Download Peripheric nervous system. Vegetative nervous system

Ministry of Health protection of the Republic of Uzbekistan
Medical Academy, Tashkent
Histology and Medical Biology Department
Subject – Histology
Theme: Peripheric nervous system.
Vegetative nervous system.
Methodic recommendation for practical classes
Tashkent - 2011
For medical-pedagogic and stomatological
faculty (Lesson № 1 - III semestre)
Theme: Peripheric nervous system.
Vegetative nervous system.
1. Histology and Medical biology department.
Facilities: histologic preparations, microscopes, atlases, slides,
computer.
2. Period – 3 hours
3. Aim:
- to know the structure and histophysiology of sensoric nerve ganglia,
structure of the nerve trunk;
- to have an idea on the vegetative nerve system;
- to know the structure of vegetative ganglia;
- to identify the mentioned above structures on histologic preparations.
Tasks
A student should know:
-
a structure of sensoric medulla ganglia;
a structure of a peripheric nerve;
central parts of vegetative nerve system;
vegetative nervous plexus;
a structure of the vegetative nerve ganglion.
A student should obtain practical skills in:
Defining on histologic specimens sensoric and vegetative nerve ganglia,
their structural elements; finding structural components of a nerve trunk;
explaining characteristic structure of nerve ganglia, describe and sketch the given
specimens.
4. Motivation.
The nervous system, both the central and peripheric ones regulates all the
vital processes in an organism and its interactions with an environment. The
peripheric nervous system unites all the peripheric nerve ganglia, trunk and
endings (terminals).
The nerve system, by its physiologic functions, is divided into somatic and
autonomic (vegetative) ones. The somatic nervous system innervates the whole
body except the inner organs, vessels and glands, which are innervated by the
autonomic one. Obtaining knowledge on the structure and histophysiology of the
peripheric nervous system is necessary for understanding coordinative functions of
nervous system, for proper diagnosting of the nervous system impairments
(diseases).
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5. Intersubject and intrasubject correlations.
Obtained knowledge may be useful in studying histology of the organ systems,
normal physiology, pathologic anatomy and physiology, therapy of nervous system
diseases, surgery and other clinic disciplines.
6. Content of the classes.
6.1 Theory. Items to be considered
1. The structure of a nerve trunk. It contains nerve fibres and layers of
connective tissue. The nerves are mostly combined (afferent and efferent fibres),
contain myelinated and unmyelinated fibers of somatic and vegetative nervous
systems. Endoneurium is a nerve fiber covered with delicate layer of loose
connective tissue containing reticular fibers and hemocapillaries. Perineurium is a
bundle of nerve fibers covered with thicker layer of connective tissue containing
small blood vessels. Epineurium is an externar cover of a nerve, made up of dense
connective tissue containing adipocytes, blood and lymphatic vessels.
The nerves reaction to injury, their regeneration.
2. Sensetive (sensory) nerve ganglia. They are located in the posterior roots
of the spinal cord and along the cranial nerves (the 5,7,8,10-th pairs).
2.1. A spinal node has a spindle-like shape, is covered with a dense connective
tissue capsule. The nerve fibers and thin layers of connective tissue with blood
vessels (endoneurium) are in its center and pseudounipolar neurons at the
peripheric zone. Every neuron is surrounded with a layer of oligodendroglia
(mantle cells and satellite ones). Thin layer of connective tissue forms it external
cover. The axon and dendrite of these neurons are myelinated and make T-shape
divergence. Their dendrites within a spinal cord nerve stretch to the periphery and
axons within the posterior radiculi enter the spinal cord. The neurons contain
acetylcholine, gastrin, glutamine acid, somatostatin, cholecistokinine, VIP.
2.2. Cranial ganglia. Their peculiar structure and difference from that of the
spinal ones.
3. Vegetative nerve system.
3.1. Central parts of the sympathetic and parasympathetic nervous system.
Centers of the sympathetic nervous system: nuclei of the lateral horns at the
thoracic and upper lumbal segments of a spinal cord; Centers of the
parasympathetic nervous system: nuclei of III, VII, IX, X pairs of cranial nerves
and vegetative centers (nuclei) of sacral segments of the spinal cord. Axons of
neurons in these nuclei constitute preganglionar fibers (cholinergic ones).
3.2. Vegetative nervous ganglia. Sympathetic ganglia are the extramural
(sympathetic trunk), paravertebral ones. Parasympathetic ganglia are found in the
walls of internal organs (intramural) such as the digestive system, heart, uterus,
gall bladder, bronchi and others. The postganglionar sympathetic fibers contain
noradrenalin mediator and parasympathetic ones – acetylcholine. Majoroty of inner
organs are innervated by both sympathetic and parasympathetic nervous systems.
3.3. The vegetative nervous ganglia structure. Multipolar neurons in groups or
scattered are covered by a connective tissue capsule. Every neuron is surrounded
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by a glial cells and basement membranes and covered by external connective tissue
layer. The intramural (parasympathetic) ganglia. They form plexus in the inner
organs. The intramural ganglia consist of three types of neurons (Dogel’s cells):
1) the first type – efferent cells are large in size, contain short dendrites, their
long axons are directed to the organs;
2) the second type – afferent cells have processes of equal length; their long
dendrites and axon form synapses with the I and III types of cells in the
neughbouring ganglia;
3) the third type are associated or intercalated cells; they connect several cells
of the I and II types within its ganglion; their axons penetrate other ganglia and
make synapses with the first type cells.
4. What is a reflex arch.
A reflex arch is a functional unit of the nervous system and consists of a
chain of neurons providing the reaction of functioning organs to the irritation of
receptors.
The somatic reflex arch consists of 3 parts:
1) a receptor link consists of pseudounipolar neurons in the sensoric spinal nodes
(ganglia);
2) an associative link contains multipolar intercalated neurons of the posterior
horn of the spinal cord;
3) an effector link – multipolar motorneurons of the spinal cord anterior horns;
their axons form neuromuscular synapses with skeletal muscles.
The vegetative reflex arch:
1) a receptor link (sensory link) consists of afferent pseudounipolar neurons in the
spinal ganglia; their dendrites form nerve endings in the inner organs and
glands;
2) an associative link is formed of multipolar neurons located in lateral horns of the
spinal cord;
3) an efferent link contains multipolar neurons of the vegetative ganglia, their
axons terminate on smooth muscles, glands and heart.
6.2 Analytic part.
Solving of the situation tasks.
1. A specimen of the spinal ganglion (node). It contains fibres entering the
spinal cord. What type of information do they transmit to the spinal cord from the
ganglion?
2. In the nodes there are large round-shaped cells with large nuclei. They are
surrounded by small cells. What cells are they?
3. What cells contain only one process which makes then the T-shape
divergence?
4. A specimen of the cross cut nerve stem demonstrates small dark circles and
white zone among them in the middle area. What structures are they?
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5. Bundles of nerve fibers surrounded with a light stria containing blood
vessels and fat cells ( adipocytes) are seen in the preparation. How do we call this
formation?
6. A preparation of the small intestine impregnated with silver. Neurons which
axons and dendrites do not differ are seen between the mascular layers. What type
of neurons are they?
7. In the intramural vegetative plexus there are seen processes of one neuron
making synapses either with dendrites or bodies of neurons in the other nodes.
What type of a neuron is it?
8. Virus infection have resulted in death of neurons of spinal ganglia. Which
link of reflex arch has failed?
9. A person was administered substances blocking the noradrenaline effect.
Indicate, please, in which parts of the vegetative nervous system was there blocked
the transmission of nerve impulses?
6.3.
The Practical part.
Micropreparations for independent self-studying.
Preparation № 1. Cross cut of the nerve stem obtained from the frog
ischiadic nerve. Processed in the osmic acid.
The preparation demonstrates cross cut nerve fibres constituting the nerve.
The nerve fiber is covered by a delicate layer of loose connective tissue –
endoneurium. The nerve fibers are united in bundles which are covered, in the
their turn, by a thin layer of loose connective tissue – perineurium. The connective
tissue covering the united in one group all fascicles, a nerve trunk, is epineurium.
It contains blood vessels and fat cells. It is necessary to find in the specimen the
cross-cut nerve bundles and sketch them. The nerve fibres look like dark circles
(spots) with light core which corresponds to axial cylinder. A dark ring around
the axis is a myelinated sheath.
Designate, please: 1) a myelinated nerve fiber; 2) an axial cylinder; 3)
myelinated sheath; 4) endoneurium; 5) perineurium; 6) blood vessels
See fig. 1 in the text of the methodic recommendation and in Almazov I.V.,
Sutulov L.S. atlas fig 269,270.
Preparation № 2. A spinal cord ganglion. Stained with Hematoxylin-eosin.
It is a longitudinal cut of a ganglion. At lower magnifications it is seen that
the capsule of ganglion is formed of dense non-oriented connective tissue. There
are visible thick dorsal root containing sensory nerve nodules and more thin
anterior radiculus containing axons of the motoric cells of the spinal cord.
Pseudounipolar neurons are located in the nodules, their processes constitute nerve
fibers of the dorsal root. The processes make T-shape division, one of which, a
dendrites is directed to the periphery and the second one – an axon, enters the
spinal cord. Pseudounipolar cells look-like round shaped ones because their
processes are not visible in the specimens if not stained specially (silver
impregnation). The cell body of each neuron is surrounded by a layer of neuroglial
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cells and collagen fibres. The neurons are located mostly at the peripheral part of a
ganglion while the central one contains predominantly nerve fibres.
Find on the preparation the pseudounipolar neurons, mantle cells and nerve
fibers. Sketch a part of nodule at higher magnification and designate: 1) a capsule;
2) pseudounipolar cells; 3) mantle cells (satellite cells); 4) collagen fibres; 5) nerve
fibres.
See fig. 2 in the text of the methodic recommendation and in Almazov I.V.,
Sutulov L.S. atlas fig. 287 А, Б.
Preparation № 3 The Auerbach intramural nerve plexus. A specimen of a
small intestine.
Silver impregnation.
The specimen demonstrates nerve ganglia connected with each other by
nerve fibres. The ganglia contains stellate neurous of dark-brown or black color
surrounded by small glial cells and nerve fibres. Light areas seen among the
ganglia represent loose connective tissue where this plexus is located.
By the morphology there are three types of neurons found in these plexus:
1) efferent neurons with long axons (Dogel type I cells) have numerous short
branched dendrites and the long axon leaving the ganglion;
2) neurons (afferent) with processes of equal length (Dogel type II cells) have
several not long processes which do not differ by morphologic signs and are not
branched;
3) associative neurons (Dogel type III cells), their processes enter the
neighbouring ganglia and terminate in the dendrites of their neurons; the
intermuscular nerve plexus (the Auerbach one) is located between the longitudinal
and circular oriented muscular layer of the gastro-interstinal organs. It is the most
large plexus out of three plexus found in these organs. It refers to the
parasympathetic nervous system.
Find, please, nerve ganglia, sketch and designate: 1) vegetative nerve
ganglion; 2) multipolar neurons; 3) nuclei of glial cells; 4) nerve fibers,
smooth muscular tissue; 5) loose connective tissue.
See fig. 4 in the text of the methodic recommendation and in Almazov I.V.,
Sutulov L.S. atlas fig. 323, 324, 325.
Preparation № 4 Solar plexus (celiac plexus) (for demonstration).
Silver impregnation.
It is the extramural vegetative plexus of the sympathetic nervous system. It
has the identic structure with that of the intramural ones.
See fig. 5, 6, 7.
Schemes and electron microphotographs for studying:
Fig. 1. A nerve trunk. Cross section. Processed in osmium acid.
Fig. 2. A spinal cord ganglion (node). Stained with Hematoxilin – eosin.
Fig. 3. Spinal cord ganglion. Light Microscopy, higher magnification.
Stained with Hematoxylin – eosin.
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Fig. 4. The Auerbach intramural vegetative muscular plexus. Silver impregnation.
Fig. 5, 6. A vegetative nerve ganglion of the solar plexus.
A scheme and light microscopy. Silver impregnation.
Fig. 7. A ganglion of the solar plexus. Micropreparation. Silver impregnation.
Fig. 8. An ultrastructure of the pseudounipolar neuron and its environments. A
scheme.
Fig. 9. Scanning electron microscopy of a peripheric nerve in cross section.
Fig. 10. The somatic and vegetative reflex arches. Nerve nodules (ganglia). A
scheme.
7. Types of checking levels of knowledge and obtained practical skills
- oral
- written
- solving the situation tasks
- checking the practice skills the ability to handle with histologic preparation
- drawing adequately the preparations in a sketch-book
8. Criteria for estimation of knowledge by current control
№
Mark
Level of knowledge
1
Advancement in %
and points
96-100 %
“5” excellent
2
91-95 %
“5” excellent
3
86-90 %
“5”
1. Answer is complete, logic knowledge is higher
the limits of the program. Practical skills are
perfect, there is ability to work creatively and can
render help to others.
2. Answer is sufficient enough, data were
obtained from various additional text-books,
practical skill is perfect, is able to give answer to
the additional questions can advocate his (her)
point of view.
3. Answer is sufficient enough, knowledge is
obtained from other publications and valid.
Practical skill is perfect. Active.
1.Answer is sufficient enough, but level of
knowledge is within the limits of the program.
Practical skills are perfect, a student is able to
explain the preparations correctly.
2.Answer is sufficient, information obtained from
various text-books, no private point of view about
the material, coped with practice fully and is able
to explain it.
3.Answer is within the limits of the material given
in the recommended text-book. Obtained full
practical skill. However, no answer to the
additional questions, he (she) could not give full
answer to additional questions, and was unable to
advocate his (her) own point of opinion.
1.Answer is sufficient and logic but within the
limits of the program. Coped with practical skill
7
4
81-85 %
“4”
5
76-80 %
“4” good
6
71-75%
7
66-70 %
“3” satisfactory
7
66-70 %
“3” satisfactory
fully. No sufficient answer to the additional
questions and mistaken but sometimes is
inaccurate.
2.Answer is full but sometimes is not accurate or
mistaken. Knowledge is obtained from text-books
and partially from other sources. Practical skill is
complete.
3.Answer is full, practical skill is complete but
answer to the additional questions was not full.
Mental outlook is not broad enough.
1.Answer within the limits of the program.
Practical skill is not perfect enough. There are
some mistakes in answering to the additional
questions
2.Answer is sufficient within the limits of the
program. Practical skills are perfect. No full
answer to the additional questions, there are some
mistakes
3. Answer is sufficient within the limits of the
program. Practical skills are perfect. No answer to
the additional questions.
1.Answer is within the limits of the program,
practical skill is partially insufficient. Answer to
the additional questions is fragmentary there are
some mistakes.
2.Answer is sufficient, practical skill is partially
correct, there are some mistakes. Answer to the
additional questions is fragmentary, there are
some mistakes.
3.Answer is correct, but not complete. Practical
skill is not sufficient. No complete answer to the
additional questions.
1.Answer is not sufficient enough. Practical skill
is not complete enough. There are mistakes is
answering to the additional questions.
2.Answer is in the limits of the program. There
are mistakes in practical skill. Answer to the
additional questions is fragmentary and there are
mistakes.
3.Answer is in the limits of the program, but
fragmentary. Practical skill is not full enough,
there are mistakes. Answer to the additional
questions is almost not correct.
1.Answer is correct, obtained practical skill is
mastered partially, cannot answer to the
additional questions, a narrow-minded person.
2.Knowledge of the program makes up 70% of
the total volume. Practical skill is not complete.
Answer to the additional questions is almost
absent, there are many mistakes.
3.Knowledge of the program makes up 60%
practical skill is completely mastered.
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8
61-65 %
“3” satisfactory
9
55-60 %
“3”
satisfactory
10
54%
“2”
unsatisfactory
Fragmentary answer is given to the additional
questions, a moderate active person.
1.Knowledge of the program makes up 60%.
Experienced in practical skill. No answer to the
additional questions.
2.Knowledge of the program makes up 60%.
Experienced partially in practical there are
mistakes in answering to the additional questions.
3.Knowledge of the program makes up about
50%. Practical skill is mastered. Almost no
answer to the additional questions.
1.Theory and practical skills make up 50%, there
are mistakes, Almost no answer to the additional
questions.
2.Knowledge of the program makes up about
50%. Practical skill also makes up 50%. No
answer to the additional questions, activity is
moderate.
3.Knowledge of the program makes up 40%.
Practical skill makes up 80%. No answer to the
additional questions.
1.Correct answer makes up 20-30%, no exact
answers of the theoretic material, practical skill is
mastered partially. No answer to the additional
questions.
2.No answer to the theory, practical skill is
obtained. No answer to the additional questions.
9. Chronologic schedule of class hours
№ Steps of the studies
1
2
3
4
5
6
7
Introduction
Discussion of the theme of the lesson
studies and estimation of the initial
knowledge by students.
Summary of the discussion
Explanation by the given preparations,
electron micrographs, schemes and
drawings
Obtaining practical skills independently
Checking the level of the acquired
theoretic knowledge and practical skills
obtained at the practical classes,
estimation the students activity
Conclusion made by a tutor. Estimation of
the students knowledge according to 100
points system and announcement of the
results. Giving home task for the next
lesson
Kind of activity
Interrogatory
(inquest) explanation
Lasting period
135 min
5 min
30
5
20
Studying of electron
micrographs, schemes
Control implemented
of the obtained
practical skills
55
Information questions
for the self dependent
study
10
10
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10. Questions for Control:
1. Morphologic characteristics of the nerve system development.
2. Structure and function of a reflex arch, its variants.
3. The spinal cord nuclei and their contacts.
4. What structures form the peripheric nerve system.
5. The morpho-functional peculiarity of the neurons in the spinal cord ganglia.
6. Where are directed the axons of the spinal cord ganglia to and what do the form?
7. Indicate the structural components of a spinal cord ganglion.
8. Where are directed the dendrites of neurons of the spinal cord ganglia and what
structures do they form?
9. The sources of spinal and vegetative nerve ganglia origination.
10. Where are the sympathetic nerve system centers located?
11. Where are the parasympathetic nerve system centers located?
12. What differs the peripheric parts of sympathetic nerve system from that of the
parasympathetic ones?
13. A structure of the vegetative ganglion?
14. What types of neurons are there found in the vegetative ganglia?
15. The vegetative nerve system reflex arch, its neurons.
16. What is the difference in the structures and functions of somatic and vegetative
reflex arches?
17. Morphology of a nerve trunk.
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