Functional organization of the autonomic nervous system Receptor → Afferent neuron → center → efferent neuron → effector organ. Reflex Arc is the pathway of reflex action. Autonomic reflex action: concerned with reflexes of internal organs or viscera such as gastrointestinal tract, urinary bladder … etc.Somatic reflex action: when the responding tissue is the skeletal muscle.It is an unavoidable beneficial inborn response brought about by a stimulus (a sudden change of the external or internal environment. Autonomic motor neurons: involves two neurons in the efferent pathway: preganglionic and post-ganglionic neurons with autonomic ganglia in between.It is a thick myelinated type Aα fiber with fast conduction of about 100m/sec. Somatic motor neurons have their cell bodies within the CNS (anterior horn cell) and send axons to skeletal muscles, which are usually under voluntary control.There are two major categories of motor neurons: The unit structure of the nervous system is the nerve cell (neuron). Neurons of the peripheral nervous system (PNS) that conduct impulses away from the central nervous system (CNS) are known as the motor or efferent neurons. functions of the heart, glands, and viscera. The autonomic nervous system is divided into the sympathetic and parasympathetic nervous system and controls the action of the internal organs and glands. The somatic nervous system controls the voluntary movements of the skeletal muscle.
It includes cranial and spinal nerves, the peripheral nervous system is either somatic or autonomic. (there is no cytoplasmic continuity between neurons). the site of contact between the axon terminals of one neuron and the cell body or dendrites of another neuron. Synapse is the site of contact between 2 neurons i.e. The connection between neurons inside the CNS is called a synapse. Ventral (efferent motor) root: Fibers of which originate in the ventral horn and travel to the periphery where they form synapses with skeletal muscles.the cell bodies of these afferent fibers are located outside the spinal cord in clusters called dorsal root ganglia. Dorsal (afferent sensory) root: fibers of which originate in the periphery from sensory receptors and terminate in the dorsal horn.Each spinal nerve arises from the spinal cord by 2 roots: The spinal cord is divided into 31 segments with a pair of spinal nerves arising from each segment.
These groups of fibers run longitudinally through the cord, some descending to relay information from the brain to the spinal cord, others ascending to transmit information to the cortex. In cross-section, the spinal cord shows a central butterfly-shaped area of grey matter with 3 projections called horns: dorsal, lateral, and ventral, The grey matter is surrounded by white matter, which consists of groups of myelinated axons. The major parts are the cerebrum (cerebral cortex), cerebellum, basal ganglia, brain stem (midbrain, pons, and medulla), the thalamus, and the hypothalamus. The brain consists of many parts that function as an integrated system.
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