Anatomy and significance of the vital signs

The sympathetic and parasympathetic nervous systems are collectively referred to as the autonomic nervous system. The complex nature of the autonomic nervous system allows for tight unconscious control of digestions, respiratory rate, urination, heart rate, blood pressure, and many other critical body functions..

Autonomic Nervous System

Autonomic Nervous System


The skeletal muscles are innervated mostly by the sympathetic nervous system.

Smooth muscle is found throughout the body where it serves a variety of functions. It is in the stomach and intestines where it helps with digestion and nutrient collection. It is found throughout the urinary system where it functions to help rid the body of toxins and works in electrolyte balance. It is found throughout arteries and veins where it plays a vital role in the regulation of blood pressure and tissue oxygenation. Without these vital functions the body would not be able to maintain even it’s most basic functions.

Smooth muscle differs from skeletal muscle in a variety of ways, perhaps the most important being its ability to be contracted and controlled involuntarily. The nervous system can use smooth muscle to tightly regulate many of the bodies subsystems for life with no thought from the user. A person does not need to think about their blood pressure for it to adapt to increasing oxygen demands from exercise. The nervous system instead uses hormones, neurotransmitters, and other receptors to control smooth muscle spontaneously. 

Smooth muscle also plays an important role in the disease process throughout the body.

From a functional aspect, smooth muscle physiology is responsible for maintaining and preserving every vital sign. Regardless of whether a patient presents with an acute emergent disease or a chronic disease, it is likely that smooth muscle has played some role in its development...Smooth muscle is a central structure involved in the regulation of airway tone. Dephosphorylation of myosin light chains terminates smooth muscle contraction. Unlike skeletal muscle, smooth muscle is phosphorylated during its activation. This creates a potential difficulty in that simply reducing calcium levels won’t produce muscle relaxation. Myosin light chain phosphatase (MLCP), instead is responsible for dephosphorylation of the myosin light chains ultimately leading to smooth muscle relaxation’ . Anatomy,Smooth Muscle, StatPearls 2020.

Smooth muscle contraction leads to bronchoconstriction (decrease in the diameter of the bronchioles) while smooth muscle relaxation leads to bronchodilation (increase in the diameter of the bronchioles). Parasympathetic stimulation causes bronchoconstriction while sympathetic stimulation causes bronchodilation. Dilation and Constriction of Bronchioles,

I would think that, during physical illness, in a patient who cannot increase their breathing rate at rest when awake [like Paula, Like Kraepelin’s patients], the body will need sympathetic stimulation [the fight flight response] to send blood to the respiratory muscles in order to keep moving air in and out of the body AND at the same time will prevent parasympathetic stimulation in order to maintain maximum bronchodilation., 1921Topics Psychiatry — Early works to 1900Manic-depressive illnessParanoiaPublisher Edinburgh : LivingstoneCollection gersteintorontomedicalheritagelibraryuniversity_of_torontoDigitizing sponsor MSNContributor Gerstein – University of TorontoLanguage English

The primary goal of the nervous system in a patient like Paula will be bronchodilation at all costs. This will disturb the teamwork between the sympathetic and parasympathetic system for as long as the respiratory crisis goes on. This seems like an absurd situation. How will “rest and digest” function of the parasympathetic system occur if this emergency persists. It can’t. This explains the lack of appetite and thirst and the diminishing fuel for thinking and motor activity. The only thing that matters, it seems, in such a situation, is to keep the patient breathing. The rest is secondary.

The only way to understand what the body is trying to accomplish, is to measure the vital signs. Blood pressure and heart rate will show sympathetic activation. Breathing rate and depth [minute ventilation] will unmask the cause of the sympathetic stimulation – the inability to increase breathing rate during a respiratory crisis plus a lower than normal volume of air passing through the body and brain. Body temperature will fall [mild hypothermia] and vasoconstriction will occur.

This will result in behaviour designed to conserve energy without eating or drinking for as long as is possible. Hence the “mild” akinetic mutism inhibiting speech and motor activity but no paralysis per se. [see post discussing akinetic mutism].

We need to study this syndrome especially as it is fully reversible and spares the brain permanent damage.

It is very cool….as long as it is not happening to you, that is.


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