What medical conditions are associated with inappropriate contraction of smooth muscle?
Asthma, cystic fibrosis etc.
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Why do cardiac cells have an innate ability to contract?
They are myogenic
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Which muscle is capable of repair?
Skeletal muscle
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Give an example, function and special feature of contractile cells
Muscle, movement, contractile proteins
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What are the three types of muscle cells?
Skeletal, smooth and cardiac
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Describe features of skeletal muscle cells
Found in skeletal muscles, voluntary contraction, long cylindrical fibres, heavily striated, movement of skeleton, maintenance of posture, production of heat
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Describe features of smooth muscle cells
Found in walls of hollow internal organs and blood vessels. Involuntary contraction. Spindle shaped. Non-striated. Peristalsis, sphincter muscles, contraction/relaxation of vessels and bronchi
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Describe features of cardiac muscle cells
Found in the heart. Involuntary contraction. Short/branching fibres. Finely striated. Circulation of blood
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Describe the anatomy of skeletal muscle
Muscles comprise several fibres (sharing of load), striations, innervation, relaxation (antagonistic muscles)
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Describe features of muscle fibre banding
Z disc, H band, M band, I band, sarcomere (see ppt animation)
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What are the components in the sliding filament model?
Actin, myosin, troponin
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Describe the structure of an actin filament
Contractile fibre which consists of multiple subunits
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Describe the structure of the troponin complex
Consists of TnI, TnC and TnT - binds to tropomyosin
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Describe the process of contraction using the sliding filament model
Neuromuscular junction. Sarcoplasm releases calcium ions. Calcium ion binds to troponin. Tropomyosin exposes binding site on actin. Myosin head binds to actin. ATP hydrolysis causes myosin head to be released. Formation of a powerstroke. Contraction
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Describe the process of relaxation using the sliding filament model
Calcium ion removed from troponin. Tropomyosin covers binding site on actin. Myosin head unable to bind. Contractile proteins move back
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Describe the structure of myosin
Thick filament made up of a light chain (tail) and heavy chain. Contains two globular heads which each contain an actin-myosin binding site and an ATP-binding site
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Describe the structure of a myosin filament
Myosin tails are arranged to point toward the centre of the sarcomere and heads point towards side of myosin filament band
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What happens to the bicep and tricep during relaxation?
Bicep relaxes and tricep contracts (antagonism)
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Why does lifting weights cause muscle to develop?
Exerting skeletal muscle leads to a tear in the muscle. Muscle will repair itself and develop to become stronger
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Smooth muscle cells connect to form what?
Single-unit syneytia similar to cardiac muscle (impulses/contractions occur more slowly in smooth muscle compared to cardiac muscle)
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Describe the process of contraction for smooth muscle
Increase cytosolic calcium ions. Ca2+ reacts with calmodulin. Activation of myosin kinase. Phosphorylation of myosin light chain. Activation of myosin ATPase. Attachment of myosin head with actin. Contraction of sliding filament mechanism
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What are the uses of smooth muscle?
Contraction, peristalsis, used in arteries, bronchioles (look at structures for blood vessels and bronchiole). Other areas - organs
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Describe the structure of intercalated discs in cardiac muscle
Desmosome (gap junctions) connect sarcomeres. Opening/closing of gap junctions to allow substances to pass through. Discs join cardiac myofibrils
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Describe the innervation for cardiac muscle
Innate ability to contract (cardiac conduction system - apex of heart)
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Why is cardiac muscle more sensitive to calcium?
Calcium is toxic to cardiac muscles (needs to be regulated)
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Can you name any other areas where you would expect to find smooth muscle?
E.g. oesophagus, GI tract
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Other cards in this set
Card 2
Front
Why do cardiac cells have an innate ability to contract?
Back
They are myogenic
Card 3
Front
Which muscle is capable of repair?
Back
Card 4
Front
Give an example, function and special feature of contractile cells
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