Pathological Processes Flashcards
What is the most commonly used fixative for sugical specimens in the UK?
- Formalin
Give two reasons for fixing tissues?
- To inactive tissue enzymes and denature proteins
- To prevent bacterial growth
- To harden tissue
What is stained by Haematoxylin and what is stained by Eosin?
- Haematoxylin- Nucleus and Nucleic acids
- Eosin- Proteins, cytoplasm, extrocellular maxtix, collagen, connective tissue
Give two advantages of preforming cytology rather than a biopsy for histology?
- Faster result
- Cheap
- Minimally invasive
- Relatively safe
Why would a person require a coroner biopsy?
If the deceased is unknown
If they have not seen a doctor within 14 days of death
If cannot give a cause of death
Unnatural death
Occupational disease or accident
If related to a medical disease or treatment
Died in custody or care of the state
If was a result of termination of pregnancy
What substance is present in blood would confirm the presence of myocardial infarction?
- Troponin T or I
Why would Troponin be present in the blood after an MI?
- An area of cardiac muscle has undergone necrosis due to lack of blood supply or infarction
- In necrosis cell membranes become leaky and intracellular proteins leak out of the cells and can be measured in the blood
Apart from excessive alochol intake, name other consitions in which fatty liver is seen?
- Diabetes mellitus
- Obesity
- Carbon tetrachloride toxicity
In addition to fat, what else can accumulate within hepatocytes in patients who drink alcohol to excess?
- Mallory hyaline
How does cirrhosis appear histologially?
Bands of fibrosis surrounding nodules of regenerating hepatocytes
What is an opsonin?
- A substance that coats foreign material and makes them easier to phagocytose
Give some examples of opsonins?
- CRP, C3b, C4b, C1q, IgG, IgM, Pentraxins, Collectins, Ficolins
Briefly explain how exudate forms
- Tissue injury is followed by the release of vasoactive mediators. These induce arterioles to dilate and capillary hydrostatic pressure therefore increases
- Inflammatory mediators also cause endothelial cells to contract and the walls of venules become leaky. Fluid and plasma proteins pass out into the extravascular space as a result of the increase in capillary hydrostatic pressure adn the leaky vessel walls.
- As plasma proteins have passed into extravascular space the interstitial fluid colloid osmotic pressure increases and this holds the fluid in the extracascular space
What is a free radical?
- Reactive oxygen species
- Molecules with a single unpaired electron in an outer orbit
How does the body protect itself against feww radicals?
- Vitamin A, C, E are components of the anti-oxidant system as they donate an electron to the free radical neutralising it
- Transferrin and ceruloplasmin sequester iron and copper to prevent them catalysing the production of free radicals
- Enzymes such as superoxide dismutase, catalase and glutathione peroxidase neutralises free radicals
What is chemotaxis?
- The directional movement towards a chemical attractant
What is diapedesis?
- Diapedesis is the passage of blood cells through intact blood vessel walls
Give an example of a chemoattractant
- Endotoxin
- Thrombin
- Fibrin degradation products
- C5a, C3a, C4a
- Leukotriene B4
- Interleukin 8
Give two features seen at colonscopy that are typical features of crohns
- Discontinuous distribution
- Cobblestone appearance to bowel muscosa
- Strictures
- Fistulas
- Rectal sparing
- Involvement of the ileum
What are two classical histiological features of Crohns disease?
Transmural inflammation
Granulmomas
How is an ulcer within the intestinal tract defined?
- A breach in the lining of the bowel to the level of the submucosa or deeper
- Through the muscularis mucosa
What is the name of this conditon?
Erythema nodosum
What is the structure labelled with the black arrow? and what is affecting the area outlined with white arrows?
- The appendix
- Crohns disease
What are some risk factors for poor healing?
- Obesity
- Diabetes mellitus
- Treatment with steroids
What is the name of the tissue seen at the base of the wound?
Why is it so red?
How does this tissue help to close the wound?
- Granulation tissue
- Contains many small developing blood vessels
- Myofibroblasts that will contract and pull the edges of the wound together
Why are scars white?
Hairless
Stretched?
- White- small blood vessels regree leaving fibrous car with few vessels, melanocytes dont regenerate
- Hairless- hair follicles do not regenerate in an area of damaged skin as they are complex structure
- Stretched- Elastic fibres do not regenerate in an area of damaged skin and therefore scars can stretch as they mature
What are abdominal adhesions?
- Bands of fibrous tissue that form between abdominal tissues and organs
In paracetemol toxicity why is PT raised?
- Paracetemol toxicity has caused liver failure
- PT is a test dependant on clotting factors produced by the liver and in liver failure the clotting factors are not produced and the PT increases
In paracetemol toxicity why is ALT raised?
- Because hepatocytes have died as a result of paracetamol toxicity and ALT has leaked of the damaged cell membranes of these cells and can be measured in the blood
Why is no paracetemol detected in the blood 2 days after paracetemol is taken?
- All the drug has been metabolised
Describe the area to the right of the picture indicated by the black arrow
- Area of necrosis where the cellular architecture is preserved and where there is a ghost outline of necrotic cells
- coagulative necrosis
What could cause coagulative necrosis?
- Infarction
- Chemical injury
Which commonly used drug increased the PT and is monitored by regular INR measurements?
Warfarin
When is warfarin indicated?
- Deep vein thrombosis
- Pulmonary embolism
- Cardiac arrhythmias and atrial fibrillation
- Following cardiac valve replacement
How does warfarin work?
- Inhibits the synthesis of vitamin K dependant clotting factors
Apart from pregnancy give risk factors for DVT?
- Flying
- OCP
- Immobility
- recent operation
- HRT
- Obesity
- Smoking
- Severe burns, cardiac failure, old age, previous DVT, family history, Malignancy
Why is a woman in late pregnancy predisposed to DVT?
- In pregnancy blood is hypercoagulable and the presence of the pelvic tumour can compress venous outflow from the legs resulting in venous stasis
Why is heparin chosen instead of warfarin with DVT?
- Warfarin takes a few days to become effective
- Low molecular weight heparin is effective almost immediately
What is an embollism?
- Blockage of a blood vessel by a solid, liquid or gas at a distant site from its origin
What is a saddle embolus?
- Large embolus that straddles the bifurcation of the pulmonary embolus
What things can embolise?
- Thrombus
- Air
- Amniotic fluid
- Objects like bullets
- fat
.. A 64 year old m an has a colectomy for colon cancer.. The specimen is sent to the histology department for sampling,, processing and reporting.. During the process of embedding the tissue is impreg nated and surrounded with a hardening agent..
What agent is most commonly us ed for this purpose in the UK??
A.. Alcohol
B.. Formic acid
C.. Ice
D.. Paraffin wax
E.. Xylene
Parafin wax
.. A 57 year old man presents with severe abdominal pain.. A blood test shows amylase levels of 480 U//LL (rref:: 40 - 140)) and acute pancreatitis is diagnosed.. Despite supportive tre atment the patient dies.. An autopsy is performed and small white nodules are seen throughout the peritoneal cavity..
What do these nodules represent??
A.. Caseous necrosis
B.. Coagulative necrosis
C.. Fat necrosis
D.. Gangrenous necrosis
E.. Liquefactive necrosis
Fat necrosis
.. A 25 ye ar old man hits his thumb with a hammer..
Which of the following mediators is most likely to contribute to the pain??
A.. Bradykinin
B.. C3b
C.. C5a
D.. Serotonin
E.. Tumour necrosis factor
Bardykinin
A 74 year old man presents with a persistent cough and night sweats.. On examina tion he is found to have an enlarged lymph node in his neck.. A biopsy is taken and the histology report describes the presence of granulomas..
Which of the following are required for a histological diagnosis of this type of chronic inflammation ?
A.. Caseo us necrosis
B.. Epitheloid histiocytes
C.. Giant cells
D.. Lymphocytes
E.. Macrophages
Epitheloid histiocytes
.. An 11 year old boy presents with haematuria.. On questioning his mother also feels that her son’s hearing is becoming worse.. Alport syndrome is suspected..
Which type of collagen i s abnormal in this condition??
A.. Type I
B.. Type II
C.. Type III
D.. Type IV
E.. Type V
Type IV
A 32 year old man is involved in a house fire and suffers burns to 50%% of his body.. He is treated in the intensive care unit but three days later,, despite supportive care , he become s hypotensive and develops rectal bleeding.. H e has a generalised purpuric rash.. Blood tests are performed and a diagnosis of disseminated intravascular coagulation (DDIC)) is made..
Which of the following blood tests is usually decreased in this condition??
A.. Activated partial thromboplastin time (AAPTT))
B.. D dimers
C.. Fibrinogen
D.. International normalised ratio (IINR))
E.. Prothrombin time (PPT))
Fibrinogen
.. A 74 year old man with a history of atrial fibrillation,, diabetes mellitus,, hypertension,, and obesity develops sudden onset hem iplegia and slurred speech.. A CT scan confirms an embolic stroke..
From which of the following sites is the embolus most likely to have originated??
A.. Aorta
B.. Cardiac atrium
C.. Cardiac ventricle
D.. Heart valves
E.. Veins of the leg
Cardiac atrium
