MYOLOGY REVISION

Question 1

Tendons

Answer 1

Muscle to bone

Question 2

Ligaments

Answer 2

Bone to bone

Question 3

When will skeletal muscle only contract

Answer 3

When stimulated by a somatic motor neuron

Question 4

What are the components of a motor unit

Answer 4

Nerve fibre and muscle fibre

Question 5

Describe what occurs at a motor unit

Answer 5

-action potential arrives at the axon terminal
-exocytosis of acetylcholine containing vesicles
- acetylcholine binds to the acetylcholine receptors on the sarcolemma
- high amounts of Na+ in the ECF, high K+ in the muscle
- Na+ enters the sarcolemma through the receptors
- sodium opens voltage gated ion channels
- generates action potential
- action potential across the sarcolemma and propagates down the T tubule
- causes calcium ion channels to open
- calcium moves from terminal cistern to the T tubule
- binds to the thin filaments (actin)

Question 6

Sliding filament mechanism

Answer 6

• calcium binds to troponin C
• moves tropomyosin
• ATP binds to myosin head binding site
• converts to ADP and phosphate, releasing energy
  -moves the myosin head into position
• myosin able to bind to the actin heads
• ADP and phosphate detach from the myosin
• causes power stroke
• myosin can pull the actin to the m line
• known as contraction
• myosin will remain bound to the actin until new ATP binds

Question 7

What is a sarcomere

Answer 7

Smallest unit of muscle contraction
Z band to Z band

Question 8

What hols to myosin to the Z disc

Answer 8

Titin

Question 9

Thick filaments

Answer 9

Myosin
2 myosin heads as they are helical in structure
One binding site for ATP the other for actin

Question 10

Thin filaments

Answer 10

Actin
Proteins twisted in a helix shape
Tropomyosin blocking the actin binding site
Troponin present which allows calcium to bind