Introduction to tissue biology - week 1 Flashcards
(1) definitions (2) tissue sampling (3) recap of anatomy
Define tissue biology
= histology
- study of the morphological features of normal cells and tissues mainly using a light microscope
Why is tissue biology relevant?
- helps understanding how the body functions
- can’t recognise abnormal until understanding the normal
Define histology
= the stud of the micro anatomy of cells, tissues, organs as seen through a microscope
- examines the correlation between structure and function
- “what normal looks like”
Define pathology
= branch of medical science that involves the study and diagnosis of disease through the examination of surgically removed organs, tissues (biopsy samples), bodily fluids, in some cases whole body (autopsy)
“what disease looks like”
Define physiology
= science of life
- branch of biology that aims to understand the mechanisms of living things, form the basis of cell function at the ionic and molecular level to the integrated behaviour of the whole body and the influence of the external environment
“how normal functions”
Define cell
= fundamental unit of human life - building block
How many cells are there in the human body
37 trillion
How many different types of cells are there?
more than 200
What is the most common type of cell in the human body?
Red blood cell - 80%
Define tissue
= groups of cells that have similar structure (morphology) and function
Name 5 types of tissues
- blood
- supporting/connective tissue
- nervous tissue
- muscle
- epithelia
Define organ
= anatomically discrete collections of tissues that together perform certain specific function
eg. heart composed of muscle, nerve, connective and epithelial tissues
Define system
= group of organs working together to carry out a function
- eg. digestive system composed of the mouth, oesophagus, stomach, intestines - to absorb nutrients and eliminate solid waste
What will happen to unfixed tissue?
it will degrade by autolysis
Why is a fixative required int issue sampling?
to maintain structure
Give two examples of what fixatives do to maintain structure
- denatures proteins (eg alcohol based)
- cross-links proteins (eg. formaldehyde)
Name the commonest fixative
Formalin (27% formaldehyde)
What happens during tissue sampling?
- tissue is cut, small pieces are being removed and placed into cassettes
What are cassettes?
small perforated baskets
Name the three steps which make up processing and embedding
- Dehydration
- Clearing
- Infiltration with wax
What happens at step one of processing/embedding?
tissue blocks passed through graded alcohols
What happens at step 2 of processing/embedding?
solvent that is miscible with alcohol and paraffin wax
What is the reason for having step three of processing/embedding?
infiltration with wax provides rigidity and support to allow sections to be cut
What happened to the impregnated tissue
its further embedded into a paraffin block, and encased with more molten wax
What happens after the sample embedded into a paraffin block?
sectioning
How thin is the sample cut in “sectioning”
into o.oo4 mm thick sections
What is used to cut the sample into thin sections?
a microtome
What happens after the sample was cut with a microtome?
its mounted onto glass slides by floating it onto a water bath
Why does the section have to be stained in the end?
- tissue elements are colourless
- reveal structural detail using a light microscope
what are the most common staining techniques?
Haematoxylin and Eosin
name the two types of dyes used in tissue staining
basic dyes and acidic dyes
What charge do basic dyes have?
a postive charge
What attribute does the +ve charge give basic dyes?
makes them bind to negatively charged tissue components
Name an example of a basic dye
haematocylin
What charge do acidic dyes have?
negative charge
what attribute does the -ve charge give acidic dyes?
it makes them bind to positively charged tissue components
Name an example of acidic dyes
eosin
define basophilia
binding of basic dyes to tissue component
What colour is the stain of a basophilia?
blue
What does “components” in basophilia include? (3)
- nuclear chromatin
2, cytoplasm RNA - certain extracellular matrix proteins eg. cartilage
Define acidophilia
binding of acidic dye to tissue
What colour is a acidophila stain?
pink
What do “components” of acidophilia include? (3)
- cytoplasmic proteins including cytoskeleton
- intracellular membranes
- most extracellular protein fibres eg. collagen
name three types of microscopy
- light microscope
- election microscope
- fluorescence microscope
By how many times does a light microscope increase a sample?
x1000
By how may times does an electron microscope increase a sample?
x100,000
What does a fluorescence microscope show?
antibodies or probes with fluorescent tag
What are the two types of electron microscopes?
transmitting electron microscope (TEM) and scanning electron microcope (SEM)
The SEM shows the image in 3D yes or no?
YES
