Cell Injury & Fate Flashcards
What are the two types of cell injury?
Lethal and sublethal
What is lethal cell injury?
Produces cell death
What is sublethal cell injury
Reversible cell damage can progress to cell death
What is an example of direct cell injury?
Myocardial infarction
How does a myocardial infarction occur?
Direct cell injury due to ischaemia, causes cell death through infarction, hypertrophy insufficiently compensates increased demand
Sub-lethally damaged cells can be recovered
What are the 8 causes of cell injury?
Oxygen deprivation, chemical agents Infectious agents Immunological agents Genetic agents Nutritional imbalance physical agents aging HICGINPA
What three factors contribute to the cellular response to injurious injury?
Severity
Duration
Type
What consequences of injurious stimuli depend upon?
Type of cell
Status
Which intracellular mechanisms are vulnerable to injury?
Cell membrane integrity
ATP generation
Protein synthesis
Integrity of the genetic apparatus
What is atrophy?
Shrinkage in the cellular size, by the loss of cell substance
What is an example of atrophy?
Dementia
Amyloid Beta, phosphorylation of tau, dissociates from the MF and accumulates into filamentous neurofibrillary tangles, reduction in neural function, apoptosis
What is hypertrophy?
Enlargement of cells, consequently resulting in an increase in size of the organ
Hypertrophy response to physiological or pathological stresses
What is hyperplasia?
An increase in the number of cells in an organ
Whatis metaplasia?
Reversible change whereby an adult type cell is replaced by another
What lines the cervix?
Squamous epithelium
What lines the internal endocervical canal?
Columnar epithelium
During cervical expansion what happens to the exposed columnar epithelial cells?
The columnar epithelium cells react to external factors (Vaginal pH) and change into squamous epithelial
These changes are reversible
What is barrets Oesophagus?
Acid reflux induces metaplasia
Squamous lined epithelium exchanged into columnar epithelium
What is dysplasia?
Precancerous cells which show genetic and cytological feature, not invading underlying tissue
Cells do not express malignancy, have not invaded the basal lamina
What is the clinical significance of cervical cancer screening?
Aims to identify cells in the dysplastic stage marks patients with an increased risk of cancer
What stage does alcohol-induced fatty liver begin at?
Steatosis
What does ethanol consumption do to the liver?
Ethanol metabolism to shift the redox state of liver and inhibit beta oxidation due to sterol regulatory element binding protein I being activated
Lipogenic enzymes
What does ethanol metabolites do?
Activates element binding protein 1 (lipogenic enzymes)
Fatty deposits cause fatty liver disease
What is ballooning degeneration?
Hepatocytes increase in size
What is necrosis?
Confluent (Region of cells) associated with inflammation
What is coagulative necrosis?
Substance changes, molecular structure does not
Tissue retains the same structure
Nuclei are absent, neutrophil polymorphs present
The architecture of dead tissue is preserved
What is coagulative necrosis associated with?
Ischemia infarction
What are the four types of necrosis?
Liquefactive, caseous, fat and coagulative
What is liquefactive necrosis?
Results in a transformation of the tissue into a liquid viscous mass
Cellular death proceeds into lysosomal digestion, formation of pus filled cysts
What is caseous necrosis?
Activated cytolytic T lymphocytes kill M TB infected macrophages, resulting in collateral damage.
Host degenerates self tissue to control uninhibited multiplication of bacilli.
What composition is the necrotic area?
Granular
What is fat necrosis?
Release of lipases digests and hydrolyzes triglycerides to free fatty acids and glycerol
FFAs combine with calcium in the extracellular fluid and deposits.
Blue area is calcium
What ion do FFAs combine with in the extracellular fluid?
Calcium
What is apoptosis?
Controlled and programmed cell death with no secondary inflammation
What is the distinctive comparison between apoptosis and necrosis?
Necrosis is associated with inflammation
Apoptosis concerns the death of individual cells
Active cell death requires ATP
Both physiological and pathological
How is the intrinsic pathway of apoptosis triggered?
Response to internal stimuli (biochemical stress, DNA damage)
Which gene is activated that halts the cell cycle?
P53 gene, initiates gene repair
What is BCL-2?
Consists of pro and anti apoptotic members balance determines the direction of apoptosis
Establishes molecular switch
What is the extrinsic apoptotic pathway?
Triggers apoptosis in response to external stimuli, by ligand binding at death receptors on the cell surface
What family of receptors do death receptors concern with?
Tumour necrosis factor receptor
what is the execution phase in regards to apoptosis?
Cascade activiation of caspases
What is the initiator caspase?
Caspase 8
What does caspase 8 do?
The initiator caspase cleaves pro-caspases into active executioner caspases
PRO –> EXECUTIONER
What are the functions of executioner caspases?
Cause the degradation of cellular structures (cytoskeleton and nucleus)
What is pyknosis?
Nuclear shrinkage
What is karyorrhexis?
Nuclear fragmentation
What do dead cells phagocytose in?
Phagocytosis into membrane vesicles –> apoptotic bodies
Why is there no inflammation in apoptosis?
Vesicles result in no cytoplasmic leakage
What are the causes of apoptosis?
Embryogenesis: Death of intermediate cells between fingers
Deletion of autoreactive T cells in the thymus
Shedding of the endometrium
Response to DNA damage that irreparable
