NERVOUS SYSTEM. Prof. Dr. Sc.agr. Ir. Suyadi, MS. Nervous System = Systema Nervorum. A complex mechanism by which the organism is brought into functional relation with its environment, and its various parts are coordinated. Parts of the nervous system. Central Nervous System (CNS) :
Prof. Dr. Sc.agr. Ir. Suyadi, MS.
The nervous system is divided into the
The PNS consists of:
The CNS consists of:
The peripheral nervous system is subdivided into :
The Sensory-Somatic Nervous System
*Note: These do contain a few sensory neurons that bring back signals from the muscle spindles in the muscles they control.
A neuron is a cell specialized to conduct electrochemical impulses called nerve impulses or action potentials.
The Spinal Nerves
The autonomic nervous system consists of sensory neurons and motor neurons that run between the central nervous system (especially the hypothalamus and medulla oblongata) and various internal organs such as the:
It is responsible for monitoring conditions in the internal environment and bringing about appropriate changes in them. The contraction of both smooth muscle and cardiac muscle is controlled by motor neurons of the autonomic system.
The actions of the autonomic nervous system are largely involuntary (in contrast to those of the sensory-somatic system). It also differs from the sensory-somatic system is using two groups of motor neurons to stimulate the effectors instead of one.
The autonomic nervous system has two subdivisions,
The preganglionic neuron may do one of three things in the sympathetic ganglion:
Perception of work
The main structure of a neuron is the cell body, the dendrite (receives signals) and the axon (sends signals). Signals are sent to and from the central nervous system via action potentials (ion channels) which allow signals to travel by changing the concentration of ions (sodium outside, and potassium inside) within the axons and dendrites.