Pathology Flashcards
Define pathology
The study of structural, biochemical and functional changes in cells, tissues and organs that underlie disease
Define systemic pathology
- Pathology of organ systems
- The study of alterations in specialised organs and tissues that are responsible for disorders that involve these organs
Define anatomic pathology
- Examination of tissues taken during life (biopsy) or after death (necropsy)
- Examines nature and extent of disease process
Define clinical pathology
Examination of blood and other body fluids, as well as cells (cytology) during life
List the 4 aspects of disease
- Aetiology
- Pathogenesis
- Molecular and morphologic changes
- Clinical manifestation
What is meant by aetiology?
- Cause of disease
- Can be internal (e.g. aging, immunologic defects) or external (e.g. external agents or deficiencies)
- Most commonly multifactorial
What is meant by pathogenesis?
- Mechanism of disease development
- Sequence of events in response of cells or tissues to aetiologic agent from initial stimulus to ultimate expression of disease
What is meant by molecular and morphologic changes in disease?
- Biochemical (molecular) and structural (morphologic) alterations induced in cells and organs
What is the difference between symptoms and signs?
- Symptoms: what the animal is feeling (nausea)
- Signs: what the clinician sees (vomiting)
List the major processes of pathology
- Inflammation
- Healing
- Thrombosis
- Neoplasia
- Metabolic dysfunction
- Necrosis
What are the “pillars of inflammation”
The cardinal signs
- Heat
- Redness
- Swelling
- Pain
- Loss of function
What is the process and function of inflammation?
- Vascular and interstitial tissue changes that develop in response to tissue injury
- Designed to sequester, dilute and destroy causal agent
What are the processes involved in healing?
- Angiogenesis
- Fibrosis
- Regeneration
What is epithelisation?
Regenerative process that covers defects in injured skin and other epithelial surfaces
What is thrombosis?
Interaction of blood coagulation system and platelets to form (within a vascular lumen) an aggregate of fibrin and platelets (thrombus)
What leads to neoplasia?
- Intrinsic genetic mutations in somatic cells that underlie abnormal mechanisms for control of mitosis, differentiation and cell-to-cell interactions
- Leads to uncontrolled mitosis and expanding mass of uncontrolled cells
What is the effect of neoplasia?
Impinges on adjacent normal tissue
What is the role of metabolic dysfunction in pathology?
- Abnormalities/imbalances of carb, fat and protein metabolism in cell leads to accumulation of glycogen, fat or protein
- Also complexes of abnormally folded and branched proteins, lipoproteins and amyloid
What is necrosis?
Death of cells and tissues in living animals
What is the definition of diagnosis?
Conclusion concerning the nature, cause or name of a disease
List the different types of diagnosis
- Clinical
- Clinical pathologic
- Morphologic (lesion)
- Aetiologic
- Disease
Outline what is meant by a clinical diagnosis
- Based on data obtained from case history, clinical signs and physical examination
- i.e. severe acute contagious blood diarrhoea
Outline what is meant by clinical pathologic diagnosis
- Based on changes observed in chemistry of fluids and haematology, structure and function of cells collected from living patient
- i.e. severe leukocytosis
Outline what is meant by morphologic diagnosis
- Based on predominant lesions in tissue
- Can be macroscopic (gross) or microscopic (histologic)
What is included in a morphologic diagnosis?
- Severity
- Duration
- Distribution
- Location (organ or tissue)
- Nature (degenerative, inflammatory, neoplastic)
Outline what is meant by aetiologic diagnosis
Names the specific cause of the disease
List methods that can be used to reach a diagnosis
- Morphology
- Molecular biology
- Microbiology
- Immunology
- Genetics
- Informatics
What is a biopsy?
Removal and examination of tissue sample from a living animal body for diagnostic purposes
What is a necropsy?
Methodical examination of the dead animal
What is meant by a macroscopic examination?
- Observation by the unaided eye
- Observe deviations in size, colour, texture, location from normal organs/tissues
What is meant by microscopic examination?
- Light microscopy (histopathology, often stained, specialised microscopes e.g. dark field)
- Electron microscopy: trans or scanning
List molecular techniques that can be used in diagnosis
- PCR
- In situ hybridisation (ISH)
- Genomics (DNA sequencing, DNA microarrays)
- Transcriptomics (RNA sequencing)
- Proteomics, metabolomics, immunological approaches
What are molecular techniques used for in diagnosis?
Detection of, or detection of alterations from normal, in nucleic acids and protein
What is putrefaction?
Colour and texture changes, gas production, odours produced by post-mortem bacterial metabolism and dissolution of host tissues (decomposition)
What is rigor mortis?
Contraction of muscles after death
What causes rigor mortis and on what timescale does it occur?
- Depletion of ATP and glycogen
- Starts 1-6 hours after death, persists for 1-2 days
What is algor mortis?
Gradual cooling of the cadaver
Why may gradual heating of the cadaver occur following death?
Bacterial processes