Table of Contents
What are myelin figures in cell injury?
Myelin figures: aggregates of damaged cell membranes (phospholipids). They either phagocytosed by other cells or further degraded into fatty acids and calcify. 43. Marked dilatation of mitochondria and appearance of large densities.
What are myelin figures in necrosis?
Dead cells may ultimately be replaced by large, whorled phospholipid masses called myelin figures. These phospholipid precipitates are then either phagocytosed by other cells or further degraded into fatty acids; calcification of such fatty acid residues results in the generation of calcium soaps.
Are myelin figures reversible?
Myelin figures are concentric whorls of membranes derived from damaged cell membranes. It is seen in both reversible and irreversible injury.
What is the hallmark of irreversible cell injury?
Irreversible cell injury: mitochondria swell, lysosomes swell, damage to plasma membrane and lysosomal membranes leads to enzyme leakage; acidosis somewhat protective by inhibiting enzymatic reactions.
Why myelin figures are formed?
Membranous whorls derived from the rough endoplasmic reticulum became partly electron dense, forming myelin figures. The apposing membranes of the smooth endoplasmic reticulum were closely approximated or fused with each other to connect with the peripheral lamellae of myelin figures.
What are myelin figures made of?
a rolled-up or scroll-like arrangement of a lipid bilayer within a cell, superficially resembling the myelin sheath of nerves; myelin figures are observed with the electron microscope in the cytoplasm or as inclusion in mitochondria and autophagic vacuoles where they may represent artifacts of lipid fixation.
How myelin figures are formed?
What is reversible cell injury in pathology?
Cell injury is classified as reversible if the injured cell can regain homeostasis and return to a morphologically (and functionally) normal state. Acute cell swelling is the classic morphologic change in reversible injury; however, it is also the typical early change of irreversible cell injury.
What is pathogenesis of cell injury?
MECHANISM OF CELL INJURY 1.DEPLETION OF ATP 2.MITOCHONDRIAL DAMAGE 3.INFLUX OF INTRACELLULAR CALCIUM & LOSS OF CALCIUM HOMEOSTASIS 4.ACCUMULATION OF OXYGEN-DERIVED FREE RADICALS (OXIDATIVE STRESS) 5. DEFECTS IN MEMBRANE PERMEABILITY. 7. Depletion ofATP • Usuallyin hypoxicandchemicalinjuries.
What happens when the myelin sheath is damaged?
A demyelinating disease is any condition that causes damage to the protective covering (myelin sheath) that surrounds nerve fibers in your brain, the nerves leading to the eyes (optic nerves) and spinal cord. When the myelin sheath is damaged, nerve impulses slow or even stop, causing neurological problems.
What are the different types of cell injury in pathology?
Types of cell injury: Reversible injury. Irreversible injury Irreversible Injury Ischemic Cell Damage (leads to cell death)
What are the three mechanisms of cell injury?
The responses induced by cellular injury fall into four main patterns: the ischaemic/anoxic, oxidative, heat shock and acute phase responses.
What is necroptosis in pathology?
Necroptosis is a programmed form of necrosis, or inflammatory cell death. Conventionally, necrosis is associated with unprogrammed cell death resulting from cellular damage or infiltration by pathogens, in contrast to orderly, programmed cell death via apoptosis.
What are the various mechanisms of cell injury?
Cell injury and adaptation The responses induced by cellular injury fall into four main patterns: the ischaemic/anoxic, oxidative, heat shock and acute phase responses.
What are the factors of cell injury?
In principle, cell injury can occur due to the following factors: Excessive or overly prolonged normal stimuli. Action of toxins and other adverse influences that could inhibit the vital cell functions (e.g., oxidative phosphorylation or protein synthesis) Deficiency of oxygen and/or essential nutrients and metabolites.
How is myelin sheath damage diagnosed?
Demyelinating conditions, especially MS and optic neuritis, or inflammation of the optic nerve, are detectable with MRI scans. MRIs can show demyelination plaques in the brain and nerves, especially those caused by MS. Your healthcare provider may be able to locate plaques or lesions affecting your nervous system.
What is the pathophysiology of cell injury?
Cell injury results when cells are stressed and can no longer adapt Injury may progress through a reversible stage Reduced oxidative phosphorylation with resultant depletion of energy stores in the form of adenosine triphosphate (ATP) Cellular swelling caused by changes in ion concentrations and water influx
What are the most common causes of cellular injury?
The more common causes (etiologic agents) of cellular injury are grouped, discussed, and illustrated in the following sections. Oxygen Deficiency Hypoxia, a reduction in oxygen supply, is one of the most common and most important causes of injury; indeed, it is often the ultimate cause of cell injury.
What is an example of a cell membrane injury?
CCl4is an example of cell membrane injury caused by chemical modifications (see the following section). Cell membranes can also be injured directly by defensive molecules of the immune system and by bacterial cytotoxins (see later). Carbon Tetrachloride and Cell Membrane Injury
How do cells respond to injury at the cellular level?
This chapter is focused on the response to injury at the cellular level, but the student must remember that an injured cell is affected not only by its direct injury but also by neighboring and distant cells, stroma, and vasculature, and that the injured cell in turn affects cells and tissues around it (and at distant sites).