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27 Cards in this Set
- Front
- Back
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describe the muscular system |
-series of muscles that moves the skeleton -muscles are the movers and stabilizers of the body -muscles generate internal tension, under the control of the nervous system, manipulates the bones of the body to produce movement. |
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what are the major types of muscle? |
-skeletal: made up of individual muscle fibers held together by connective tissue - cardiac - smooth |
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what is fascia? |
the outer layer of connective tissue that wraps the actual muscle |
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what is epimysium? |
a layer of connective tissue that is underneath the fascia and surrounds the muscle -the fascia and epimysium are connected to the bone and help to form the muscle's tendon. |
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what is the connective tissue that wraps the bundle of muscle fiber called the fascicle? |
perimysium |
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define endomysium |
- the deepest layer of connective tissue that surrounds individual muscle fibers -each fascicle is made up of individual muscle fibers that are wrapped by endomysium |
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what role does connective tissue play in muscle movement? |
they allow the forces generated by the muscles to be transmitted from the contractile components of the muscle to the bones, creating motion. - each layer of connective tissue extends the length of the muscle to form the tendon. |
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what are tendons? |
the structures that attach muscles to bone and provide the anchor from which the muscle can exert force and control the bone and joints. - tendons have poor vascularity and are susceptible to slower repair and adaptation |
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define sarcomere |
the functional unit of muscle that produces muscular contraction and consists of repeating sections of actin and myosin |
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what two proteins structures are important to muscle contraction ? |
- tropomyosin: located on the actin filament and blocks myosin binding sites located on the actin filament, keeping myosin from attaching to actin when the muscle is in a relaxed state - troponin: located on the actin filament, plays a role in muscle contraction by providing binding sites for both calcium and tropomyosin when a muscle needs to contract. |
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What is neural activation? |
- skeletal muscles will not contract unless they are stimulated to do so by motor neurons - neural activation is the contraction of a muscle generated by a neural stimulation - it is the communication between the nervous system and the muscular system |
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what is a neuromuscular junction? |
- a specialized junction or synapse (a small gap between a nerve and muscle fiber) - the point at which the motor neuron meets an individual muscle fiber |
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define motor unit |
a motor neuron and all of the muscle fibers it innervates |
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what is transported from the CNS down the axon of the neuron? |
Electrical impulses also known as action potentials |
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What are neurotransmitters? |
chemical messengers that cross the neuromuscular junction (synapse) to transmit electrical impulses from the nerve to the muscle -the neurotransmitter used by the neuromuscular system acetylcholine (ACh). - ACh stimulates the muscle fibers to go through a series of steps that initiate muscle contraction |
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Describe the Siliding Filament Theory |
-describes how thick and thin filaments within the sarcomere slide past one another, shortening the entire length of the sarcomere and thus shortening the muscle and producing force Step 1: a sarcomere shortens as a result of the zlines moving closer together Step 2.: the Z lines converge as a result of myosin heads attaching to the actin filament and asynchronously pulling (power strokes) the actin filament across the myosin, resulting in shortening of the muscle fiber |
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Describe excitation-contraction coupling |
-process of neural stimulation creating a muscle contraction. - starts with the initiation of neural message (neural activation) and end up muscle contraction (sliding filament theory) |
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Describe motor units and the "all or nothing theory" |
-muscles are divided up into motor units; a single motor unit consists of one or more neuron (nerve) and the muscle fibers it innervates - if the stimulus is strong enough to trigger an action potential then it will spread through whole length of the muscle fiber - if the stimulus is NOT strong enough, there will no action potential thus no muscle contraction - Motor units cannot vary the amount of force they generate - so because of all or nothing, overall strength of a skeletal muscle contraction will depend on the size of the motor unit recruited |
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Steps in the initiation of a contraction |
1. ACh released to binding receptors 2. Action potential reaches T tubule 3. Sarcoplasmic reticulum releases Ca2+ 4. Active site exposure cross-bridge binding 5. Contraction begins |
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Steps that end the contraction |
6. ACh removed by AChE 7. Sarcoplasmic reticulum recaptures Ca2+ 8. Active sites covered, no cross bridge interaction 9. contraction ends 10. relaxation occurs, passive return to resting length |
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What are the muscle fiber types |
Type 1 (slow twitch): also referred to as red fiber; contain large of capillaries, mitochondria (which transform energy from food into ATP, or cellular energy) and myoglobin, which allows for improved delivery of oxygen. smaller in diameter, slower to produce maximal tension and more resistant to fatigue. used in long term contractions (stabilization and postural control)
Type II (fast twitch): fewer capillaries, mitochondria, and myoglobin.; also referred to as white fibers. larger in size; quick to produce max tension; fatigue faster than Type i |
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What are the 2 types of Type II muscle fibers? |
Type IIa: higher oxidative capacity; fatigue slower thatn IIx; AKA intermediate fast-twitch fibers
Type IIx: low oxidative capacity (ability to use oxygen) and fatique quickly
- both use aerobic and anaerobic metabolism almost equally to create energy. |
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What are the functional categorization of the muscles? |
- agonist - synergist - stabilizer - antagonist
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Describe an agonist muscle |
-prime mover responsible for a particular movement - EXAMPLE: gluteus maximus is an agonist for hip extension |
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Describe synergist muscles |
- assist the prime mover (agonist) during movement EXAMPLE: hamstring complex and the erector spinae are synergistic with the gluteus maximus during hip extension |
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Describe stabilizer muscles |
- support or stabilize the body, whereas prime movers and synergists perform movement patterns EXAMPLE: transverse abdominis, internal oblique, and multifidus (deep muscles in the low back) stabilize the low back, pelvis, and hips (lumbo-pelvic-hip complex) during hip extension |
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Describe antagonist muscles |
- perform the opposite action of the prime mover. EXAMPLE: Psoas (a deep hip flexor) is the antagonist to the gluteus maximus during hip extension. |
