Pathology - Fractures and Dislocations Flashcards
Possible outcomes of a normal cell undergoes
Necrosis
Apoptosis
Mixture of necroptosis and pyroptosis
Pyroptosis
Mixture of pyrexia (release of IL-1) and apoptosis
Activation of inflammasome
Happens in infl
What can damage cells
Oxygen deprivation Physical agents Chemical agents Infectious agents Immune agents Immune reactions Genetic abnormalities Nutritional imbalances
Physical agents that can damage cells
Mechanical trauma
Extremes of temp
Sudden changes in atmospheric pressure
Radiation
Reversible cell injury
Cell swelling Fatty change Eosinophilia Changes to cell membrane Mitochondrial swelling Dilation of endoplasmic reticulum w/ detachment of ribosomes Chromatin clumping
Changes to cell membrane that counts `as reversible cell injury
Cell membrane blebbing/ blunting/ loss of microvilli
Cell adaptations
Reversible changes in the size, number, phenotype, metabolic activity or functions of cells in response to changes in their environments
Types of cell adaptations
Hypertrophy
Hyperplasia
Metaplasia
Atrophy
Hypertrophy
Increase in the size of cells that cause an increase in the size of the affected organ
Related to increased workload
May be physiological or pathological
Physiological hypertrophy
Can be seen in uterus during pregnancy
Pathological hypertrophy
Most commonly seen in myocardium - hypertension/ valvular heart disease
Hyperplasia
Increase in the no. cells in an organ/ tissue in response to a stimulus
Can only take place if the cells are capable of dividing
Which two adaptations can take place together
Hyperplasia and hypertrophy
Stimuli causing hyperplasia
Hormone
Growth factors
Metaplasia
Reversible change in which one differentiated cell type is replaced by another cell type
What is metaplasia an example of
An adaptive response where the replacement cell type is better able to withstand the adverse environment
What is metaplasia caused by
Reprogramming of stem cells
Dysplasia
If the stimulus causing metaplasia persists, disordered growth in the epithelium can occur —-> invasive carcinoma
Squamous metaplasia
Columnar cell replaced by squamous cell
Intestinal metaplasia
Squamous cells replaced by goblet cells
Atrophy
Reduction in the size of an organ or tissue due to a decrease in cell size (and size of organelles) and number
Autophagy is activated
What pathway is activated in atrophy
Ubiquitin-proteosome pathway
Autophagy
Cell eating its own organelles to reduce nutrient demand to meet the supply
Pathological hyperplasia
Excessive or inappropriate actions of hormones or growth factors acting on target cells
Drives mature cells or increases output of new cells from stem cells
Hyperplasia regresses if the stimulus is removed
Pathological atrophy causes
Disuse Denervation Diminished blood supply Inadequate nutrition Loss of endocrine stimulation Pressure
Disuse atrophy
Due to prolonged bed rest and can be accompanied by osteoporosis
Denervation atrophy
Damage to nerves supplying a muscle
Diminished blood supply causing atrophy
Atherosclerosis of blood vessels can cause atrophy
Pressure atrophy
An expanding tumour can put pressure on blood vessels causing atrophy of tissues supplied by those vessels
Irreversible injury
if the stimulus exceeds the ability of the cell to respond or adapt
Necroptosis
Has features of both necrosis and apoptosis
Inflammasome
A danger-sensing protein complex within the cytoplasm of the cell
Necrosis
Accidental/ unregulated form of cell death
Damage to membranes – lysosomal enzyme digestion of cell
Leakage of cell contents causing inflammatory reaction
Always pathological
What can necrosis be caused by
Ischaemia
Toxins
Infections
Trauma
Mechanisms underlying cell injury in necrosis
Depletion of ATP Mitochondrial damage Influx of calcium Accumulation of ROS Membrane permeability defect DNA and protein damage
Influx of Ca in cell injury
Leads to depletion of ATP
Activates enzymes causing membrane, protein, nuclear and DNA damage
Effects of ROS
Damage proteins, lipids and nucleic acids by attacking and modifying them
ROS
Reactive Oxygen Species
Apoptosis
A cell death pathway that’s induced by a tightly regulated suicide programme in which enzymes are activated that can degrade the cells own DNA and proteins and fragment cytoplasm
Physiological apoptosis
Destruction of cells during embryogenesis
Involution following hormone withdrawal
Cell loss in proliferating cell population
Elimination of self-reactive lymphocytes
Control of the inflammatory response
Apoptosis pathways
Intrinsic (mitochondrial) pathway
Extrinsic (death receptors initiated) pathway
Intrinsic pathway of apoptosis initiator
Caspase 9
What is the intrinsic pathway of apoptosis triggered by
Cell injury, DNA damage or decreased hormonal stimulation
Caspases
Proteases which can breakdown cell proteins)
Extrinsic (death receptor initiated) pathway initiator
Caspase 8
Caspase 10
What is the extrinsic (death receptor initiated) pathway activated by
FAS ligand binds FAS death receptor (CD95) on the target cell, activating caspases
Removal of apoptotic cells
Phosphatidylserine
Apoptotic cells secrete soluble factors which recruit macrophages
Apoptotic bodies get coated w. thrombospondin or bind C1q which attracts macrophages
Causes for abnormal accumulation of substances
Inadequate removal,
Excessive production of an endogenous substance
Deposition of an abnormal exogenous material
Steatosis
Fatty change
Caused by build-up of triglycerides, usually in hepatocytes
Atherosclerosis
Cholesterol accumulation in macrophagses
Dystrophic pathological calcification
Occurs when calcium is deposited in tissue which is injured or dead, calcium metabolism is normal
Metastatic pathological calcification
Seen in association w/ hypercalcaemia
May be caused by increased parathyroid hormone
Vitamin D excess
Sarcoidosis
Sarcoidosis
Disorder where macrophages accumulate in granulomas (round nodules) and these macrophages activate a Vit D precursor causing hypercalcaemia
Pathological features of non-union
Malformed callus can undergo cystic degeneration
Becomes lined with synovial-like cells creating a false joint (pseudo-arthrosis)
