Cell Injury 2 Flashcards
Cell response to injury is a…
Dynamic response
Causes of cell injury
Oxygen deprivation
-hypoxia
-ishaemia
Physical agents
-mechanical trauma
● extreme temperatures (burns, cold)
● sudden changes in atmospheric pressure
● radiation
● electric shock
Chemicals/toxins/drugs
-arsenic, copper, mercury, lead… & more
-environmental and air pollutants
-rodenticides / insecticides / herbicides, benzene… & more
-industrial & occupational hazards carbon monoxide, asbestos… & more
-therapeutic drugs overdosage
Infectious agents
-Viruses
-Bacteria
-Fungi
-Parasites (protozoa, nematodes, trematodes, cestodes, arthropods)
Immunologic dysfunction
-inflammatory reactions to endogenous self-antigens are responsible for several autoimmune diseases
● immune reactions to external agents (microbes and environmental substances)
Genetic defects
-Gene defects resulting in
● malformations
● enzyme defects causing functional impairments
Nutritional deficiencies & imbalances
-malnutrition (protein-calories deficiencies)
● vitamins / minerals deficiencies
● overnutrition
- excess dietary cholesterol / lipids / glucose
- excess dietary vitamins ( vit A, D toxity)
What 3 things does reversible cell injury cause
Hydropic change/degeneration
Fatty change/degeneration/lipidosis
Neuronal chromatolysis
What is Hydropic degeneration
Swelling/Enlargement of organs with extensive fluid
Turn pale, turgid
What is lipidosis/fatty degeneration
Hypoxia damage or toxic/metabolic injury
Accumulation of lipid vacuoles in cells
Cells commonly involved in fat metabolism
Hepatocytes
Myocardial cells
Renal tubule cells
Causes of fatty liver/ hepatic lipidosis
Increased mobilisation of fat stores
-late pregnancy (pregnancy toxaemia)
-early lactation (ketosis)
Nutritional disorders
-obesity
-increased transport of dietary lipids mobilisation from adipose tissue
Endocrine diseases
-diabetes mellitus
-increased mobilisation of triglycerides
(reduced insulin-dependent glucose uptake by cells leads to accelerated lipolysis from adipose tissue)
What is vacuolation
The formation of vacuoles
Describe the 2 types of microscopic patterns of hepatocellular lipid vacuolation
1.Macrovesicular lipidosis
-Single large round vacuoles filling the cytoplasm
-Peripheral displacement of the nucleus
-Accumulation of triglycerides with higher hydrophobicity
2.Microvesicular lipidosis
-Multiple small round vacuoles
-No peripheral displacement of the nucleus
-Indicator of more severe hepatocellular dysfunction
-Toxic hepatopathies causing mitochondrial damage
Causes of excessive hepatic glycogen accumulation
-Diabetes Mellitus (type II)
-Glycogen Storage Disease Ia (GSD Ia)- an inherited disorder caused by the buildup of a complex sugar called glycogen in the body’s cells.
-prolonged corticosteroid/ corticosteroids treatment (important in dogs especially)
-hyperadrenocorticism
What is hepatic glycogen accumulation
The build up of glycogen in the liver
What is neuronal chromatolysis
The dissolution/breaking down of the Nissl bodies of a neuron cell body
Which disease contains a mixture of reversible and irreversible cell injury?
Equine grass sickness- destruction of autonomic ganglia (nerves)
(Chromatolysis and necrosis of ganglionic neurones)
Usually fatal
Describe the differences between reversible and irreversible cell injury
-swelling?
-changes to plasma membrane/nuclear chromatin/mitochondria/lysosome?
Reversible
-general cell swelling
-blebbing of plasma membrane
-clumping of nuclear chromatin
Irreversible
-severe ER swelling
-severe mitochondrial swelling
-lysosome rupture
-cell membrane bless progress to membrane fragmentation degradation of cellular proteins)
-nuclear shrinkage & condensation with nuclear membrane rupture & chromatin fragmentation
Morphological changes associated with reversible cell injury
- decreased generation of ATP
- loss of cell membrane integrity - defects in protein synthesis
- cytoskeletal damage
- DNA damage
^ cytosolic Ca2+ in cell causes…
Sources of all the extra Ca2+
—Ca2+ overload which causes membrane damage,nuclear damage, decreased ATP.
—extracellular Ca2+, mitochondria, smooth ER
2 mechanisms of cell death
Apoptosis and Necrosis
What is Hypoxia
Oxygen deficiency— reduction in o2 conc. supplied to tissues or complete o2 deficiency (anoxia)
Causes for hypoxia
● heart failure, respiratory failure
● loss of blood supply (ischaemia)
● reduced oxygen transport in blood - anaemia, CO toxicity
● blockage of cell respiratory enzymes - cyanide toxicosis
What is Ischaemia
Block of…
Partial reduction or complete loss of blood supply caused by local impairment of the blood flow
—block of arterial blood supply
—bock of venous blood drainage
Causes for ischaemia
—thrombosis (occlusion/blockage of blood vessels)
—mechanical interference with blood flow caused by
-space occupying lesions compressing blood vessels -displacement of organs causing stretching and torsion of vessels with impairment of blood flow – venous more sensitive
Result of ischaemia
Effects on:
-Energy production
-Osmotic balance
-Membrane integrity
-Cellular pH
-Protein synthesis
What is infarction
Necrosis due to ischaemia
