S1 - Histology

Question 1

State the meaning of the term “tissue”, and provide an example of each of the 4 types

Answer 1

• Tissue is a latin word meaning ‘woven’ - collection of similar cells and their intercellular substance that perform a particular function.
  1. Epithelial - Skin
• Found on edge of other tissues and surround other tissues. Can be in clusters within other tissues (glands).
• Polarised when at surface - Apical surface and Basal surface. Apical surface can secrete substances.
• Held together by anchoring proteins and communicate through ‘junctions’ at surfaces.

2. Connective - blood, chondrocytes(cartilage), bone(osteocytes), fibroblast(fibre), teeth and adipose(fat)
   - Cells + extracellular proteins/glycoproteins
   - Main products = fibres, ‘ground substance’(extracellular gelatinous material made up of mostly water).
3. Muscle - skeletal, cardiac and smooth
   - Main function: movement, stability (of organism, organs and tissues) and movement of tissue contents
   - Minor function: to secrete hormones - Natriuretic factor (secreted by cardiac muscle to reduce plasma volume), Myostatin (secreted by muscle cells; inhibits growth of muscle)
4. Nerve - neurons
   - Can be short or very long - Sciatic nerve is the longest
   - Main fast communication system in body
   - Cells congregate into nerve fibres and fibres congregate into ‘nerves’ that can be dissected.

Question 2

State the relationship between milli-, micro-and nanometres

Answer 2

1 millimeter = 10^-3 m
1 micrometer = 10^-6 m
1 nanometer = 10^-9 m

• Largest cell is an oocyte which is visible using 10x lens.
• Measurement graticule used for sizing