Xenotransplantation

Discuss how an action potential is transmitted along a membrane.

The action potential can be defined as “A momentary change in electrical potential on the surface of a neuron or muscle cell. These action potentials occur in excitable cells such as muscle cells, neurons and in the endocrine cells. More specifically it occurs in the neuron as a nerve impulse. They either stimulate a change in polarity in another neuron or cause a muscle cell to contract.” The action potential is a stimulus that occurs in the nodes of Ranvier of the neuron. The action potential occurs when the cell is actively transmitting information from the cell body down the axon to the axon terminal. This process occurs in steps with the sodium and potassium pumps within the cell membrane playing vital roles in the transmission of the electrical charge as well as polarization and depolarization.

The "typical" neuron has four distinct parts (or regions). The first part is the cell body (or soma). This is not only the metabolic "control center" of the neuron, it is also the "manufacturing and recycling plant." (the neuronal proteins are synthesized within the cell body.) The second and third parts are processes, structures that extend away from the cell body. The function of a process is to be a conduit through which signals flow to or away from the cell body. Incoming signals from other neurons are (typically) received through its dendrites. The outgoing signal to other neurons flows along its axon. A neuron may have many thousands of dendrites, but it only has one axon. The fourth distinct part of a neuron lies at the end of the axon, the axon terminals. These are the structures that contain neurotransmitters. Neurotransmitters are the chemical medium through which signals flow from one neuron to the next at chemical synapses.

Firstly, the neuron is said to be polarized as potassium ions are found on the inside and sodium ions are found on the outside. As such it can be said that the...