1. To draw graphic of excitive tissues reactions dependence on stimulus force and time action. To show and to explain what is threshold, useful time, chronaxy.

Law “force-time” describes dependence between the stimule force and time necessary for answer reaction receiving. With increasing of a stimulus force it is required less time of its influence to tissue for answer-back reaction reception. The relation between the duration and force can be expressed by the augmentation hyperbolic curve, the both branches of which go at any stage in parallel to axes of coordinates.

C – chronaxy,

UT – utilization time

R – rheobase

Rheobase=threshold – minimal force of the stimule capable to give the 1^st answer reaction

UT or useful time – minimal time necessary for answer reaction receiving if the stimulus force is equal to 1 rheobase or 1 threshold

Chronaxy - minimal time necessary for answer reaction receiving if the stimulus force is equal to 2 rheobases or 2 thresholds

Chronaximetry – method of chronaxy assessment.

2. To draw graphically action potential phases.

A. Phases of action potential: 1 – slow depolarization, 2 – quick depolarization, 3 – repolarization, 4 – hyperpolarization, 5 – negative afterpotential, 6 – rest potential.

B. Changes of excitability: 1, 4 – supernormal period, 2 – absolute refractory period, 3 – relative refractory period, 5 – subnormal period.

Excitability changings (figure of action potentials phases and excitability changings correlation)

Action potential phase	Excitability changing	Reasons and mechanisms
Partial depolarization	Supernormal period	The less threshold is, the more excitability is
Complete depolarization	Absolute refractiveness (non-excitability)	During overshoot cellular excitability is equal to zero due to Na-channels inactivation and K-channels activaton. Membranes can not react even to epiliminal stimuli. Potentials difference is equal to 0.
Rapid repolarization	Relative refractive-ness	K-ions come from cell and negative charge is accumulated on internal membrane surface. Excitability is restored. Membrane can react to superliminal stimuli. Substances prolonging relative refractory period (antiarhythmical) decrease cardiac contraction rate and repair heart rhythm.
Slow repolarization	Supernormal period (exaltation)	Membrane is partially depolarized and is excited very easy. Answer reaction can occur even at subliminal stimuli action.
Hyperpolari-zation	Subnormal excitability	Membrane potential increasing, threshold increasing define excitability decreasing. Besides, hypoexcitability is delt with Na-channels inactivation and K-ions activation. Only epiliminal stimuli can cause answer reaction.

3. To designate graphically muscles contraction types dependently on irritation rate.

At a muscle irritation by single stimulus the single muscular contraction arises. One can distinguish the latent period lasting 0,01 sec (from irritation beginning to answer-back reaction beginning), shortnening period (actually contraction) lasting 0,04 sec and relaxation period lasting 0,05 sec. Thus, singular muscular contraction lasts 0,1 sec.

In reply to a rhythmic irritation (namely the such one our muscles are received) the muscle is reduced lengthly (for a long time). Such contraction has received the name tetanic or summarized. If each subsequent pulse approaches to a muscle in the period, when it began to be relaxed, there is an infused, dentate or incomplete tetanus.

If the interval between irritations decreases so, that each subsequent pulse comes to a muscle, at that moment, when it is in a contraction phase, there is smooth, complete, fused tetanus or holotetanus.

4. Electromyography – the method principle, its types and main indexes. Masticatory muscles electromyography – for dental faculty students.

EMG - With other words, it is registration method of skeletal muscles excitability by electrical potential oscillations occurrence under rest, at tonic tension and arbitrary movements. There are 3 main electromyogram kinds (by square of record and electrodes:

• interferential – muscular biopotentials are taken off from large surface while applying the electrodes on skin;

• local – separate motor units activity is registered by means of needle electrodes;

• stimulatory – the registration of electrical muscle answer to the stimulation of nerve innervating it.

On other hand (by appearance):

1. saturated - in norm – impossible to be analyzed;

2. non-saturated – possible to be analyzed quantitatively – oscillations are more seldom.

2 analysis types:

1) qualitative – the curve description;

2) quantitative – to estimate rate and amplitude.

Main branches of application:

1. neurology.

2. traumatology-orthopedy,

3. pediatry,

4. sportive medicine and rehabilitation medicine,

5. dentistry all branches.

5. To draw reflectory arc, to designate its main elements.

In Ahmed’s copy-book

6. To draw synapse, to explain excitement conductance mechanism.

Presy­naptic neuron	A rrive of action potential in axon terminal
	O pening of calcium channels in presynaptic membrane
	I nflux of calcium ions from ECF into the axon terminal
	O pening of vesicles and release of Ach
Passage of Ach through synaptic cleft
Postsy­naptic neuron	F ormation of Ach-receptor complex
	D evelopment of EPSP
	O pening of sodium channels and influx of sodium ions from ECF
	O pening of sodium channels in initial segment of axon
	I nflux of sodium ions from ECF and development of action potential
	Spread of action potential through axon of postsynaptic neuron

Fig.15. Sequence of events during synaptic transmission. Ach = Acetylcholine. ECF = Extracellular fluid. EPSP = Excitatory postsynaptic potential