Muscle & motility - mechanism of muscle contraction Flashcards
What is skeletal muscle?
Muscles that are attached to the skeleton and aid movement
How does skeletal muscle appear under a microscope?
Striated - stripy appearance
What does each muscle fibre contain?
- An organised arrangement of contractile proteins in the cytoplasm
- Many nuclei
- Sarcoplasmic reticulum
- Sarcoplasm - contains mitochondria and myofibrils
Why are muscle fibres not usually referred to as cells?
They contain many nuclei
What is the sarcoplasmic reticulum?
Specialised endoplasmic reticulum which stores calcium and conveys signals to all parts of the fibre at once using protein pumps in the membranes.
What is the role of mitochondria in the sarcoplasm?
Carry out aerobic respiration to generate the ATP required for muscle contraction.
What are myofibrils?
Bundles of protein filaments (thin actin filaments, thick myosin filaments) which slide past each other during muscle contraction.
What are the parts of a myofibril?
- H band
- I band
- A band
- M line
- Z line
- Sarcomere
Describe the H band
Only thick myosin filaments present
Describe the I band
Only thin actin filaments present
Describe the A band
Contains areas where only myosin filaments are present and areas where myosin and actin filametns overlap
Describe the M line
Attachment for myosin filaments
Describe the Z line
Attachment for actin filaments
Describe the sarcomere
The section of myofibril between two Z lines
