Pretest-posttest designs grew from the simpler posttest only designs, and address some of the issues arising with assignment bias and the allocation of participants to groups. One example is education, where researchers want to monitor the effect of a new teaching method upon groups of children.
The neuromuscular junction (NMJ) is the site of communication between motor nerve axons and muscle fibres.It is composed of four specialised cell types: motor neurons, Schwann cells, muscle fibres and the recently discovered kranocytes.he neuromuscular junction (NMJ) is the site of communication between motor nerve axons and muscle fibres.
Basically, acetylcholine is the neurotransmitter or chemical messenger that the nerve cell uses to communicate with the muscle cell. The result of this communication is electrical excitation of the muscle cell, what we call an action potential.The action potential of the muscle cell activates that muscle and causes the muscle cell to contract or shorten.he result of this communication is electrical excitation of the muscle cell, what we call an action potential. The action potential of the muscle cell activates that muscle and causes the muscle cell to contract or shorten.