The Kidney Anatomy is intricate, designed to efficiently filter blood, remove waste, maintain electrolyte balance, and regulate blood pressure.
Each kidney is a bean-shaped organ, approximately the size of a fist, located on either side of the spine, just below the rib cage.
The kidneys are part of the upper urinary tract and play a crucial role in the body's urinary system.
External Anatomy
1. Location:
The kidneys are retroperitoneal organs, meaning they are located behind the peritoneum (a lining of the abdominal cavity).
They are situated on either side of the vertebral column; the right kidney is typically slightly lower than the left due to the presence of the liver.
2. Size and Shape:
Each kidney is roughly 12 centimeters (about 4.5 inches) long, 6 centimeters (2.5 inches) wide, and 3 centimeters (1.2 inches) thick, resembling a large bean.
3. Renal Capsule:
A tough, fibrous membrane surrounding each kidney, protecting it from trauma and infection.
4. Renal Hilum:
The medial indentation where the renal artery enters, and the renal vein and ureter exit the kidney. It acts as a gateway for blood vessels and nerves.
Internal Anatomy
1. Renal Cortex:
The outer layer of the kidney, granular in appearance, containing glomeruli, proximal and distal convoluted tubules, and blood vessels.
2. Renal Medulla:
The inner layer, consisting of 10 to 18 renal pyramids. These cone-shaped tissues house the loops of Henle and collecting ducts. The apex of each pyramid, called the renal papilla, points towards the renal pelvis.
3. Renal Columns:
Inward extensions of cortical tissue separating the renal pyramids. These columns provide a path for blood vessels to enter and exit the cortex.
4. Renal Pelvis:
A funnel-shaped space in the center of the kidney that collects urine from the major calyces and channels it into the ureter.
5. Calyces:
The renal pelvis is divided into major calyces, which further divide into minor calyces. These cup-shaped structures enclose the tips of the renal pyramids, collecting urine and draining it into the renal pelvis.
Blood Supply
1.Renal Arteries:
Branches from the abdominal aorta, delivering oxygenated, nutrient-rich blood to each kidney.
2.Renal Veins:
Carry deoxygenated, filtered blood from the kidneys back to the inferior vena cava.
The kidneys receive a significant amount of blood flow, essential for their filtration and excretion functions.
Microscopic Structure
Nephrons:
The functional units of the kidney, with approximately 1 to 1.5 million nephrons per kidney.
Each nephron contains a glomerulus (a capillary bed that filters blood) and a renal tubule, where the filtrate is processed and converted into urine.