Muscle Tissue Flashcards
Function of skeletal muscle
They are attached to bones by tendons and assist in movement
What is the sarcolemma
The membrane of muscle fibres
They fold inward to the sat Copland forming transfers t tubules
What are myofibrils
They are cylindrical shaped organelles that run along the muscle fibres
They are the site of muscle contraction
What is a sarcomere
They are units that run end to end sling a myofibril
What are myofilaments
Myofilaments are proteins in the sarcomere that slide over each other causing a muscle to contract
Myosin is the thick myofilament
Actin is the thin myofilament
What is the A band
The region where actin and myosin overlap
What is the H zone
The region where only myosin is present
What is the M line
M line is the middle of the sarcomere
What is the i band
Region of a sarcomere where only actin is present
What is myosin
Consists of proteins wound up together
Contain myosin heads with ATPase which bind to actin binding sites
What is actin
Consists of a helix of actin sub units
Contain binding sites for myosin heads
What is tropomyosin
It is wound around actin
Troponin molecule is bound to tropomyosin and Ca2+ binding sites
What are the steps of muscle contraction
Action potential reaches the motor neurone terminal
Neurotransmitters are released into the synaptic cleft
Action potential spreads down the t tubules via the sarcolemma
Action potential causes release of ca2+ ions from the sarcoplasmic reticulum
Ca2+ ions bind to troponin changing its shape
Troponin then displaces tropomyosin exposing myosin binding sites
ATP binds to bulbous heads detaching them
Hydrolysis if ATP provides energy to recock the bulbous heads
Calcium ions are re absorbed into the sarcoplasmic reticulum via active transport from energy if hydrolysis
Troponin returns to normal shape
Tropomyosin returns to normal position blocking myosin binding sites
how are fast twitch muscle fibres adapted to their function
For fast strong movements Fatigue and contract quickly Short wide fibres Energy source from anaerobic respiration Less capillaries More SR Less myoglobin More glycogen More phosphocreatine Less mitochondria
How are slow twitch muscle fibres adapted to their function
For endurance and slow movement Long thin muscle fibres Fatigue and contract slowly Many mitochondria High myoglobin Many capillaries Low SR Low glycogen Low phosphocreatine
