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36 Cards in this Set
- Front
- Back
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Three types of muscle |
Skeletal Cardiac Smooth |
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Where is smooth muscle found? |
Hollow organs |
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Describe the structure of cardiac muscle cells |
Central nuclei Not a true syncitium Rich in mitochondria and glycogen |
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Which muscle types are striated? |
Cardiac Skeletal |
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What are the functions of skeletal muscle? |
Locomotion Breathing Postural support Heat generation Largest protein store |
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Cell membrane of a muscle fibre is the |
Sarcolemma |
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Bundles of muscle fibres are called |
Fasicles |
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Cytoplasm of muscle fibres is called |
Sarcoplasm |
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What are the T tubules? |
Invaginations of the sarcolemma that help spread innervation Relevant to excitation-contraction coupling |
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Muscle cells are called |
Muscle fibres
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What is the functional organelle of muscle cells? |
Myofibril = long cylindrical organelle for contraction |
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What is a myofilament? |
A component of the myofibril organelle Thin actin Thick myosin |
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How big are muscle fibres? |
BIG 10-30microns diameter Upto 30cm long |
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Key features of a muscle fibre: |
Syncitium (multiple nucleil Peripheral nuclei Myofibril organelles Size and long thin shape |
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What is the sarcoplasmic reticulum? |
A network of internal membranes that store and release calcium ions as part of contraction |
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What membrane surrounds entire muscles? |
Epimysium |
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What membrane surrounds multiple fascicles? |
Perimysium |
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What membrane surrounds individual muscle fibres? |
Endomysium |
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What are the short repeating units in myofibrils called? |
Sarcomeres |
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The I band contains... |
Actin filaments only |
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The A bands contain... |
Myosin, plus or minus actin |
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Z line |
The boundary between sarcomeres to which actin is anchored |
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H zone |
Myosin filaments only |
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M line |
Transverse line in middle of sarcomere that binds myosin filaments |
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When the sarcomere shortens, what happens to the... I band A band H zone Z-Z distance |
Muscle contraction I band shortens (overlap with myosin)A band has no changeH zone vanishrs Z-Z distance gets shorter |
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What two molecules regulate cross bridge formation? |
Troponin Tropomyosin |
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Which part of actin has three components, and what are they? |
Troponin T I C |
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If no ATP is available during cross bridge cycling, what happen? |
Myosin remains bound to actin = Rigor |
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How is smooth, sustained contraction achieved? |
Asynchronous cross bridge formation |
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What are the roles of calcium ions in muscle contraction? |
Interacts with troponin C to allow myosin and actin to bind Made RAPIDLY available from sarcoplasmic reticulum Ca2+ induced Ca2+ release triggers MORE After contraction it has to be pumped back into the sarcoplasmic reticulum using ATP |
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What is the calcium ion channel in the sarcoplasmic reticulum membrane called? |
The ryanodine receptor |
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Describe the arrangement of tromyosin in a low calcium state cell |
Packed into the groove of the actin chain Spanning 7 units Preventing myosin binding |
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What is the role of troponin? |
Move tropomyosin deeper into actin groove to allow myosin to bind |
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In the presence of calcium, what do the different parts of troponin do? |
T - attaches to tropomyosin ribbon I - bound to actin head C - captures calcium ions and undergoes conformational change moving the tropomyosin deeper into the actin groove, to expose the binding site for myosin |
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What triggers cross bridge formation? |
CALCIUM |
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Give symptoms of hypocalcaemia |
Recumbent cow at/close to calving S bend neck General weakness Stillborn calf Retained foetal membranes Lack of rumen sounds Still dry feces Weak heart signs Dry muzzle |
