The damage that occurs in cartilage is due to the load during a period of time, as a consequence of obesity or a fracture. The bone spur can affect the knees, feet, hips, vertebrae and joints that have a continuous motion.

This type of spur interferes with the proper functioning of the joint as close as you press the tissues are the tendons and ligaments. The constant pressure causes pain, swelling, muscle spasm and often the loss of mobility and a creep.

Usually the pain is more intense in the early hours of the morning and after a rest period.

It is important to lead a very healthy diet always trying to maintain a healthy weight because excess weight increases the pressure on the joints and exacerbates the problem by making it more painful.

The consumption of vegetables, fruits, whole grains and foods rich in calcium and magnesium, increasing fish intake (rich in Omega 3) in the diet including flaxseed.

Red meat should be avoided, and foods with saturated fats, refined sugars and sausages. Also salt, alcohol, coffee and snuff should be eliminated from the diet.

Reduce the consumption of tomatoes, peppers, potatoes and eggplants, also avoiding artificial sweeteners and light products.

Medicinal plants, through the herbal medicine have an important role in the management of the spur. Like the devil’s claw extracts, juniper, white willow and meadowsweet help ease the pain because they have anti-inflammatory action. While the green nettle and lemon are excellent for their remineralizing action.

Aromatherapy can also be used by means of friction and massage with essential oils, the most recommended those based on soybean oil, and oil with essence of pine and juniper, lemon, ginger and juniper that relieve pain, activating blood circulation and helping to eliminate toxins.

Orthomolecular Therapy is currently applied as an alternative to the pain of the scar.

The intake of supplements with antioxidants, carotene and vitamins slow the formation of scar.

Also, physical therapy works with specific techniques such as neuro-muscular bandage seeking recovery through immobilization. Place an elastic bandage that makes the swelling goes down, taking analgesic effect.

Hydrotherapy also generates significant improvements in hot water baths to which you add baking powder and camphor baths alternating with cold water. This type of baths reduces inflammation by stimulating blood circulation.

The mud wrap the affected area where there are specific inflammation, in addition to producing a soothing muscle relaxation.

Stretching exercises, although it can cause pain are necessary and should avoid inactivity. Therefore, recommend swimming, yoga and walking. Should be exercises that do not impose stress on the joints.

• The parenchymal compartment: Change is slow (dehydration or overhydration = edema), or appearance of a mass: tumor, hematoma
• The fluid compartment: The CSF is produced by the choroid plexus and absorbed in the upper longitudinal sinus. If alteration of this balance, there is a variation of the intra cranial pressure (ICP)





• The vascular compartment: Crush veins (= gene drainage decreased resorption of CSF), increase of asphyxia (PCO2 + + +)

The HIC can be compensated:
good-tolerance as the clearing of CSF are effective
Decompensated ICH may be:
commitment of the bulb in the foramen magnum -> instant death.
cone pressure, displacement of the parenchyma (viscosity)
hernia-temporal compression stems gives mydriasis, hemiplegia, and altered consciousness,
-tonsillar herniation: compression of the bulb, crisis and extension stiffness, difficulty breathing
Risk-+ + +: not to lumbar puncture as it has not done a CT scan.


Clinic:
- Headache mainly nocturnal (supine)
- Vomiting, easy in jets (meningo-cerebral damage),
-papilledema on fundus.
signs of seriousness:

• Impaired consciousness (Glasgow <8)
• yawn
• torticollis,
• pupillary asymmetry,
• crisis of hypertension (steep, arcuate)
• sign of commitment:
• Papilloedema: a sign of HIC vision of a black veil when you lean forward, listing optic atrophy (which may progress to total blindness)

Further examination:
Scanner and / or MRI (tumor, hematoma, hydrocephalus),
No lumbar puncture:
Pressure intra-spinal (but not PL)
-Infants: external sensor on the fontanel,
Method-invasive, intra ventricular drain, sensor extra dural
So monitoring of extreme situations (tumor, hemorrhage, head trauma).

• There is not no without clinical epilepsy: paroxysmal abnormalities in the EEG without clinical not enough to define epilepsy.
• The paroxysmal nature and its clinical translation are necessarily rough.
• It is stereotypical for each patient depending on the neuronal localization
• The clinical and EEG allow the formulation of a hypothesis when the neuronal localization
• The chronological sequence of symptoms may change during disease

II – THE CLASSIFICATION OF EPILEPSY.
The difference between partial and generalized epilepsy is the concept of neuronal discharge localized or generalized. There are also secondary epilepsy due to a lesion or dysfunction in general.
III – generalized seizures.
A – tonic-clonic generalized
This crisis is manifested by a sudden loss of consciousness without prodrome, with a fall. In its complete form it has a tonic phase of 10 to 20 seconds, during which there is a contraction of all muscles, with a phase flexion and extension of four limbs and trunk, contraction of the masseter. Clonic phase follows an approximately 30 seconds, characterized by sudden twitching of members in bending with clone facial and jaw.
Apnea associated with the phase of tonic contraction causes cyanosis accompanied by autonomic signs (mydriasis, piloerection, hypertension, tachycardia) and secretory phenomena (salivation and tracheo-bronchial congestion). It was also during this phase of tonic-clonic crisis that may occur biting language conventionally side.


At the end of the clonic phase, may occur a loss of urine, not specific to seizure. Breathing blocked since the start of the crisis resumed at that time, large, noisy (stertor), and cyanosis disappears gradually.
The recovery of consciousness is gradual, with postictal confusion, which can last up to an hour, during which the patient may behave with agitation.
Upon awakening, the subject has no memory of his crisis, he complained of muscle pain, headache or pain related to trauma caused by the initial drop. In some cases, the tonic phase or clonic phase are only present.
B – myoclonus:
These brief muscle jerks, predominantly proximal, affecting mostly the upper extremities, more rarely four or only the lower limbs. They are extended or flexed, causing the upper limbs dropping or a projection of the object held between the hands, legs and a sharp drop. Because of their brevity, they are not accompanied by apparent disturbance of consciousness. They may be spontaneous or provoked by stimuli, particularly visual, in an intermittent light stimulation. Myoclonus are common immediately after waking. The myoclonic jerks of sleep are not epileptic in nature.


C – “petit mal”:
This is a pure and brief suspension of consciousness during most often less than 20 seconds, totally amnesiac, without automation, sometimes associated with some eyelid tremors. In the absence of the patient interrupts his activity and resumes where it left off when he regains consciousness. The total and immediate recovery of consciousness at the end of the absence is semiological important point. In their pure form, these absences are observed mainly in children.
D – atonic:
This crisis manifested by a sudden loss of postural tone, often resulting in the fall without prodrome, with a brief suspension of consciousness. A minor form of the atonic is represented by a brief absence with loss of muscle tone in the neck and head drop forward.
E – Tonic seizures:
Some overall tonic hyperextension differ from the great tonic-clonic generalized by their brevity and preferentially occurred at night during sleep.
IV – partial seizures.
The clinical manifestations of these crises depend on the headquarters of seizure discharge:
A – The crisis Bravais-Jacksonian:
It is the archetype of partial seizures described at the end of last century, indicating a critical concern to the discharge area rolandic opposed to clinical manifestations. The crisis manifested by unilateral partial clonic jerks, which may be preceded or followed by paresthesias or tonic spasm involving the same territory. The spread of the discharge in the motor cortex manifested clinically by an extension of the clones, which respects the somatotopic organization of motor cortex. Thus, the hand and hemiface whose somatotopic representation is very important, they are preferentially affected the evolution cheiro-oral clones beginning in the fingers and then passing to the hemiface the same side is especially evocative. Many partial motor seizures are manifested by clones or tonic spasm limited to part of one body half, without having provided all the features of the crisis Bravais-Jacksonian complete.
B – clonic hemicorporelles:
They deserve to be distinguished from earlier because they immediately spread to all muscles of a body half, their long-term nature of the context in which they occur (see below) and frequency with which they can cause a deficit postictal motor or permanent sequelae.
- Seizures adversative:
When the discharge of interest to the inner or outer surface of the frontal cortex pre-rolandic, it results in motor behavior, predominantly involving the eyes, head axial muscles and upper limbs. These seizures are characterized generally by a deviation and a turn, usually but not always on the side opposite hemisphere headquarters of the landfill. It is common to see fulfilled all the crises of this type under the general term crises adversive semeiologic despite their diversity.
The oculogyric crisis manifests itself as a tonic conjugate deviation of eyes. It can be complemented by a deflection of the head in the same direction.
When the discharge of interest to the supplementary motor area to the inner surface of the hemisphere, the crisis involves: 1) a suspension of speech, or of a cry, or the repetition of a syllable (palilalia), 2) adversion oculocéphalique 3) an automatic stereotype of upper opposed the release, with elevation of the latter half-flexed position.
More unusually, crises adversive have a turn of the body, which may cause the collapse (heart roundabout).
- Postural seizures:
Can be grouped under this term all the crises in which there is paroxysmal dystonic events, often affecting the upper limb or body half the opposite side of the ictal discharge or both upper limbs and axial musculature and may then cause fall. Some of these crises are rooted in the parietal lobe, others show a spread of discharge in both frontal regions. The bilateral nature of the frontal discharges can also cause a fall atonic. Often, only the video of the crisis coupled with that of the ictal EEG allows a precise observation of the ictal semiology.
- Seizures somatomotor inhibitory:
This crisis manifested only by a transient motor deficit, their existence is discussed as they are exceptional, only the concept of a deficit of a few seconds, stereotyped and recurring frequently, can at best do consider this diagnosis . Such crises should not be confused with the deficit postictal can follow any motor prolonged crisis.
C – Seizures somato-sensory:
They have in most cases the same progression as motor seizures jaksoniennes, is also related to a landfill in an area of cortex somatotopically organized, namely the primary somatosensory area of the parietal cortex. They are expressed by paresthesia and may be followed by motor manifestations of Jacksonian type because of the spread of discharge in the motor area. More unusually, there are sensations of heat or cold and very brief exception of pain affecting their stereotyping and their paroxysmal character. Stereotypy and brevity can also relate to a seizure disorder somatognosis more sophisticated sensations of loss of all or part of one body half (asomatognosia), sensations of supernumerary phantom limb, deformation of a member … in connection with a discharge affecting the posterior parietal cortex.
We distinguish visual seizures, manifested typically by phosphenes, more rarely, visual illusions, a macroscopic or microscopic; crises hearing, manifested most often by ringing with also, but more rarely, with auditory hallucinations theme music, or noise. The verbal hallucinations are rare. It should be noted that for the patient, these illusions are perceived as real.; Note also the existence of crises olfactory and gustatory, vertiginous crises, crises that disrupt the language of crisis with a feeling of loss of contact with the world external disturbance of affection, autonomic manifestations …. There are so many crises that specific neuronal areas affected, is whether the clinical expression may be diverse and varied.
V – GET
Examination electro-encephalographic (EEG), despite the development of anatomical imaging techniques (CT scan and MRI) and functional (positron emission single photon or positron), retains all its interest in the diagnostic process and therapeutic monitoring of epilepsy or progressive. The standard EEG is always a record of activity at rest, hyperventilation and photic stimulation.
VI – ETIOLOGY.
Generally, any epilepsy depends on a genetic predisposition and acquired factors, aggression potentially epileptogenic brain. When the genetic predisposition is the predominant factor, the disease manifests itself as a primary epilepsy, or idiopathic, in the apparent absence of any acquired brain injury. The distinction between acquired lesional epilepsy and idiopathic epilepsy associated with a genetic predisposition is not simple. A lesion equal to the risk of crisis is aggravated in patients with family history of epilepsy. Conversely, aggression cerebral childhood may promote clinical manifestation of idiopathic epilepsy.
There is:

• in acute head injuries;
• during an encephalitis or meningo-encephalitis viral, bacterial or parasitic;
• in toxic comas (including acute intoxication) or metabolic
• in a patient with a brain abscess;
• the acute phase of stroke;
• after alcohol withdrawal in an ethyl;
• after weaning barbiturates or benzodiazepines.
• ill with a brain lesion known potentially epileptogenic (tumor, vascular malformation) or carrying a encephalopathy identified.

VII-TREATMENT.
The vast majority of epilepsy is treated medically. The goal of treatment is prevention of crises, it is a continuous process that must never be interrupted without notice médical.80% of patients are stabilized with monotherapy. Monotherapy as first-line required: Guardenal, valproate (Depakine), Lamictal, Tegretol, Neurontin, etc. ….
Surgical treatment aims to remove the epileptogenic zone and thus the entire crisis. It should not be confused with the surgical treatment of a focal lesion (tumor, angioma) responsible for seizures. It appeals only to a small number of partial epilepsy with frequent seizures refractory to medical treatment and in particular with temporal lobe epilepsy.

• Find a motor deficit: failure to maintain the Member ‘in air’
• Barre maneuver: the patient in the prone position, knees bent, and must keep the legs vertical to the upper limbs: horizontal arms, elbows outstretched wrists dorsiflexed maximum, we talk about deficits when the hand is widening.

Assessment of muscle tone
Search for hypo or hypertonia: passive movement of limbs and neck with someone relaxed
Assessment of voluntary movements
Tests of finger-nose, heel-knee puppets exceeded the goal, incoordination (cerebellar syndrome), slowed movement or stiff (piriformis syndrome)
Reflexes (ROT)
Search areflexia or exaggerated muscle contraction: relaxed person, members released the doctor struck with the reflex hammer and the tendon in question observed muscle contraction
Cutaneous plantar reflex (Babinski sign)
When scraping the plant externally using a blunt, there is flexion of the toes, if there is a slow and stately extension of the big toe, speaking of the pyramidal motor path



Study of walking
Done consistently, helping the person if necessary.
It then searches:
- Instability, loss of balance
- Steppage gait: drop your toes grip the ground that the person compensates by rising above the knee moderate motor deficit
- Loss of a swinging arm Parkinson
Consideration of the sensitivity
Systematically explored, the 4 members in the face, trunk.
- Search hypoesthesia: lack of sensitivity
- a paresthesia sensation painless
- Type stinging, tingling, electric shock, skin cardboard, liquid flowing …
- Deep sensibility:
- The doctor positions with members: the patient’s eyes closed and must say how it has its member
- Sensitivity superficial:
- Buffing the pad, eyes closed
- Sensitivity thermo-Algonkian
- Pique key, tube hot water – cold water
- Proprioceptive sensibility:
- Informed about the location of members is known in space, eyes closed is how our bodies
- Romberg’s sign: inability to keep balance in his feet together and eyes closed (cordonnal syndrome Post)



Visual examination
* Search homonymous hemianopia (HLH): amputation of the unilateral visual field damage in the contralateral cerebral hemisphere
* The doctor moves a finger in the 4 visual quadrants: the patient designates the quadrant moves a finger:
- Diameter and responsiveness of the pupil to light: mydriasis (pupil totally detract) or miosis (pupil fully retracted)
- Interrogation: decreased visual acuity united or bilateral blindness, diplopia (double vision)
Studies of higher functions
Testes:
- The temporo-spatial orientation (DTS)
- Memory
- Reasoning
- Language
Aphasia: all disturbances of written or oral (speaking and / or understanding reached without sensory or dementia)
Agnosia: inability to name an object, sound, color, whereas the sensory view is intact and there is no aphasia
Anosognosia: ignorance and denial by the person’s motor deficit
Aprox: inability to perform movements without paralysis or trouble understanding (greeting, combing, drawing a cube, put his shirt …)
Ataxia: loss of balance
II-neurological syndromes
Pyramidal syndrome
* Associated paralysis and hypertension, due to a partial or total disruption of the pyramidal tract
* Downlink of voluntary movement (cell bodies of neurons in the cortex prérolontique, axons in the anterior horns of the spinal cord)
* Signs vary by level of achievement: hemiplegia, cranial nerve damage, paraplegia …
Syndrome extrapyramidal
* Hypertonia, tremor, akinesia (inability or difficulty in moving)
* Achievement of basal ganglia: headquarters automatic movements and associated
Cerebellar syndrome (cerebellum)
* Disruption of the static and walking, the execution of movements, tone
* Achievement of the cerebellum or cerebellar pathways
Pseudo tumor cerebra
* Headache, vomiting, visual disturbances, dizziness, apathy, or even convulsions
* Reflects the increased pressure inside the skull
* Emergency neurosurgical

• Route the afferent and efferent between the CNS and the rest of the body
• Treatment of partial information by spinal reflexes.

Embryonic Development:
It develops from the caudal portion of embryonic neural tube. Distinguish a few weeks, two separate parts in the gray matter: the basal plate and alar plate, separated by a furrow, eventually becoming the central canal. As it grows, the blades extend and produce the gray mass of adult marrow. The white outer marrow is formed from neural axons.
Anatomophysiological:
The bone extends from the foramen magnum to the first or second lumbar vertebra. Hence, a filament fiber, fossil embryogenesis, from the meninges, extends to the coccyx, the terminal filum.
31 pairs of spinal nerves exit the spinal cord and innervate the body. She has two bulges, one from which the cervical nerves of upper limbs, forming the brachial plexus, the other from which the lumbar nerves of the lower limbs forming the lumbosacral plexus.
It has a slightly flattened and has two grooves, the median anterior and posterior midline.
Composition of the spinal cord:
Like the brain, spinal consists essentially of “white” and substance “gray”:
The white matter contains the myelinated neurons extensions: It completely surrounds the gray matter which way, is framed into three parts, called posterior, lateral and anterior. These cables, made up of groups of neurons called a type beams carry impulses to a specific destination (beams spinal ascending and descending)
The gray matter contains the bodies of neurons and the neuroglia: It has roughly the shape of an H, the side deck is appointing gray commissure, dug a thin channel called the central canal, extension of the 4th ventricle. The ‘pipes’ of H divide into pairs of posterior and anterior horns. Note that exists in some regions, particularly the chest, lateral horns.


The posterior horns contain sensory neurons of the spinal nerves, other neurons form the reflex arc with spinal motor neurons of anterior horns.
The anterior horn contains motor neurons whose axons form the spinal nerves.
The lateral horns contain them when to visceral motor neurons (involuntary)
But unlike the organization of the brain, spinal level, is the gray matter that lies at the center and white edge.
The gray matter:
As the cerebral gray matter, it contains multipolar neuronal cell bodies, extending them, and glial cells. Seen in cross section, spinal presents an aspect of H whose center is the central canal. From both sides, there are symmetrical gray masses, linked by a bridge, the gray commissure. The anterior and posterior projections are called respectively the posterior horns and anterior horns.


The anterior horn contains mostly cell bodies of motor neurons, while the posterior horns are very rich in interneurons. The axons of motor neurons extend into the spinal nerves before reaching their target. The horns on its side when serving visceral smooth muscles via the anterior roots.
The sensory receptors when to them, carry nerve impulses via the posterior roots. Their cell body is located in a bulge of the posterior root, the spinal ganglion. The two roots, anterior and posterior then join to form the spinal nerves, which is observed on both sides of the spinal cord.
The white matter:
Made up of nerve fibers, it is the color white to the presence of myelinated fibers, as bundles of predominantly vertical. It divides into the posterior cord, lateral and anterior, thus linking the bodies of a somatotopic manner, by ascending and descending.
Physiology:
The beams descending spinal
These are bundles s engine, leading nervous impulses from the brain down to the anterior horns of the spinal cord where the neurons coordinate the activity of skeletal muscles:
The pyramidal tracts, also called cortico-spinal drive the motor impulses to skeletal muscles. These are the main vehicles of voluntary control. Their origin dates back to the pyramidal cells of the frontal gyrus, then descend in the midbrain, pons and pyramids of the medulla
The beams extrapyramidal from subcortical structures influence motility by interfering with muscle coordination and balance
The ascending spinal bundles:
they drive the influx of sensory receptors associated with the affected areas of the brain or cerebellum. We note several major ascending spinal bundles: bundles Goll, cuneiform, spino-thalamic, spino-cerebellar ….
The columns of Goll for example, lead information on the members’ position and posture, and touch sensations throughout the body.

The reflex arc:
When you accidentally burn yourself on the edge of a hot pan, have you not noticed that you had already withdrawn your hand before you even have felt the pain? This is made possible by the existence of the spinal reflex arc, which can react to stimuli given automatically and much faster than if it did need intervention and analysis of higher centers. In our case, although the stimulus arrives at the brain, but for information since the reflex arc has averted the immediate danger.
The reflex arc is divided into 5 sequences:
A receiver receives information (often nociceptors)
A sensory neuron via the spinal nerve transmits nerve impulses to the spinal cord
One or several synapse between sensory neuron and an efferent motor neuron transmits information leading to the creation of a nerve impulse at the anterior horn gray
The information is transmitted to an effector (often, a skeletal muscle).
The CNS is then optionally informed.
Example:the tendon reflex, reflex front stretch

I – Organization of the nervous system:
It is divided into two main parts: The central nervous system (CNS), comprising the brain and spinal cord and peripheral nervous system (PNS), comprising parts nervous outside the CNS.

• The CNS is the central regulator and integrator of sensory information, from which it develops appropriate motor responses.
• The SNP consists mainly of the nerves, whose main function is to enable the transmission of information and the return of the response prepared by the CNS. Functionally, there are two types of channels: the sensory (or afferent), composed of nerve fibers carrying nerve impulses, and motor or efferent pathways, carrying the response of the CNS. The motor pathways are also divided into the somatic nervous system, also called the voluntary nervous system, because it allows the use of skeletal muscles consciously, and autonomic nervous system, which regulates unconscious (hence independent) activity smooth muscle (heart, digestive system ….). This system also faces two subdivisions, the sympathetic nervous system and parasympathetic, each opposing the other.

II – Histology:
The nervous tissue is very rich in cells, and contains little extracellular space. It is composed of two types of cells, neurons and glial cells.


The glial cells are not excitable cells surrounding neurons and protecting them. They form the backbone of the nervous system and give a good portion of firmness. Distinguish between glial cells, whose function is to support, nutrition and isolation of neurons. There are five types. Unlike neurons, glial cells retain their mitotic capacity, this explaining that the majority of brain tumors are gliomas.
Schwann cells: they form the myelin sheaths surrounding the axons of neurons in the peripheral nervous system
Oligodendrocytes: like Schwann cells, they form sheaths of myelinated, but along the thick axons of neurons in the CNS.
Astrocytes: star-shaped, hence their name, represent more than half the volume of the SN. They attach with their extensions to neurons and capillaries, and thereby promote their nutrition. They also govern the chemical environment, buffered potassium and reuptake and recycling certain neurotransmitters.


The microglial cells: macrophages are individuals who contribute to the protection of the CNS in phagocytosis of pathogens and dead cells
The ependymal cells: they line the cavities of the brain and spinal cord, forming a barrier between the CSF and interstitial fluid.
The neurons are the functional units of the nervous system. They have extreme longevity (> 100 years) are amitotiques, which means that a neuron destruction will never be replaced, and offer an exceptional rate of metabolism, which explains why they can not live more than a few minutes without oxygen and glucose. The cells are complex, with three functional areas, an area receiving a conducting zone and a zone secretory.
A – Structure of the neuron:
The cell body or soma, is composed of a large nucleus and granular cytoplasm. It contains all the usual organelles except centrioles, related to its structure amitotique. Its rough endoplasmic reticulum or Nissl bodies and Golgi apparatus are well developed, indicating a very intense activity.
There follow numerous cytoplasmic extensions neural begin in the perikarya. There are two types, dendrites and axons.
The dendrites are relatively short extensions to the many ramifications, so many. They form the structure receiving, receiving very large numbers of signals through the area they cover. Their points of contact, the synapses, are sites of chemical transmission (neurotransmitters) and appliances. They then carry this information to the cell body by short-range signals, potential graduates.
The axon is a unique cytoplasmic extension, from a conical region of the cell body, the axon hillock. Their size can be very short, as extremely long, like the axons of motor neurons of the toes, more one meter, making the axon of the cell the longest in the human body. The axon may form some ramifications, called collaterals. It ends with a bunch of very many short branches, the terminal arborization, including the bulbous tip is called the terminal button. The axons are conducting structure of the neuron, generating nerve impulses and propagated to the target, the axon terminal. In these buttons, the nerve impulse causes the release of neurotransmitters, chemical substances stored in vesicles of endings. These neurotransmitters are released into the extracellular space, and excite or inhibit neurons with which they come into contact.
The myelin sheath: the long axons and / or large diameter, are coated with a substance, lipid and segmented, the myelin sheath. This sheath electrically insulates axons from each other, but also increases the speed of electric transport. The sheath is composed of a large number of cells, called Schwann cells, not touching. These intervals are called nodes of Ranvier.

B – Neuronal Classification:
It is based on the number of extensions of the neuron. The neuron is thus unipolar, bipolar or multipolar. The multipole are most common in humans, particularly in the CNS. The Bipolar are quite rare, rather they are found, indeed, in some sense organs, such as eye or olfactory mucosa. The unipolar neurons when their part, are found primarily in the lymph.
It also classifies the neuron according to its function:

• sensory neurons, or related, which are mostly unipolar stimuli related to the CNS
• Motor neurons, or efferent, carrying impulses from the CNS to the PNS. They are mostly multipolar and form synapses with target cells.
• Finally, also speak of interneurons, located between the sensory and motor

III – Physiology:
The human body is a holistic perspective, electrically neutral. From a microscopic point of view, including the neural level, there are energy flows. This energy is expressed in volts or millivolts. This measure represents the potential difference between two different point of loads. Basically, to distinguish the voltage of the amperage, you can make the connection with a waterfall. The height of the waterfall, shown between the drop point and end point represents voltage, while its speed is the amperage. Thus, we can have a very low voltage with a large amperage or conversely, a large voltage with low amperage. The product of two represents a power expressed in watts.

I – The resting membrane potential:
At rest, if measure the potential difference between the neuronal cytoplasm and membrane, then records a potential difference of-70mV. The membrane is thus negatively charged relative to the cytoplasm. It is the resting potential (Vm). The membrane is called “biased”. This potential is created by differences in ion concentrations: the cytoplasm, for example, is rich in potassium and low in sodium, in contrast to the extracellular fluid. This difference is maintained through ion channels, passive or active. This causes a concentration gradient, whose translation is the electric potential of resting membrane.
II – Action potential:
Neurons communicate with each other through action potentials along their axons: it is a reversal of the membrane potential of about 100mV (the potential goes thus-70mV to +30 mV). These potentials are identical (their intensity does not decrease) along the axon. Its production is based on several changes occurring in its area “trigger” of the neuron:
there is first an increase in permeability to Na ions, due to the opening of sodium channels, voltage-dependent response to stimuli. The extracellular Na diffuses into the cell. This influx depolarizes the axonal membrane to a critical threshold, the excitation threshold, approximately-55mV. At this threshold, the process s’entretien itself, below, it turns off. Other voltage-dependent sodium channels open, so too, until a depolarization reaching 30 mV
Then, a phase of decreased permeability to Na settled: the intracellular load causes a natural resistance at the threshold of 0 mV increased (repulsion of electric charges of same sign), the channels close after a few milliseconds of depolarization. The sodium diffusion decreases, then stops.
Meanwhile, voltage dependent potassium channels open, causing a release of K into the extracellular medium. It re polarization. Sometimes there is a small hyperpolarization due to higher input of K, which then exceed the resting potential of -70 mV.
These phenomena cause disparities ion over the initial balance. Indeed, there are therefore in excess of K and Na deficit in the cell. This equilibrium is soon restored by the actuation of pumps sodium and potassium correcting these changes.
It is important to understand that this will spread not only from obtaining the threshold. Thus, all stimuli will not create any potential actions, the law of all or nothing, and it is our only similarity with the laws of binary computing. Stimuli below causes a so-called subthreshold depolarization.