Renal Nerve Supply and Blood Vessels Quiz

Location and External Anatomy of the Kidneys

• The kidneys are bean-shaped and retroperitoneal, located in the superior lumbar region between T12 and L5.
• The right kidney is crowded by the liver, so it lies lower than the left.
• The kidneys have a convex lateral surface and a concave medial surface with a vertical renal hilum.
• The renal hilum leads to the internal space called the renal sinus, where the ureters, renal blood vessels, lymphatics, and nerves enter and exit.
• The adrenal (suprarenal) gland sits atop each kidney.
• The kidneys are surrounded by three layers of supportive tissue: renal fascia, peri-renal fat capsule, and fibrous capsule.

Internal Anatomy of the Kidneys

• The internal kidney has three distinct regions.
• The kidneys are part of the urinary system, which also includes the ureters, urinary bladder, and urethra.

Function of the Kidneys

• The kidneys maintain the body's internal environment by regulating total water volume and total solute concentration in water.
• They regulate ion concentrations in extracellular fluid (ECF) and ensure long-term acid-base balance.
• The kidneys excrete metabolic wastes, toxins, and drugs, and produce erythropoietin (regulates blood pressure) and renin (regulates RBC production).

Nephrons

• Nephrons are the structural and functional units that form urine, with over 1 million per kidney.
• Each nephron has two main parts: the renal corpuscle and the renal tubule.
• The renal corpuscle consists of the glomerulus and glomerular (Bowman's) capsule.
• The glomerulus is a high-pressure capillary bed composed of fenestrated endothelium, allowing for efficient filtrate formation.
• The glomerular capsule is a cup-shaped, hollow structure surrounding the glomerulus, consisting of two layers: parietal and visceral.

Renal Tubule

• The renal tubule is about 3 cm (1.2 in.) long and consists of a single layer of epithelial cells.
• The renal tubule has three major parts: proximal convoluted tubule, nephron loop, and distal convoluted tubule.
• The proximal convoluted tubule is closest to the renal corpuscle, and the distal convoluted tubule is farthest from the renal corpuscle.
• The distal convoluted tubule drains into the collecting duct.

Collecting Duct

• The collecting ducts maintain water and Na+ balance and help maintain acid-base balance of blood.
• They receive filtrate from many nephrons and run through the pyramids.
• The ducts fuse together to deliver urine through papillae into minor calyces.

Types of Nephrons

• There are two major groups of nephrons: cortical nephrons (85% of nephrons) and juxtamedullary nephrons.
• Juxtamedullary nephrons have long nephron loops that deeply invade the medulla, and ascending limbs have thick and thin segments.
• Juxtamedullary nephrons play an important role in the production of concentrated urine.