Basic Muscle Histology

Question 1

Types of muscle cell

Answer 1

• Skeletal
• Cardiac
• Smooth

Question 2

Types of muscle fibre

Answer 2

• Red fibre (type 1, slow twitch, S)
• Intermediate red fibre (type IIa, intermediate twitch, FR)
• White fibre (type IIb, fast twitch, FF)

Question 3

Contraction speed, fatigue rate and glucose metabolism rate of the different muscle fibres

Answer 3

• Red = slow contract, don’t fatigue quickly, low glucose metabolism
• Intermediate red = fast contract, intermediate fatigue rate, intermediate glucose metabolism rate
• White = fast contract, fatigue quickly, high glucose metabolism

Question 4

Myoglobin content of red and white fibres

Answer 4

• Red = high
• White = low

Question 5

Where is white muscle fibre found?

Answer 5

Muscles that move the eye

Question 6

Differences between cardiac and skeletal muscle

Answer 6

• Skeletal has multiple nuclei found at the edges, cardiac has 1 found centrally
• Mitochondria are bigger and more prevalent in cardiac
• Skeletal has triads (1 T-tubule between 2 terminal cisternae of SRs), cardiac has diads (1 T-tubule to 1 terminal cisterna)

Question 7

How does contraction of smooth muscle work?

Answer 7

• Dense plaques at edge of cells and dense bodies throughout the middle of the cell
• Randomly connected by the actin-myosin chains
• When chains contract the cell is pulled at different angles to become smaller