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Local vascular blood volume increases and blood flow accelerates.

[chng xuè]

Local vascular blood volume increases and blood flow accelerates.

Chinese name

Hyperemia

Foreign name

congestion

Congestion

Word : hyperemia

Pinyin: chng xi

English : congestion

Basic explanation

[hyperemia; congestion] Increased local vascular blood volume and accelerated blood flow

Extended meaning: Excitement-he was a little bit excited with his head congested.

Fill up, cheer up-read more books and congest yourself

explain in detail

Phenomenon, capillary blood volume increase and blood flow acceleration due to excessive fatigue or stimulation.

Congestion concept

Hyperemia refers to increased blood content in the blood vessels of a tissue or organ. Can be divided into arterial congestion and venous congestion. Arterial congestion is caused by increased blood input to local tissues or organs, resulting in increased blood content in arterial vessels. Because venous return is blocked, the blood content of capillaries and small veins in local tissues or organs increases, which is called venous congestion.

Broadly speaking, it is a state in which blood volume is increased in a part of an organ. But generally it does not include passive congestion (congestion) caused by the increase of venous blood, but refers to arterial (active) congestion in one finger. In addition to inflammation, warm, mechanical, chemical, and mental irritation can be an important cause of congestion. These stimuli can lead to congestion through excitation of the vasodilating nerve or paralysis of the vasoconstrictor. When arterial congestion is caused by a large amount of blood to accelerate circulation, local signs of redness, increased temperature, swelling, and hyperfunction occur. The phenomenon of excessive expansion of small blood vessels in local tissues and organs of the body and an increase in blood content than normal.

Congestive etiology

1. Arterial congestion: due to the effects of neurohumoral fluid, the arterioles are dilated, resulting in excessive blood inflow into local organs or tissue arteries and congestion occurs. The causes of congestion can be divided into two types, physiological and pathological, according to the causes of initiation. Increased vasodilation nerve excitability or decreased vasoconstriction nerve excitability, increased release of vasodilating active substances, etc., cause arteriolar dilation, accelerated blood flow, and increased arterial blood input microcirculation perfusion. Common are: physiological congestion, such as gastrointestinal mucosa after eating, skeletal muscle during exercise, and uterine congestion during pregnancy; inflammatory congestion, which is seen in the early stages of local inflammatory reactions, caused by the action of inflammatory factors Axonal reflex excites the vasodilating nerve, and vasoactive substances such as histamine and bradykinin expand the arteries; congestion after decompression, such as long-term compression of local organs or tissues, is seen in bandaged limbs or After a large amount of ascites compresses the organs in the abdominal cavity, the blood vessel tension in the tissue is reduced. If the pressure is suddenly relieved, the arterioles in the compressed tissue will reflect and expand, causing local hyperemia.

2. Venous congestion (congestion)

Vein compression causes stenosis or occlusion of the lumen, such as tumors compressing local veins; pregnant uterus compresses common iliac vein; incarcerated intestinal hernia, intussusception, and intestinal torsion compress mesenteric veins.

Blockage of venous cavity, such as venous thrombosis, obstruction of venous return, resulting in localized congestion. However, because there are many venous branches and abundant anastomotic collaterals, congestion occurs in the venous lumen obstruction only when the veins are blocked and the collateral circulation cannot be established effectively.

Heart failure, such as left heart failure caused by mitral stenosis and hypertension, leads to pulmonary congestion; right heart failure, which occurs during pulmonary heart disease, leads to systemic circulatory organ congestion. Congestive heart failure occurs in both the pulmonary and systemic circulations.

Hyperemia classification

According to its mechanism of occurrence can be divided into arterial congestion and venous congestion.

Arterial congestion, also known as active congestion, is referred to as congestion, which is mainly due to the increase in the amount of blood flowing into the tissue due to the dilatation of small arteries. Generally speaking, the time of arterial congestion is short and it is good for the body. It is called physiological congestion. Such as: hyperemia of skin after hot water bath, hyperemic gastric mucosa after meals. Pathological arterial congestion is seen in inflammatory congestion.

Venous congestion, also known as passive congestion or stasis, refers to the reduction in the amount of blood drawn from the veins through the tissues, and the blood stasis in the small veins and capillaries. The small veins and capillaries in the blood stasis area were significantly dilated and the blood content increased, but the blood perfusion volume in the area decreased. It can be divided into local and systemic congestion according to its cause and the scope of the spread. Local congestion occurs due to local venous compression and blockage of the venous lumen. Systemic congestion occurs due to heart failure and increased intrathoracic pressure.

Under pathological conditions, venous congestion is far more common than arterial congestion, so the former is more clinically significant. Due to hypoxia, tissue metabolism disorders and accumulation of intermediate metabolites during stasis, the mild ones cause degeneration of local parenchymal cells, corresponding morphological changes and reduced functions, and severe cases cause local tissue necrosis. Shrink due to malnutrition. Common blood stasis includes chronic lung stasis and chronic liver stasis.

Congestive lesions and consequences

Congestive arterial congestion

Arterial congestion increases blood volume in organs and tissues, and the volume may increase slightly. If hyperemia occurs on the body surface, it can be seen that the color of the local tissue is bright red and the temperature increases. Arterial congestion is a temporary vascular response. After the cause is eliminated, the local blood volume returns to normal immediately, without leaving adverse consequences, and has no significant impact on the body. Arterial hyperemia of the inflammatory response is the beginning of a series of vascular reactions. It is involved in inflammatory vascular phenomena and has a positive effect.

Congestive venous congestion

Venous congested tissues and organs can swell due to blood stasis; venous congestion that occurs on the surface of the body can cause cyanosis due to reduced blood oxygenated hemoglobin and increased hemoglobin in the blood; due to local blood stasis, capillary The expansion leads to increased heat dissipation, which reduces the temperature on the body surface. Venous congested tissue shows dilated small veins and capillaries under the microscope, filled with blood, and sometimes accompanied by edema. Due to the reduced partial blood oxygen pressure, the organs and tissues are relatively hypoxic, which may weaken the metabolic function.

as a result of:

The effect of venous congestion on the body depends on the extent of the congestion, the organs that are congested, the extent of the congestion, the rate at which the congestion occurs (acute or chronic), and the status of collateral circulation. Systemic congestion affects the function of many important organs, and corresponding dysfunctions (such as kidney, liver, and lung) can occur. Local venous congestion mainly affects the function of local organs.

Long-term venous congestion causes accumulation of metabolic intermediates in local tissues, thereby damaging capillaries and increasing their permeability. In addition, the hydrostatic pressure in small veins and capillaries increases during congestion, leading to edema in local tissues. Severe bleeding may even occur in severe cases. Such as pulmonary congestion, the capillaries of the alveolar wall are dilated and congested. In severe cases, edema fluid may appear in the alveolar cavity and even bleeding. If the red blood cells in the alveolar cavity are swallowed by macrophages, their hemoglobin becomes hemosiderin, making the sputum brown. These macrophages are often found in the context of left heart failure and are therefore called heart failure cells.

Long-term congestion, due to insufficient supply of oxygen and nutrients and accumulation of metabolic intermediates, can also cause atrophy and degeneration of parenchymal cells. For example, in chronic hepatic congestion (Figure 3-2), hepatocytes atrophy (mainly in the central zone of the hepatic lobules) and steatosis (mainly in the zone around the lobules), so that the liver section shows a betel nut-like pattern, called betel nut liver . More acute and severe liver congestion can cause hepatocyte necrosis.

In some organs, while chronic congestion causes atrophy of parenchymal cells, interstitial cells can proliferate. For example, in chronic hepatic congestion, central lobular hepatocytes atrophy, connective tissues proliferate, and finally congestive liver cirrhosis is formed.

Because veins usually have abundant anastomotic branches, when a vein is blocked, the anastomotic branch can be expanded in time, which helps local blood return and plays a compensatory role. This circulation of blood through the anastomotic branch is called the collateral circulation. The most typical example is the venous blood flow of part of the portal vein system in cirrhosis, which is returned to the right heart through the collateral circulation. The important ways are as follows: transgastric coronary vein inferior esophageal vein odd vein superior vena cava At this time, the mucosal veins of the lower esophagus and gastric fundus are highly dilated and curved, protruding from the mucosal surface; Peri-umbilical abdominal veins superior abdominal veins internal mammary veins superior vena cava, the patient's peri-umbilical abdominal veins are highly dilated and curved, forming a so-called "caput medusae" -like shape; trans-mesenal vein hemorrhoid vein Plexus internal iliac vein inferior vena cava, the hemorrhoid vein plexus is highly dilated, forming hemorrhoids.

Collateral circulation has a certain degree of compensation, but when the degree of congestion exceeds the range that can be compensated by collateral circulation, various pathological changes caused by venous congestion will eventually occur. For example, in the case of cirrhosis, despite the collateral circulation described above, patients still have congestive splenomegaly, gastrointestinal congestion, and ascites. In addition, although the collateral circulation has the positive significance of compensating venous return, the collateral veins are excessively varicose and sometimes can rupture secondary (such as varicose veins in the lower esophagus, which can cause fatal major bleeding).