Human Anatomy, Part 1 - K. A. Dyubenko, A. K. Kolomiyytsev, Yu. B. Chaykovsky 2002

Special Part
Endocrine glands (ductless glands), glandulae endocrinae (glandulae sine ductibus)
Peripheral Endocrine Organs — Adrenal Glands

The Adrenal Glands, glandulae suprarenalis [adrenalis], are paired Organs located in the retroperitoneal space above the upper pole of the Kidney (Fig. 345) at the level of the X-XII thoracic vertebrae.

Externally, the Adrenal gland is enclosed by the renal fascia, fascia renalis, and the adipose capsule of the kidney. The right adrenal gland is triangular in shape and flattened in the anteroposterior direction; its upper curved surface caps the upper pole of the kidney and abuts the posterior surface of the Liver.

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Fig. 345. Adrenal gland, glandulae suprarenalis.

1 - superior suprarenal Arteries and Veins; 2 - inferior suprarenal arteries and veins; 3 - adrenal gland; 4 - renal artery; 5 - kidney; 6 - renal vein; 7 - INFERIOR VENA CAVA; 8 - aorta; 9 - central vein

The left adrenal gland is crescent-shaped, adjacent to the upper pole and medial border of the kidney; its upper surface touches the Spleen, Pancreas, and the cardiac part of The Stomach.

The adrenal gland has three surfaces: the anterior, facies anterior, the posterior, facies posterior, and the renal, facies renalis. The outer surface of the adrenal gland is covered by a Connective Tissue capsule, from which fine trabeculae extend into the parenchyma, forming the stroma of the organ.

On the anterior surface, there is an area of grooves known as the hilum, through which arteries and veins enter and exit, and nerves pass. The total weight of the adrenal glands in an adult is 10-20 g, the vertical dimension is 30-60 mm, and the anteroposterior dimension is 5-8 mm.

The parenchyma of the adrenal gland consists of the cortex and the medulla. The cortex, cortex, has a yellowish color on a freshly cut surface and is located peripherally. The cortical parenchyma is formed by Epithelial Tissue, which in turn develops from the coelomic epithelium. It is divided into three zones: the zona glomerulosa, located outermost; the zona fasciculata, in the middle; and the zona reticularis, located deepest (Fig. 346).

Fig. 346. Microscopic Structure OF THE adrenal gland (according to I. V. Almazov and L. S. Sutulov):

1 - capsule of the gland; 2 - zona glomerulosa; 3 - zona fasciculata; 4 - zona reticularis; 5 - medulla; 6 - sinusoidal capillary

The medulla, medulla, has a brownish color and is located centrally; it is represented by chromaffin Cells, which are derivatives of Nervous Tissue, with wide Blood capillaries situated between them.

More than 50 biologically active compounds have been isolated from the adrenal cortex. Based on the Physiological effects of cortical Hormones on The Human Body, they are divided into three groups:

- mineralocorticoids - hormones that primarily regulate mineral and Water METABOLISM;

- glucocorticoids - hormones that mainly affect carbohydrate and Protein metabolism;

- Sex Hormones - androgens (androgenic Steroid Hormones, chemically and physiologically similar to testicular testosterone), estrogens, and progesterone (Female Sex Hormones).

Function. The adrenal medulla produces hormones: epinephrine (adrenaline) and norepinephrine (noradrenaline), which enhance myocardial contractility, constrict Skin Blood Vessels, and elevate blood pressure.

Blood supply to the adrenal glands is provided by the superior, middle, and inferior suprarenal arteries. Venous drainage is carried out by the right and left suprarenal veins. The right suprarenal vein empties into the inferior vena cava, while the left vein, after joining v. phrenica, drains into the left renal vein.

Lymphatic drainage from the cortex and renal capsule occurs via superficial Lymphatic vessels. Deep lymphatic vessels drain Lymph from the medulla and the zona reticularis of the cortex. Lymph flows into the Lymph Nodes located around the aorta and the inferior vena cava.

Innervation. Efferent Innervation of the adrenal glands is supplied by fibers from the celiac, renal, and suprarenal nerve plexuses.