Histotechnology Lesson 5.1 and 5.2 question n answers graded A+

Histotechnology Lesson 5.1 and 5.2Fixation (histology) the process of fixing tissues with chemical of physical fixatives to preserve tissues Fixative actions (5) •Preserves the tissues in a life-like condition •Stops abnormal enzyme activity and metabolism •Stops autolysis by inactivating the lysosomal enzymes •Stops bacterial and fungal growth •Stops putrefactive changes Give 2 qualities of a perfect fixative •Works quickly with minimum distortion, penetrate the tissue rapidly, and evenly •It should have no hypotonic or hypertonic effect on tissue (causes minimum shrinkage or swelling) Physical fixation heat fixation, microwave fixation, and freezing chemical fixation uses organic or non-organic solutions to maintain morphology; chemical fixatives can coagulant, cross linking, compound fixatives heat fixation raising temperature can accelerate the process of fixation; excessive heat can damage cells Name 2 ways that microwaves can be used in fixation. 1) microwave fixation and 2) microwave assisted fixation simple fixative vs compound fixative simple fixative contains only 1 chemical substance while a compound fixative contains 2 or more chemical compounds formaldehyde commonly called formalin; 10% neutral buffered formalin is used reacts with nuclear proteins and nucleic acids formalin acts by polymerizing action (creates methylene bridges) artefact something observed in a scientific investigation or experiment that is not naturally present but occurs as a result of the preparative or investigative procedure. Glutaraldehyde chemical fixative often used in electron microscopy; penetrates slowly excellent morphology preservation Mercuric chloride examples are B5 and Zenkers fixes nucleoproteins; best used for hematopoietic and reticuloendothelial tissues osmium tetroxide an oxidizing chemical fixative; adds on to double bonds and blackens them only fixative that truly fixes lipids used also in electron microscopy acetic acid acts as a coagulant in action with nucleic acids does not fix proteins penetrates very rapidly alcohols denature proteins and nucleic acids •Alters the shape of the molecules without altering the reactive group •Preserve the chemical reactivity of many cellular materials •Excellent for histochemical investigations