Gross Anatomy of the Kidneys

Anatomical Position of the kidneys

• retroperitoneal, between T12 and L3 vertebrae 

• right kidney positioned lower due to the liver 

External Kidney Border

• each kidney has a convex lateral border and a concave medial border 

What are the different protective layers surrounding the kidneys

• renal capsule

• perirenal fat

• renal fascia

• perirenal fat

Renal Capsule

• thin, tough fibrous capsule that tightly adheres to the renal surface

Perirenal fat

• cushioning layer 

• adipose capsule 

Renal fascia 

• encloses kidney and adrenal gland

• gerota’s fascia

Pararenal Fat

• outermost layer

• provides additional cushioning and insulation 

What is the kidney divided into

• cortex

• medulla 

Renal Cortex

• outermost layer beneath renal capsule

• houses renal corpuscles and convoluted tubules

• main site of filtration

Renal Medulla

• inner portion organized by renal pyramids 

• striated appearance due to collecting ducts and loops of henle 

• main function is reabsorption and secretion of urine 

Renal Pyramides

• cone shaped

• 8-18 pe kideny 

• apex inward to form the renal papilla, projecting into minor calyces 

Renal Columns

• extensions of cortical tissue between pyramids 

• contain interlobar arteries and veins 

• provide structural support and pathway for blood vessels

Calyces

• urine collection chambers

• major and minor

• funnel urine toward renal pelvis

Major Calyces

• formed by convergence of 2-3 calyces 

• passageway funneling urine toward renal pelvis 

Minor Calyces

• cup-shaped structures that receive urine from the papillae of renal pyramids 

Renal Pelvis

• funnel-shaped upper expanded end of the ureter 

• collects major from the major calyces 

• narrows to form the ureter at the hilum 

Lobes

• each kidney has 8-18 lobes

• renal pyramid+ overlaying cortex+renal column on either side

Kidneys and arterial supply

• kidneys receive 20-25% of cardiac output (1.2 L  of blood flow)

Renal Artery

• branch of abdominal aorta

• enters at the hilum 

Arterial Supply Pathway

Renal Artery → segmental arteries → interlobular arteries → arcuate arteries → interlobular arteries → afferent arterioles → glomeruli 

What do efferent arterioles exit glomeruli and form:

• peritubular capillaries

• vasa recta 

Peritubular Capillaries 

• around the cortical nephron

Vasa Recta

• straight vessels along juxtamedullary nephrons

What eles is the renal microculation divided into

• cortical capillary plexus

• medullary capillary plexus

Where does blood from from the kidneys into?

• blood exits the kidneys through the renal vein

How does blood flow out of the kidneys?

• Arcuate veins → interlobular veins → segmental veins