Pathophysiology

Question 1

3

Causes of altered cellular functions

Answer 1

Adaption
Injury
Ageing

Question 2

5

Cellular adaption & types

Answer 2

Changes based on the environment to escape and protect from injury

Atrophy (decreased size)
Hypertrophy (increased size)
Hyperplasia (increase cell number)
Metaplasia (reversible replacement of mature cell to less mature cell)
Dysplasia (irreversible deranged cell growth)

Question 3

7

Cellular Injury & causes

Answer 3

Unable to maintain homeostasis due to stimuli or stress

Hypoxia, nutritional imbalance, chemical agents, physical agents, infection, genetics, ageing

Question 4

3

Hypoxia & causes

Answer 4

Insufficient oxygen supply to tissues in order to maintain homeostasis

1. Lack of oxygen entering body (respiratory disease, low atmospheric O2)
2. Lack of O2 transport (CVD, anaemia, low Hb, reduced RBC production)
3. Ischaemia (lack of/restricted blood flow)

Question 5

4

Mechanisms of cellular injury (list)

Answer 5

ATP depletion
Altered calcium homeostasis
Defects in membrane permeability
Free radicals

Question 6

ATP Depletion

Mechanism of cellular injury

Answer 6

Loss of O2 reduces ATP synthesis
Failure of Na/K pump = cellular swelling
Anaerobic glycolysis = lactic acidosis
Overall decreased protein synthesis, membrane transport, lipogenesis, loss of membrane integrity

Question 7

Altered calcium metabolism

Mechanism of cellular injury

Answer 7

Lack of ATP = reduced Ca transport out of cell
High cytosolic Ca = damages plasma membrane, cytoskeleton, activates destructive enzymes, damages mitochrondia

Question 8

Defects in membrane permeability

Answer 8

Loss of selectivity in transport in all types of injury
* Na, Ca, water influx

Question 9

Free radicals

Mechanisms of cellular injury

Answer 9

Atoms with unpaired electron
Lipid peroxidation, oxidative stress = alters proteins, DNA, and mitochondria
Esp during reperfusion

Question 10

2

Types of cellular injury

Answer 10

Reversible: cellular swelling (ATP pumps), lipid accumulation (alt liver metabolism) (reversible)
Irreversible: cannot restore homeostasis (DNA & lysosomal leakage, enzyme induced autolysis)

Apoptosis and necrosis

Question 11

2

Apoptosis & types

Answer 11

Programmed cell death, selective self destruction (condensation, blebs, fragmentation)
1. Pathologic = infected cells, damaged DNA, pre-cancerous cells
2: Physiologic = developmental, no inflammation, occurs too great in degenerative conditions (Alzheimer’s)

Question 12

Necrosis & characteristics

Answer 12

Premature death from injury/noxious stimuli = autolysis, self destruction (ER/Mit swelling, blebs, breakdown, leakage)

• Inflammatory cells (macro, neutro), areas of cell loss
• Clumping of genetic material (karyolysis), cell membrane and organelle disruption
• Lysosome disruption, digestive enzyme leakage, autolysis

Question 13

5

Types of necrosis

Answer 13

1. Coagulative: ischaemic injury, protein denaturation (kidneys, heart, adrenals)
2. Liquefactive: ischeamic injury to brain (cell dissolusion due to digestive enzymes)
3. Caseous: coag+liquefactive (cheese like, TB infection)
4. Fat: adipose injury, lipase action (breast, pancreas, abdominal organs)
5. Gangrenous: severe hypoxic injury, dry or wet

Question 14

Ageing & types

Answer 14

Accumulation of changes over time

1. Cellular ageing: genetics (DNA repair defects, genetic abnormalities, mutations, alt signalling) & environmental (free radicals, reduced enzymes, abnormal protein accumulation) = atrophy, loss of function and cells
2. Tissue ageing: progressive stiffness, rigidity, scarcopenia