APBI 319 - M2 L2

Cell degeneration

due to cell membrane injury by bacterial action → fluid can't kept out → swelling

• if damage bad → rupture →  die aka necrosis

How cells can adapt to injury

1. atrophy: shrinking

2. hypertrophy: growing

3. hyperplasia: multiplying

4. neoplasia: uncontrolled multiplication

5. metaplasia: changing form

Mutualistic

• host and microbe benefit

  • ex. skin + intestinal tract have populations of bugs

Infectious relationship

• when bug can colonize and reproduce on/in host

  • elicits host response

  • ex. normal flora can become pathogenic; normally non-pathogenic bugs can become so in an immunocompromised host

Opportunistic pathogen

might require host tissues during its life cycle; not generally associated w/ disease unless in unusual location or host

Obligate pathogen

• must have host to survive and depends on host for survival

  • when in host, pathogens generally elicit disease response

Facultative pathogen

can survive outside a host and infect them

Carriers

• w/ both asymptomatic + sub-clinical infections, proportion of pop can carry

• danger = not showing signs of disease but can be exposing and infecting others w/ dangerous pathogens

Pathology

• scientific study of nature of disease and its causes, processes, development, and consequences

  • clinical pathology = study of samples taken usually from living animals

    • you examine the samples w/ respect to their cellular constituents or chemical constituents

    • can provide you w/ info in assessing health status of fish

    • helps in detecting + predicting problems that haven't shown characteristic disease signs

Hypoxia

•  loss of ability to carry on sufficient aerobic oxidative respiration

  • most common cause of cell injury and death

• cause: ischemia

• local causes:

  • blockage of arteries that bring in fresh blood

  • any blockage of veins that let blood leave; fresh blood can't flow in

  • shunting of arterial blood other places

• systemic: failure of heart to pump enough blood

Ischemia

loss of arterial blood flow

Hypoxaemia

when blood is too low in oxygen

• ex:

  • heart can't pump enough blood through gills

  • reduced O₂-carrying capacity of blood (anaemic hypoxia)

  • haemoglobin problems

Acute inflammation

response to recent or ongoing injury

• features:

  • dilatation

  • leaking of vessels

  • involvement of neutrophils - circulating immune cells

Chronic inflammation

late-phase inflammation + response to prolonged problems

• features:

  • infiltration of more cells

  • presence of fibrin

Inflammation

Common response to most infections

• noxious, non-infectious things can also produce this

Signs:

• swelling

• redness

• fluids in tissues or cavities

• fibrin coatings

• granulomas

• pus

Granulomas

swollen, irregular/bumpy, white-yellow nodules

Fibrin

insoluble protein essential to clotting of blood, derived from fibrinogen; released from damaged vessels

• activated by clotting cascades when blood meets tissue fluids

• forms meshwork that controls bleeding, walls off stuff, then becomes framework that'll form scar

• appearance: white, lacy material (ex. BKD)

  • BKD causes ___ deposits; it will appear as white lacy enveloping organs

• can be reabsorbed, or form adhesions (after vaccinations)

Pus

fluid product of inflammation that has liquid containing leucocytes and debris of dead cells and tissue elements liquefied by proteolytic enzymes

Ascites

 fluid in abdominal cavity

Edema

excess fluid between cells

Leaky vessels

problem w/ fluids and blood movement

• caused by microbes or toxins

  • blood leaking from vessels

  • signs of vessel damage in certain infections + some nutritional problems

Necrosis

 cells swell and break open, release content, and can damage neighbouring cells → provoke inflammation

Pressure problems

problem w/ fluids and blood movement

• if can't get rid of excess fluid →  excretion problems (gills, kidneys)

• osmotic stress

• pump and vessel problems

Autolysis

• dead cell being self-digested by lysosomal enzymes

  • is temperature dependent and varies with cause

  • if seeing all kinds of dead tissue →  likely this

  • gills = good indicator

Malformation

• when smth wrong before birth

  • deformities depend on when animal is affected in development

    • range from embryonic death - subtle, internal anatomic differences

  • in fish: skeletal and heart anomalies; linked to nutrition, incubation temp, toxins, and some infections

    • genetic, environmental, infections causes

Aplasia

complete failure of organ to form

Hyperplasia

• increase in # of cells in a tissue or organ

  • organ increases in size by increasing number of cells

  • skin + gills might thicken due to inflammation

Atrophy

• shrinkage in size of cell; loss of cell substance without cell actually dying

  • many cells shrinking so organ does too

  • causes: starvation, low / cut off blood supply, nerve damage, pressure

Hypertrophy

• increase in size of cells and thus organ

  • can be adaptive

    • muscles increase w/ exercise, cardiac hypertrophy due to valve failure

  • can be hormonal response (Gonads) or pathological change (coronary arteriosclerosis in salmon - thickened vessels)

Neoplasia

• new growth; Cancer

  • can be benign

  • local lesions (not spreading)

  • malignant: growing by invasion and spreading to other areas / tissues

Fatty change

accumulation of excess fat within non-fat cells

• tends to happen in liver

• body can't deal with normal amount of fat and also when too much fat

• liver = normal place to store fat → becomes overwhelmed → fats deposited in other locations

Pigments

• melanin can show pathological changes

  • it's normally dark and present in immune cells in fish

  • changes can be response to nerve impulses (colour change, injury)

Calcium

•  hard, white, crunchy

  • might increase in response to cancers, metabolic problems, dietary issues if bad + chronic injuries

Mucus

• substance that can make things translucent/cloudy

  • irritants affecting orgs like skin or gills can cause major changes in quantity and quality of mucus

Latent

hidden (infections)

Chronic

long term, low level (infections)