Key Terminology & Definitions - Pathology Flashcards
1
Q
Aetiology
A
Cause of disease
2
Q
Pathogenesis
A
Mechanisms (progression from initial stimulus to disease expression) that lead to diseased state in response of cells and tissues to aetiologic agent.
3
Q
Gross pathology
A
Recognition and description of macroscopic, morphological changes to tissues and organs in the live or dead animal at biopsy, surgical removal or PM examination.
4
Q
Antemortem
A
Before death
5
Q
Post mortem
A
After death
6
Q
The examination of a body after death =
A
PM examination / necropsy / autopsy
7
Q
Yellow
A
Icterus
8
Q
Pallor
A
Loss of blood/anaemia
9
Q
Red-purple
A
Congestion, sepsis, bruising
Haemorrhage
10
Q
Green
A
Bile imbibition, pseudomelanosis (green-black) (bacteria making sulfur compounds (H2S) = smell), some fungi
11
Q
Gelatinous
A
Oedema, serous atrophy of fat
12
Q
Pluck
A
Trachea, tongue, larynx, thyroids and parathyroids, oesophagus, heart and lungs.
13
Q
Agonal
A
Changes that occur at or around time of death
14
Q
Algor mortis
A
Cooling of the body after death
15
Q
Rigor mortis
A
Contraction of muscles after death (due to lack of ATP, no re-cock of myosin head).
16
Q
Autolysis
A
Breakdown of tissue as result of enzymes contained within cells = self-digestion
17
Q
Putrefaction
A
Breakdown of tissues by bacteria
18
Q
Desiccation
A
Loss of H2O from tissues exposed to the air after death
19
Q
Livor mortis
A
Pooling of blood in dependent sites due to gravity
20
Q
White / grey / yellow
A
Lack of blood, necrosis, icterus, fibrosis
21
Q
Black
A
Melanin (melanosis, flat, melanoma, raised)
22
Q
Gas (consistency)
A
Trapped in tissue = emphysema or autolysis
23
Q
Fluid (consistency)
A
Looks or feels wet = oedema, blood, transudates, fluid
24
Q
Soft (consistency)
A
Fluid rich, cell/stroma poor
25
Firm (consistency)
Fluid poor, cell/stroma rich
26
Hard/gritty (consistency)
Mineralised stroma/matrix, cartilage, bone, calcified tissue
27
Innate immunity
Pre-existing frontline defence that is always there; normal immune system animals are born with (non-specific)
28
Pathogen-associated molecular patterns (PAMPs)
Molecules with conserved motifs that are associated with pathogen infection that serve as ligands for host pattern recognition molecules such as Toll-like receptors (innate immunity)
29
Pattern recognition receptors (PRRs)
Recognise PAMPs and target them for clearance
30
Macrophage
APC - phagocytosis and activation of bactericidal mechanisms
| Adaptive immunity) - stimulate already primed effector and memory T-cells (B cells as well
31
Dendritic cell
APC - antigen uptake in peripheral sites, specialised in activation of naive T-cells
32
Neutrophil
Phagocytosis and activation of bactericidal mechanisms
33
Eosinophil
Killing of antibody-coated proteins
34
Basophil
Promotion of allergic responses and augmentation of antiparasitic immunity
35
Mast cell
Release of granules containing histamine and active agents
36
Selectins
Bind carbohydrates and initiate leucocyte-endothelial interaction
37
Integrins
Bind to cell-adhesion molecules = an extracellular matrix, strong adhesion
38
Immunoglobulin superfamily
Various roles in cell adhesion, ligand for integrins
39
Phagocytosis
Engulfment and internalisation of materials such as microbes for their clearance and destruction
40
The complement system
A group of serum proteins circulating in inactive form, once activated ---> target cell membrane lysis, chemotaxis, opsonisation to enhance phagocytosis
41
Opsonisation
Bacteria are altered by opsonins so as to become more readily and more efficiently engulfed by phagocytes
Enhancement of macrophages and phagocytosis
42
TLRs
Toll-like receptors (PRR) - innate immunity
43
CLRs
C-type lectin receptors (PRR) - recognise cell wall components - sugars/polysaccharides of bacteria/fungi
44
RLRs
Rig-i-like receptors (PRR) - RNA helicases, recognise viral RNAs
45
NLRs
Nod-like receptors (PRR) - sense bacterial products in products
46
Epitope
Part of an antigen molecule to which an antibody attaches itself
47
cDC
Conventional dendritic cells - professional APC, constitute expression of co-stimulatory molecules and stimulate naive T cells
48
MHC
Major histocompatibility complex that presents antigen to T-cells (MHC I = CD8^+, MHC II = CD4^+)
49
MHC I
Co-expressed but not covalently linked - CD8^+ (cytotoxic T helper cells = co-receptor)
50
MHC II
Heterodimer of alpha and beta chain - CD4^+ (T helper cells = co-receptor)
51
Cytokines
Proteins that mediate the effector functions of the immune system, they have endocrine, paracrine and autocrine actions
Enhance the expression of adhesion molecules in acute inflammation
E.g. TNF and IL-1
52
Chemokines
Chemoattractants for different leucocytes
Large family of small, secreted proteins that signal through cell surface G protein-coupled heptahelical chemokine receptors
Stimulate the migration of cells, most notably white blood cells (leukocytes)
Large family of cytokines
Many act on granulocytes
53
Granulocyte
Type of white blood cell that has small granules, containing proteins,
E.g. Neutrophils, eosinophils, and basophils
54
CD
Cluster of differentiation molecule
55
Pleiotropy (cytokines)
One cytokine produces multiple effects
56
Redundancy (cytokines)
More than one cytokine induces the same effect
57
Synergy (cytokines)
Two (or more) cytokines work together to induce an effect
58
Antagonism (cytokines)
One cytokine can inactivate the effect of another
59
IL-1 family (cytokines)
Promote inflammation (most are proinflammatory)
60
Interferons (INFs)
A group of signalling proteins made and released by host cells in response to the presence of several viruses
61
TNF
Tumour necrosis factor - cytokine that regulates development, effector function and homeostasis of cells of the skeletal, neuronal and immune systems
62
Adaptive immune responses
Humoral and cell-mediated responses using B and T lymphocytes, slower to develop and more specific
63
Antigen
```
Processed peptide derived from a foreign or altered-self protein and presented by MHC class I (e.g. cytotoxic CD8 t cell) or II (e.g. helper CD4 t cell)
May be protein, lipid, carbohydrate, nucleic acid - soluble, particulate, simple or complex
```
64
BCR
Membrane-bound immunoglobulin
65
Antibody
Secreted immunoglobulin
66
CH regions
Encode for different isotypes (functional classes) of antibodies
67
Thymocyte
Very early T cell lymphocyte in the thymus
68
Positive selection
Selects thymocytes bearing receptors capable of binding self-MHC molecules, resulting in MHC restriction
69
Negative selection
Selects against thymocytes bearing high-affinity receptors for self-MHC/peptide complexes, resulting in self-tolerance
70
TREG cells
Regulatory T-cells - negatively regulate immune responses - deplete local area of stimulating cytokines, produce inhibiting cytokines, inhibit APC activity, directly kill T cells
71
TREG cell - effector cytokine and effector functions
IL-10, TGR-beta (transforming growth factor) - regulation, suppression of immune and inflammatory responses
72
TH17 cell - effector cytokine and effector functions
IL-17A, IL-17F, IL-22 - inflammation
73
TH2 cell - effector cytokine and effector functions
IL-4, IL-5, IL-13 - allergic and anti-helminth responses
74
TFH cell - effector cytokine and effector functions
IL-4, IL-21 - B cell help in germinal centres
75
TH1 cell - effector cytokine and effector functions
IFN-gamma, TNF - cell-mediated immunity, macrophage activation, inflammation
76
TCM cells
Central memory T cells - live longer/divide more, can differentiate into several subsets depending on cytokine environment, IN 2^y lymphoid tissues
77
TEM cells
Effector memory cells - first-line defences, rapidly re-acquire effector functions on second Ag exposure, in tertiary tissues e.g. LNs
78
Avidity
Overall strength between the antibody and antigen
79
MAC
Membrane attack complex - complex of proteins typically formed on the surface of pathogen cell membranes as a result of the activation of the host's complement system, and as such is an effector of the immune system
80
FC receptor
Antibody receptor involved in antigen recognition
81
IgM Ab
First Ab produced in primary response (surface bound IgM is naive BCR).
Complement fixation leading to MAC formation and target lysis.
Formation of dense Ab-pathogen complexes that are efficiently engulfed by macrophages.
82
IgG Ab
All variants bind Fc receptors, enhancing phagocytosis by macrophages, most abundant
83
IgA Ab
Isotype found in secretions, doesn't fix complement = no inflammation.
Effective at neutralising toxins and pathogens.
84
IgE Ab
Allergy and asthma + protecting against parasitic helminths and protozoa.
Degranulation of eosinophils/basophils.
Release of molecules (pro-inflammatory e.g. histamine to damage large pathogens.
85
Oedema
Release of excess fluid into tissues or body cavities
86
Exudation
Release fluids from the circulation
87
Exudate
Extracellular fluid (oedema) rich in protein and cells, has high specific gravity (thick, heavy, goopy)
88
Pus
Purulent exudate - rich in leucocytes (mainly neutrophils), debris of dead cells and maybe microbes = inflammation (maybe infection)
89
Transudate
Low protein content and little or no cellular material, low specific gravity e.g. heart, liver + kidney disease
90
Erythema
Heat redness
91
Endotheliotropic
Agent that directly targets endothelium
92
Transcytosis
Transportation of fluids and proteins through endothelial cells
93
VEGF
Vascular endothelial growth factor - mediator for transcytosis
94
Stasis
Vascular congestion
95
Lymphangitis
Secondary inflammation of lymphatic vessels e.g. bug bites going up arm
96
Adeno
Gland
97
Lymphadenitis
Inflammation of draining lymph nodes
98
Reactive/inflammatory lymphadenitis
Increase in size of lymph nodes due to hyperplasia of lymphoid follicles
99
Margination
When blood flow slows and stasis occurs, due to inflammation, the leucocytes start to make contact with the endothelial surface
100
Selectins
Proteins which mediate rolling (three types), bind to ligands in response to cytokines
101
Cytokines
Secreted by cells as part of the inflammatory response, enhance the expression of adhesion molecules
102
L-selectin
Expressed on leucocytes, complementary to E-selectins
103
E-selectin
Expressed on endothelial cells
104
P-selectin
Expressed on platelets and endothelial cells (clotting)
105
Integrins
Mediate the further rolling and slowing down of leucocytes to allow stronger adhesions to form; two types, beta-1 and beta-2
106
ICAM-1
Leukocyte-associated transmembrane protein on endothelial cells, binds to beta-2 integrins on neutrophils, monocytes and lymphocytes
107
VCAM-1
Leukocyte-associated transmembrane protein on endothelial cells, binds to beta-1 integrins on eosinophils, monocytes and lymphocytes
108
Diapedesis/transmigration
Movement of leucocytes through endothelium, down a chemokine concentration gradient
109
PECAM-1
Platelet endothelial cell adhesion molecule - mediates migration of leucocytes across vessel wall
110
Leucocyte adhesion deficiencies
Characterised by recurrent bacterial infections due to inability of leucocytes to adhere and reach site of inflammation
111
Chemotaxis
Migration of cells along a chemical gradient
112
Exogenous chemotactic agents
Bacterial products e.g. lipids, peptides
113
Endogenous chemotactic agents
Released by cells e.g. cytokines, complement system, arachidonic acid metabolites
114
G protein-coupled receptors
Found mostly on leucocytes, recognise short bacterial peptides containing N-formylmethionyl residues
115
Toll-like receptors (TLRs)
Recognise components of different types of microbes e.g. bacterial lipopolysaccharide
116
Cytokine receptors
Leucocytes express receptors for cytokines that are produced in response to microbes
117
Opsonin receptors
Proteins used to coat organisms of particles for phagocytosis e.g. antibodies, complement proteins and lectins (binds to CHOs)
118
Histamine
In mast cell granules, cell-derived mediator of inflammation, binds to H1 receptor on microvascular endothelial cells to cause dilation of arterioles and increased permeability of venules
119
Serotonin
In platelets, certain endocrine cells + mast cells in some species, cell-derived mediator of inflammation, platelet released a reaction - causes dilation of arterioles and increases permeability of venules
120
Heterophagy
Cell eating another cell
121
Thrombosis
Abnormal clotting of blood
122
Arachidonic acid
Oxidised to form pro-inflammatory (+ anti-inflammatory) material / degraded by cyclooygenase to form prostaglandins or 5-lipoxygenase to form leukotrienes and lipoxins
123
Leukotrienes
Increased vascular permeability, vasoconstriction and bronchospasm (effects of asthma)
124
Lipoxins
Inhibit neutrophil adhesion and chemotaxis
125
NSAIDs
Non-steroidal anti-inflammatory drugs, inhibits COX-1 and COX-2
126
COX-1/COX-2
Cyclooxygenase-1/2
127
Platelet-activating factor
Phospholipid-derived mediator - from platelets, basophils, mast cells, neutrophils, macrophages and endothelial cells
128
Neuropeptides
Secreted by sensory nerves and leucocytes, includes substance P and neurokinin A
129
Plasma protein derived mediators
Group of plasma proteins triggered by antibody fixation or microbial antigens, cause inflammation, phagocytosis and cell lysis
130
Catar
Mucous + serous inflammation (inc fluid + neutrophils), in gut
131
Abscess
Junction between acute and chronic inflammation, when pus not cleared up, exudate is firm, doesn't have enzyme in neutrophils to continue pus production
132
Gamma-delta-T cell
Functions like cells of immune system (+ NK T-cell)
133
B-cell specific receptor
Detects antigen in naive, natural state
134
T-cell specific receptor
Antigen is processed and presented by MHC I/II
135
Immunoglobulin-alpha/beta (innate immunity)
Complex formed by B-cell with other transmembrane proteins (B-cell has very short cytoplasmic tail means itself cannot transmit signals upon engagement with antigen), have signalling motifs in their cytoplasmic chains
136
ITAM
Immunoreceptor tyrosine kinase activatory motif, signalling motif in which its phosphorylation triggers signalling cascades leading to transcription of B-cells + their activation
137
V(D)J recombination
The mechanism of somatic recombination that occurs only in developing lymphocytes during the early stages of T and B cell maturation. It results in the highly diverse repertoire of antibodies/immunoglobulins and T cell receptors (TCRs) found in B cells and T cells, respectively.
138
DN
Double negative thymocytes - don't express CD4 or CD8, undergo beta selection, involving combination of T-cell receptor gene segments, those that survive express both CD4 and CD8 = double-positive
139
DP
Double positive thymocytes - undergo positive and negative selection to become a single positive (SP), only express CD4 or CD8
Negative selection screen removes autoreactive cells
140
Antigen presenting cell
DC, macrophage and B-cells - increase expression of MHC II CD80 and CD86
141
Fc receptors (adaptive immunity)
Fragment crystallisable region (Fc region) is the tail region of an antibody that interacts with cell surface receptors called Fc receptors and some proteins of the complement system. This property allows antibodies to activate the immune system.
142
Hypertrophy
Cells too big
143
Hyperplasia
Too many cells
144
Dysplasia
Disorganised arrangement of cells and abnormal pattern of tissue growth
Poorly differentiated cells
145
Metaplasia
Abnormal differentiation - change from one cell type to another
146
Cyst
Distended space +/- content
147
Atrophy
Cells too small
148
Pyogranulomatous inflammation
Neutrophilic + granulomatous inflammation
149
Coagulative necrosis
Tissue structure preserved, neutrophils
150
Caseous necrosis
Loss of architecture, usually associated with granulomas, macrophages
151
Liquefactive necrosis
Loss of structure, usually hard to capture on histology, neutrophils
152
Haemorrhage
Erythrocytes outside blood vessels
153
Thrombosis
Abnormal fibrin clotting inside vessels
154
Congestion/hyperaemia
Too many erythrocytes inside blood vessels (alveolar septa)
155
Thromboembolus
Abnormal material in blood vessel e.g. cartilage, bone, contrast medium, brain etc
156
Hypersensitivity
Excessive reaction to antigens
157
Autoimmunity
Immune system reacts to self-antigens
158
Immunodeficiency
Immune system fails to respond when it should
159
Amyloidosis
Creation of abnormal proteins that impair tissue function
160
Atopy
Localised reactions, often progress from acute perivascular inflammation to chronic inflammation/type IV hypersensitivity
161
Anergy
Inactivation of lymphocytes that antigen - no co-stimulatory signal, negative signal received
162
Suppression (peripheral tolerance)
Mediated by T regulatory cells - produce IL-4, IL-10, TGF-beta to inhibit lymphocyte activation
163
SLE
Systemic lupus erythematosus - prototypical autoimmune disorder, autoantibodies to range of cell components
164
Predominant antibody
Antinuclear antibody (AA) - form immune complexes (like type III hypersensitivity) and deposit in glomeruli, blood vessels, skin, joints
165
SCID
Severe combined immunodeficiency disorder - defects in humoral and cell-mediated immunity (T and B cells)
Often manifests as viral or fungal infections
Sever lymphoid hypoplasia
166
Amyloid
Pathologic protein formed of beta-pleated sheets of non-branching fibrils
167
Primary amyloidosis
Immune cell dysfunction, usually AL type, most common immune cell dysfunction that produces this is plasma cell tumour
168
Secondary amyloidosis
(Also known as reactive systemic amyloidosis)
Chronic inflammation or tissue destruction, most common, in cheetahs with helicobacter gastritis, secondary to chronic inflammation (prolonged elevation of SAA), can be idiopathic or due to non-immunologic neoplasia (paraneoplasia = not plasma cells)
169
Amyloid light chain (AL)
Derived from immunoglobulin light chain, associated with immunoglobulin secreting cells (B cells, plasma cells), usually primary amyloidosis
170
Amyloid-associated (AA)
Derived from serum amyloid A (SAA) synthesised in the liver and released during systemic inflammation (acute), usually secondary amyloidosis
171
A-β
Derived from amyloid precursor protein (APP), associated with amyloid angiopathy in Alzheimer's and other forms of canine neurodegeneration
172
Familial amyloidosis
AA form - primarily deposits in kidneys - glomerular in cats, medullary in dogs, also in liver
173
Amyloid of ageing
A-β form - cerebrovascular amyloidosis in old dogs, may also deposit in heat, GIT and lungs
