Pathology Flashcards
Characteristic cell in acute inflammation?
Neutrophil polymorph initially
Also monocytes later (become macrophages)
Characteristic cell(s) in chronic inflammation?
Lymphocytes, plasma cells and macrophages
Essential macroscopic appearances of acute inflammation
Rubor/Redness (dilation of blood vessels)
Calor/Hotness (hyperaemia form dilation +systemic fever)
Tumor/Swelling (from oedema/exudate)
Dolor/Pain (pressure from chemical mediators)
Loss of function
3 processes in acute inflammatory response:
Changes in vessel calibre and flow
Increase vascular permeability (contraction of endothelium)
Formation of fluid exudate (emigration of neutrophil polymorphs)
In formation of cellular exudate, explain the 4 stages of neutrophil emigration
Margination - the process just before neutrophils adhere to vessel wall (requires slow of fluid etc.)
Adhesion - also called pavementing
Emigration - migrate through endothelium using amoeboid movement
Diapedesis - where RBCs also escape - passive and implies more severe inflammation
Role of macrophage in acute inflammation
Secrete inflammatory mediators, proliferate, phagocytose, discharge lysosomal enzymes.
They have a longer life than neutrophils (weeks to months)
Role of neutrophil polymorph in acute inflammation
Short lived cells, first on the scene (usually die there). They phagocytose, release inflammatory mediators
Role of endothelial cells in acute inflammation
Become sticky so inflammatory cells can adhere, become porous, grow into areas, open capillaries
What are the 4 outcomes of acute inflammation
Resolution
Suppuration
Organisation
Progression to chronic inflammation
Describe resolution as the outcome of acute inflammation (and what 3 conditions it requires)
Resolution - complete restoration of tissues, it requires minimal cell death, regenerative capacity of tissue (liver) and destruction of causal agent
Describe suppuration as the outcome of acute inflammation
The formation of pus (dead neutrophils, bacteria, debris and lipid). Almost always caused by infection.
This can form an abscess
Describe an abscess
Pus accumulates, it is surrounded by a pyogenic membrane consisting of sprouting capillaries, neutrophils and fibroblasts. bacteria within are inaccessible to antibodies/antibiotics
Desribe organisation as an outcome of acute inflammation
The replacement of tissue by granulation tissue as part of the process of repair. Occurs if lots of fibrin is formed which cannot be removed, lots of tissue is necrotic or exudate cannot be removed
New capillaries grow into material and macrophages follow. Fibroblasts proliferate resulting in fibrosis.
The exudate is “organised”
Describe the progression to chronic inflammation as an outcome of acute inflammation
Occurs if chronic agent is not removed, the character of exudate changes with lymphocytes, macrophages, plasma cells and giant cells predominating. Also accompanies organisation
What are some systemic effects of acute inflammation?
Pyrexia Weight loss Reactive hyperplasia of reticuloendothelial system Haematological changes Amyloidosis
How to treat acute inflammation (for 1. sports injury, 2. mosquito bite, 3. skin rash)
Depends on cause:
1) RICE
2) Antihistamine, NSAIDs, Hydrocortisone
3) Steroid cream (only if bacterial infection is not present otherwise you dampen immune response)
What 2 ways can you define chronic inflammation?
Over a prolonged time
Different cells invovled (lymphocytes, plasma cells, macrophages)
List some causes of chronic inflammation
Resistance to infective agent - TB, leprosy
Endogenous material - uric acid crystals
Exogenous material - silica, asbestos
Primary granulomatous disease - Crohn’s, Sarcoidosis
Transplant rejection
List 4 macroscopic appearances of chronic inflammation
1) Chronic ulcer
2) Chronic abscess cavity
3) Granulomatous inflammation
4) Fibrosis
List 4 microscopic appearances of chronic inflammation
1) Characteristically lymphocytes, plasma cells and macrophages
2) Exudation is not a common feature
3) Evience of continuing destruction
4) Possible tissue necrosis
Describe a granuloma
cells, causes, stain
This is an aggregate of epitheloid histocytes (a type of macrophage), some of which fuse to form giant cells and organise to wall of infection, sometimes necrosis centrally. Other cells such as lymphocytes, neutrophils etc. also present. Seen in TB, leprosy, Chron’s and sarcoidosis.
They can be stained using Ziehl-Neelsen
What happens to B, T and macrophages in chronic inflammation? (cellular cooperation)
B => Plasma cells to produce antibodies
T => cause cell-mediated immunity
Macrophages respond to chemotactic stimuli and produce cytokines such as IFa, TNFa and others
What are the 2 outcomes of injury (RR) and briefly describe what each needs
Resolution – initiating factor removed, tissue not permenantly damaged (can regenerate)
Repair - initiating factor still present, tissue cannot repair
3 types of cells based on their potential for renewal
Labile cells - good capacity to regenerate (some epithelium)
Stable cell populations (hepatocytes)
Permenant populations (nerve cells)
When considering tissue repair, describe organisation
the REPAIR of tissue by production of granulation tissue and a fibrous scar. dead tissue is removed by phagocytes.
Describe how granulation tissue forms (a form of repair)
Capillaries proliferate and grow into the area as loops
Simultaneously, fibroblasts divide and secrete collagen and other matrix
Myofibroblasts secrete collagen and cause wound contraction.
Describe stages of apoptosis
Healthy cell, nucleus condenses (pyknosis), cytoplasmic blebs form, cell breaks up into apoptotic bodies (each containing 1 or 2 organelles), these are often phagocytosed
What is the main enzyme which carries out apoptosis?
Caspase enzymes (the executioner)
Describe the internal signalling which regulates caspases and apoptosis
BcL2 proteins act as the internal trigger: Bcl2 protein inhibits caspases Bax protein (also a member of Bcl2 family) activates caspases
p53 can upregulate Bax as this detects DNA damage
Describe the external signalling which regulates caspases and apoptosis
Fas receptor acts as an external trigger. Fas ligand from outside the cell binds to this receptor and activates caspases
When is apoptosis useful?
In development
Get rid of dysfunctional cells (in the gut)
Get rid of cells with DNA problems
What is autophagy?
Where due to stress, cell components are isolated into vacuoles and prevents cell death
What are some characteristic features of necrosis?
Mutliple cells die
Not programmed
Due to external stimulus
What is hypertrophy?
Give example
Cells increase in size, not in number (bigger muscle)
What is hyperplasia?
Give example
An increase in cell number but not size
Benign hyerplasia of the prostate
What is atrophy?
A decrease in size of a tissue either by decreased size or number of cells
Muscle atrophy in ALS
What is metaplasia?
example
change in differentiation of a cell from one fully-differentiated type to a different fully differentiated type. (functional plasticity).
(squamous to columnar in barrett’s oesophagus)
What is Dysplasia?
example
Imprecise term for the morphological changes seen in cells in the progression to becoming cancer (cells are growing but not quite right).
What is a homeobox gene?
A gene who’s prodcut controls function and migration of cells through development
How do telomeres work and how do they cause aging?
Telomeres help unwrap DNA but get shorter each time they help. They cannot help at the Hayflick limit (shortess a cell can be).
What is atherosclerosis?
Atherosclerosis is the hardening of plaques in the arterial walls
What is an atheroma?
Atheroma is like a lipidy plaque on the inside of blood vessels. Accumulation of these can lead to atherosclerosis (hardening).
What is the best theory to describe atherosclerosis and describe it?
Endothelial damage theory
The delicate endothelium are damaged by free radicals, nicotine and CO which causes damage, platelet adheration fibirn etc. LDL moves into intima and is oxidised causing damage, monocytes move in and become macrophages then foam cells there is inflammation. Smooth muscle from tunica media proliferates and endothelium grows over the top making the lumen slightly narrower
What are the risk factors for atherosclerosis and explain the pathophysiology behind each of them
Using the endothelial damage theory:
Smoking, free radicals, nicotine, CO, hypertension, uncontrolled diabetes (high levels of free radicals, superoxide anions/glycosylation), hyperlipidaemia all damage endothelium. Free radicals also cause increased oxidation of LDLs
Obesity causes more pro-inflammatory cytokines, women have more oestrogen receptors which protects against vascular injury
What are the 2 (4) types of autopsy and what are they/what is the difference?
Hospital autopsy (<10%) - requested by consultant to confirm cause of death (must be pretty much known).
Medico-legal autopsies (>90%) - occur in medico-legal centre at the request of the coroner. These can be divided into 2:
1)Coronial - routine, confirm cause of death if unkown
2)Forensic - clarify suspected crime
Give 3 reasons why a death may be referred to the coroner for autopsy
1) cause of death is unknown (no chronic conditions, not seen doctor in 14days)
2) Presumed iatrogenic cause - usually to prove the doctor did not kill the patient
3) Presumed unnatural - due to road traffic accidents, suicide, murder, industrial death
Who can refer a death to a coroner?
Doctors, registrar of BDM, properly interest parties (relatives, police, technicians etc.)
What is the difference between the 2 different people who perform autopsies? (histopathologists/forensic pathologists)
Histopathologists do all hospital autopsies and some coronial autopsies, while forensic pathologists do some coronial autopsies.
What 4 questions does an autopsy try to answer?
Who was the deceased?
When did they die?
Where did they die?
How did they die?
Describe the 5 general parts to an autopsy
History/scene of death (sometimes) External examination - identification/injuries/clothing Evisceration/disembowelment Internal examination (in situ first) Reconstruction for funeral