The ANS is divided into the sympathetic and parasympathetic departments, which to a certain extent are antagonists

So, with stimulation of the sympathetic division of the ANS, there is:

- an increase in the frequency and strength of heart contractions;

- increase in blood pressure;

- dilation of the pupils, bronchi;

- decrease in intestinal tone;

- increase adaptive-trophic potency of organ tissues.

In general, with irritation of the sympathetic division of the ANS, the body mobilizes forces to overcome some opposition and to fight.

When stimulating the parasympathetic division of the ANS, there i s:

- a decrease in the strength and frequency of contractions of the heart;

- decrease in blood pressure;

- intestinal motility increases, etc., i.e. the body comes to rest.

In the ANS the central and peripheral parts are distinguished.

The central part of the sympathetic nervous system is represented by the lateral nucleus of the lateral horns of the spinal cord in the thoracic and lumbar region, and the central section of the parasympathetic nervous system is represented by the vegetative nuclei of III, VII, IX and X pairs of cranial nerves in the middle and medulla oblongata, the lateral nucleus of the lateral horns of the spinal cord sacral department.

The peripheral department is represented by ganglia!

The peripheral ganglia of the ANS lie both outside the innervated ganglia (this is the para- and revertebral ganglia), and in the wall of the innervated organs are the intramural plexuses in the wall of the digestive tube, heart, uterus, etc.).

The reflex arc in the ANS begins with a sensitive autonomic neuron (pseudo-unipolar), whose body lies in the spinal node. These neurocytes transmit impulses from innervated organs to the nuclei of the central part of the ANS, i.e. form the afferent link of the reflex arc.

The efferent link (from the center to the working body) in the ANS is always two-neural:

The 1st neuron lies in the above central nuclei of the ANS, the axon of this 1st neuron forms a preganglionic fiber (usually myelin) and terminates in the cholinergic synapse in one of the peripheral vegetative ganglia.

The bodies of 2 neurons lie in the peripheral ganglia of the ANS of the efferent link of the reflex arc. According to morphology, these are multipolar neurocytes of different sizes and shapes. The axons of these cells form postganglionic fibers (usually be myelin-free) and end in the working organ with terminal effector devices.

The second neurons of the efferent link in the sympathetic division are adrenergic, and in the parasympathetic division are cholinergic.

In the peripheral ganglia of the ANS, in addition to the bodies of the second neurons of the efferent link of the reflex arc, there are:

- MIF cells (small intensely fluorescent cells) are inhibitory neurocytes in the peripheral ganglia of the sympathetic division;

- peptidergic neurocytes, produce hormones VIP and somatostatin;

- Neurocytes of the local reflex arc (receptor, associative, motor, inhibitory).

Intramural ganglia are composed of Dogel cells:

1. Receptor neurocytes (Dogel type II cells) - these are equally spaced neurocytes. 2-4 shoots depart from the body, among which it is difficult to differentiate the axon. The processes without branching far away from the body: dendrites in the innervated organ form sensitive endings, and axons end with synapses on the bodies of motor and associative neurocytes of neighboring ganglia. Dogel cells of type II are afferent (sensitive) neurocytes of local reflex arcs.

2. Motor neurocytes (Dogel type I cells) - have short dendrites with lamellar extensions (receptor sites). Dendrites do not leave the ganglion; they receive impulses from receptor and associative neurocytes. The axons of motor neurocytes are very long, leave the ganglion as part of postganglionic myelin-free fibers and end with motor plaques on smooth muscle cells of internal organs.

3. Associative neurocytes (Dogel type III cells) - are similar in morphology to Dogel type II cells, but their dendrites do not go beyond the ganglion and form synapses with axons of sensitive neurocytes, and axons transmit impulses to motor neurocytes of neighboring ganglia.