would healing
What is a DVT?
Deep vein thrombosis - a clot within a vein
What is a pulmonary embolism?
Blockage of the artery in the lungs caused by the breaking off of a DVT into the bloodstream
What is a thrombosis?
The formation of a solid mass made of the constituents of blood within the circulatory system
What is Virchow’s triad and what constitutes it?
The 3 categories of factors that are thought to contribute to thrombosis: blood flow, vessel wall and blood components
What are the 5 possible outcomes of thrombosis?
What is an embolism?
The blockage of a blood vessel by solid, liquid or gas at a distant site from its origin
Define thrombocytopenia and thrombocytosis
Thrombocytopenia - lack of platelets
Thrombocytosis - abundance of platelets
In what ways can the coagulation system be inhibited?
Use of antithrombin 3 - group of enzyme that inhibit serine protease, thrombin and factor 10a
Use of protein C - vitamin k dependent zymogen that cleaves factor 5a and 8a and works together with co factor protein s to degrade them
What are the effects of a venous thrombosis?
Infarction due to compression of arterial vasculature
What are the effects of an arterial thrombosis?
Infarction which depends on site and collateral circulation
What is heparin and its mechanism?
Naturally occurring anticoagulant in the body that increases the effect of Antithrombin 3
What is warfarin and its mechanism?
A vitamin k antagonist that aids in anticoagulation by inhibiting the synthesis of clotting factors 2, 7, 9 and 10
The thickening and hardening of the intima and media walls of elastic and large and medium sized muscular arteries due to deposition of intracellular and extra cellular lipid
What is ARTERIOSCLEROSIS?
Thickening and hardening of walls of arteries and arterioles usually due to diabetes or hypertension
What are the layers of the normal arterial structure?
Endothelium - subendothelial connective tissue - internal elastic lamina - muscular media - external elastic lamina - adventitia
In atherosclerosis, hows does plaque develop?
Yellow lipid deposits in the intima form a fatty streak
The fatty streak develops to form a simple plaque which is yellow/white in colour with an irregular outline
Simple plaque undergoes calcification resulting in a complicated plaque
What are some common sites for atherosclerosis?
Arteries of the legs - popliteal artery
What are some of the microscopic features of atherosclerosis?
Accumulation of foam cells
Proliferation of smooth muscle cells
Extracellular lipid deposition
Scattered T lymphocytes
What are the cellular events that lead to atherosclerosis?
Chronic Epithelial injury - causes a chronic inflammatory response
Endothelial dysfunction - caused by chronic epithelial injury
Smooth muscle immigration from media to intima - promoted by PDGF
Macrophages and smooth muscle cells engulf accumulated lipid and form foam cells
Smooth muscle proliferation in response to cytokines, growth factors, collagen, matrix deposition and neovascularisation
What are the effects of atherosclerosis of the coronary artery?
Reduced blood flow to myocardiocytes which can result in myocardial infarction, arrhythmias, cardiac failure, angina pectoris and sudden death
What is the effect of atherosclerosis of the carotid artery?
Cerebral ischaemia leading to a stroke
What is the effect of atherosclerosis of the mesenteric arteries?
Ischaemia of the bowel
What are the effects of atherosclerosis in peripheral vasculature?
Intermittent claudication - muscle pain/cramp/ache which occurs after mild exercise, usually in calf muscle
Leriche’s syndrome - group of symptoms caused by a certain type of peripheral arterial disease of the legs
Ischaemia rest pain
What are some risk factors for atherosclerosis?
Age - more common in elderly
Gender - more common in males
Hyperlipidemia - mainly LDLs
Excessive alcohol intake
Infection - mainly bacterial
Geography - lower incidence in South America, Africa and Asia
What is atherogenesis and which cells are involved?
Development of plaques within blood vessels
Smooth muscle cells
What are the 3 typical signs of hyperlipidemia?
What preventative measures can be taken to avoid atherosclerosis?
Decrease fat intake - LDLs
Intake of aspirin
Regular exercise and control of weight
Lipid lowering drugs e.g. statins
Sensible alcohol intake
What does the size of a cell population depend on and what cell regulate it?
Proto-oncogenes regulate it