Week 1 Muscular System Flashcards
Functions of skeletal muscle
Breathing and Movement
Postural Support
Heat production during cold stress
Metabolic (oxidative) centre
Define skeletal muscle
Voluntary muscle, moved consciously over 600
Define smooth muscle
Involuntary muscle, controlled unconsciously. In walls of blood vessels and internal organs
Define cardiac muscle
Controls itself (autogenic) with assistance from nervous system and endocrine system, only in heart.
What is excitation contraction coupling
An electric signal travels down t-tubules and causes the release of Ca2+ from SR. The Ca2+ binds to troponin and causes change in tropomyosin, this exposes the active sites on actin and then the myosin binds to these active sites causing a shortening/contracting
What is the sliding filament theory
The myosin cross bridges are activated and they bind strongly to actin, this change in the cross bridge then causes the power stroke to happen. The pulling of the actin filament past the myosin results in muscle shortening and generation of muscle tension. ATP is required (myosin ATPase)
Whats the power stroke
In the sliding filament theory the power stroke is where the myosin head tilts towards the arm of the cross bridge and drag actin and myosin filaments in opposite direction
What are sarcomeres
Sarcomere is the basic unit of striated muscle tissue seperated by Z lines, contains myosin and actin
What is actin and myosin
Actin is in the thin filament of a sarcomere which has its sites opened up by ATP/electrical signal in which myosin heads bind to conduct contraction
Myosin is in the thick filament of a sarcomere in which its head binds strongly to the binding sites of actin to conduct contraction by bringing the filaments closer
What is Troponin and tropomyosim
Troponin is where Ca2+ binds in the thin filament
In relaxed muscle, tropomyosin blocks the attachment site for myosin cross bridge
Define the muscle fibre and myofibril
Muscle fibres contain many myofibrils, and myofibrils contain many sacromeres responsible for contraction.
What is temporal recruitment?
Temporary recruitment of muscle fibres to complete an action/contraction.
What is tetanus regarding action potential?
Tetanus is a sustained muscle contraction
What is twitch regarding action potential?
Twitch is a short muscle contraction
What are the 4 ways in which you can categorize muscle fibres?
Colour, Physiologically (twitch characteristics), histological classification (myosin ATPase activity) and Immunocytological classification (MHC expression).
