Concept About Autonomic Nerves System
Regulation of body function:
1- Endocrine system: sends signals to target tissues by blood-borne hormones.
2- Nervous system: send signals to target tissues by transmission of electrical impulses over nerve fibers.
Nervous system contains from two type:
1- Central nervous system: includes the brain and spinal cord.
2- Peripheral nervous system: includes neurone located outside the brain and spinal cord.
Peripheral nervous system consists of two division:
1-Efferent division: neurons carry signals from the brain and spinal cord to the peripheral tissues.
2-Afferent division: neurons carry signals from the peripheral tissues to the brain and spinal cord.
Efferent division is consists of two parts:
1- Preganglionic neurons: the cell body originating in the central nerveos system and make a synaptic connection in a ganglia.
2-Postganglionic neurons: the cell body originating in the ganglia and terminates on effector organ.
Ganglia
is a synaptic connection of aggregation of nerve cell body located in the peripheral nervous system, and it is function as rely station between a preganglionic neuron and postganglionic neuron.
Synaptic cleft
is a space that separates two neurons, and it is form a junction between two or more neuron and help nerve impulse pass from one neuron to the other neuron.
Efferent division contains two systems:
1- Autonomic system: neurons originating in the central nervous system and terminate indirectly to involuntary muscle with the mediation of ganglia.
2-Somatic system: neurons originating in the central nervous system and terminate directly to muscle without the mediation of ganglia.
Autonomic nervous system ( neurons are contains lightly myelinated ) and somatic nervous system ( neurons are contains heavily myelinated)