The voltage-gated sodium channel Voltage-gated channels of the Cell Membrane There are two separate and specific voltage-gated channels, one for Na+ and the other for the K+. The principle operator of the stages of action potential ie. causing the depolarization and repolarization of the membrane is the so called voltage-gated Sodium channel. However, the voltage-gated potassium […]
Action potential of Nerve and Muscle fibers The action potentials are the rapid changes in the resting membrane potential. Nerve signals are transmitted by action potentials. Each action potential begins with a sudden change from the normal resting negative potential to a positive potential, and ends with an equally rapid change back again to normal
Resting potentials of nerve and muscle Fibers In the resting state of membrane i.e. the state under which the membrane of the nerve or muscle fibers is not transmitting signals, the fluid inside the nerve or muscle cells has greater concentration of K+ and the fluid outside the Na+. The potential across the membrane is a
Principles of membrane potential Basic Physics of Membrane potential In the tissue the fluid outside (interstitial fluid) and inside (intracellular fluid) are electrolytic solutions, containing 150 to 160 mEq / litre of positive ions (cations) and the same concentration of negative ions (anions). Generally a very small excess of negative ions accumulate immediately inside the cell
Properties of nerve fibers Stimulus Nerve fibers have ability of nerve fibre to respond to stimulus. It is an external agent that brings about visual response. It can be also be from within and can elicit response which can not be visualized. Types of stimulus Electrical: this is the most common stimulus to bring about neuronal
Classification of Nerve fibers Nerve fibers are classified as Type A, Type B and Type C fibers based on the diameter, myelination and propagation speed. According to the diameter of the fiber, a physiological property of nerve fiber varies. As diameter increases, the conduction velocity increases which requires lower threshold of excitation with greater magnitude of response. Time of
Nerve fibers Nerve fibres are axons of neurons which can be either insulated or naked. Insulation is provided by sheaths which may be either myelin sheath of lipoid layer or thin tubular covering of neurilemma or schwann sheath. The nerve fibres with myelin sheath are known as myelinated and those without myelin sheath are known as unmyelinated fibres. Myelinated fibres
Supporting cells of nervous system Supportive cells of CNS are known as Glial cells or Neuroglia. Neuroglia is a special type of interstitial tissue which provides nourishment to the neurons. Glial cells serve as a connective tissue of the CNS and provide support the neurons, both physiologically and metabolically. They constitute 90% of cellular population, and
Classification of neurons Anatomical classification According to the number of processes that arise during embryological development. All developing neuroblast pass the stages where processes are formed. Apolar neuron There are no processes present in apolar types of neurons. Unipolar neuron They have a simple processes developing from soma. This process may split into two, one
Neurons Neurons are basic building blocks for communicating information using both chemical and electrical signals. Neurons are designed with specialized properties to receive process and transmit the information. Neurons like any cell have a cell membrane boundary, cellular organelles and extensions which perform conduction of information and reception. Cell membrane is electrically excitable. Neuronal shape and
