MEDICAL BIOLOGY, HUMAN ANATOMY, PHYSIOLOGY AND PATHOLOGY - Ya.I. Fedonyuk 2010

ANATOMY, PHYSIOLOGY, PATHOLOGY

CHAPTER 3. ANATOMICAL AND PHYSIOLOGICAL ASPECTS OF BODY FUNCTION SELF-REGULATION

GENERAL ISSUES IN THE ANATOMY AND PHYSIOLOGY OF SENSORY SYSTEMS

Sense Organs (organa sensuum) are anatomical structures that perceive external stimulus energy, transform it into a Nerve Impulse, and transmit it to the Brain, where this impulse is analyzed.

The process of sensory perception in humans occurs through five channels: Touch, Hearing, Vision, taste, and smell. Accordingly, the sense organs include the eye, ear, Skin, nasal mucosa, and Tongue.

The Development of sense organs is of great importance for ADAPTATION TO ENVIRONMENTAL conditions. For example, a dog is quite sensitive to trace odors of low concentrations of organic acids released by animal bodies (trail scent), while remaining virtually insensitive to the scent of plants that have no biological significance for it.

The perception of stimuli from the external and internal environment is carried out by receptors (specialized structures) that transform stimulus energy into a nerve impulse. They are classified as follows: 1) exteroceptors, which transmit information to the Central Nervous system about Changes in the external environment; 2) proprioceptors, which provide information about the body's position in space;

3) interoceptors, located in Internal Organs, which detect the subtlest changes in the body's internal environment; 4) chemoreceptors, which respond to changes in the chemical and gas COMPOSITION OF THE Blood; 5) osmoreceptors, which perceive changes in the Osmotic Pressure of the blood; 6) thermoreceptors, which perceive Temperature changes; 7) volume receptors, which measure the blood volume flowing to the left atrium; 8) mechanoreceptors, which respond to pressure and organ stretching.

For a sensation to arise, the following links of a single process are required: 1) structures that perceive the stimulus, 2) nerves through which this stimulus is transmitted, and 3) the brain, where it is converted into a conscious fact. I.P. Pavlov called this entire apparatus an analyzer. The cortical end of the analyzer performs the analysis and Synthesis of the received information.

Based on I.P. Pavlov's DOCTRINE OF THE two signaling systems, all analyzers can be divided into two groups:

I. Analyzers of the first signaling system (concrete-contemplative thinking)

A. Analyzers of the external world: 1. Exteroceptors (organs of cutaneous sensation, hearing, vision, taste, and smell).

B. Analyzers of the body's internal world:

1. Proprioceptors transmitting impulses from organs of animal life (musculoskeletal sensation).

2. Interoceptors transmitting impulses from organs of vegetative life (viscera, Blood Vessels).

II. Analyzers of the second signaling system (Abstract-logical thinking):

1. Analyzers of spoken language.

2. Analyzers of written language.

The analyzers of the First and Second signaling systems differ anatomically. Analyzers of the first signaling system possess all three components: a receptor, a conductor, and a cortical end. Analyzers of the second signaling system consist only of a cortical end (the cortical ends of speech analyzers). They perceive their signals (secondary signals) on The basis of primary signals that constitute the first signaling system, without which they cannot function.

The concepts of "sense organs" and "analyzers" are distinct. Sense organs include the eye, ear, skin, tongue, and Nose, which house only the peripheral part of the corresponding analyzer and are thus responsible for the perception of sensory stimuli.

Aristotle already described five Senses: vision, hearing, taste, smell, and touch. Correspondingly, we distinguish visual, auditory, gustatory, olfactory, and tactile analyzers. In addition, there are systems for pain perception, as well as for perceiving THE POSITION OF the body and its individual parts in space. Various Sensory systems in internal organs are also known, which perceive chemical stimuli, pressure, and stretching.

The work of analyzers begins with the perception of physical or chemical energy by receptors, which is then transformed into nerve impulses. Via sensory (afferent) pathways, these impulses are conducted to the corresponding sensory areas of the Cerebral Cortex, where a specific sensation—visual, auditory, tactile, etc.—is formed.

For the development of human intellect and mental activity, information arriving from the external environment—which the body receives through the functioning of analyzers—is essential. As a result of the analysis of sensory information, a subjective reflection of objective reality emerges, enabling the living Organism to adapt to environmental conditions.

Information arriving from the body's internal environment plays a vital role in the mechanisms of physiological regulation of Functions.