Gross Anatomy of Kidney

Structures of the kidney. Image courtesy of en.wikipedia.org/wiki/File:KidneyStructures_PioM.svg under the terms of the GNU Free Documentation License.

Location

The human kidneys are paired, bean-shaped organs that lie against the posterior abdominal wall on each side of the vertebral column. Each kidney has a convex lateral surface and a concave medial surface; each measures about 12cm long, 5cm wide,2.5cm thick and weighs 125-170g in adult male and 115-155g in adult females. The left kidney lies slightly above the right kidney.

See an illustration of the location of human kidney

Structure

The kidney can be divided into two distinct regions:

  1. Outer portion

•  called the renal cortex and it is filled with glomeruli, capillaries and highly convoluted tubules

  2. Inner portion

• called renal medulla which lacks glomeruli and consists of parallel tubules and small blood vessels

The renal medulla is subdivided to renal pyramids, and the tip of each pyramid is called renal papilla. Pores on each papilla are the openings of collecting ducts. Hilum, a slit in the concave medial surface of kidney serves as the port of entry for blood vessels, renal nerves, lymphatic vessels and ureter. The hilum opens into renal sinus which includes renal pelvis and its extensions, the major and minor calyces.

Each kidney is protected by three layers of connective tissue:

• fibrous renal fascia - binds kidney to the abdominal wall
• adipose capsule - a layer of fat that cushions the kidney and holds it in place
• renal capsule - fibrous sac that protects the kidney from infection

Blood Supply

The kidneys have a rich blood supply. Each kidney receives blood from the aorta via the renal arteries, (which divides and into interlobar arteries) and return blood to the inferior vena cava via the renal veins.

Diagram below shows the sequence of blood circulating through the kidney:

• The following movie shows an animated representation of the anatomy of a kidney.