Histology and Pathology of Muscle

Question 1

What is the difference between hypertrophy and hyperplasia?

Answer 1

hypertrophy - increasing individual cell mass

hyperplasia - increasing cell number

Question 2

Which types of muscles are striated?

Answer 2

cardiac and skeletal

Question 3

Describe the nuclei in each muscle cell type?

Answer 3

skeletal - multinucleated, peripheral
cardiac - mononucleated, central
smooth - mononucleated, central

Question 4

Explain the differences in regeneration between the three muscle types

Answer 4

skeletal - satellite cells can be activated, proliferate and specialise into new muscle fibres
cardiac - no satellite cells so no regeneration
smooth - cells can divide by mitosis, also new cells by pericytes

Question 5

Describe the connective tissue layers in skeletal muscle

Answer 5

endomysium - surrounds each muscle fibre
perimysium - fibrous sheath surrounding fasicles
epimysium - dense, encloses entire muscle

Question 6

What are intercalated discs?

What are they made up of?

Answer 6

The structures that hold cardiac muscle cells together so that the cells can contract as one unit
They are made up of desmosomes, adhering junctions and gap junctions

Question 7

What is the specific cell structure of cardiac muscles?

Answer 7

they are branched

Question 8

What is the array of SR and t-tubules called in each of the muscle cell types?

Answer 8

skeletal - triad
cardiac - diad
smooth - no interaction

Question 9

What is the role of dystrophin in skeletal muscle cells?

Answer 9

links muscle cells together and attaches myofibrils to cell membrane

Question 10

Define the term motor unit

Answer 10

A motor neurone and the muscle fibres it innervates

Question 11

What is the difference between Type IIa and IIb muscles fibres?

Answer 11

Type IIa
- red
- fast twitch
- more prone to fatigue than type I
Type IIb
- white
- slow twitch