Lecture 11 Flashcards
What are the functions of skeletal muscle?
- Movement
- Heat Production
- Posture
- Communication
What are the Latin and Greek prefixes of muscle?
- Myo-
- Sarco-
What are the tissues involved with the musculo-skeletal system?
- Bone
- Skin
- Subcutaneous fat
- Fascia (connective tissues - goes between groups of muscles)
- Muscles
- Arteries/Veins
- Nerves
What are the different layers of connective tissues associated with the muscle and where are they?
- Epimysium
> around the bulk of the muscle - Perimysium
> wraps around the fascicle - Endomysium
> around a muscle fibre (cell)
What is the purpose of all these layers of connective tissues?
To transfer any force produced from the muscle to the bone.
What is a fascicle?
A group of muscle cells grouped together covered by the perimysium.
What is the name for a muscle cell?
- Myocyte
- Myofibre
What is the myocyte made of?
Myofibrils (made of thick and thin fibres - myofilaments)
Some features of a muscle cell?
- up to 40cm
- parallel
- cylindrical
- multi-nuclear
- striated (due to protein arrangement)
What is the name given to the individual arrangements of proteins and what are its parts?
Sarcomere - Thick and thin filaments
What separates sarcomeres?
Z disks
What is the name of the cell membrane of the myocyte? What sits underneath this?
Sacolemma
Sarcoplasmic reticulum
What is the main function of the sarcoplasmic reticulum?
Stores calcium
In the sarcomere, what is the name of the thick and thin proteins?
Thick - Myosin
Thin - Actin
How do these work together to form contraction?
The myosin have myosin heads which attach to the actin and then flex which causes the Z disks to come closer together which forms a contraction.
How much contraction of the sarcomere can occur?
It can go from 2µm to 1µm, half.
What is the name given to the overlap of actin and myosin?
Interdigitate
What are the ingredients required for muscle contraction?
- Energy
- Calcium ions (Ca2+)
Muscle form determines function.
Length - of muscle fibres
> fibre can shorten up to 50% of resting length
> large ROM = long fibres
> longer resting length = can shorten more = greater ROM
Number - of muscle fibres
> cross-sectional area
> tension (= force) is directly proportional to cross-sectional area
> greater number of fibres = greater CSA and greater tension
Arrangement - of muscle fibres > fibres oblique to muscle tendon = pennate (structure) > more fibres into same place > reduced shortening but increased CSA > clique to line pull (uni, bi, multi)
What is the factor affecting the tension/force?
The amount of myofibres.
What is the advantage of a pennate arrangement?
What is the disadvantage of a pennate arrangement?
More myofibres so more force.
Some long, some short fibres so less ROM.
What are the names of the tissues in a muscle from biggest to smallest?
Myofibres (myocyte)
Myofibril
Sarcomere
Myofilament (thick and thin proteins - Myosin and Actin)
Muscle tone
- Even relaxed muscles are slightly active
- Nerve impulses activating muscle fibres
- Does not produce movement
- Keep muscles firm and healthy
- Helps stabilise joints and maintain posture
