Pathology basis of disease

Question 1

What is the 5 pathological processes?

Answer 1

1. cell injury, necrosis
2. immunology, inflammation and repair
3. circulatory disturbance
4. disorders of growth
5. pigmentations and deposits

Question 2

What is the 4 groups of changes in circulatory disturbances?

Answer 2

1. fluid distribution imbalance
   - oedema
2. disorder of haemostasis
   - haemorrhage
   - inappropriate coagulation (thrombosis/ bleeding disorder)
3. hyperaemia and congestion
4. infarction and ischaemia

Question 3

What is disease?

Answer 3

• it is an abnormality of tissue structure or function (lesion)
• the outcome of the host-pathogen-environment interactions

Question 4

What are the factors of H-P-E interactions?

Answer 4

1. agent of disease
2. effect on host
3. host response
4. environment

Question 5

what is the 4 stages of infectious disease?

Answer 5

1. exposure
2. colonisation
3. sub-clinical
4. clinical

Question 6

what will free radical do to skin?

Answer 6

free radical formation in skin causing cell membrane damage and subsequent cell death, leading to inflammation.

Question 7

what does cell injury first starts with?

Answer 7

cell injury first starts with biochemical alterations. morphological. changes lag behind biochemical changes so a cell showing chnages consistent with moderate cell injury may already be dead.

Question 8

What is the difference between clinical pathology and anatomical pathology?

Answer 8

clinical pathology:
- attempt to detect biochemical changes

Anatomical pathology:
- attempt to detect morphological changes

Question 9

when will cell injury occur?

Answer 9

once the cell’s adaptive capacity is surpassed, it is unable to respond to functional demands for homeostasis: cell injury occurs.

cell injury can be reversible (recovery), but past that point the cell dies (irreversible injury)

Question 10

cell degeneration and necrosis can lead to:

Answer 10

1. cell injury (cell degeneration)
   - mainly cytoplasmic changes for degeneration (reversible) cloudy swelling, hydropic change, fatty degeneration.
2. cell death (necrosis and apoptosis)
   - follows mainly detecting nuclear changes e.g. pyknosis, karyorrhexis, karyolysis for cell death

Question 11

what is the causes of cell injury

Answer 11

1. physical agents
   - heat, radiation, cold
   -the extent of the injuries may be increased by local hypoxia associated with vascular damage
2. chemical agents
   - toxins, poisons, drugs, metabolites
   - free radicals
3. genetic factors
   - often operate through deviant biochemical mechanisms that lead to atrophy, dystrophy or even cell death e.g. storage diseases.
4. infectious agents
   - virus, bacteria, fungi, protozoa, algae, metazoan parasites, prions/infectious proteins
5. by-products of inflammation/ immunity

Question 12

2 major causes of cell injury:

Answer 12

1. membrane damage
   - plasma and/or organelle membranes- due to altered biochemical synthesis or structural disruption of molecules
2. energy (ATP) depletion

Question 13

how is membrane being damaged?

Answer 13

• many agents damage cell membranes via intermediates known as free radicals.
• free radicals are highly reactive oxygen species with very short half lives
• chain reaction such as lipid peroxidation can cause widespread membrane damage and more.

Question 14

list anti-oxidants in cells.

Answer 14

1. superoxide dismutases
2. catalases
3. vitamin E
4. glutathione
5. selenium
6. ascorbate

Question 15

How will energy (ATP) depletion leads to cell injury?

Answer 15

• Na-K-ATPase ion pump fails if ATP production is disrupted.
• membrane damage is followed by influx of Na2+, Ca2+ and H2O into the cell and its organelles
• this leads to cellular and mitochondrial swelling which further disrupts aerobic respiration
• water influx leads to cellular swelling and mitochondria swelling which will have an on going effect on energy production
• hypoxia is the most common reason for ATP depletion, as oxygen is vital for energy production.

Question 16

what may hypoxia develop?

Answer 16

hypoxia may develop with a leision anywhere from the nostrils down to mitochondrial enzymes and so may involve:
1. air not reaching the lungs

2. oxygen not reaching the blood
3. oxygenated blood not reaching the tissues
   - circulatory disturbance
   - reduced O2 carrying capacity of blood
4. respiratory poisons acting at specific cellular sites in the respiratory pathway

Question 17

How can ATP be produced in hypoxia?

Answer 17

• in hypoxia, ATP is produced by anaerobic glycolysis which yields much less energy and produces lactic acid which lowers cell pH and inhibits enzymic activity
• cells with higher metabolic rates (e.g. neurons, myocardial fibres, hepatocytes, renal epithelium) are more susceptible to hypoxia

Question 18

What is the light microscopic changes of cell injury seen in the cytoplasm?

Answer 18

1. membrane failure leads to cytoplasmic swelling (cloudy swelling) - often sublethal and reversible
2. hydropic degeneration as water accumulates fine vacuoles
3. small or large lipid droplets (vacuoles) can accumulate (fatty change/ fatty degeneration)
4. Vacular change (water or lipid) is reversible up to point, but then becomes irreversible leading to cell death.

Question 19

when does reversible cell injury become irreversible?

Answer 19

• become irreversible when it loses the ability to restore mitochondrial function
• ATP depletion
• profound disturbances in membrane function
• ATP is likely yo be the critical substrate determining irreversible cell damage.

Question 20

state the 2 mechanisms in irreversible cell injury (necrosis).

Answer 20

1. oncosis (swelling) = continuum with sublethal cell injury [nuclei can be pyknotic/ karyorrhectic and finally karyolytic]
2. Apoptosis = programmed cell death

Question 21

what things are with brown pigments?

Answer 21

• haemosiderin
• bile pigments
• copper
• melanin
• lipofuscin
• artefact- acid haematin
  etc