Lecture 11 Flashcards
What is a single muscle cell (myofibre) wrapped by?
endomysium
What is a small group of muscle cells (myofibre) called?
Fascicle
What is the Fascicle wrapped by?
perimysium
What are a group of fascicles wrapped by?
epimysium
What is each individual muscle cell (myofibre) made up of?
Myofibrils
What are the microfilaments and how are they arranged?
There is a thick and thin microfilament inside the myofibrils and these lay on top of each other.
What proteins are the thick and thin filaments made out of?
Thick protein - Myosin
Thin protein - Actin
Describe a sarcomere.
A sarcomere is the region between 2 Z lines (regions where the thin filaments are alone and aligned), and in the middle of the sarcomere is where the 2 filaments overlap each other.
How do muscle contract?
The Z lines both closer to each other, and the thin filament is drawn over the thick filament.
Does the length of the filaments change when the muscle contracts?
No, only the Z lines get closer together (muscle shortens).
What ion is essential for muscle contraction?
Calcium ions (Ca2+).
What 3 factors determine the overall function of a muscle?
- Length of muscle fibres.
- Number of muscle fibres.
- Arrangement of muscle fibres.
What is required of the muscle fibres for a large Range of Movement (ROM)?
The longer the muscles fibres the longer the range of movement as muscle fibres can shorten by up to 50% of their length.
What determines the force/tension a muscle can produce?
The number of muscle fibres [Cross Sectional Area (CSA) ] the greater the number of muscle fibres the greater the tension force that can be produced.
What does the arrangement of muscle fibres contribute to?
If muscle fibres are arranged oblique to muscle tendons (to an angle) then more muscles fibres are able to fit in the same space compared to if they were arranged parallel, hence greater force (uniaxial, bi, multi - number of directions of muscle fibres).
