Intro to pathology Flashcards by Leah Stevenart

Define pathology

Study of disease

Study of structural, biochemical & functional changes in cells, tissues & organs that underlie disease

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What is general pathology

Study of basic responses of cells & tissues to insults & injuries, irrespective of organs, systems or species of animal involved

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What is systemic pathology

(pathology of organ systems)

Study of alterations in specialised organs & tissues

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What is anatomic pathology

Examination of tissues taken during life (biopsy) or after death (necropsy)

Examines nature & extent of disease process

Macroscopic (gross)

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What is clinical pathology

examination of blood & other body fluids, as well as cells (cytology) during life

Microscopic (histologic) & biochemical

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define aetiology

cause of disease

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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)

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Define molecular & morphologic changes

biochemical & structural alterations induced in cells & organs

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Define clinical manifestation

Functional consequences of molecular & morphologic changes

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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

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What are molecular vs morphologic changes

molecular:
- biochemical alterations in cells/tissues
- alter function

morphologic changes:
- structural alterations in cells/tissues

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What is the difference between symptoms and signs?

Symptoms: Subjective to patient

Signs: Objective & observed by clinician (e.g. reduced growth, production loss)

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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)

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What are the major processes of pathology?

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Define inflammation

Vascular & interstitial tissue changes that develop in response to tissue injury & that are designed to sequester, dilute & destroy causal agent

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Define healing

Repair of injured tissue

Involves angiogenesis, fibrosis & regeneration

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define angiogenesis

Formation of new blood vessels

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Define fibrosis

Formation of fibrous connective tissue by fibroblasts

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Define epithelisation

regenerative process that covers defects in injured skin & other epithelial surfaces

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Define thrombosis

Interaction of blood coagulation system & platelets to form, within vascular lumen, an aggregate of fibrin & platelets

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define neoplasia

Uncontrolled, abnormal growth of cells due to genetic mutations, leading to unregulated division and mass formation that may affect nearby tissues.

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

Imbalance in carbohydrate, fat, or protein metabolism causing buildup of substances like glycogen, lipids, or misfolded proteins (e.g. amyloid, pigments)

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? When does it occur?

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? What factors influence it?

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 & when 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