3- Muscle Contraction And Dysfunction Flashcards
How is skeletal muscle organised?
- Skeletal muscle (exists as a bundle) composed of muscle fascicles and coated in epimysium sheath
- Muscle fascicle coated in perimysium – this is an external sheath
- Each fascicle is composed of many skeletal muscle fibres
- Muscle fibres are individual muscle cells that have been fused together
- Muscle fibres have an internal structure within the perimysium
- Outer membrane of muscle cells is called the sarcolemma
Describe the structure of the sarcolemma
- Has many nuclei
- Muscle cells contain many mitochondria and myosin filaments (contractile proteins) for energy production and contraction respectively
What is the sarcomere?
- functional unit of skeletal muscle contraction
- actin filaments surround myosin filaments
What causes the striated pattern in skeletal muscle?
Overlap between actin and myosin filaments
The I-band:
- No overlap of thick and thin filaments
- Diffracts very little light
The A-band:
- Significant overlap between thick and thin filaments
- Diffracts a lot of light
What is the sarcoplasmic reticulum?
- An organelle that lies closely opposed to the contractile proteins
- Endoplasmic reticulum that is modified specifically to store (and release) calcium
What is a contraction?
Describe the events leading to cell shortening
Describe the interaction between actin and myosin
Describe and explain the steps involved in the contractile cycle
What causes the rise in calcium to initiate a contraction?
How is contraction initiated?
Describe the structure of an axon
In the CNS what forms the myelin sheath?
What happens in multiple sclerosis?
What can multiple sclerosis cause?
