Metasympathetic nervous system (MNS)

It governs such structures as:

1) smooth muscles;

2) epithelium absorbing:

3) epithelium secreting;

4) local circulation;

5) local endocrine elements;

6) local immune elements.

MNS is a complex of microrganglionar structures located in walls of inner organs possessing motor activity or automaty (stomach, intestine, urinary vesicle, heart, bronchi, uterus particularly uterus cervix). Intestine and heart MNS are studied the best.

Example: there are nervous plexuses in alimentary tract:

· subserosal;

· intermuscular (of Auerbah);

· submucosal (of Meisner).

There are multiplied microganglii in every plexus. 3 types are differentiated in every microganglion:

· efferent – the axon of which is in direct contact with myocyte;

· afferent – their axons can be switched to efferent axons either axon can pass to paravertebral or prevertebral ganglii with switching to other neurons; also axons of these afferent neurons can come up to spine and to be swithed here to other neurons; thus, afferent impulsation coming from microganglii can be closed at different levels;

· associative neurons.

The similar picture is a characteristic of heart too.

MNS functions:

1) central influencings transmittance – due to the fact that parasympathetic and sympathetic fibers can get into contact with metasympathetic system and thus make the correction of its influence on the management objects;

2) MNS can also perform role of separate and integrating structure id est there are ready reflectory arcs (afferent – associative – efferent neurons) in it.

There are term as “tone of VNS”: hypersympaticotony and hyperparasympaticotony.

 

Materials for auditory self-work.

4.1.List of study practical tasks necessary to perform at the practical class.

 

Materials and methods: bed, scale.

Investigation object: person.

 

Task 1. To perform pupils investigation

Pupils investigation better to carry out at day dispersed light of middle force. The investigated person sits on a chair with the face turned to the window, turns his head behind to the chair back and looks into ceiling (pupils are seen distinguishly). To mark pupils size and equality. To close one investigated person eye with hand (or scale) and to pay the attention to convergent size change and equality of other eye pupil, then to open it. To mark pupil reaction, to assess this reaction: alive, middle or weak.

Under norm at bright lighting the pupil is narrowed. In dark room, on the contrary, pupils are dilated. Dilated pupil’s state is called midriasis. The constant narrowing state – miosis.

 

Task 2. Reflex to eyes convergence

To determine investigated person pulse while his sitting for 15 seconds. Then the investigated person converges eyeballs axes for 15 seconds. After this it‘s necessary to determine pulse again. To make the conclusion.

 

Task 3. Vasomotor skin functions investigation

The investigated person rises one hand up (maximally) with divergent extensed fingers, other puts down for 30 sec. It is necessary to determine skin colour difference. Then the investigated person stretches both hands before himself for 30 seconds.

Under normal conditions hands colour must become equal in course of this time. At vegetative disfunction the skin colour leveling are retarded or becomes zyanotic for long, hand putted down or raised up becomes pale for 1 or more minutes.

Task 4. Dermographism

There exist 2 main dermographism types: white and red.

White dermographism is caused by light stroke skin irritation with acute subject. Under norm after 5-20 sec one can see white stripe (width - several millimeters), that disappears after 1-10 min.

If stroke irritation is performed stronger and slower, red stripe appears, that continues longer (for 1-1,5 min), sometimes even for 1-2 hours - red dermographism. It is necessary to pay the attention to oedema existance or absence (jugum, elevation).

At dermographism investigation you should mark:

· its character (white, red, mixed), 

· stripe width,

· reaction duration.

When analyse you should take into account that red dermographism is maximally expressed on skin in upper body part, white one – on lower extremities.

On one’s face they can use another way - white spot (stain) probe- finger pressure to skin in course of 3 sec leads to white spot appearing for 2-3 sec. Doctor should remember that at hypersympathicotony white spot disappears slower.

 

Task 5. Erben’s reflex

To count investigated person’s pulse for 1 min while his staying. Then the investigated person must be turned forward or to squat down and to turn his head till chin touching with knees. Then counting pulse again for 1 min should be performed.

In healthy people pulse is retarded on 4-12 beats per minute. At hyperparasympathicotony pulse is very seldom; at hypersympathicotony - very quick.

 

Task 6. Abrams’ reflex

The investigated person lying on his back is trying to take his chin to his breastbone, but doctor impedes.

Under norm pulse is retarded more than on 12 per minute. It indicates to hyperparasympathicotony and is thought to be positive probe.

2. Literature recommended:

1. Lecture course.

2. Mistchenko V.P., Tkachenko E.V. Methodical instructions for dental students (short lecture course).-Poltava, 2005.-P. 13-17.

3. Mistchenko V.P., Tkachenko E.V. Methodical instructions for medical students (short lecture course).-Poltava, 2005.-P. 19-21.

4. Mistchenko V.P., Tkachenko E.V. Methodical instructions on Normal Physiology on practical classes for dental and medical students.-Poltava, 2005.-P. 53-55.

5. Ganong W.F. Review of Medical Physiology.-21^st ed.-2003.-Section II.

6. Kapit W., Macey R.I., Meisami E. The Physiology Colouring Book: Harpers Collins Publishers, 1987.-P. 25.

7. Guyton – Ganong – Chatterjee. Concise Physiology /Ed. By Dr Raja Shahzad Gull: M.B.B.S., F.C.P.S., King Edward Medical College.-Lahore, 1998 (1^st Edition).-P.315-320.

8. Guyton A.C. Textbook of Medical Physiology.-NY, 1992.-P.686-698.

3. Materials for self-control:

A. Control questions:

1. Vegetative nerves structural features:

· autonomic nervous system centres;

· ganglions;

· synapses cholino- andrenoreceptive structures.

2. Autonomic nervous system functional features:

· vegetative innervation comparative characteristics;

· vegetative reflexes;

· autonomic nervous system influence on salivation.

3. Autonomic nervous system and behaviour reactions.