37 Questions
What is the main difference between necrosis and apoptosis?
Necrosis is an outcome rather than a process, while apoptosis is a physiological cell deletion process.
Which of the following is NOT a potential cause of cellular injury?
Emotional stress
What is the rate of cell replication in the human body?
10,000 new cells per second
What role does apoptosis play in the regulation of cell populations?
Apoptosis has an opposite role to mitosis in the regulation of cell populations.
What term refers to areas of dead cells within a tissue or organ?
Necrosis
What is the most common outcome of necrosis?
Accidental cell death
Which of the following is NOT a goal of fixation?
Enhancing cytoplasmic staining
Which process is responsible for the uncontrolled release of intra-cellular enzymes from lysosomes?
Autolysis
What is the action of micro-organisms such as bacteria and fungi in tissue putrefaction?
Production of gases
Which of the following is NOT a factor affecting the rate of fixation?
Cell replication rate
What is the primary effect of coagulant fixatives on proteins?
Denaturation
Which type of fixative results in cytoplasmic flocculation and poor preservation of mitochondria and secretory granules?
Coagulative/precipitant fixatives
What type of fixative forms cross-links within and between proteins and nucleic acids?
Formalin, glutaraldehyde, and other aldehydes
Which chemical groups are most reactive with methylene hydrate in aldehyde fixatives?
[OH] groups
What is the main purpose of fixation?
Arrest autolysis
What is the effect of non-coagulant cross-linking fixatives on proteins?
Cross-linking
What is the primary role of aldehyde groups in certain fixatives?
Cross-linking
What is the effect of coagulative/precipitant fixatives on cellular architecture at the light microscopy level?
Cytoplasmic flocculation and poor preservation of certain cellular components
What is the primary role of formalin in histopathology specimens?
To preserve cells/tissues in life-like condition
What is the overall aim of histology fixation and processing?
To enable sectioning/staining of tissues
What is the effect of formalin on histopathology specimens?
It replaces the normal fluid in the cells with a gel-like rigid compound
What is the primary purpose of fixation in histology?
To preserve cells/tissues in life-like condition
What is the main function of formalin in the treatment of histopathology specimens?
To disinfect tissues and replace water with a gel
What step in the specimen processing timeline involves using fresh formalin for 18h?
Fixation
What method allows for sectioning and staining of histopathology specimens?
Microtomy
What is the effect of non-coagulant cross-linking fixatives on proteins?
Flocculation and poor preservation of mitochondria and secretory granules
What is the primary role of formaldehyde-releasing preservatives in feminine care products?
To prevent polymerization and inhibit reactions
Which of the following is true about the reaction of formaldehyde with nuclear proteins and nucleic acids?
It penetrates between nucleic acids and proteins, stabilizing the nucleic acid-protein shell, and modifying nucleotides by reacting with free amino groups
What is the primary role of formaldehyde in fixation?
To penetrate between nucleic acids and proteins, stabilizing the nucleic acid-protein shell, and modifying nucleotides by reacting with free amino groups
What is the main purpose of using formalin as a fixative?
To act as a penetrant and fixative
What is the effect of formaldehyde on unsaturated lipids?
It reacts with C+C and -SH bonds in unsaturated lipids but does not interact with carbohydrates
What is the outcome of the oxidation of formaldehyde by the oxygen in the air?
Formation of formic acid
What is the primary action of formaldehyde in aqueous solution?
To penetrate between nucleic acids and proteins, stabilizing the nucleic acid-protein shell, and modifying nucleotides by reacting with free amino groups
What is the effect of formaldehyde on carbohydrates?
It does not interact with carbohydrates
What chemical group is most reactive with methylene hydrate in aldehyde fixatives?
Amino groups
What is the action of methanol formed by the oxidation of formaldehyde?
It polymerizes to form paraformaldehyde
What is the primary effect of formaldehyde on proteins?
It forms cross-links within and between proteins
Study Notes
- Cellular injury can be caused by various physical and chemical agents, leading to disruption of membranes, metabolic interference, and potentially reversible damage or cell death.
- Necrosis is a pathological term for areas of dead cells within a tissue or organ, resulting from accidental cell death. Apoptosis, on the other hand, is a programmed cell death process that regulates cell populations.
- Fixation is the process of preserving cells and tissues, preventing post-mortem changes such as ischemia, autolysis, and putrefaction.
- Temperature, size of specimen, volume, pH and buffers, osmolarity, concentration, and duration are factors that influence the rate and quality of fixation.
- Fixatives, which are largely irreversible, help stabilize proteins, prevent autolysis, and prevent bacterial decomposition, allowing for further preparative procedures.
- Fixatives can be coagulative/precipitant, which denature proteins and make them insoluble, or non-coagulant cross-linking, which form bridges between proteins and nucleic acids.
- Commonly used fixatives include formaldehyde, glutaraldehyde, and alcohol. Aldehyde groups in these fixatives react with specific amino acids in proteins, forming stable cross-links.
- Coagulative fixatives maintain tissue histomorphology at the light microscopy level but result in poor preservation of mitochondria and secretory granules, making them less useful for ultrastructural analysis.
- Non-coagulant cross-linking fixatives are useful for ultrastructural analysis as they preserve tissue architecture without causing cytoplasmic flocculation.
- All fixatives are hazardous and require careful handling to ensure safety.
Test your knowledge on cellular injury, tissue preservation and fixation, standard fixation methods, formalin treatment, tissue selection, and sampling of surgical specimens. This quiz covers important concepts related to pathological sciences and surgical cut-up.
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