Human Anatomy. Part 2 - K. A. Diubenko, A. K. Kolomiitsev, Yu. B. Chaikovskyi 2008

Special Section
Cardiovascular system, systema cardiovasculare - General Overview
Arteries - Arteriolo-venular anastomoses (AVA)

Arteriolovenular anastomoses, anastomosis arteriolo-venularis (Fig. 5), are vascular connections within the HMCR through which arterial Blood enters the Veins, bypassing the capillary bed (V. V. Kupriyanov). Arteriolovenular anastomoses have a length of 4 mm and a diameter of 30-500 μm, are found in most Organs, and are capable of contracting 2-12 times per minute. They are divided into two groups:

1. True anastomoses, or shunts, through which pure arterial blood flows, discharging directly into the venous bed. Arteriolovenular anastomoses serve as pathways for accelerated Circulation and, when necessary, can divert arterial blood into the Venous system.

2. Atypical anastomoses, or half-shunts, which are connections between arterioles and venules via a short capillary-type vessel, carrying mixed blood. They divert blood from distal arterioles into initial venules. The Regulation of Blood flow in these anastomoses is mediated by smooth Muscle Cells in the arteriole wall or by surrounding glomus cells capable of shutting off the blood flow.

Thus, There are two pathways of BLOOD FLOW IN the HMCR: transcapillary, which serves for substance exchange, and juxtacapillary (or extracapillary), which ensures hemodynamic balance. Arteriolovenular anastomoses play an important role in regulating local Blood Circulation, regulating blood pressure, stimulating venous return, oxygenating venous blood, and participating in the body's compensatory responses to Circulatory Disorders.

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Fig. 5. Classification scheme of arterio-venous anastomoses (arrows indicate the direction of blood flow).

I - shunts: a - with constant blood flow; b, c, and d - with regulated blood flow (b - arterio-venous anastomoses without an intermediate segment; c - arterio-venous anastomoses with intermediate segments; d - branched arterio-venous anastomoses). II - half-shunts: a - with constant blood flow; b - with regulated blood flow. III - arterio-venous anastomosis bounded by glomus cells: 1 - arteriole; 2 - venule; 3 - glomus; 4 - myoid cells.

Fig. 6. Diagram of the SYSTEMIC AND PULMONARY circulation (after F. Kiss and J. Szentágothai)



Last update: 08/08/2026

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