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What are the three types of muscle cells?
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Compare and contrast the three muscle cells.
- 1. skeletal muscles are striated and tubular, contain many nuclei, and contract voluntarily, attached to the bone.Â
- 2. Smooth muscles are not striated, have one nucleus, contract involuntarily, and are found in walls of internal organs.
- 3. Cardiac muscles are striated and tubular and branched one nucleus, contract involuntarily, found in the wall of the heart.
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what are the functions of skeletal muscles?
- Support the body
- bone movement
- maintain body temperature
- protect internal organs and stabilize joints.
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What is an antagonistic pair?
- Whenever one muscle pulls the other one relaxes.
- E.X: biceps and triceps.
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Muscles can only ___ They cannot ____
Muscles can only pull they cannot push.
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What's the difference between a flexor and an extensor?
- Flexors contract to bend a joint (biceps)
- Extensors contract to straighten a join (triceps)
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What is the hierarchy of muscles? (largest to smallest)
- 1. Muscle
- 2. muscle fibre bundle
- 3. muscle fibre
- 4. myofibril
- 5. myofilament.
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what is a muscle fiber bundle?
a section of muscle fibres. a layer of connective tissue wraps around each bundle. blood vessels and nerves run between the bundles.
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Whats a tendon?
band of tissue made by collagen
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what do nerves do?
trigger and control muscle contractions.
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what can you find in muscle fibre?
you can find myoglobin, sarcoplasm, sarcoplasmic reticulum and myofibril in muscle fibre.
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what is a muscle fiber?
long muscle cell bound by a membrane called the sarcolemma.
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What is sarcolemma?
the membrane that regulates the entry and exit of materials into the cells.
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What is myoglobin?
it binds to oxygen and stores it for cellular respiration during muscle contraction.
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What is sarcoplasm?
the cytoplasm of a muscle fibre cell which stores myoglobin and glycogen used in muscle contractions.
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what is sarcoplasmic reticulum?
organelle in sarcoplasm that stores calcium ions needed for muscle contraction
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What is myofibril?
organized bundle of myofilaments responsible for muscle contraction. stations are formed on it due to a contraction unit called a sarcomere.
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What is a myofilament?
theres two types thin filament and thick filament. each contain there own protein structure that's responsible for muscle contraction. proteins are called actin and myosin.
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What is thin actin myofilament?
consists of two strands of protein (actin) that are wrapped around each other.
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What is thick myosin filament?
consists of two strands of protein (myosin) wrapped around each other.
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Describe how myosin and actin contribute to muscle contraction.
- 1. myosin heads attach to actin through chemical bonding.
- 2. myosin heads flex backwards and inwards a few nanometers. the actin that is attached is pulled in the direction the myosin pulls it.
- 3. ATP energy separates the myosin and actin and resets the myosin head to reposition it.
- 4. the process repeats.
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What do calcium ions do in muscle contraction?
Actins binding sites are blocked by a long filament composed of proteins called tropomyosin, when calcium ions attach themselves to a different protein on actin called troponin it repositions the tropomyosin- troponin complex which leaves the actions binding site ready to be bound with myosin.
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explain hat the sarcoplasmic reticulum does for muscle contraction.
the muscle fibre is stimulated by a nerve pulse and releases calcium ions which are diffused into the myofibrils. nerve impulse signals the muscle fibre to stop contracting. calcium ions return back to the sarcoplasmic reticulum through active transport.
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