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myofilaments consist of which main proteins
- myosin: Thick or
- actin: thin
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multiple ___ are organized into a muscle fiber
myofibrils
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multiple fibers are organized into a ___
fascicle
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multiple fascicles are organized into a ___
muscle
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Each tropomyosin molecule has a calcium-binding protein called ____ bound to it.
troponin
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explain excitation process that leads to excitation-contraction coupling and contraction.
1) a nerve signal arrives at the synaptic knob and opens voltage-gated Ca channels. Ca ions enter the knob and stimulate the release of Acetocholine (ACH).
2) Ach diffuses across the synaptic cleft and binds to receptors in the sarcolemma.
3) Receptors are ligand-gated. 2 ACh molecules need to bind to open a receptor.
4) Na flows in, K flows out until the voltage jumps from RMP -90 to +75mV, which created the end-plate potential.
5) Ion channels in the sarcolemma open in response to the end-plate potential, allowing Na in and K out of the sarcolemma.
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Explain the steps of excitation-contraction coupling:
1) a wave of action potential spreads from the motor end plate in all directions to the t-tubules, which are linked to Ca channels in the terminal cisternea of the sarcoplasmic reticulum.
2) Ca channels open in the sarcoplasmic reticulum (SR) and flow down the concentration gradient to the cytosol.
3) Ca binds to the troponin in the thin filament (actin). The troponin-tropomyosin complex changes shape, exposing the active sites on the actin filaments.
4) ATP initiates contraction by binding to myosin head. Myosin ATPase hydrolyzes aTP into ADP and phosphate, releasing the energy needed to cock it's head forming a cross bridge.
5) Myosin releases the ADP and P, and flexes into a bent position, tugging (power stroke) the thin filament along.
6) APT binds to the myosin, breaking the cross bridge, and repeating the process.
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abducotrs
away from the midline.
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adductors
toward the midline.
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______ are the filaments of myofibrils
Myofilaments
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the agonist or antagonist apposes the prime mover
antagonist
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another name for prime mover is
agonist. Initiates movement
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the ____ helps the agonist
synergist
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adbuctors move away or toward the midline
away from the midline.
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adductors move away or toward the midline
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____ is a functional unit of a muscle fiber
sarcomere (from z-disc to z-disc).
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2 muscle fiber typles
- type 1: oxidative (slow) (endurance)
- type 2: glycolytic (fast). IIA & IIB. (power athletes)
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protein that functions as a muscle spring
titin.
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synapse between a nerve fiber and muscle fiber: also called a motor end plate
neuromuscular junction
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motion that moves the leg back
extension
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motion that moves leg forward
flexion
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occurring on the same side
ipsillateral
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occurring on the opposite side
contralateral
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moving medial foot up
inversion
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moving later part of foot up
eversion
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moving toes up
dorsiflexation
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moving toes down
plantarflexion
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4 strategies to regain balance
- 1) ankle strategy
- 2) hip strategy
- 3) step strategy
- 4( suspensory strategy.
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ankle strategy, forward sway.
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ankle strategy, backward sway.
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hip strategy, forward sway
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hip strategy, backward sway.
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process of walking is called the
gait cycle.
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Name each graph of joint angle during gait
Hip, knee, ankle
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list steps in gait cycle
- 1) heel strike
- 2) foot flat
- 3) midstance
- 4) heel off
- 5) toe off
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