Examining Cells And Tissues

Question 1

Name the 4 types of tissues.

Answer 1

Epithelial
Connective
Muscle
Nervous

Question 2

Describe an epithelial tissue layer.

Answer 2

At the edge of/surrounding other tissues.
Polarised surfaces, basal surface and apical
Apical surface often secretes sugar to attract water in glycolic
Held by anchor proteins
Lateral and basal junctions allow communication

Question 3

Describe a connective tissue layer.

Answer 3

Made of cells, extracellular proteins, glycoproteins and gels
Main cells = fibroblasts, chrondocytes, osteoblasts, stem and blood
Produces=fibres, gel-like substances, waxes, gels

Question 4

Describe nervous tissue

Answer 4

Nerve cells (neurones) and support cells
Longest is sciatic
Allow fast communication
Congregate to fires-visible to eye

Question 5

Describe muscle tissue.

Answer 5

Skeletal (striated) and cardiac and smooth (both unstriated)
Contract= movement, stabilising, peristalsis
Secretion of hormone= natriuretic factors (h2o balance in kidney) and myostatins (stop heart overgrowth)

Question 6

Define the limit of resolution.

Answer 6

The smallest distance at which 2 objects can be separated and still be distinguishable as separate.

Question 7

List some requirements for the sample under a light microscope.

Answer 7

Preservation to prevent rotting -use formalin
Embed tissue in paraffin to slice thinly
Stain components with H&E

Question 8

How is tissue fixation done?

Answer 8

A buffered solution is used. Often formalin
Formalin=formaldehyde (37/40%), distilled water, NaH2PO4, anhydrous NaH2PO4
Mix solution then leave cell to sit for 24 hours

Question 9

How is paraffin wax embedding done?

Answer 9

Dehydrate in alcohol after fixation.
Immerse in hot/liquid paraffin overnight
Orient in mould and add more wax
Allow to solidify
Ease out of mould carefully
Slice thinly using a microtome

Question 10

What colours does H&E staining produce?

Answer 10

Haematoxylin stains the nucleus blue as its attracted to the acidic DNA.
Eosin stains the cytoplasm and ECM pink as attracted to basic proteins
H+E make nucleus clear and cytoplasm detailed.

Question 11

Why doesn’t H&E show fat Molecules?

Answer 11

As when they are dehydrated in alcohol and some of the fixation process causes them to break down.

Question 12

What are the advantages of cell culturing?

Answer 12

Absolute control over environment grown in.
Homogeneity (all same cell)
Less animal testing

Question 13

What are the disadvantages of cell culturing?

Answer 13

Hard to maintain cell health
High cost for small amount of cells
Dediffernetiation of cells
Instability/aneuploidy (cells change type)
The normal 3D bio environment is lost (normal influence of other cells missing)