bicarbonates, nutrients and oxygen for the cell; and carbon dioxide and metabolic wastes released by the neuronal cells. The ECF and ICF (cytosol) contains negatively charged particles (anions) and positively charged particles (cations). These charged particles are involved in the conduction of impulses. The neurons maintain an uneven distribution of various inorganic ions Note: The charged particles have potential energy.
The potential dif- ference is the measure of potential energy between two points which is measured in volts or millivolts. Cell body Cell body Cell body Dendrites Dendrites Trigger zone Trigger zone Trigger zone Dendrites Axon Axon Axon Myelin sheath Myelin sheath Myelin sheath Axon terminal Axon terminal Axon terminal Figure . . Types of Neurons XI Std Biology-Zoology Chapter- Na + influx into the cell.
When the axon is not conducting any impulses i.e. in resting condition, the axon membrane is more permeable to K + and less permeable to Na + ions, whereas it remains impermeable to negatively charged protein ions. Table: . Ionic Channels in the Axolemma Leakage Channels are ionic channels that remain open all the time K + leakage channels are more in number than the Na + leakage channels.
Sarcolemma has greater permeability to K + ions than Na + ions. These ions keep moving continuosly maintain the potential difference across the axolemma. Ligand-gated Channels are chemically gated channels which open or close in response to a chemical stimuli. They are located between the presynaptic membrane of the first axon and post synaptic membrane of the cell body of second neuron [i.e.
dendrites and cell bodies ]. The neurotransmitter acetylcholine opens ligand channels that allow Na + and Ca ++ ions diffuse inward and K + ions diffuse outward. Voltage-gated Channels are mechanically gated channels which open in response to a physical stimulus in the form of vibration such as touch and pressure. These channels open in response to a change in membrane potential.
There are two types of voltage-gated channels. i. Sodium voltage-gated channel ii. Potassium voltage-gated channel The axoplasm contains high concentration of K + and negatively charged