Vasodilation: what it is, how it works and what it is used for.

Let's see what vasodilation consists of, in what situations it occurs and how it affects the organism.

The circulatory system is a transport system used by living beings to move nutrients, metabolic compounds, oxygen, carbon dioxide, hormones and many other substances within the body. Through this system of veins, arteries and capillaries flows the blood, a reddish liquid whose color is attributable to the red blood cells, which transport oxygen to each and every cell of the body.

An adult human being has approximately 5,000,000 red blood cells per microliter of blood, which is 1,000 times more than the proportion of white blood cells. Moreover, from end to end (and counting veins, arteries and capillaries), our circulatory system would occupy in a straight line about 100,000 kilometers, 2.5 times the circumference of the earth. As you can see, this transport network moves in astronomical figures.

Beyond the importance of the circulatory system, the heart's energy expenditure, heart disease and its impact on society and many other informative topics, there is a term related to the circulatory system that not everyone knows. We tell you all about vasodilation and what it implies at the physiological level..

What is vasodilation?

Vasodilatation is a process in which the diameter of the blood vessels (veins or arteries) increases (veins or arteries), after which a more hollow cavity is formed and more blood flow is allowed. This concept is the opposite of vasoconstriction, an event in which the vessels are narrowed by the action of small muscles in their walls.

The Clínica Universidad de Navarra (CUN) gives a much more exact medical definition of the term: "A dilatation of the lumen of the blood vessels, either as a consequence of an increase in intravascular pressure (passive vasodilatation), or, more frequently, by a decrease in vasomotor tone, as a consequence of relaxation of the vascular musculature".

Generally, vasodilatation has a positive connotation and vasoconstriction is associated with pathologic processes.. This is mainly because vasodilatation commonly occurs in response to natural events, such as low oxygen levels in the body or an increase in body temperature (physiological processes that occur in sports, for example).

When does vasodilation occur?

There are multiple causes of vasodilatation in the organism. Among them, we find the following:

• Exercise: as the diameter of the vessels expands, more blood flows, allowing more oxygen and nutrients to reach the muscles during times of activity.
• Alcohol: these types of beverages are natural vasodilators. Interestingly, as more blood reaches the skin, it is common to feel a sensation of warmth in times of drunkenness.
• Inflammation: inflammatory processes occur in response to physiological stress due to a blow or bacteria, among others. This induces local vasodilatation.
• Natural chemicals: some hormones, such as histamine, are natural vasodilators in the body.
• After consumption of vasodilators: drugs that will be discussed later.

As you can see, vasodilation generally has a specific purpose: to increase blood flow to an area that requires more oxygen, nutrients or cellular action.

This is particularly striking in the case of inflammation, as it makes good biological sense to widen the diameter of veins and capillaries to allow more blood flow to the affected area. to the affected area. Macrophages and mast cells, cells of the immune system that respond in a general way to pathogen attacks, by acting locally cause the outflow of fluid from the blood into the tissues, generating edema.

The process of alcohol consumption is also very interesting. These drinks, at the level of the circulatory system, increase cardiac activity and produce peripheral vasodilatation, which explains the reddening of the skin and the increase in surface temperature after consumption.

Interestingly, this does not help to resist the cold more, as a higher surface blood flow implies a higher heat loss. Medical portals therefore stipulate that there may be an increased risk of hypothermia following alcohol poisoning in an exceptionally cold environment.

Spontaneous vasodilation

Spontaneous vasodilation of a tissue involves a rapid response of the tissue to a stimulus in order to obtain the increased blood flow required. Strong emotions, such as joy, despair or fear, lead to increased work of the heart in pumping blood.. As a consequence, vasodilation is activated to result in a more consistent and stronger blood flow.

Have you ever wondered why we turn red when we make a mistake? When humans feel that they have done something wrong or blush for any other reason, the parasympathetic system is activated and adrenaline is released throughout the bloodstream. This causes an increase in heart rate, agitated breathing, increased sweating and a characteristic vasodilatation in the facial area.. Thus, as there is increased blood flow under the skin, the person is said to have flushed (literally, there is increased blood flow).

Vasodilation and temperature

It is known to every biologist that vasodilation is an excellent regulatory mechanism in all animals with a blood system. When it is very hot, the surface thermoreceptors send a signal to the brain that something must be done to dissipate heat.

As a result, a process of vasodilation is activated, which allows blood to flow to the allows blood to flow to the outermost layers of the skin.. This promotes a thermal exchange with the environment, which helps the individual to lower its body temperature.

If you observe a fennec (a desert fox), you will see that it has disproportionately large ears compared to the rest of its body. This characteristic is not anecdotal: in addition to excellent hearing, it gives the animal a greater surface irrigation, which allows it to dissipate heat at times of heat loss. dissipate heat during the hottest times of the day.. Fascinating, isn't it?

Diseases associated with this physiological process

Although we have previously mentioned that vasodilation is usually associated with health, this is not always the case. Here are some diseases that are relatively related to this physiological event.

Shock

Shock has several causes: low blood volume in the body, inadequate cardiac pumping capacity and excessive widening of the blood vessels, or vasodilatation (also known as distributive shock).

If exaggerated, dilation of the blood vessels can reduce blood pressure.. This, in some cases, leads to a decrease in blood flow and a lower supply of nutrients and oxygen to certain body tissues. Blood vessels can become excessively dilated for reasons such as these:

• An allergic reaction or bacterial infection of a serious nature.
• Overdose of vasodilator drugs.
• Spinal cord injury.
• Certain endocrine disorders.

Low blood pressure (hypotension).

This event is closely linked to the previous case. When blood pressure is much lower than normal, the patient may experience a severe deficit at the physiological level.. This causes nausea, dizziness, confusion, malaise and even loss of consciousness in the individual.

Hypotension can cause the previously described shock if it happens pathologically, so a rapid medical approach is sometimes necessary. This includes administration of intravenous blood, medications to increase blood pressure and cardiac strength, and other drugs.

Vasodilators

Vasodilators, as the name implies, are drugs that widen (vasodilate) blood vessels. They act directly on the muscles in the walls of veins and arteries, preventing them from contracting and the diameter of the space from decreasing. As a result of the administration of these drugs, blood flows more easily through the ducts, which prevents the heart from pumping as fast, thus lowering high blood pressure.

Physicians often prescribe the use of vasodilators in the following scenarios: high blood pressure (on a regular basis or during pregnancy and childbirth), heart failure and pulmonary hypertension, among other clinical conditions..

However, the use of vasodilators is not without risk. Medical portals report that they report certain side effects, such as increased heart rate (tachycardia), palpitations, nausea, vomiting, flushing, headache and many other clinical signs. For this reason, their consumption is only considered when a medical professional has prescribed them for a specific reason.

Summary

Vasodilatation is a normal physiological process, as it occurs when we are nervous, when we exercise, when the temperature rises, with the consumption of alcohol and in many other common events during an individual's life. during the life of the individual.

Unfortunately, there are certain pathological processes that can arise in response to excessive vasodilation. Hypotension can result in insufficient blood and oxygen reaching the brain and other organs of the body, which can be life-threatening.

Bibliographic references:

• Shock, MSDmanuals. Retrieved January 31 from https://www.msdmanuals.com/es/hogar/trastornos-del-coraz%C3%B3n-y-los-vasos-sangu%C3%ADneos/presi%C3%B3n-arterial-baja-y-choque-shock/choque-shock#:~:text=The%20excessive%20dilatation%20of%20those%20of%20ox%C3%ADGene%20to%20those%20of%20organs.&text=The%20mechanisms%20by%20which%20these%20diseases%20produce%20vasodilatation%20of%20the%20organs%20are%20varied.
• Vasodilatation, Clínica Universidad de Navarra. Retrieved January 31 from https://www.cun.es/diccionario-medico/terminos/vasodilatacion.
• Vasodilators, Mayoclinic.org. Recogido a 31 de enero en https://www.mayoclinic.org/es-es/diseases-conditions/high-blood-pressure/in-depth/high-blood-pressure-medication/art-20048154