How to examine cells and tissues Flashcards
state the meaning of the term “tissue”.
tissue is defined as a collection of cells that are adapted to perform a specific function
state the relationship between milli-, micro- and nanometres
milli is 10-3
Micro is 10-6
Nano is 10-9
explain the value of histology in diagnosis
histology allows us to determine the health of cells by making it possible to examine the regularities of tissue distribution, cell shapes and whether or not the cells are cancerous.
describe common biopsy techniques (e.g. curettage, needle, transvascular, etc.) giving examples of tissues which can be sampled by each method
Direct venipuncture for blood smears and haematological issues.
Transvascular biopsy where a device travels through the blood vessels to the site where a biopsy can be taken ( the heart, kidney, lungs, brain etc)
Sharp needles for needle biopsy and punch biopsy ( for skin)
Scraping method for diagnosing skin inflammation, fungal illnesses etc.
Surgery and then dissection by a histologist for frozen section analysis immediately.
explain why tissue needs to be fixed and state which fixatives are commonly used
fixation removes the water aka stiffens the sample and stops the sample from decaying or digested by microbes, it protects it from damage so it can be viewed easily.
common fixatives are formalin which is a 37% aldehyde and 9% saline. it is isotonic so the formaldehyde can penetrate and react with the amino acids within proteins forming methylated brights between the chains thus preserving its structure.
or freeze fixation to temp
Describe how tissue processing can lead to the formation of shrinkage and other artefacts
an artefact is something that in the view of the microscope that is not meant to be there.
during formalin fixing if the specimen is left in the solution for over 48 hours the amount of fixation artefacts increase.
Discuss the value of histological staining and state the components of tissue stained by routine stains, such as Haematoxylin and Eosin (H&E) and specialist methods, such as immunohistochemistry and immunofluorescence
Haemotoxylin stains acids so nucleus and certain acidic proteins are stained
Eosin stains alkaline things like the cytoplasm and proteins, collagen and elastic fibres
Massons Trichrome stringing shows keratin and muscle fibres as red
blue or green collagen and bone
dark brown to black cell nuclei
Periodic Acid-Schiff identifies anything with sugar attached like glycoalx.
immunohistochemistry stains the antigen specific to the antibody that has been labelled to localise cell and tissue targets.
define organ
two or more tissues combined to create a structural unit that has particular function that are a sum of its parts
Provide an example of each of the 4 types of tissue
Epithelial tissue : covers internal and external surfaces in the body, lines body cavities and hollow organs and is the main tissue in gland eg the epidermis your skin.
Connective tissue: binds structures together for a framework and support for organs( includes blood, cartilage, bone, teeth and fat )
Muscle tissue composed of calls that contract and shorten in order to facilitate movement. Eg cardiac tissue
Nerve tissue (neural tissue): found in brain, spine and in nerves. An example is neurons . They are excitable cells that transduce stimuli into electrical signals in the form of action potentials.
