Stimulation of Skeletal Muscle Fibers 1. This synapse is also called a n___ m___ j___. The type of motor neuron involved belongs to the branch of the peripheral nervous system called the ___ nervous system. The region of the muscle fiber's plasma membrane, or s___, that receives messages sent by the motor neuron is called the m___ e___ plate. This region of the membrane is capable of receiving messages from the motor neuron because it is lined with membrane proteins which act as r___s for neurotransmitters. This region is also different than other parts of the membrane in that it is highly folded. This folding serves to increase the s___ a___ of this region, and therefore maximize the number of these membrane proteins. This, in turn, helps make the communication between neuron and muscle fiber more effective. When an electric signal called an a___ p___ propagates to the end of a motor neuron's axon, or pre-s___ t___, this stimulates the opening of gated calcium channels. Since these channels respond to a change in membrane potential, they are a type of v___-gated ion channels. When these channels open, calcium ions from the e___ fluid move to the i___ fluid. These ions move in this direction when these channels open because their concentration is higher in the ___ fluid in comparison to that in the ___ fluid. Since these ions cross the plasma membrane of the neuron with the aid of a protein transporter that does not require ATP, this type of transport is classified as f___ d___. 3. Calcium ions stimulate the migration of s___ v___ towards the membrane of the synaptic terminal. These vesicles contain the neurotransmitter ___. Therefore, the motor neurons that communicate with skeletal muscle fibers are classified as c___ c___. 4. Once the vesicles merge with the plasma membrane, the neurotransmitter molecules they contain are released via e___ into the space that separates the motor neuron from the muscle fiber, called the s___ c___. The neurotransmitters then move away from their point of release via s___ d___, moving down their concentration gradients towards the motor end plate. 5. Since the neurotransmitter receptors on the motor end plate bind to the neurotransmitter a___, the synapses between motor neurons and skeletal muscle fibers are classified as c___ c___. These receptor proteins have built-in ion channels. When neurotransmitters bind to these receptor proteins, the gate of the ion channel portion of the receptor opens up, letting the ion flow across the membrane. This ion moves from the ___ fluid to the s___ fluid.
