Anatomy-Lexicon

Tasks of the parasympathetic nervous system

Synonyms in a broader sense

Parasympathetic, sympathetic, nervous system, brain, nerve water, spinal cord, nerve

Parasympathetic tasks

In addition to the sympathetic nervous system, the parasympathetic nervous system is part of the autonomic nervous system and is responsible for physical activity under resting conditions. Consequently, the sympathetic nervous system is characterized as the active part of the autonomic nervous system.

Parasympathetic tasks on the organ

Organ effect

heart Slower and less vigorous beating (decreased heart rate and contractility)

lung Narrowing of the airways

eye Constriction of the pupil

Salivary glands Increased secretion of saliva

Gastrointestinal tract Increased digestive activity (increased motility)

liver Increased glycogen production

bladder Promotion of the urge to urinate and urination

Tasks of the parasympathetic nervous system

1. Presynapse 2. Synaptic cleft 3. Postsynapse

The task of the parasympathetic nervous system, which is ultimately achieved on the organ, must be generated in "encrypted" form by the original cell and then passed along the cell processes to the organs.
The electrical stimuli are passed on via so-called neurotransmitters.

Neurotransmitters are chemical messengers that - as the name suggests - can transmit information to different places, so they are a kind of "delivery boy". A distinction is made between exciting (excitatory) and inhibitory (inhibiting) Neurotransmitters.

The neurotransmitters are used for chemical Transmission of information, while the electrical potentials are generated by the cell and its extensions (Axons and Dendrites) run that electrical Serve to forward information. The transmission of chemical information is always important when information is to pass from one cell to the next, because between cells there is always a gap, albeit a tiny one, which the information cannot easily jump over. However, since the human body is large, it takes a whole network of Cells, because one cell cannot span our entire organism (even if it is Neurons whose appendages can be up to a meter long).

Once the electrical line has reached the “end” of a cell, i.e. its axon end, it ensures that the axon end becomes a type of Neurotransmitters is released. The axon end from which it is poured is called Presynapse (pre = before, i.e. the synapse before synpathetic gap). The neurotransmitter is released into the so-called synaptic gap, which lies between cell 1 (information line) and cell 2 (information reception), between which it is to be switched. After its release "migrates" (diffused) the neurotransmitter through the synaptic gap to the extension of the second cell, the postsynapse (post = after, i.e. the synapse after the synaptic gap). This contains receptors that are precisely designed for this neurotransmitter. So he can bind to it. Due to its binding, an electrical potential is now generated again at the second cell.

When the information is switched from one cell to the next, the order of the information types is consequently:

electric to the axon end of the first cell
chemically in the synaptic cleft
electric from the binding of the neurotransmitter to the second cell

By binding the neurotransmitter, cell 2 can now react in two ways: Either it will excited and creates a so-called Action potential or it will inhibited and the likelihood that it will generate an action potential and thus excite more cells decreases. Which of the two paths a cell takes is determined by the type of neurotransmitter and the type of receptor.

Both in the sympathetic and in the parasympathetic system there is a strict sequence of information forwarding:

Cell of origin (Cell 1)
Cell in a ganglion/ Plexus / in the organ wall (cell 2)
organ

Example of a parasympathetic task

The first cell (Cell of origin) in the skull (cranial part of the parasympathetic nervous system) or in the lower Spinal cord (sacral parasympathetic component) is excited from higher centers (e.g. the Hypothalamus and the Brain stem). The excitation continues through her entire axon up to the first switching point. In the parasympathetic system, this is either in one Nerve nodes (ganglion), in one Nerve plexus (Plexus) or directly in the wall of the organ to be influenced. There, as a result of the transmitted excitation, the neurotransmitter Acetylcholine released from the presynapse. Acetylcholine diffuses through the synaptic cleft to the synapse of the second cell (Postsynapse) and binds to a suitable receptor there. This bond excites the cell (because acetylcholine is one of the most exciting Neurotransmitters). Exactly as in the first cell, this excitation is passed on again via the cell and its appendages to the recipient: the organ. There - as a result of the excitement - another neurotransmitter - this time it is acetylcholine - is released from the synapse of cell 2. This neurotransmitter then acts directly on the organ.