V.According to receptors localization:

1. Superficial:

1. Skin:

• cremasteric,

• planter,

• abdominal et al.

2. From mucous membranes:

• corneal;

• conjunctival et al.

2. Deep:

1. Muscular.

2. Tendinous:

• biceps jerk;

• triceps jerk;

• knee jerk;

• ankle jerk et al.

3. Periosteal:

• carpo-radial et al.

VI.According to biological significance:

1. Sexual.

2. Defensive.

3. Alimentary et al.

VII.According to principle - what part takes part in reflex realizing:

1. Somatic.

2. Vegetative.

VIII.According to ending result:

1. Alimentary.

2. Respiratory.

3. Cardiac.

4. Vessel.

5. Salivatory et al.

Receptor is a specialized structure at the terminoma (end) of afferent neurons. It responds to minor changes around it, inside or outside the body.

Receptors tasks:

1. giving information about stimulus nature;

2. giving information about stimulus force;

3. giving information about stimulus action time;

4. analysis can not be realized without them.

There are several approaches to the receptors classification (and, thus, several receptors types).

Receptors classification

1. According to the localization:

1. Exteroreceptors:

A. Skin

2. B. Visual mucosas (particularly of oral cavity)

2. Visceroreceptors:

1. Interoreceptors – in inner organs

2. Proprioreceptors – in motor apparatus and vestibular apparatus.

2. According to the activity character:

1. Exteroreceptors:

1. Contact:

1. tactile (cutaneous):

• tactile corpuscles for touch - Meissner's corpuscles and Merkel's discs;

• Pacinian corpuscles for pressure;

• Rouffinian bodies for vibration

2. temperature:

-free nervous terminals for heat;

-end bulb of Krause for cold;

-receptors of burning sensation

3. nociceptors (pain receptors):

-of skin;

-of mucosas (visual);

4. of taste (4):

-for bitter;

-for sugar;

-for salty;

-for sour.

2. Distant or telereceptors - give response to stimuli arising away from the body:

1. photoreceptors (to light);

2. phonoreceptors (to sound);

3. olfactory;

4. temperature (if the irritation source is very powerful)

2. Interoreceptors:

1. Presso- (baroreceptors):

-in vessels;

-in sexual organs.

2. Chemo-receptors.

3. Nociceptors.

4. Temperature.

3. Proprioreceptors - give response to change in the position of different parts of the body:

1. Muscular (muscle spindle)

2. Tendinous (Golgi tendon organ)

3. Of ligaments

D. Of joints

E. Receptors in labyrinthine apparatus namely, crista ampullaris in semicircular canals and macula in utricle and saccule.

3. By the nature:

1. Mechanoreceptors.

2. Thermoreceptors.

3. Nociceptors.

4. Electromagnetic receptors (which detect light on the retina of an eye)

5. Chemoreceptors – they detect:

• taste in the mouth;

• smell in the nose;

• oxygen level in the artery blood;

• osmolality of the body fluids;

• carbon dioxide.

4. According to structure:

1. Simple (primary-sensing) – nerve ending:

• olfactory;

• cutaneous.

2. Complex (secondary-sensing) – they have a special receptor cell in front of nerve ending:

• photo-;

• phono-.

Fig.16.Cutaneous receptors.