Lecture 17: Cell Injury and Cell Death Flashcards
What is necrosis?
Severe cell swelling and rupture
What is Apoptosis?
Internally controlled cell death
What is oncosis?
Internally controlled cell death
What are two types of cellular adaptations?
Hypertrophy
Atrophy
What is Hypertrophy?
the enlargement of an organ or tissue from the increase in size of its cells.
What is atrophy?
A progressive and degeneration or shrikage of muscles or nerve tissues
What are some causes of cell Injury?
Hypoxia
Physical agents
Temperature, trauma, radiation
Chemical agents
Drugs etc
Immunologic reactions
Infectious agents
Genetic derangements
Nutritional imbalances
What mode if action does trauma take in cellular injury?
Mechanical disruption of tissue
What mode if action does Contact with strong acid
take in cellular injury?
Coagulates tissue protein
What mode if action does Carbon Monoxide inhalation take in cellular injury?
Prevents oxygen transport
What mode if action does Paracetamol Overdose
take in cellular injury?
Metabolites bind to liver cell protein and lipoproteins
What mode if action does Bacterial Infections
take in cellular injury?
Toxins and enzymes
What mode if action does Ionising radiations
take in cellular injury?
Damage to DNA
5 general biochemical mechanisms?
ATP depletions
Oxygen and oxygen derived free radicals
Loss of intercellular calcium hemostasis
Defects in membrane permeability
Irreversible mitochondrial damage
What are three different types of Cell injury?
Reversible cell injury
Irreversible cell injury
Ischaemic/Reperfusion injury
What is reversible cell injury?
Cell swelling, pallor, hydropic change, vacuolar degeneration
What is irreversible cell injury?
Mitochondrial swelling, lysosomes swells, damage to membrane, leakages of enzymes
What is Ischaemic/ Reperfusion injury?
New damage on reperfusion mediated by free oxygen radicals
What are some examples of reversible Cell injury?
Decrease generation of ATP
Loss of cell membrane integrity
Defects in protein synthesis and DNA damage
What are some examples of irreversible cell injury?
Sever mitochondrial changes
Extensive damage to plasma membranes
Swelling of lysosomes
How does cellular swelling occur?
- Decrease in ATP
- Decrease in activity of Na/K Pump
- Increase in Na in the cell
- Increase in water in cell (Osmosis)
- Cellular swelling
Describe one pathway of Enzymatic Degradation Cell?
- Membrane damage to Lysosomes
- Leakage of Lysosomal Enzymes into Cytosol
3.Enzymatic Degradation of the cell
Describe the pathway of Enzymatic degradation of cell starting with damage to cell membrane?
- Damage to cell membrane
- Increase in Ca in cell
- Ca activates proteases and other enzymes
4.Enzymatic degradation of Cell
Describe a pathway to trigger Apoptosis?
- Damage to Mitochondria
- Cyt C leakage
- Activates Caspaces
Triggers apoptosis
Characteristics of Apoptosis?
Programmed cell death
Individual cell deletion in physiological growth control and in disease
Activated or prevented by many stimuli
Increased apoptosis results in excessive cell loss e.g, atrophy
Characteristics of Necrosis?
Death of tissue following bioenergy failure and loss of plasma membrane integrity
Includes inflammation and repair
How does necrosis effect cell size?
- Cellular swelling
- Many cells affected
How does apoptosis affect cell size?
Cellular shrinkage
One cell affected
How does necrosis affect cell uptake?
Cells contents ingested by macrophages
Significant inflammation
How does apoptosis affect cell uptake?
Cell contents ingested by neighbouring cells
No inflammatory response
How does necrosis affect cell membrane?
Loss of membrane integrity
Cell lysis occurs
How does apoptosis affect cell membrane?
Membrane blebbing, but integrity maintained
Apoptotic bodies form
How does necrosis affect cell organelles?
Organelle swelling and lysosomal leakage
Random degradation of DNA
How does apoptosis affect cell organelles?
- Mitochondria release pro-apoptotic proteins
Chromatin condensation and non-random DNA degradation
What is the process of Autophagy?
- Increased quantity of autophagosomes formation Atg proteins participation
No inflammatory response
Is necrosis ‘programmed’ or ‘accidental’?
Accidental
Is apoptosis ‘programmed’ or ‘accidental’?
Programmed
Name 6 different types of Necrosis?
- Coagulative
- Liquefactive
- Gangrenous
- Caseous
- Fat necrosis
- Fibrinoid necrosis
Describe coagulative necrosis?
Commonest form
Occur in most organs
Cells retain their outlines
Protein coagulate and metabolic activity caeses .
Given an example of coagulative necrosis?
Myocardial infarction
Describe liquefactive necrosis?
Seen in brain
Due to lack of substantial supporting stroma
Neural tissue may totally liquify
Give an example of liquefactive necrosis?
Bacterial or fungal infection, CNS hypoxia
Describe gangrenous necrosis?
Putrefaction of the tissue
Cause is mostly infectious/ bacteria.
Appear black
What are the different types of gangrenous necrosis?
Wet gangrene
Dry gangrene
Gas gangrene
Give an example of gangrenous necrosis?
limb ischaemia
Describe caseous necrosis?
Tuberculosis is main cause
Structureless dead tissue
Amorphous pink material in centre with necrotic debri
Give an example of caseous necrosis?
Tuberculosis
Describe fat necrosis?
Causes
Enzymes
Trauma
Describe fibrinoid necrosis?
Seen in Two conditions
Malignant hypertension
Autoimmune diseases
