Autonomic reflex

Introduction The autonomic nerve is the spinal nerve that is emitted by the spinal cord and is mainly distributed in the trunk and limbs. The visceral nerves emitted by the brain and spinal cord are mainly distributed in the internal organs, controlling and regulating the functions of the internal organs, blood vessels and glands. Because it is not subject to human will, it is called autonomic nerve, also called autonomic nerve. Autonomic dysreflexia (AD), or autonomic hyperreflexia, refers to a group of clinical syndromes characterized by a sudden rise in blood pressure caused by spinal cord injury (SCI) in the T6 spinal cord or above. In 1860, Hilton and Bowlby in 1890 made a preliminary description of this phenomenon. Head described this syndrome for the first time in 1917. In 1947, Guttmann first confirmed that the paroxysmal hypertension is the main feature of autonomic dysreflexia through a large number of observations of SCI casualties.

Cause

Pathogenesis: The remains of the spinal cord distal to the injury plane are a prerequisite for the development of AD. Under normal circumstances, all visceral vascular reflexes are integrated at the level of the spinal cord, maintaining relatively stable blood pressure. After SCI, the stimulation below the injury plane, through the ventral nerve (sympathetic) and pelvic nerve (parasympathetic), from the dorsolateral side of the spinal cord, but blocked at the SCI, excitatory interneurons, followed by sympathetic nerves Synapses occur in preganglionic neurons, causing reflex excitability of the sympathetic efferent fibers, stimulating visceral and limb vasoconstriction below the injury plane, resulting in an increase in blood pressure.

Therefore, the plane of the SCI will directly affect the extent and extent of sympathetic excitement.

an examination

Related inspection

Nervous system check blood pressure

The clinical manifestations of AD are related to sympathetic excitation and massive release of adrenergic transmitters, including: elevated blood pressure, slow pulse, severe headache, facial flushing, nasal mucosal congestion, sweating above the plane of injury, chills, chills Anxiety, nausea, urinary sensation, short-term vision, oral metal taste, dizziness, dizziness, convulsions, and cerebral hemorrhage. The most objective indicator of diagnosis of AD is elevated blood pressure. But how much blood pressure rises is the onset of AD, there is still debate. Recommended diagnostic criteria:

1. The systolic blood pressure rise is greater than 20% of the original normal value.

2, at least one of the following 5 items: sweating, chills, headache, facial congestion, chills.

Differential diagnosis

The functional characteristics of the autonomic nervous system are mainly:

1 sympathetic and parasympathetic sputum effects. The effects of sympathetic and parasympathetic on organs that receive dual innervation are generally paralyzed. For example, the sympathetic nerve accelerates the heartbeat and the gastrointestinal motility slows down. The parasympathetic nerve slows the heartbeat and strengthens the gastrointestinal motility. But this embarrassing effect is complementary. In addition, sympathetic excitation is often accompanied by the secretion of the adrenal medulla, so it is called the sympathetic adrenal system. The vagus nerve is often accompanied by the secretion of islets, so it is also called the vagus-islet system. From the perspective of energy metabolism, the function of the sympathetic nerve can promote energy consumption, while the function of the parasympathetic nerve enhances energy storage, and the two complement each other. Because it is easier to store after consumption, it is stored for future consumption.

2 tension effects. In the quiet state, the autonomic nerve fibers often have low-frequency impulses that are transmitted to the effector, which plays a slight regular stimulation, called the tension effect. For example, cutting off the vagus or sympathetic nerve that governs the heart can accelerate or slow the heartbeat, respectively, which means that the vagus nerve is not cut to slow the heartbeat, and the sympathetic nerve accelerates the heartbeat. However, the two comparisons vary depending on the species of the animal, such as rabbits, and the sympathetic effect is strong. The horse has a strong vain effect.

3 Sympathetic-adrenal activity and emergency response. When animals encounter various emergencies, such as strenuous exercise, blood loss, and cold, a series of sympathetic reactions occur in the body - the phenomenon of extensive enhancement of adrenal system activity is called emergency response (stress response). The American physiologist WB Cannon proposed an emergency theory based on this reaction. These reactions include: accelerated heartbeat, extensive contraction of skin and visceral blood vessels, bronchiectasis, accelerated glycogen decomposition, etc. The physiological significance of this is to mobilize various potential forces in the body to adapt to the dramatic changes in the environment. If the sympathetic chain of the animal is removed, the animal's ability to cope with an emergency is greatly diminished.

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