The kidney filters the blood and produces urine.

Key features:

Fibrous capsule (aka, renal capsule)

• A layer of connective tissue that protects the kidney.

Hilum

• Cleft on concave, medial surface where the renal arteries and veins, nerves, and ureters enter and exit the kidney.
• Continuous with the renal sinus.

Renal sinus

• A space where fat, blood vessels, and structures that drain urine reside.

Renal pyramids

• Contain urine-collecting tubules and ducts, which is what gives them their striated appearance.
• Collectively, the renal pyramids constitute the renal medulla (which is why some authors refer to the renal pyramids as the medullary pyramids).

Renal medulla

• Inner area of the kidney that comprises the renal pyramids.

Renal cortex

• Outer area of the kidney that extends between the pyramids of the medulla as renal columns.

Renal papilla

• Is at the apex of the renal pyramid

Corticomedullary junction

• Is the wide base of the renal pyramid, where it meets the cortex

Renal lobe

• Comprises a single renal pyramid and the renal column and cortex that surround it.

Renal calyces

• Minor and major
• Drain urine from the collecting ducts of the pyramids.

Renal pelvis

• Wide, flattened end of the ureter that receives the urine from the major calyces, and funnels it out of the kidney.

Arterial Supply:

Renal artery

• Enters the kidney at the hilum; recall that the renal artery arises from the descending abdominal aorta.
• Gives rise to segmental arteries.

Segmental arteries

• Branch to form interlobar arteries, which travel between the renal lobes, within the renal columns.

Interlobar arteries

• Give rise to arcuate arteries; notice that these arteries “arc” over the bases of the renal pyramids.

Arcuate arteries

• Give rise to multiple interlobular arteries, which radiate through the cortex (hence, their alternative name, cortical radiate arteries).

Interlobular arteries

• Give rise to afferent arterioles

Afferent arterioles

• Carry blood to glomerulus

Efferent arterioles

• Carry filtered blood away from glomerulus

Peritubular capillary beds

• Where gas exchange occurs
• Vasa recta weaves around nephron loop of juxtamedullary nephron.

Nephron Anatomy:

• Nephrons are the functional units of the kidney; they filter the blood to produce urine.
• Two nephron types:
  — Cortical (aka, superficial), which reside primarily in the renal cortex
  — Juxtamedullary, which travel through the renal pyramids

Features of the Juxtamedullary nephron:

• Renal corpuscle comprises:
  — Outer glomerular capsule (aka, Bowman’s capsule)
  — Inner glomerulus, which is a dense collection of capillaries
• Proximal convoluted tubule
• Nephron loop
• Distal convoluted tubule
• Collecting duct, which drains to the renal papilla