Intro to pathology Flashcards
Define pathology
Study of disease
Study of structural, biochemical & functional changes in cells, tissues & organs that underlie disease
What is general pathology
Study of basic responses of cells & tissues to insults & injuries, irrespective of organs, systems or species of animal involved
What is systemic pathology
(pathology of organ systems)
Study of alterations in specialised organs & tissues
What is anatomic pathology
Examination of tissues taken during life (biopsy) or after death (necropsy)
Examines nature & extent of disease process
Macroscopic (gross)
What is clinical pathology
examination of blood & other body fluids, as well as cells (cytology) during life
Microscopic (histologic) & biochemical
define aetiology
cause of disease
define pathogenesis
Sequence of events in response of cells/tissues to aetiologic agent from initial stimulus to ultimate expression of disease
mechanisms or disease development
(origin)
Define molecular & morphologic changes
biochemical & structural alterations induced in cells & organs
Define clinical manifestation
Functional consequences of molecular & morphologic changes
What are some internal vs external causes of disease?
Most commonly: >1 cause (multifactorial)
e.g. nutritional deficiency causes immunosuppression which allows infection to cause severe disease
What are molecular vs morphologic changes
molecular:
- biochemical alterations in cells/tissues
- alter function
morphologic changes:
- structural alterations in cells/tissues
What is the difference between symptoms and signs?
Symptoms: Subjective to patient
Signs: Objective & observed by clinician (e.g. reduced growth, production loss)
How do genetic, biochemical, and structural changes lead to disease manifestation?
If these changes are large enough, they may cause functional abnormalities, leading to clinical manifestations (symptoms/signs)
What are the major processes of pathology?
Define inflammation
Vascular & interstitial tissue changes that develop in response to tissue injury & that are designed to sequester, dilute & destroy causal agent
Define healing
Repair of injured tissue
Involves angiogenesis, fibrosis & regeneration
define angiogenesis
Formation of new blood vessels
Define fibrosis
Formation of fibrous connective tissue by fibroblasts
Define epithelisation
regenerative process that covers defects in injured skin & other epithelial surfaces
Define thrombosis
Interaction of blood coagulation system & platelets to form, within vascular lumen, an aggregate of fibrin & platelets
define neoplasia
uncontrolled & abnormal growth of cells due to intrinsic genetic mutations in somatic cells, leading to unrestrained mitosis & formation of mass of uncontrolled cells that impinge on adjacent normal tissue
What causes neoplasia?
Intrinsic genetic mutations in somatic cells that affect:
- Mitosis control
- Differentiation
- Cell-to-cell interactions
These changes result in unrestrained mitosis & formation of expanding mass of uncontrolled cells
Define metabolic dysfunction
Abnormalities or imbalances of carbohydrate, fat & protein metabolism in cell which lead to accumulation of glycogen, lipid or protein & complexes of abnormally folded & branched proteins, pigments, lipoproteins & amyloid
define necrosis
death of cells & tissues in living animal
define diagnosis
Conclusion concerning nature, cause or name of disease
Accuracy of diagnosis is limited by evidence (e.g. lesions) available to study
Define lesions
abnormal structural changes that occur in body
What are the types of diagnoses?
Define clinical diagnosis
Based on data obtained from case history, clinical signs & physical examination
Define clinical pathologic diagnosis
Based on changes observed in chemistry of fluids & haematology, structure & function of cells collected from living patient
Define morphologic diagnosis
Describes severity, duration, distribution, location (organ or tissue) & nature (degenerative, inflammatory, neoplastic) of lesion
Define aetiologic diagnosis
Names specific cause of disease
Define disease diagnosis
States common name of disease
What are the methods to detect morphologic changes?
Macroscopic or microscopic examination
What are the methods to reach a diagnosis
Morphology, molecular biology, microbiology, immunology, genetics, informatics
What is macroscopic examination
Observation by unaided eye
Observe deviations in size, colour, texture & location from normal organs & tissues
What are the methods of microscopic examination
Light microscopy
- Histopathology - often using stains
- specialised microscopes
Electron microscopy
- Transmission EM - 2D, shows internal cell structure
- Scanning EM - 3D, restricted to surface
What are some immuno & molecular techniques to reach a diagnosis
- Immunostaining / immunohistochemistry
- Polymerase chain reaction (PCR)
- In situ hybridization (ISH)
- Genomics (DNA sequencing, DNA microarrays)
- Transcriptomics (RNA sequencing)
- Proteomics
- Metabolomics
To detect (or detect alterations from normal in) nucleic acid (DNA/RNA), protein or other metabolites
What is putrefaction
Colour & texture changes, gas production & odours that are caused by post-mortem bacterial metabolism & dissolution of host tissues (post-mortem decomposition)
What are some common post-mortem changes?
Rigor mortis
Algor mortis
Livor mortis (hypostatic congestion)
Post-mortem clotting
Haemoglobin imbibition, bile imbibition
Pseudomelanosis
Bloating
Softening
Lens opacity
What is rigor mortis & why does it occur? (post-mortem)
Contraction of muscles occurring after death
Due to depletion of ATP & glycogen
Commences 1-6h after death & persists for 1-2d
What is algor mortis (post-mortem)
Gradual cooling of cadaver
Depends on species, size, age & environment
What is livor mortis (hypostatic congestion) (post-mortem)
Gravitational pooling of blood to down side of animal
Where does post-mortem clotting mainly occur?
Heart & blood vessels
within several hours of death
What is haemoglobin imbibition & why does it occur (post-mortem)?
Red staining of tissue
Once integrity of blood vessel walls is lost, haemoglobin released by lysed erythrocytes penetrates vessel wall
What is bile imbibition (post-mortem)?
Bile in gallbladder penetrates its wall & stains adjacent tissue yellow/green/brown
What is pseudomelanosis & why does it occur post-mortem?
Blue/green discoloration of tissue by iron sulphide (FeS)
Formed by reaction of hydrogen sulphide (H2S) generated by putrefactive bacteria & iron from haemoglobin released from lysed erythrocytes
Why does bloating occur post-mortem?
Result of post-mortem bacterial gas formation in lumen of GIT
Why does softening occur post-mortem?
Softening if tissue results from autolysis of cells & connective tissue often aided by putrefactive bacteria
When does lens opacity occur post-mortem?
Occurs when carcass is very cold or frozen
Change will reverse to normal transparency on warming
What is the difference between thrombosis & a blood clot?
Thrombosis = before death
Blood clot = after death
