Olfactory sensory system, odor classification, olfactometry.
Pain
Nociceptive & Anti-nociceptive Systems
Pain is a person's psycho-physiological emotional state, which occurs when super-strong stimuli act
Pain - a signal about the destructive effect of irritants or the degree of oxygen starvation of tissues that violate their vital functions
Manifestations of pain
1) Psychic phenomena: these are experiences of pain, which consist of feelings and emotions in the form of fear, anxiety.
Specific behavior is formed.
2) Moving phenomena:
increase the muscle tone
protective reflexes
3) Vegetative phenomena:
associated with the activation of the sympathetic system
Types of pain
1) somatic:
superficial (skin), deep (muscles, bones, teeth, joints, connective tissue)
2) visceral - various organs, smooth muscle contractions, accompanied by ischemia)
Pain can be: sharp, dull, cutting, piercing, drilling phantom pains, double pain, projection pain.
Pain is a disease - migraine.
Peripheral Mechanisms of Pain
Any strong irritants acting on receptors of sensory systems can cause a feeling of pain: bright light, strong sound, high and low temperature.
Structure of nociceptive system (system of pain sensitivity)
Receptor department: mechanical and chemoreceptors, mediator P.
Mechanoreceptors respond to pressure; chemoreceptors at: pH below 6.0, increased concentration of K +, histamine, bradykinin, prostaglandins
Conductor department: spinal nerves, spinothalamic pathways, specific thalamic nuclei .
From the head, signals travel along the trigeminal nerve (V pear) to the thalamus.
Cortical department: sensory zone I - postcentral gyrus, sensory zone II - Sylvian furrow, orbital cortex.
The phenomenon of double pain
There are two types of fibers coming from nociceptors to the spinal cord, the brain stem.
Fast - holding on myelin fibers type A. There is a clearly localized sense of pain
Slow - carrying on fibers type C. The pain does not have a clear localization
Structure anti-nociceptive system (anti-pain)
Level 1: spinal cord, reticular formation, raphe nuclei (medulla), and central gray peri-aqueductal gray in the midbrain (PGA)
Level 2 :
the hypothalamus:
1) inhibits the spinal cord
2) activate the first level
3) inhibits the thalamus
Level 3:
the cerebral cortex (sensor zone II)
The neurons of the antinociceptive system produce endogenous opioid substances (endorphins, dinorphins, enkephalins) that bind to the opioid receptors of various tissues, especially the CNS neurons.
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This causes inhibition in the neurons of the nociceptive system and, as a consequence, the state of analgesia or hypolgesia.
Endorphins
are the natural pain relievers that the human body produces. They act by stimulating special opiate receptors.
The term is an abbreviation for the term "endogenous morphine" - morphine-like chemical compounds that the body produces.
Opiate receptors are located in synapses (pulse switching zone) of other types: acetylcholine, adrenal, dopamine, GABA, etc. This means that endorphins regulate the "second level" - regulate the activity of regulatory systems.
According to modern data, they exercise control over all regulatory systems of the body.
Functions of endorphins
Anesthesia in the extreme situation of the struggle for life with simultaneous activation of thinking.
- After the termination of an extreme situation - "suppression" of adrenaline reactions, return to normal work of the cardiopulmonary system, and other internal organs.
Anesthesia
Anesthesia occurs when exposed to the nociceptive system:
receptor deactivation - local anesthesia
conduction deactivation - conduction anesthesia
deactivation of the cortex centers - general anesthesia –narcosis
Сan effects on antinociceptive system:
1) acupuncture
2) electro acupuncture.
3) hypnosis
Taste sensory system
• Receptor department of taste system. Taste nipples, their types. Functional mobility of receptors. The study of basic taste sensations. Gastro-lingual reflex.
• The taste system allows you to create taste sensations. The sense of taste is provided with the participation of mechano-, thermo-, chemoreceptors; closely related to smell. Taste analyzer allows you to evaluate the organoleptic properties of food.
• There are 13 types of chemoreceptors of taste cells, they provide the formation of four primary taste sensations.
• The threshold of sensitivity varies for different tastes, the lowest - for the bitter.
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• Thus, the sensitivity for bitter taste is higher than for the rest - it is biologically justified, poisons are usually bitter taste, they must be distinguished in small quantities (protection)
• Taste cells belong to the secondary sensory receptors, are part of the taste buds. The taste bud resembles an onion, in the narrow part there are microvilli in which the receptors are located.
• Microvilli through the taste pore in contact with the oropharynx
• The tip of the tongue is more sensitive to sweets.
• (mushroom papillae), lateral surfaces - to sour and salty
• (leaf-shaped nipples), root - to the bitter (fluted papillae); filiform nipples provide tactile sensations.
• Recently, the taste of “minds” has been discovered and, accordingly, specific receptors that are distributed over the surface of the tongue.
• The conductor division is represented by the fibers of the facial, glossopharyngeal and vagus nerve (the first neuron), the nucleus of a single tract is the second neuron, then the nucleus of the thalamus and the cortical section are located in the lower part of the posterior central gyrus.
• Taste sensitivity depends on the functional state of the body: in a hungry person, up to 50% of the taste buds are active, in a well-fed person, it is much less.
• With emotional arousal decreases the ability to distinguish tastes, with aging.
• In case of pathology in the oral cavity (stomatitis), taste sensitivity decreases, as well as in diseases of the gastrointestinal tract, blood and respiratory organs.
• Disorders of taste sensitivity: Agevziya, Hypogemia, Hypergeusia, Parageusia, Dysgeusia.
Olfactory sensory system, odor classification, olfactometry.
• The system allows to determine the presence of odorous substances in the air. It is important in ensuring safety, sexual behavior, eating behavior, emotional.
Odor classification
• 1) camphor, 2) musky, 3) floral, 4) mint, 5) ethereal, 6) caustic, 7) putrid
• Currently, receptors of 100 primary olfactory sensations are found.
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• The peripheral part is the dendrites of bipolar olfactory neurons, located in the nasal mucosa (olfactory membrane).
• Terminals of dendrites are club-shaped, at the ends are cilia, and in their membranes are receptor proteins.
• Cilia immersed in a layer of mucus. Odorous substances - odorants interact with receptors in which cAMP is synthesized, sodium channels are opened, RP forms, which goes into PD (olfactory receptors are primary sensitizers)
• The sensitivity of the olfactory receptors is very high, this is ensured by the fact that the interaction of the odorant and the receptor produces many cAMP molecules and, accordingly, opens a large number of Na + channels (amplification mechanism).
• Conductor division: the first neuron is the olfactory nerve (I pair), the second is the mitral cells of the olfactory bulb.
• In the area called the glomerulum, the mitral cell contacts the axons of the olfactory neurons (about a thousand).
• In each olfactory bulb about a thousand glomeruli, it is assumed that each is responsible for the primary olfactory sensations.
• The axons of the mitral cells form the olfactory tract, through which information reaches the cortex.
• The cortical region includes the pregusiform region, the olfactory gyrus, the hippocampus. From these formations, efferent pathways are directed into glomeruli (granular cells, which are inhibitory neurons and interact with mitral cells), here a “contrasting” of olfactory sensations is provided.
• The ability to adapt is highly developed in the olfactory analyzer (within a few seconds or minutes); it is believed that this property is provided by the conductor and cortical regions.
• Disturbance of smell:
• 1) hyposmia, 2) hyperosmia, 3) anosmia, 4) parosmia, 5) olfactory agnosia.
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