Pathology Flashcards
Some uses for PCR?
Diagnosis of neoplasms
Identification of micro-organisms
Steps in PCR?
94-96ºC - The strands are separated, this is called denaturing.
50-60ºC - The oligonucleotide primers attach to the separated strand (annealing)
72ºC - The taq DNA polymerase binds and extends the strand from the primer (amplification).
How long does PCR typically take?
A couple of hours
What is the drawback to the extreme sensitivity of PCR?
contamination.
What is grade in cancer?
How closely the neoplasm resembles normal tissue.
What grade represents a better prognosis in cancer?
Well differentiated cancer (resembles normal tissue)
What is stage in cancer?
The anatomical spread of the cancer.
What is TNM?
A staging system for cancer.
What is an atheroma ?
The patchy accumulation of fat with the arteries.
What is a fatty streak?
The deposition of fat within the tunica intima this is digested by macrophages.
How does a fatty streak become a plaque?
- Some of the foam cells die and release fat into the extracellular space.
- Prompts a chronic inflammatory response.
- More macrophages and T-cells are recruited.
- Smooth muscle cells in the media multiply and migrate into the intima, they become fibroblast like and start secreting collagen and other matrix compounds.
What is in the core of a plaque?
Necrotic lipid tissue.
What is superficial to the core of the plaque?
The fibrous cap containing smooth muscle cells and collagen (facing the lumen)
The chronic inflammation with macrophages, T-lymphocytes and smooth muscle cells.
What are the vascular effects in inflammation?
- Relaxation of pre-capillary sphincters to produce hyperaemia (increased blood flow)
- Increased capillary permeability.
What are the actions of circulating cells in inflammation?
- Adhesion of leucocytes
- emigration
- chemotaxis
What is diapedesis of red cells in inflammation?
Escape of red cells through the damaged endothelium.
Degranulation of mast cells can release what pre-synthesised mediators?
Histamine
Serotonin
Heparin
Proteases
Degranulation of mast cells can release what newly synthesised mediators?
Prostaglandins
Platelet activating factor
Cytokines
Eosinophil chemotactic factor
What are the roles of macrophages in inflammation?
- Phagocytosis
- Release of antimicrobial factors such as proteases
- Release of cytokines
- Presentation of antigens to activate other cells
How can we distinguish between neoplastic and reactive proliferations?
Reactive proliferations are polyclonal, neoplastic proliferations are monoclonal.
PCR can be used to distinguish between the two.
What are Natural killer cells, what is their role?
What receptors do they have?
Leucocytes that that can destroy virally infected and neoplastic cells with requiring previous sensitisation.
They have Ig Fc receptors
What is the role of fibroblasts? (2)
ECM secretion in healing
Cytokine secretion
What are the four cascade systems of plasma proteins?
- Coagulation
- Complement
- Fibrinolytic
- Kinin
Explain briefly the complement cascade?
The Classical stimulation is Ab-Agor manna-binding lectin.
The alternative is endotoxin,
This causes C3b to cause opsonisation, C3a/C5a to cause chemotaxis and degranulation of mast cells and the membrane attack complex
Brief description of the kinin system?
Activated factor XII can activate bradykinin which can:
- Activates plasmin
- Pain
- Vascular dilation and permeability
What are the three alternative routes of action that can happen following tissue injury?
If there is a population of cells that can regenerate and there is minimal damage to the matrix then healing by resolution can occur.
If the cells cannot regenerate and/or there is extensive tissue damage then granulation tissue and scarring occurs
If there is continued tissue damage then chronic inflammation can occur.
What are the tow conditions that cause COPD?
Chronic bronchitis and Emphysema
What is chronic bronchitis and what is it’s clinical definition?
Chronic bronchitis is persistent inflammation of the bronchi. Definied clinically as a persistent cough for at least 3 consecutive months in 2 years.
What causes Chronic bronchitis?
Caused by irritants that damage the respiratory mucosa, most commonly Tobacco smoke.
What can cause narrowing of the brochi in chronic bronchitis? (3)
Increased mucus in the lumen (due to hypertrophy of mucus glands)
Inflammatory oedema of the wall.
Hypertrophic smooth muscle layer.
When chronic damage to the bronchial epithelium results in metaplasia of that epithelium what is the resultant type of epithelia?
Stratified squamous.
What symptoms is the nickname Blue Bloater used to describe in patients and what is this usually the result of?
Blue - due to cyanosis
Bloater - overweight due to exercise intolerance
Usually the cause of chronic bronchitis.
What is an infective exacerbation of chronic bronchitis?
Infection due to the fact the the excess mucus in bronchitis has increased the chances of this occurring.
What do clinicians mean when they refer to a chest infection?
infective exacerbation of chronic bronchitis or pneumonia.
What exactly is emphysema?
The abnormal enlargement of the airspaces distant to the terminal bronchioles due to destruction of the alveolar walls and the respiratory bronchiole walls.
What is the pathogenesis of emphysema?
Protease/anti-protease imbalance.
The tobacco smoke causes neutrophils and macrophages to release large amounts of proteases
The tobacco smoke free-radicals inactivates anti-proteases so that more proteases are present.
The proteases go onto destroy lung tissue.
What is alpha-1-antitrypsin deficiency?
Inherited deficiency in alpha-1-antitrypsin, so that even air-pollution can lad to early onset emphysema.
What are the clinical features of emphysema?
The ‘pink puffer’ image. Patients typically use accessory muscles and a lot of effort to breathe and therefore are not cyanotic, they may also breathe through pursed lips.
Can be Barrel chested and have a low BMI.
What is bullous emphysema and what complication can arise from it?
When bullae (air filled sacs) are produced just below the visceral pleura in emphysema
If a Bulla ruptures this can cause pneumothorax.
What is the type of pathogen associated with acute bronchitis?
Viruses e.g. in laryngotracheobronchitis
In type 2 respiratory failure what causes increased inspiration hpoxia or hypercapnia?
Hypoxia (it is usually hypercapnia)
Effects of lung cancer?
Ectopic hormone production
Cachexia
What is a haemothorax?
Blood in the pleural cavity.
What is the characteristically coloured sputum in pneumonia?
Rusty coloured and green speckled.
What does pyrexial mean?
Fever.
What exactly is pneumonia?
Inflammation of the parenchyma by a virus or bacteria.
Two main anatomical types of pneumonia?
Lobar or bronchopneumonia.
What are the five physiological means by which hypoxaemia occurs?
Hypoventilation Shunt Inspired PO2 (Altitude) V/Q mismatch (ventilation/perfusion) Diffusion block
What is hypoxaemia?
Low oxygen in blood.
What are the two main blood supply systems to the lungs? what does each supply?
Bronchial circulation - arises from systemic circulation to supply smooth muscle, nerves and interstitial tissue
Pulmonary circulation - arises from the pulmonary arteries and the right side of the heart, supplies capillary networks of the alveoli.
Difference in pulmonary and systemic circulation?
Low pressure, low resistance.
What is a pulmonary embolus?
Obstruction of the pulmonary arterial system by a factor that was previously in the venous system.
What clinical signs would a large pulmonary embolus produce?
Sudden onset of chest pain
Breathlessness
Collapse
Low BP
Why might you not perform thrombolysis?
Coma
Recent Haemorrhage
Severe hypertension
Activating factors for platelets and their function?
Activating factors: Thrombin, Exposed collagen
Function: Secretion of pro-thrombotic substances, Aggregation to form a plug of platelets stuck together.
Activating factors for the coagulation cascade and it’s function?
Activating factors: Abnormal surfaces, tissue thromboplastin.
Function: Production of thrombin, production of fibrin
What substances do endothelial cells produce which inhibit blood clotting?
NO and prostacyclin which inhibit platelets
Thrombomodulin: inhibits the clotting factor pathway
What factors that inhibit the coagulation cascade are in the normal circulation?
Antithrombin III
Protein C
What spinal levels supplies the sympathetic innervation of the heart?
T1-T5
Three components of Virchow’s triad?
Damage to vessel wall
Alterations in flow of blood
Alterations in coagulability of blood
Two examples of alterations in the flow of blood?
Turbulence, stagnation.
What can cause hypercoagulabilty of blood?
Increased viscosity
Thrombosis/thrombolysis
What are the three possible outcomes following a thrombosis?
Complete resolution with disappearance of thrombus
Organisation by granulation tissue to produce a scar, could cause stenosis or complete occlusion
Fragments of the thrombus break off into the circulation (embolism)
Possible origins of embolisms?
Gas, e.g. nitrogen in divers, or air in trauma
Fat e.g. after extensive trauma or burns
Possible consequences of emboli?
Systemic emboli may cause infarction if they block an end artery
Pulmonary emboli - breathlessness or no symptoms ranging to death.
Following endothelial injury, what factors promote coagulation?
Platelets adhere to ECM via Von Willibrand factor
Activated platelets release ADP and thromboxane
Fibrin polymerisation eventually forms platelet plug
What are the three major macroscopic types of atherosclerotic lesion?
Fatty streak
Fibrolipid plaque
Complicated lesion