Muscle physiology Flashcards
Which of the three muscle types have pacemaker cells?
Cardiac m Smooth m (in single-unit muscle)
List the three muscle types in order of increasing speed of contraction.
Smooth, cardiac, skeletal
Which of the three muscle types have T tubules?
Skeletal and cardiac
What are muscle fascicles?
Groups of muscle fibres, surrounded by perimysium
Name four scaffold proteins in muscle fibres.
Desmin, titin, obscurin, nebulin
What is the function of desmin?
Intermediate filament that:
Forms scaffolds between Z lines
Allows side-side organisation and large force generation
Connects mitochondria and the nucleus to the Z-disks and
Binds the myofibrils to the sarcolemma
What is titin?
Scaffold protein that: Stabilises the myofibril Anchors the thick filament to the Z disk Acts as a tension sensor, allowing an appropriate response. Largest protein in the body.
What is obscurin?
Connects the myofibril to the sarcoplasmic reticulum, allowing communication
What is nebulin?
Scaffold protein with own kinase activity; interacts with desmin to determine Z disk width and stabilise actin filaments.
How long does the creatine store in muscle lasts?
10 seconds
How long does the glycogen store in muscle last?
From 10 seconds to a few minutes
Can the amount of time the glycogen supply in muscle is used for be altered by training?
By a small amount
For how long can muscle use oxidative, aerobic pathway?
Hours
What is the colour difference between fast and slow twitch muscles?
Fast twitch- pale
Slow twitch - dark due to myoglobin
Do larger diameter motor neurons lead to more rapid or slower contraction?
Rapid
Do sarcomeres shorten in length during muscle contraction?
Yes
Describe the positioning of the sliding filaments at rest.
Some overlap
Myosin heads are cocked, with is ATP-dependent
Describe thick filaments
Polypeptides made of 2 large heavy chains and 4 light chains with two globular heads containing an ATP binding site each, with a long tail.
What is tension in a muscle fibre and therefore, produced force, proportional to?
Number of cross-bridges between thick and thin filaments