Muscle Fibre Structure
The thin filaments are referred to as:
Actin
Are cross-bridge heads located on actin or myosin?
Myosin. The head portion of a myosin molecule forms the cross-bridge
When ATP breaks down what are the by-products?
ADP and Pi
True or False? Filaments change in length.
False. Filaments stay the same and do not change in length
The basic functional unit of a muscle fiber is referred to as:
Sarcomere
Which direction does the cross bridge head bend in?
Towards the middle of the sarcomere
True or False: Tropomyosin is a long filamentous protein which covers cross bridge binding sites on actin.
True
The bands that stays the same length are:
The A-bands
Which structure is missing in the sequence?
Fascicle, Muscle fibre, ____________, sarcomere
Myofibril
True or False? Myosin filaments slide past Actin filaments
False. Actin filaments slide past myosin filaments.
Calcium ions bind to...?
Troponin
What is acetylcholine?
What is the name that refers to Actin and Myosin?
Myofilaments.
Is cross-bridge bending synchronous or asynchronous?
Asynchronous.
ATP energy is stored in which portion of the myosin molecule?
Head
What causes the thick and thin filaments to slide over each other during muscle contraction?
Movement of myosin heads attaching and detaching from actin
Which myofilament (Actin or Myosin) is attached to the Z-line?
Actin
True or False? Each time a sarcomere is stimulated, many cross-bridges form.
True: Each sarcomere contains many myosin filaments - all of which contain myosin heads which are capable of binding to actin and forming cross-bridges
What is released when the actin-myosin cross-bridge forms?
Phosphate
Calcium is released from this storage area when an electrical impulse stimulates muscle contraction.
Sarcoplasmic reticulum