The kidneys. Structure, functions

The kidney , ren, is a paired bean-shaped organ. The kidneys are located in the abdominal cavity, in the lumbar region, on either side of the spine .

The size of the kidney.

Each kidney reaches a length of 10-12 cm, a width of 5-6 cm, its thickness is about 4 cm. The mass of one kidney is 120-200 g. The left kidney is somewhat longer than the right kidney, sometimes it has a large mass. The color of the kidneys is often dark brown.

The surface of the kidney.

In the kidney, the front and back surfaces, the lateral and medial margins, the upper and lower ends are distinguished.
The anterior surface , facies anterior, convex and inverted somewhat laterally. The upper 2/3 of the right kidney is adjacent to the liver, and the upper third of the left kidney is to the stomach.

The posterior surface , facies posterior, is flattened. The side portion of each kidney is attached to the square muscle of the waist.

The lateral margin , margo lateralis, is convex and is directed somewhat towards the back wall of the stomach; The medial margin , margo medialis, is concave and faces downward, medially and forward.

In the middle of the medial edge of the kidney there is a depression - the renal gates, hilum renalis, which passes into the renal sinus, sinus renalis. The portal of the kidney is bounded by two projections of the medial margin, of which the posterior protrusion protrudes. As a result, the posterior surface of the kidney is wider than the anterior, and the renal sinus is more anterior to the anterior.

In the renal sinus are the renal pelvis, pelvis renalis, renal cups, calices renales, renal vascular and nerve branches, lymph nodes and fatty tissue. The mutual arrangement of the listed entities entering the gates is such that the veins lie in front, the arteries and nerves behind the veins, and the renal pelvis and ureter are posterior to the arteries.

The upper end , extremitas superior, the kidneys are wider than the lower extremitas inferior. At the upper ends of the adrenal glands, glandulae suprarenales. These ends are closer to the median plane of the body than the lower ones; The latter are more deviated from the spinal column.

The kidneys are covered with a dense fibrous capsule, capsula fibrosa, which consists of an outer connective tissue layer and an internal smooth muscle; Fibers of smooth muscles penetrate into the tissue of the kidney. The capsule is weakly fused to the substance of a healthy kidney, and if you make an incision on it, it is easy to remove.

Each kidney is surrounded by a fatty capsule, and outside - a renal fascia.

The fat capsule , capsula adiposa, directly envelops the kidney, covering the thicker layer with its posterior surface; Through the kidneys it penetrates into the renal sinus.

You will be interested to read this:

• Urinary organs.
• The ureter .
• Bladder .
• Urethra.