Objective 4 Flashcards
What is sarcolemma?
Muscle cell plasma membrane
How long are the fibers of the skeletal muscle?
Each fiber is 10-100 um in diameter, and up to 100+ cm long (entire length of the muscle)
What is sarcoplasm?
Muscle cell cytoplasm
Describe skeletal muscle fiber cells
Multi-nucleated; many mitochondria
What do glycosomes within skeletal muscle fiber do?
They provide local glycogen storage
What is myoglobin?
a protein for local oxygen and iron storage
What are the specialized organelles of skeletal muscle fiber?
myofibrils, sarcoplasmic reticulum, T-tubules
Describe Myofibrils
They are densely packed, rod-like contractile elements
What percentage of muscle volume do myofibrils make up?
They make up ~80% of the muscle volume
Describe the arrangement of myofibrils within a fiber
The arrangement of myofibrils within a fiber is such that a perfectly aligned repeating series of dark A bands and light I bands is evident
What are myofibrils made up of?
many sarcomeres (smallest contractile unit of a muscle)
Describe Sarcoplasmic Reticulum (SR)
SR is an elaborate network of smooth endoplasmic reticulum that surrounds each myofibril
- Paired terminal cisternae form perpendicular cross channels
What is the function of Sarcoplasmic Reticulum (SR)?
SR functions in the regulation of intracellular calcium levels
How do the T tubules associate within the SR?
T tubules associate with the paired terminal cisternae
What are T tubules (Transverse Tubules)
T tubules are continuous within the sarcolemma
- the lumen of each T tubule is continuous with the extracellular space
