Download Methodological Instruction to Practical Lesson № 21

MINISTRY OF PUBLIC HEALTH OF UKRAINE
BUKOVINIAN STATE MEDICAL UNIVERSITY
Approval on methodological meeting
of the department of pathophisiology
Protocol №
Chief of department of the pathophysiology,
professor
Yu.Ye.Rohovyy
“___” ___________ 2008 year.
Methodological Instruction
to Practical Lesson
Мodule 2 : PATHOPHYSIOLOGY OF THE ORGANS AND SYSTEMS.
Contenting module 7. Pathophysiology of endocrine and nerve systems.
Theme 21: PATHOPHYSIOLOGY OF THE NERVOUS SYSTEM.
Chernivtsi – 2008
1.Actuality of the theme.
The nervous system as a main regulatory system of an organism in this or
that measure participates in pathogenesis of each diseases. The earliest and
obligatory form of participation of the nervous system in pathology is defensive
and adaptive the response. The protective reflexes (cough, vomiting), protective
inhibition, response hypotalamo-hypophysial-adrenal system belong to such
responses. At the same time during development of diseases the nervous system
becomes the object of a defeat itself. It is defensive and adaptive the response of
the damaged nervous system are reduced, and it becomes a source of pathological,
harmful to an organism reflexes. Itself graving and character of violations of
nervous activity depend on localization of pathological process and appear as a
complex of diverse symptoms. Frequently there is a pain, which on the essence is
typical pathological process, but at the same time has signal and adaptive
significance. The disturbance of nervous activity is always reflected in the function
of internal organs. The fundamental knowledges of the reasons and mechanisms of
disorders motor, sensitive and trophic functions of the nervous system are
necessary for understanding of pathogenesis nervous diseases, and also many
symptoms of a damage of internal organs.
2. Length of the employment – 2 hours.
3. Aim:
To khow pathogenesis of neurogenic dystrophy, pathogenesis of the
neurosis.
To be able:
To analyse the causes and universal mechanisms of disturbances in all the
nervous system functions.
To analyse the mechanisms of the formation of generators of the
pathologically intensified excitation.
To perform practical work:
To analyse the mechanisms of the pathologic pain as the changed system of
the pain sensitivity.
To analyse the characteristics of Alzheimer’s disease.
4. Basic level.
The name of the previous
disciplines
1.
histology
2.
biochemistry
3.
physiology
The receiving of the skills
Anatomic structure of the nervous system.
Functions of the nervous system.
Scheme of pyramidal and extrapiramidal pathes.
Passage of sensitive fibres in spinal cord and brain.
Mechanism of transfer of excitation in nervous
synapses.
Structure and function of the vegetative nervous
system.
5. The advices for students.
1. Identify functional subdivisions of the nervous system.
The nervous system has the next very important functions:
1. Regulating function 2. Motor 3. Sensitive 4. Secretory and trophicity
functions
2. Characterize the causes and universal mechanisms of disturbances in all
the nervous system functions.
Pathogenic influence on the nervous system may be caused by:
1. Mechanical factors (brain stem trauma)
2. Physical factors as ionizing radiation, electric current, noise, vibration, high
and low temperature, electromagnetic field.
3. Hypoxia
4. Hypoglycemia
5. Chemical and toxic substances, the so-called neurotrophic poisons
6. Disorders of electrolytes and hydrogen ions in blood
7. Starvation, especially vitamin and microelement deficiency
8. Age
9. Psychoemotional stress
All these factors selectively disturb:
1) bioenergetic processes in the nervous cells
2) formation, transportation, excretory metabolism of the neuromediators
3) permeability of ion channels in neurons
The loss of ability to maintain the definite quantity of membranous potential by
the nervous cell due to impairment of excitation transmition from one nervous cell
to another, from one part of the nervous system to another.
3. Define common terms that describe alterations in motor functions.
Movements are influenced by the cerebral cortex, the pyramidal system, and the
motor units. Dysfunction of any of these areas may cause motor disorders.
Hypotonia is a decreased muscle tone shown by passive movement of a muscle
against resistance. It is thought to be due to decreased muscle spindle activity
secondary to decreased excitability of neurons. Hypotonia is caused by cerebral
damage or in rare cases by pyramidal tract damage.
Hypertonia is an increased muscle tone shown by passive movement of a
muscle with resistance.
Spasticity, a type of hypertonia, results from hyperexcitability of the stretch
reflexes. Rigidity, another hypertonia, is produced by tonic reflex activity. The
involved muscles are firm and tense; the increase in muscle movement is even and
uniform throughout the range of passive motion.
Hyperkinesia is excessive movement; whereas dyskinesias are abnormal,
involuntary movements.
Hypokinesia, or decreased movement, is a loss of voluntary movement despite
consciousness and normal peripheral nerve and muscle function. Types of
hypokinesia include paresis/paralysis, akinesia, bradykinesia, and loss of
associated movement.
Hemiparesis/hemiplegia is paresis/paralysis of the upper and lower extremity
on one side. Diplegia is the paralysis of both upper and lower extremities due to
cerebral hemisphere injuries. Paraparesis/paraplegia refers to weakness/paralysis
of the lower extremities. Quadriparesis/quadriplegia refers to paresis/paralysis of
all four extremities. Both paraparesis/paraplegia and quadriparesis/quadriplegia
may be caused by dysfunction of the spinal cord.
Spinal shock is the complete cessation of spinal cord functions below the
lesion. It is characterized by complete flaccid paralysis, absence of reflexes, and
marked disturbances in bowel and bladder function. Disturbances originating in the
anterior horn cells or the motor nuclei of the cranial nerves are called
amyotrophies. Paralytic poliomyelitis is the prototype of these disorders. In the
amyotrophies, muscle strength, muscle tone, and muscle bulk are affected in the
muscles innervated by the involved motor neurons. Several brain stem syndromes
involve damage to one or more cranial nerve nuclei. These are called nuclear
palsies and may be caused by vascular occlusion, tumor, aneurysm, tuberculosis,
or hemorrhage. Bulbar palsies involve cranial nerves IX, X, and XII.
Akinesia is a decrease in associated and voluntary movements. It is related to
dysfunction of the extrapyramidal system. Pathogenesis is related to either a
deficiency of dopamine or a defect of the postsynaptic dopamine receptors.
Bradykinesia is slowness of voluntary movements.
4. Describe the pathologic pain as the changed system of the pain sensitivity
The pathologic pain conditions the development of the structural and functional
changes, and impairments in the cardio-vascular system in the inner organs, system
of microcirculation, tissue dystrophy, disturbance of the vegetative reactions,
changes in the activity of the nervous, endocrine, immune and other systems. The
pathologic pain has disadaptive and pathogenic significance for the body and is
caused by formation of generators of the pathologically intensified excitation in the
nociceptive system (Krizhanovsky I. N., 1980). Under the influence of the primary
generator (or stimulus) formed in some part of the nociceptive system, other
formations of the system of pain sensitivity are involved into the pathological
process. So, it is a pathological algic system (PAS) which is the base of the pain
syndrome.
5. Identify chemicals that modulate the pain
Tissue injury results in the release of prostaglandins, bradykinins, and histamine
that depolarize adjacent nociceptors. Lymphokines released from lymphocytes in
chronic inflammatory lesions may contribute to some chronic pain. Substance P,
neurokinin A, and calcitonin-gene-related peptide are released from peripheral
pain receptors to permit the spread of pain locally. Norepinephrine and 5hydroxytryptamine contribute to pain inhibition in the medulla and pons.
Endorphins are neuropeptides that inhibit transmission of pain impulses in the
spinal cord and brain. All endorphins attach to opiate receptors on the plasma
membrane of the afferent neuron. The combination of the opiate receptor and
endorphin inhibits the release of excitatory neurotransmitters, thereby blocking the
transmission of the painful stimulus. Stress, excessive physical exertion,
acupuncture, and their interconnection are factors that increase the level of
circulating endorphins.
6. Differentiate between acute and chronic pain.
Acute pain may be somatic, visceral, or referred. Somatic pain originales from
the skin or close to the surface of the body. Visceral pain occurs in internal
organs, the abdomen, or skeleton. It is poorly localized because of fewer mechanoreceptors in the visceral structures. It is associated with nausea and vomiting,
hypotension, restlessness, and possible shock. Visceral pain often radiates or is
referred. Referred pain is present in an area removed or distant from its point of
origin. The area of referred pain is supplied by the same spinal segment as the
actual site of injury. Impulses from many cutaneous and visceral neurons converge
on the same ascending neuron and the brain cannot distinguish between the origin
of the two.
Acute pain is a warning of actual or impending tissue injury. Physiological
responses include increased heart rate, increased inspiratory rate, elevated blood
pressure, pallor or flushing, dilated pupils, and diaphoresis. The response is
basically one of sympathetic nervous stimulation. Psychologically, individuals
often respond to acute pain with fear, anxiety, and a general sense of
unpleasantness or uneasiness. The stress of fear may subsequently contribute to the
physiologic signs of pain.
Chronic pain is prolonged; it may last longer than 6 months and may either
persist or be intermittent. Physiological responses to chronic pain depend on the
persistent or the intermittent nature of pain. Intermittent pain produces
physiological responses similar to acute pain; whereas persistent pain permits
physiological adaptation. Individuals with chronic pain often are depressed, have
difficulty sleeping and eating, and may become preoccupied with their pain.
Common chronic pain conditions include low back pain, neuralgias,
hyperesthesia, myofascial pain syndrome, hemiageusias, and phantom limb pain.
Sometimes, chronic pain is associated with cancer. Low back pain results from
poor muscular tone, inactivity, muscle strain, or sudden vigorous activity.
Neuralgias are painful conditions that result from infections or damaged
peripheral nerves. Hyperesthesias are characterized by increased sensitivity and
decreased pain threshold to tactile and painful stimuli that usually do not produce
pain. Myofascial pain syndromes are common causes of chronic pain.
7. Define the trophicity function of the nervous system and dystrophic
process.
Nervous trophicity is such an action of the nerves on the tissue which results in
metabolic changes according to the needs at each given moment. It means that the
trophic action of the nerves is connected with their other functions (sensitive,
motor, secretory) and together with them provides an optimum function of each
organ. Neurogenic dystrophy is presented as complex multifactor process, which
begins with the process in which the nervous system ceases “to control
metabolism” in the tissue, and after that there arise complex disorders of
metabolism, structure and function.
8. Discuss pathogenesis and manifestation of neurodystrophic changes
The main peculiarities of the dystrophic process is that they have no tendency to
healing. The experience has shown that the pathogenic effects on any part of the
nervous system (brain cortex, hypothalamus, motor, sensitive, secretory nerves) are
always accompanied by a change of metabolism in corresponding organ. It
concerns carbohydrates, fats, proteins, nucleic acids, etc. There are observed not
only quantitative, but also qualitative changes of the organelles of the nervous
elements. Obviously the disorder of oxidizing phosphorilation and Caaccumulating ability of mitochondria together with energetic abilities of the cell
are connected with this. The mitotic activity is reduced in the denervated tissue.
The impulse activity, the development and the action of mediators (adrenaline,
serotonin, acetylcholine, etc) cease the axonic transport of “substances of
trophicity” is disturbed or stoped; the function (motility, secretion ceases or is
perverteded. The process involves genome, the synthesis of ferments is disturbed,
metabolism acquires a more primitive character, the output of macroerges is
disturbed. The organ with disturbed innervation can become a source of
autoantigen.
9. Alzheimer's disease - is the most important cause of dementia
(progressive dementia, decreased number of neurons in nucleus
basalis,
generalized cerebral atrophy, granulovascular degeneration especially affecting
temporal and frontal lobes.
10. Parkinsonism (paralysis agitans). Usually present after age 50. There
are degeneration of nigral neurons leads to loss of dopaminergic inhibition and
relative excess of cholinergic activity. Remember - dopamine is synthesized by
neurons in the substantia nigra. Universal mechanisms of disturbances of the all
functions are the following: loss of ability to maintain the definite quantity of
membranous potential by the nervous cell due to disturb to pass excitation from
one nervous cell to another, from one part of the nervous system to another. If the
nervous system (their components - nerves and others) is damaged so much, that
its connection with the body of neuron is lost, it degenerates and than is a cessation
of axoplasmatic flow and transportation of substances of axoplasm. The cessation
of the moving function leads to paralyses or parhesis. The pathologic processes
and the disturbances of the sensitivity are called hyperesthesia (the increase of it),
hypoesthesia (the decrease of it) and anesthesia (the lack of sensitivity). Depending
on the character of the lost sensitivity there are distinguished the tactile anesthesia
(strictly anesthesia), the analgesia alerga, the thermal one (thermanesthesia) and
loss of deep or proprioceptive sensitivity. If the pathologic process is located in the
spinal cord or in the brain the disorder of sensitivity depends on the disturbance of
the ascending pathways, There are two centripetal systems of sensitivity. One of
them is called lemnisk and contains the nervous fibers of large diameter which
conduct stimuli from the proprioreceptors muscles, sinews, joints and partially
from cutaneous receptors of touch and pressure (tactile receptors).
5.1. Content of the theme. Identify functional subdivisions of the
nervous system.Characterize the causes and universal mechanisms of disturbances
in all the nervous system functions.Define common terms that describe alterations
in motor functions.Describe the pathologic pain as the changed system of the pain
sensitivity.Identify chemicals that modulate the pain. Differentiate between acute
and chronic pain.Define the trophicity function of the nervous system and
dystrophic process.Discuss pathogenesis and manifestation of neurodystrophic
changes.
5.2. Control questions of the theme:
1. Identify functional subdivisions of the nervous system.
2.Characterize the causes and universal mechanisms of disturbances in all the
nervous system functions.
3.Define common terms that describe alterations in motor functions.
4.Describe the pathologic pain as the changed system of the pain sensitivity
5.Identify chemicals that modulate the pain.
6. Differentiate between acute and chronic pain.
7. Define the trophicity function of the nervous system and dystrophic process.
8.Discuss pathogenesis and manifestation of neurodystrophic changes.
9. Alzheimer's disease.
10. Parkinsonism (paralysis agitans).
5.3. Practice Examination.
Task 1. The soldier with heavy shrapnel of wound of backbone was delivered to a
hospital. The availability of section of the right half of spinal cord was
established in the injured man. This conclusion is confirmed by such data
of an objective inspection
А. Absence of proprioceptive sensitivity in the right part
В. Absence of algesic and temperature sensitivity in the right part
C. Absence of proprioceptive sensitivity in a left side
D. Absence of proprioceptive and algesic sensitivity in a left side
E. Absence of proprioceptive and temperature sensitivity in the right part
Task 2. The symptoms of disturb of the central nervous system functionexcitation, euphoria, weakening of attention, professional errors appeared
after immersing of diver on depth 60 m. These symptoms are connected
with the toxic influence on neurons
А. Oxygen В. Carbonic gas С. Nitrogen D. Ammoniac
Е. Lactate
Task 3. Ragged electcal net wire falled down on the head of a man during rainy
storm. Man died after this accident. He died because of :
А. Disorders of brain blood circulation В. Paralysis of respiratory centre
С. Paralysis of vasomotorial centre
D. Oppression of brain cortex
Е. Irritation of vagal nucleuses
Task 4. The disorders of coordination of movements, atonia of muscles, violation
of balance, shivering of trunk and extremities are observed in
experimental animal after deleting one of brain parts. What part of brain
is deleted?
А. Substatia nigra В. Red nucleus С. Striped body
D. Pale sphere
Е. Cerebellum
Task 5.
Trophic lesions of skin of damaged extremity appeared in patient after
traumatic section of ischiatic nerve testify to degeneration of nervous
fibre. The main mechanism of degeneration is
А. Discontinuance of axoplasmatic flow
В. Loss of excitability by a
nerve С. Phagocytosis of the nervous endings D. Destruction myelinic
membrane
Е. Damage of Ranvie’s isthmus
Task 6. The worker of an agriculture was delivered to reanimation department with
symptoms of a poisoning by phoshoorganic substance (bradycardia,
myossis, sweatting, spasm) . These disorder have arisen because of:
А. Acceleration of the axonal transport of cholinacetyltransferase
В. Oppression of cholinacetyltransferase activity
С. Stimulation of the retrogradic transport of choline
D. Simplification of acetylcholine thow out from synaptosomes
Е. Disorder of acetylcholine interaction with receptor
Real-life situations to be solved:
Task 1
Last year, five years old boy had polyomyelitis. Now he is not able to work.
The movements by his right leg are completely absent. Right crus and right thigh
are atrophic. Muscles tone of the right leg is reduced. Tendinous- periosteal
reflexes are absent.
1. What form of disturbance of motor activity is observed in the child?
2. What neurons of aback brain are injured by polyomyemilis virus ?
3. Why algesic and reflestory movements are absent in the patient ?
4. Explain the reason of appearance of muscles atrophic of the right leg.
5. Explain the reason of disappearance of reflexes.
Task 2
In the patient, who was delivered to clinic with heavy trauma of backbone
paraplegia of lower extremities is observed. Muscle tone is increased. Tendinous
reflexes are strengthened.
1. What type of paralysis is present in patient?
2. Why does muscle tone is saved ?
3. Explain mechanisms of strengthening of tondinous reflexes.
Literature:
1.Gozhenko A.I., Makulkin R.F., Gurcalova I.P. at al. General and clinical
pathophysiology/ Workbook for medical students and practitioners.-Odessa, 2001.P.259-262.
2.Gozhenko A.I., Gurcalova I.P. General and clinical pathophysiology/
Study guide for medical students and practitioners.-Odessa, 2003.- P.328-343.
3.Robbins Pathologic basis of disease.-6th ed./Ramzi S.Cotnar, Vinay
Kumar, Tucker Collins.-Philadelphia, London, Toronto, Montreal, Sydney,
Tokyo.-1999.