Microsopic Structure + Function

Question 1

Define tissue
What are the 4 types of tissues?

Answer 1

• a group of cells, organised to perform the same specific function
• epithelial, muscle, nervous, connective

Question 2

Describe common biopsy techniques

Answer 2

Curettage
Needle
Transvascular

Question 3

Why are tissues fixed + which fixatives are used?

Answer 3

• to protect the biopsy from damage (digested by microbes/destroyed by decay)
• fixative formalin (37% formaldehyde + 0.9% sodium chloride)
• is isotonic, better penetration of formaldehyde = reacts with. a.a. groups + forms methylated bridge between protein chains

Question 4

Method to prepare a histological image

Answer 4

1. Tissue procurement- biopsy
2. Fixation- formalin
3. Embedding- paraffin was- microtome
4. Cutting into thin sections
5. Staining
6. Examination using microscope

Question 5

Describe H&E staining

Answer 5

H&E: immersed in haematoxylin (DNA + RNA), wash in water, transfer into alcohol, slides immersed in eosin (acidic so binds to cytoplasm., collagen, elastic fbr.), wash w alcohol, mounted on slide

Question 6

Describe the process of immunohistochemistry and immunofluorescence

Answer 6

Antibodies w fluorescent dyes are complementary to the target antigen a.a. sequence
Using enzymes. acts. secondary an. complexes is more sensitive (indirect immunohistochemistry)
Enz. used are normally peroxidases

Question 7

Define ‘limit of resolution’

Answer 7

Minimum distance at which two objects can be distinguished