PATH2220 Study Guide - Final Guide: Fibroblast, Electrocardiography, Bradycardia
Blood Vessels and Disease
Tissue Damage and Trauma:
• Cellular Injury
o Numerous causes → physical, chemical
o Various mechanisms
▪ Disruption
▪ Metabolic interference
▪ Free radicals
o Causative agents
▪ Trauma
▪ Thermal injury → hot/cold
▪ Drugs
▪ Poisons
▪ Ionizing radiation
o May be reversible or may lead to cell death
• Ischemia and infarction
o Ischemia brought on by reduced blood flow
▪ No transfer of oxygen
▪ No transfer of fuel/glycolytic substances
▪ Accumulation of metabolites
o Mechanisms include occlusion of the blood flow via arteries to the
organ
o Injury is amenable to repair up to a certain point of no return and
ultimate cell damage/death
• Shock
o Pathological process characterized by profound circulatory failure
resulting in life-threatening hypoperfusion of the bodies vital
organs
o Compensatory mechanisms maintain blood pressure until they fall
resulting in hypotension
o Types of shock
▪ Cardiogenic → commonly due to myocardial infarction →
failure of the hearts pumping mechanism
▪ Hypovolemic → due to reduction in effective circulation
blood volume → e.g. anaphylactic reaction
o Consequences
▪ Irreversible neural damage
▪ Renal failure
▪ Cerebral infarction
▪ Infarction in any area/organ
• Trauma
o Leads to cell death by
▪ Disrupting cells
▪ Denaturing cells
▪ Causing vascular thrombosis/blocking of blood flow
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o Primary injury → damage to the tissues as a result of the initial
trauma
o Secondary hypoxic injury → damage to muscles/tissues as a result
of a lack of adequate oxygen
• Tumours
o Result from genetic alteration in cells with subsequent loss of cell
growth factors resulting in abnormal neoplastic growth
o Can cause damage in several ways
▪ Direct pressure effect on adjacent tissues/organs →
reducing blood flow
▪ Compress/infiltrate blood vessels → reducing flow
▪ Release hormones/active compounds → can cause systemic
effects
▪ Destructive effect with metastasis and direct invasion
• Acute inflammation
o Most common biological response to a noxious or local injury
o Can be triggered by physical, chemical or invading organs
o Repair and regeneration → wound healing, organization
o Complications of injury → hypertrophic scar, keloid
On a Cellular Level:
• Blocking of protein synthesis → glucose deprivation
• Prevention of oxygen utilization → deprivation
• Failure of membrane integrity
o Complement mediated cytolysis
o Perforin mediated cytolysis
o Blockage of ion channels
o Failure of membrane ion pumps
o Alteration of membrane lipids
o Cross linking of membrane proteins
• Build up of free radicals → toxic
• Damage to nucleus/nucleolus
o Damages both transcription and translation
o If cell goes into mitosis before the damage is repaired, it can lead
to cell death
o Damaged DNA can lead to mutation
• Damage to mitochondria
o Leads to impairment of metabolic pathways
o Results in energy deficiency → particularly of ATP within cell
• Damage to lysosome
o Injury leads to degeneration
o Liberation and activation of enzymes leads to autophagy
Adaptations and Outcomes:
• Adaptations
o Hypertrophy → increase in size of individual cells resulting in
overall increase in organ size
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