Reflex. Reflex arc diagram
The basic principle of the nervous system is reflex.
A reflex is the body’s response to irritation, which occurs with the participation of the nervous system.
A nerve impulse arising from irritation travels a certain path, called a reflex arc.
A reflex arc is a neural pathway along which nerve impulses are conducted during a reflex.
The reflex arc consists of five parts:
- receptor – a nerve ending that perceives irritation (Receptors are located in organs, muscles, skin, etc. Each type of receptor reacts to a specific stimulus: light, sound, touch, smell, temperature, etc. Receptors convert these stimuli into nerve impulses – signals nervous system);
- a sensitive pathway that transmits an impulse to the central nervous system (this part of the reflex arc is formed by sensitive neurons);
- a section of the central nervous system (an intercalary neuron that lies in the brain or spinal cord);
- motor path (executive, or motor, neuron that transmits an impulse to the executive organ or gland);
- working body.
Human reflexes are varied.
Example: withdrawal of the hand in response to an injection or burn of the skin, profuse discharge of tears under the influence of substances that irritate the eyes, sneezing when foreign particles enter the nasal cavity.
Somatic reflex arcs carry out motor reflexes.
Vegetative reflex arcs coordinate the work of internal organs.
The reflex reaction consists not only in excitation, but also in inhibition, that is, in the delay, weakening or complete cessation of the excitation that has arisen.
The interrelation of excitation and inhibition ensures the coordinated work of the organism.