Week 1 – Introduction to Disease Pathology

A comprehensive set of question-and-answer flashcards covering key definitions, mechanisms, clinical examples, post-mortem procedures, and specific diseases introduced in Week 1, Lesson 1 of the Disease Pathology course.

What is pathology?

The study of disease that bridges basic science and medicine, underpinning diagnosis, treatment, prevention, and genetic technologies.

What does the prefix “patho-” mean?

Suffering or disease.

What does the suffix “-ology” mean?

To speak of or to study.

Give three macroscopic patterns of disease that pathology observes.

Organ damage (and recovery), presence of fluid/pus, and contributions to syndromic surveillance.

Pathology is mainly concerned with which broad category of disease?

Infectious disease.

Name a non-infectious yet transmissible disease discussed in the lecture.

Devil facial tumour disease.

List four disease mechanisms mentioned in the lecture.

Direct trauma, signal blockers, receptor agonists/antagonists, intracellular or extracellular parasites, membrane damage, and failed repair mechanisms (any four).

What are ‘signal blockers’ as a disease mechanism?

Agents that interfere with cellular signalling pathways, disrupting normal cell function.

What do receptor agonists and antagonists do pathologically?

Alter cell function by overstimulating (agonist) or blocking (antagonist) specific receptors.

How do intracellular parasites cause damage?

They live and replicate inside host cells, eventually rupturing and killing them.

How do extracellular parasites cause damage?

They remain outside cells, releasing toxins or consuming host tissues.

What is meant by membrane damage as a disease mechanism?

Cell injury caused by chemicals or hypoxia that disrupts the plasma membrane.

What does ‘failed repair mechanisms’ mean?

Replacement of functional tissue with non-functioning cells such as scar tissue.

Define thermal trauma.

Tissue damage produced by excessive heat, such as a burn to the skin.

How does heat damage skin cells in burns?

Heat disrupts cell membranes and ‘boils’ intracellular contents; severity depends on temperature and exposure time.

Describe a first-degree burn.

A superficial burn causing minor scarring and little long-term impact.

Why are second- and third-degree burns potentially life-changing?

They destroy deeper skin layers, often requiring grafts and leaving significant scarring or functional loss.

In burns, what does ‘dysfunction’ versus ‘dysfunction of repair’ signify?

Initial cell damage versus later replacement of skin by scar tissue that may impair function.

Which WWII patient group pioneered modern plastic surgery for burns?

Members of the ‘Guinea Pig Club’ in the 1940s.

Why did pilots who crashed into the sea sometimes fare better after burns?

Sea water cooled burns reducing damage, though some later died from hypothermia.

What type of burn can hairless pets (dogs, cats, guinea pigs) easily suffer?

UV light burns (sunburn).

Why is ultraviolet light dangerous to skin?

It causes highly damaging DNA lesions, with varying tolerance across body sites and individuals.

Define diarrhoea.

Any increase in faecal water content, ranging from soft stools to watery fluid.

State the main function of the small intestine.

Digestion and nutrient absorption.

State the main function of the large intestine.

Water absorption from intestinal contents.

Why can exercise-related diarrhoea be clinically insignificant?

It may occur transiently between bowel movements without underlying pathology.

What intestinal changes may appear when diarrhoea lasts 24–48 h?

Possible minor villus cell loss but still minimal pathological change.

List three effects of diarrhoea persisting longer than 48 h.

Villus destruction and surface-area loss, possible blood in stool, dehydration and electrolyte loss.

What numeric faecal score indicates ideal stool consistency?

3–4 on the 1–7 faecal scoring chart (species and diet dependent).

Name one virus and one bacterium that damage intestinal cells in diarrhoea.

Virus: Parvovirus. Bacterium: Campylobacter (toxin damage).

What additional risk does parvovirus-induced damage create?

Disruption of gut integrity increases risk of secondary bacterial infection.

Why can villus loss lead to dangerous dehydration?

Reduced absorptive surface means water loss can exceed intake, especially if vomiting occurs too.

What systemic conditions may follow severe, prolonged diarrhoea?

Hypovolaemia, electrolyte imbalance, disseminated intravascular coagulation (DIC), and death.

Which age group of dogs is most likely to die from parvovirus enteritis?

Puppies.

Is diarrhoea considered an evolutionary adaptation?

Yes; in many cases it helps expel pathogens quickly.

Give a simple supportive treatment for most mild diarrhoea cases.

Offer a light diet and plenty of fluids to maintain hydration.

Why is oxygen required for the Na⁺/K⁺ pump?

Aerobic metabolism generates ATP that powers the pump (3 Na⁺ out / 2 K⁺ in) to maintain cell volume and membrane potential.

What happens to cells if ATP is absent?

Na⁺ accumulates, water follows, cells swell, membranes rupture, and the cells die.

Provide two examples of hypoxic injury discussed.

Crush injuries and devitalised skin (degloving); infarcts from blood clots were also mentioned.

Define an infarct.

Tissue necrosis caused by obstruction of its blood supply, e.g., myocardial infarction.

What is the chief goal of cardiopulmonary resuscitation (CPR)?

Maintain blood flow (and minimal oxygen) to the brain to keep vital cells alive.

State the recommended compression–breath ratio and rate during CPR.

30 compressions to 2 breaths, at about 120 compressions per minute.

How does CPR preserve cellular integrity?

It supplies just enough oxygenated blood to sustain ATP production for the Na⁺/K⁺ pump in brain cells.

What tissue commonly heals by fibrous scar formation?

Skin, muscle, tendons, and ligaments.

How does bone differ from soft tissues in healing?

Bone usually regenerates well, though callus formation can limit joint movement.

What is fibrin and its pathological relevance?

An insoluble protein in blood clots; fibrin on serosal surfaces can cause adhesions (e.g., pleurisy, pericarditis).

Describe the steps of a gross post-mortem examination.

Inspect animal in situ, assess external, internal organs and environment to build a diagnostic picture.

List three types of post-mortem samples that may be collected.

Tissues for histopathology, fluids for culture/PCR, and blood for serology.

Differentiate pathological changes from post-mortem (PM) changes.

Pathological changes occur due to disease; PM changes arise after death (e.g., autolysis) and are not the cause of death.

Which PM change can mimic pneumonia and cause diagnostic confusion?

Hypostatic congestion (gravitational pooling of blood).

Name four consequences of Fasciolosis in sheep.

Blood loss, protein loss, liver damage, and predisposition to clostridial ‘black disease.’

How do snails contribute to Fasciolosis epidemiology?

They act as intermediate hosts; larval stages (rediae) can damage snail reproductive tissue causing castration and gigantism.

Can the liver regenerate after Fasciolosis damage?

Yes, but the process is slow.

Does Fasciolosis impact individual sheep only or large populations?

It affects sheep populations in significant numbers.