Introduction to tissue biology - week 1

Question 1

Define tissue biology

Answer 1

= histology
- study of the morphological features of normal cells and tissues mainly using a light microscope

Question 2

Why is tissue biology relevant?

Answer 2

• helps understanding how the body functions
• can’t recognise abnormal until understanding the normal

Question 3

Define histology

Answer 3

= 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”

Question 4

Define pathology

Answer 4

= 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”

Question 5

Define physiology

Answer 5

= 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”

Question 6

Define cell

Answer 6

= fundamental unit of human life - building block

Question 7

How many cells are there in the human body

Answer 7

37 trillion

Question 8

How many different types of cells are there?

Answer 8

more than 200

Question 9

What is the most common type of cell in the human body?

Answer 9

Red blood cell - 80%

Question 10

Define tissue

Answer 10

= groups of cells that have similar structure (morphology) and function

Question 11

Name 5 types of tissues

Answer 11

• blood
• supporting/connective tissue
• nervous tissue
• muscle
• epithelia

Question 12

Define organ

Answer 12

= anatomically discrete collections of tissues that together perform certain specific function
eg. heart composed of muscle, nerve, connective and epithelial tissues

Question 13

Define system

Answer 13

= 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

Question 14

What will happen to unfixed tissue?

Answer 14

it will degrade by autolysis

Question 15

Why is a fixative required int issue sampling?

Answer 15

to maintain structure

Question 16

Give two examples of what fixatives do to maintain structure

Answer 16

1. denatures proteins (eg alcohol based)
2. cross-links proteins (eg. formaldehyde)

Question 17

Name the commonest fixative

Answer 17

Formalin (27% formaldehyde)

Question 18

What happens during tissue sampling?

Answer 18

• tissue is cut, small pieces are being removed and placed into cassettes

Question 19

What are cassettes?

Answer 19

small perforated baskets

Question 20

Name the three steps which make up processing and embedding

Answer 20

1. Dehydration
2. Clearing
3. Infiltration with wax

Question 21

What happens at step one of processing/embedding?

Answer 21

tissue blocks passed through graded alcohols

Question 22

What happens at step 2 of processing/embedding?

Answer 22

solvent that is miscible with alcohol and paraffin wax

Question 23

What is the reason for having step three of processing/embedding?

Answer 23

infiltration with wax provides rigidity and support to allow sections to be cut

Question 24

What happened to the impregnated tissue

Answer 24

its further embedded into a paraffin block, and encased with more molten wax

Question 25

What happens after the sample embedded into a paraffin block?

Answer 25

sectioning

Question 26

How thin is the sample cut in "sectioning"

Answer 26

into o.oo4 mm thick sections

Question 27

What is used to cut the sample into thin sections?

Answer 27

a microtome

Question 28

What happens after the sample was cut with a microtome?

Answer 28

its mounted onto glass slides by floating it onto a water bath

Question 29

Why does the section have to be stained in the end?

Answer 29

- tissue elements are colourless - reveal structural detail using a light microscope

Question 30

what are the most common staining techniques?

Answer 30

Haematoxylin and Eosin

Question 31

name the two types of dyes used in tissue staining

Answer 31

basic dyes and acidic dyes

Question 32

What charge do basic dyes have?

Answer 32

a postive charge

Question 33

What attribute does the +ve charge give basic dyes?

Answer 33

makes them bind to negatively charged tissue components

Question 34

Name an example of a basic dye

Answer 34

haematocylin

Question 35

What charge do acidic dyes have?

Answer 35

negative charge

Question 36

what attribute does the -ve charge give acidic dyes?

Answer 36

it makes them bind to positively charged tissue components

Question 37

Name an example of acidic dyes

Answer 37

eosin

Question 38

define basophilia

Answer 38

binding of basic dyes to tissue component

Question 39

What colour is the stain of a basophilia?

Answer 39

blue

Question 40

What does "components" in basophilia include? (3)

Answer 40

1. nuclear chromatin 2, cytoplasm RNA 3. certain extracellular matrix proteins eg. cartilage

Question 41

Define acidophilia

Answer 41

binding of acidic dye to tissue

Question 42

What colour is a acidophila stain?

Answer 42

pink

Question 43

What do "components" of acidophilia include? (3)

Answer 43

- cytoplasmic proteins including cytoskeleton - intracellular membranes - most extracellular protein fibres eg. collagen

Question 44

name three types of microscopy

Answer 44

- light microscope - election microscope - fluorescence microscope

Question 45

By how many times does a light microscope increase a sample?

Answer 45

x1000

Question 46

By how may times does an electron microscope increase a sample?

Answer 46

x100,000

Question 47

What does a fluorescence microscope show?

Answer 47

antibodies or probes with fluorescent tag

Question 48

What are the two types of electron microscopes?

Answer 48

transmitting electron microscope (TEM) and scanning electron microcope (SEM)

Question 49

The SEM shows the image in 3D yes or no?

Answer 49

YES