Basic Pathology Flashcards
Define inflammation
The local physiological response to to tissue injury, it is not itself a disease but a manifestation of disease
What beneficial effects might inflammation have?
Destruction of invading organisms and the walling off of an abscess cavity to prevent spread of infection
What harmful effects might inflammation have?
May produce disease e.g. abscess in the brain would act as a space occupying lesion; compressing vital surrounding structures
Define acute inflammation
the initial and often transient series of tissue reactions to injury
Define chronic inflammation
the subsequent and often prolonged tissue reactions following the initial response
How else can inflammation be categorised?
By differences in cell type involved
Outline the steps of acute inflammation
- Initial reaction of tissue to injury
- Vascular component: dilation of vessels
- Exudative component: vascular leakage of protein rich fluid
- Neutrophil polymorph is the characteristic cell recruited to the tissue
- Outcome may be resolution, suppuration (abscess), organisation, or progression to chronic inflammation
List some causes of inflammation
Microbial infections, hypersensitivity reactions, physical agents, chemicals, bacterial toxins, tissue necrosis
How might a bacteria cause inflammation?
Release specific exotoxins- chemicals synthesised by them that specifically initiate inflammation- or endotoxins, which are associated with their cells walls
When do hypersensitivity reactions occur?
When an altered state of immunological responsiveness causes an inappropriate or excessive immune reaction that damages the tissues
What are the macroscopic appearances of inflammation?
- Redness (Rubor)
- Heat (Calor)
- Swelling (Tumor)
- Pain (Dolor)
- (loss of function)
Why does redness occur in inflammation?
dilation of small blood vessels within the damaged area
Why does heat occur in inflammation?
(only in skin) due to increased blood flow (hyperaemia) through the region, resulting in vascular dilation and delivery of warm blood to the area
Why does swelling occur in inflammation?
- Swelling results from oedema- the accumulation of fluid in the extravascular space as part of the fluid exudate
- to a much lesser extent, the physical mass of cells migrating to the area
- as the inflammation process progresses, formation of new connective tissue also contributes to swelling
Outline why pain occurs in inflammation
- Stretching and distortion of tissue due to inflammatory oedema and pus under pressure in an abscess cavity
- Some chemical mediators of acute inflammation e.g. bradykinin, prostaglandins and serotonin, are known to induce pain
Why does loss of function occur in inflammation?
Movement is consciously and reflexively inhibited by pain, while severe swelling may physically immobilise the tissue
What is essential for the histological diagnosis of acute inflammation?
presence of neutrophil polymorphs
Name the 3 processes involved in acute inflammation
- Change in vessel calibre and, consequently, flow
- Increased vascular permeability and formation of the fluid exudate
- Formation of the cellular exudate- emigration of the neutrophil polymorphs into the extravascular space
List the time course mechanisms of increased vascular permeability
- Immediate transient chemical mediators
- Immediate sustained severe direct vascular injury
- Delayed prolonged endothelial cell injury
Give some examples of immediate transient chemical mediators that increase vascular permeability
histamine, bradykinin, nitric oxide, C5a, leucotriene B4, platelet activating factor
Give an example of immediate sustained severe direct vascular injury
trauma
Give examples of delayed prolonged endothelial cell injury
X-rays, bacterial toxins
List the stages in neutrophil polymorph emigration
- Margination of neutrophils
- Pavementing of neutrophils
- Pass between endothelial cells
- Pass through basal lamina and migrate into adventitia
What do endogenous chemical mediators cause?
- Vasodilation
- Emigration of neutrophils
- Chemotaxis
- Increased vascular permeability
- Itching and pain
List some chemical mediators released from cells
Histamine (others include: lysosomal compounds, eicosanoids, serotonin and chemokines)
The plasma contains four enzymatic cascade systems (which are interrelated), what are they?
- Complement
- The kinins
- The coagulation factors
- Fibrinolytic system
Draw the effect of coagulation factor XII (Hageman factor)
Refer to notes
Draw the diagram for the kinin system
Refer to notes
List the descriptive terms used for the macroscopic appearance of acute inflammation
- Serous
- Suppurative (purulent)
- Membranous
- Pseudomembranous
- Necrotising (gangrenous)
What are the systemic effects of inflammation?
Pyrexia (fever) Constitutional symptoms Weight loss Reactive hyperplasia of the reticuloendothelial system Haematological changes Amyloidosis
What is granulomatous inflammation?
A specific type of chronic inflammation
What is a granuloma?
An aggregate of epithelioid histiocytes
List the cells involved in chronic inflammation
Plasma cells, capillary endothelium, lymphocytes, multinucleate giant cells, macrophage, fibroblasts
What are the causes of chronic inflammation?
- Primary chronic inflammation
- Transplant rejection
- Progression from acute inflammation
- Recurrent episodes of acute inflammation
What are the macroscopic appearances of chronic inflammation?
- Chronic ulcer
- Chronic abscess cavity
- Thickening of the wall of a hollow viscus
- Granulomatous inflammation
- Fibrosis
List some microscopic appearances of chronic inflammation
- Cellular infiltrate consists of lymphocytes, plasma cells and macrophages
- Few eosinophil polymorphs may be present, but neutrophil polymorphs are scarce
- Multinucleate giant cells
- Production of new fibrous tissue
- Tissue necrosis
What are the predominant features in repair? and what are these processes regulated by?
Angiogenesis followed by fibroblast proliferation and collagen synthesis resulting in granulation tissue. Regulated by growth factors which bind to specific receptors.
List some examples of granulomatous disease
tuberculosis, leprosy, Chron’s disease, sarcoidosis
Describe the appearance of an epithelioid histiocyte
vague histiological resemblance to epithelial cells, large vesicular nuclei, plentiful eosinophil cytoplasm and are often rather elongated
Name an excretory product of epithelioid histiocytes
angiotensin converting enzyme
What clinical use do epithelioid histiocytes have?
Measurement of its activity in the blood can act as a marker for systemic granulomatous disease
What might the presence of granulomas be augmented by?
The presence of caseous necrosis or by the conversion of some of the histiocytes into multinucleate giant cells
Small traces of what element can induce granuloma formation?
Beryllium
Draw the cellular cooperation that occurs in chronic inflammation
See notes
When do histiocytic giant cells tend to form?
Particularly when foreign particles are too large to be ingested by just one macrophage
How are multinucleate giant cells thought to be formed?
‘By accident’ when two or more macrophages attempt simultaneously to engulf the same particle; their cell membranes fuse and the cells unite
In which condition are Langhan’s giant cells characteristically seen?
Tuberculosis
When are ‘foreign body giant cells’ characteristically seen?
In relation to particulate foreign body material
When are touton giant cells often seen?
When macrophages attempt to ingest lipids, and in xanthomas/ dermatofibromas of the skin
Give an example of how acute inflammation is involved in the CV system
In the response to acute MI and the generation of some complications of MI such as cardiac rupture
Give two conditions which chronic inflammation is associated with
Initiation, propagation and progression of cancer, myocardial fibrosis post MI
Outline how inflammation makes an important contribution to development of atheroma
Macrophages adhere to endothelium, migrate into the arterial intima and with T-lymphocytes, express cell adhesion molecules which recruit other cells into the area. The macrophages are involved in processing the lipids that accumulate in atheromatous plaques.
Explain the difference between exudate and transudate
Exudates have a high protein content beacue they reulst from increased vascular permeability. Transudates have a low protein content because the vessels have normal permeability characteristics.
Define granulation tissue
An important component of healing that comprises small blood vessels in a connective tissue matrix with myofibroblasts.
Define fibrous
Fibrous describes the texture of a non-mineralised tissue of which the principle component is collagen (e.g. scar tissue)
Describe the process of repair after surgical incision
Incision, Exudation of fibrinogen, weak fibrin join, epidermal regrowth and collagen synthesis, strong collagen join
List some cells that regenerate
hepatocytes, pneumocytes, all blood cells, gut epithelium, skin epithelium, osteocytes
List some cells that do not regenerate
myocardial cells, neurones
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
Define thrombosis
The formation of a solid mass from blood constituents in an intact vessel in a living person
What is the first stage of thrombosis?
platelet aggregation
What happens when platelets aggregate?
The 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
What 3 factors are involved in the triad used for assessing a patients’ risk of thrombosis
- Change in vessel wall
- Change in blood flow
- Change in blood constituents
Define embolism
This is the process of a solid mass in the blood being carried through the circulation to a place where it gets stuck and blocks a vessel
List some less common causes of embolus
air, cholesterol crystals, tumour, amniotic fluid, fat
Define ischaemia
Simply a reduction in blood flow to a tissue without any other implications
Define 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.
List the organs less susceptible to infarction
liver, lungs and brain (due to multiple blood supplies)
List the steps involved in atherosclerosis
- Irritant
- Damage to endothelium
- LDL- cholesterol deposits
- Monocytes -> macrophages -> ‘foam cells’
- Plaque grows
- Smooth muscle cells migrate out of the layer into fatty plaque, forming a fibrous cap which shields the thrombotic material from blood
- Macrophage death induces calcium secretion into the plaque
- Plaque occludes the artery, hardens artery and can rupture
- If ruptured, thrombosis occurs and can completely block artery or embolise
Define apoptosis
Programmed cell death
Define necrosis
Unprogrammed cell death as a result of cell damage
What can a lack of apoptosis cause?
cancer
What can an excess of apoptosis cause?
psoriasis
Define hypertrophy
An increase in size of a tissue caused by an increase in size of constituent cells
Define hyperplasia
An increase in size of a tissue caused by an increase in number of constituent cells
Define atrophy
Decrease in size of a tissue caused by a decrease in size or number of constituent cells
Define metaplasia
Change in differentiation of a cell from one fully-differentiated type to a different fully-differentiated type
Define dysplasia
imprecise term for the morphological changes seen in cells in the progression to becoming cancer
What is paternally inherited and associated with parental lifespan?
Telomere length
Give some characteristics of ageing
Balding, senile dementia, cataracts, deafness, dermal elastosis, loss of teeth, hypertension and ischaemic heart disease, osteoporosis, prostatic hyperplasia (in men), diverticular disease of colon, degenerative joint disease, ankle oedema due to heart failure
How and why can basal cell carcinoma of the skin be cured easily?
It only invades locally- it never spreads to other parts of the body and can be cured with complete excision