Diversity of cells Flashcards
What substance is used during the general fixation of a tissue sample?
10% Formaldehyde/Acetic acid
What substance is used during the general dehydration of a tissue sample?
70% ethyl alcohol, then 90% ethyl alcohol, and then 100% ethyl alcohol
What is the purpose of fixation during general tissue processing?
To fix all organelles and structures in place
What is the purpose of dehydration during general tissue processing?
This replaces all water in the tissue sample with alcohol
What substance is used during the clearing process of general tissue processing?
Xylene
What is the purpose of clearing within general tissue processing?
This replaces all alcohol in the dehydrated cell with xylene
What substance is used during the infiltration stage of general tissue processing?
Paraffin wax
What is the purpose of infiltration during general tissue processing?
This replaces all xylene with paraffin wax so that the tissue can be preserved
Describe the process of embedding and sectioning during the histological preparation of a tissue sample
The tissue sample in its paraffin wax cassette is added to a mild and more wax is added. The sample is labelled and placed in a microtome. This cuts the wax block and tissue into thin sections of between 4 and 6 microns. The slides are then prepared in a water bath.
What are the 3 types of stains?
Acidic stains, Basic stains and Neutral stains
What colour are acidic stains?
Red or pink
What colour are basic stains?
Blue or purple
What colour are neutral stains?
Neutral stains give a different colour to different components
Give an example of an acidic stain
Eosin
Give an example of a basic stain
Hematoxylin or Toluidine blue
What does Hematoxylin bind to?
DNA/RNA and colours the nucleus blue/purple
What does Eosin bind to?
amino acids/proteins, therefore colouring the cytoplasm pink
What are the 4 basic tissue types?
Epithelium, Connective tissue, muscle tissue, nervous tissue
What is the function of epithelial tissue?
Covers surfaces of the body, lines hollow organs and forms glands
What is the function of connective tissue?
Forms the framework of the body and have a dynamic role in the growth and homeostasis of tissue and, via fat, in energy storage. It also contains vessels so is used for the transport of nutrients.
What is the function of muscle tissue?
Specialised to contract and generate force
What are the 3 major types of muscle tissue?
Cardiac, skeletal and smooth
What is the function of nervous tissue?
Specialised to connect impulses
What is nervous tissue formed from?
Neurons and supporting cells
What are the two distinct surfaces of epithelial tissue?
Apical and Basal
What are the characteristics of epithelial tissue?
Polarity (2 layers), tightly adherent due to junction complexes and cytoskeleton, and avascular
What are the two types of epithelial tissue?
Covering epithelium and glandular epithelium
What are the 3 types of covering epithelium?
Simple, pseudo-stratified and stratified
What is meant my simple epithelium?
Contains only 1 layer of epithelial cells
What is meant by stratified epithelium?
Contains 2 or more layers of epithelial cells
What is meant by pseudo-stratified epithelium?
Contains only 1 later of epithelial cells, however, appears as more than 1 layer upon histological examination
What are the 3 types of simple, pseudo-stratified and stratified epithelium?
Squamous, cuboidal and columnar
What is meant by squamous epithelium?
The cells are flattened and the cytoplasm bulges over the nucleus
What is meant by cuboidal epithelium?
The cells width and height are equal and so the cells appear cube-like
What is meant by columnar epithelium?
The cells height is 2-5 times greater than its width, so cells appear column-like
What are cilia?
Cilia are hair like protrusions used to move substances such as mucus in airways such as the nose.
What is the function of keratin?
Keratin is a layer of dead cells that allows protection for the epithelial tissue. This is found of the epithelial tissue that makes up the skin