3. Sea vegetables. Sea vegetables are rich in iodine. Iodine attaches to tyrosine (an amino acid) to form thyroxine. If you have insufficient levels of iodine, it becomes a rate-limiting step in the production of thyroid hormones and you'll inhibit your thyroid function.
Confidence votes 48. Special glia called Schwann cells form the myelin sheath which cover axons in the peripheral nervous system. The myelin sheath is actually two layers. The first layer surrounding the axon is called the myelin sheath and it is made up of the plasma membrane of the Schwann cells. The Schwann cells cytoplasm creates the second layer and is called the neurolemma. A neuron in the peripheral nervous system with a myelin sheath is called a myelinated neuron.
In between the myelin sheaths are what is called Nodes of Ranvier. So if you follow propagation of an action potential you will see that it starts with the addition of charges through the dendrites into the soma (cell body) and into the axonal hillock.he main purpose of myelin is to cover neuron â¦ cells so that it can conduct action potential more quickly. If you examine a myelinated neural axon within peripheral nervous system, you will see Schwann cells that cover the cell's axon with myelin sheaths.