Pathology Flashcards
When is inflammation a good reaction ?
Infection
Injury
When is inflammation bad ?
Autoimmunity
Over-reaction to stimulus
How is acute inflammation classified?
Sudden Onset
Short duration
Usually resolves
How is chronic inflammation classified?
Slow onset or sequel to acute
Long duration
May never resolve
What cells are involved in inflammation?
Neutrophil polymorphs - acute inflammation Macrophages Lymphocytes Endothelial cells Fibroblasts
What are Neutrophil polymorphs?
• Short lived cells
• First on the scene of acute inflammation
• Cytoplasmic granules full of enzymes that
kill bacteria
• Usually die at the scene of inflammation
• Release chemicals that attract other
inflammatory cells such as macrophages
What are Macrophages?
- Long lived cells (weeks to months)
- Phagocytic properties
- Ingest bacteria and debris
- May carry debris away
- May present antigen to lymphocytes
What are lymphocytes?
• Long lived cells (years)
• Produce chemicals which attract in other
inflammatory cells
• Immunological memory for past infections
and antigens
What is the importance of endothelial cells in inflammation?
• Line capillary blood vessels in areas of
inflammation
• Become sticky in areas of inflammation so
inflammatory cells adhere to them
• Become porous to allow inflammatory cells
to pass into tissues
• Grow into areas of damage to form new
capillary vessels
What are fibroblasts?
- Long lived cells
* Form collagen in areas of chronic inflammation and repair
What is an example of acute inflammation?
• Acute appendicitis
What happens during acute appendicitis?
– Unknown precipitating factor – Neutrophils appear – Blood vessels dilate – Inflammation of serosal surface occurs – Pain felt – Appendix either surgically removed or inflammation resolves or appendix bursts with generalised peritonitis and possible death
Give an example of Chronic inflammation?
Tuberculosis
What happens during TB inflammation
– No initial acute inflammation – Mycobacteria ingested by macrophages – Macrophages often fail to kill the mycobacteria – Lymphocytes appear – Macrophages appear – Fibrosis occurs
What is the definition of acute inflammation?
The initial and often
transient series of tissue reactions to injury
What is the definition of chronic inflammation?
The subsequent and
often prolonged tissue reactions following the
initial response.
What type of cells are commonly seen histologically in TB?
Multinucleate giant cell - macrophages fused together
seen also in reaction to silica in the lungs.
What is commonly seen on a X-ray of a patient that has overcome TB?
Apical fibrosis
What is resolution?
–initiating factor removed
–tissue undamaged or able to regenerate
What is repair?
–initiating factor still present
–tissue damaged and unable to regenerate
How does repair work?
• replacement of damaged tissue by fibrous tissue • collagen produced by fibroblasts • examples –heart after myocardial infarction –brain after cerebral infarction –spinal cord after trauma
Which cells regenerate?
- hepatocytes
- pneumocytes
- all blood cells
- gut epithelium
- skin epithelium
- osteocytes
which cells do not regenerate?
- myocardial cells
* neurones
What is chirrosis?
Liver fibrosis and regenerative nodules causes by repetitive injury ie: alcoholism
What is Lobar Pneumonia?
- affects only 1 lobe of the lung.
- lobe fills with pus, neutrophil polymorphs.
- treat with antibiotics
- pneumocytes can regenerate
How to abrasions heal?
ie: Road rash, scraped knee
•scab formed over surface
•epidermis growing out from the adnexa, protected by scab
•thin confluent epidermis
How does healing by 1st intention work? (skin wounds)
- Incision
- -> Exudation of fibrinogen - weak fibrin join
- -> Epidermal regrowth and collagen synthesis - Strong collagen join (white scar)
what is granulation tissue?
new connective tissue and microscopic blood vessels that form on the surfaces of a wound during the healing process
What are the clinical features of inflammation?
- tissue that is: Swollen, red, tender and warm.
* may be some loss of function depending on the degree of inflammation and tissue type.
What are some causes of inflammation?
- Necrosis/infarction/direct trauma
- Infection (bacteria, virus, fungi,portazoa,parasites)
- Chemical or other physical agents for example radiotherapy
- Autoimmune reactions, particularly hypersensitivity states.
What is a granuloma?
- Collection of histocytes
* A form of chronic inflammation (type IV hypersensitivity)
What is Rheumatoid arthritis?
•Inflammatory arthritis with granulomatous features with no overt cause.
•affects mainly joints
•can also cause: lung nodules and fibrosis
cardiovascular arteritis and valvitis
and other systemic conditions ie amyloid
Name some drugs that can be used in Rheumatoid arthritis
analgesics NSAIDs Steroids Disease modifying drugs: Methotrexate, sulphasalazine, Lefunomide
What are the key cells seen in acute inflammation?
Polymorphonuclear neutrophils
What is an abscess?
Acute inflammation with fibrotic wall.
why don’t blood clots form all the time?
- Laminar flow - cells travel in the centre of arterial vessels and don’t touch the sides
- Endothelial cells which line vessels are not ‘sticky’ when healthy
What is thrombosis?
The formation of a solid mass from blood constituents in
an intact vessel in a living person.
What are the 3 factors that can cause thrombosis?
- Change in vessel wall
- Change in blood flow
- Change in blood constituents.
How does thrombosis work?
- Platelet aggregation
- Clotting cascade
- Formation of large protein molecule fibrin.
Platelets release chemicals when they aggregate which cause other platelets to stick to them and also which start off the cascade
of clotting proteins in the blood. Both these reactions
involve positive feedback loops so that once they have started they are difficult to stop. Once the clotting cascade has started there is formation of the large protein molecule fibrin which makes a mesh in which red blood cells can become entrapped.
What is an embolism?
Is the process of a solid mass in the blood being carried through the circulation to a place where it gets stuck and blocks the vessel.
What is the most common cause of an embolism?
Thrombus (e.g. a deep venous thrombosis of the leg veins which breaks off and embolises through the large veins and right side of the heart to the lungs).
What are other causes of embolisms?
- Air ( pressurised system ie: IV/blood)
- Cholesterol crystals (atheromatous plaques)
- Tumour
- Amniotic fluid (rare)
- Fat ( severe trauma)
What happens if an embolus enters the venous system?
It will travel to the vena cava through the right side of the hear and lodge somewhere in the pulmonary arteries.
Why can an embolus in the venous system not enter arterial circulation?
The blood vessels in the lung split down to capillary size (through which only single red blood cells can squeeze) so the lungs
act as a filter for any venous emboli.
What is ischaemia?
A reduction blood flow to a tissue without any other implications.
What is an infarction?
The reduction in blood flow to a tissue that is so reduced that it cannot even support mere maintenance of the cells in that tissue so they die.
What usually causes an infarction?
macroscopic event caused by thrombosis of an artery
e.g. thrombus in the left anterior descending coronary artery causing infarction of the anterior
wall of the left ventricle.
Which organs are less susceptible to infarction due to dual arterial supply?
Liver - with portal venous and hepatic artery supplies,
Lung - with pulmonary venous and bronchial artery supplies
Brain around the circle of Willis with multiple
arterial supplies.
what conditions is commonly seen in the aorta of patients over the age of 60- 70?
atherosclerosis
Where are atherosclerotic plaques not seen
In low pressure systems eg: pulmonary arteries
Where is atherosclerosis commonly seen?
High pressure systems:
eg: porter and systemic arteries
What is a plaque?
Fibrous tissue
lipids - cholesterol
lymphocytes
what are the risk factors for atherosclerosis?
- smoking - cigarettes
- hypertension
- poorly controlled diabetes
- Hyperlipidaemia
What is the mechanism of atherosclerosis?
Endothelial damage theory:
- Endothelial damage
- Platelet aggregation
- Thrombus formations
- endothelial cells grow over the thrombus
- atherosclerotic clot
What can damage/kill endothelial cells?
- Smoking: free radicals, nicotine, CO
- Hypertension: Shearing forces
- Poorly controlled diabetes: superoxide anions, glycosylation products
- Hyperlipidaemia: high lipid levels damage cells.
Which drug can be used as to reduce formation of plaques?
Asprin - inhibits platelet aggregation
What are the complications of atherosclerosis?
- Cerebral infarction
- Carotid atheroma: emboli causing transient ischaemic attacks or cerebral infarcts
- MI - cardiac failure
- Aortic aneurysms- rupture causes sudden death
- Peripheral vascular disease with intermittent claudication
- Gangrene
What is apoptosis?
Programmed cell death - Single cell
What is necrosis?
Traumatic cell death - group of cells
What are some clinical examples of necrosis?
• Toxic spider bite • Frostbite • Cerebral infarction • Avascular necrosis of bone ( seen commonly in #NOF) • Pancreatitis
What are 3 types of necrosis?
Coagulative necrosis - semi solid
Liquifactive necrosis - liquid (common in brain)
Caseous necrosis
How does apoptosis work?
- Nucleus condenses (pyknosis), cytoplasmic blebs form, cell shrinkage.
- breaks down into apototic bodies
- Phagocytes engulf bodies.
When does apoptosis happen?
- Fully differentiated cells
2. Resting cell