Kidney

• Kidney external feature

  • Reddish brown bean-shaped organ
  • 10 lenght, 2.5cm in thickness
  • 2 surfaces: anterior and posterior
  • 2 poles: superior and inferior
  • 2 border: medial and lateral
  • hilum on medial border

  
• Kidneys are responsible for

  • Removal of excess water, salts, wastes protein metabolis and drugs from blood
  • returning nutrients and chemicals to blood
  • balancing body fluids
  • releasing hormones that regulate blood pressure
  • producibg active form of vitD
• • Kidney lies on each side of vertebral column at level of t12-l3
  • right kidney is lower than left due to liver
  • left kidney lies deep to 11,12th ribs

  
• Each kidney has 2 poles

  • superior pole: of right kidney is 2.5cm lower than left
  • inferior pole
• Layers covering kidneys

  • fibrous capsule
  • perinephric fact: adipose capsule that lies external to fibrous capsule. Surround kidney, suprarenal gland and their vessels. Extends into renal sinus
  • renal fascia of gerrota: condensed part of endothoracic fascia. Lies external to perinephric fat.
  • paranephric fat: extraperitoneal fat of lumbar region lies external to renal fascia of gerrota

  
• Posterior aspect of each kidney is related to

  • 4 muscles: diaphragm (superiorly), psoas major (inferiorly and medially), quadratus lumborum (inferiorly), transversus abdominis
  • 3 nerves: subcostal n, iliohypogastruc, ilioinguinal nerves
  • subcostal artery and vein

  
• Anterior aspect of right kidney is related to

  • Right suprarenal
  • right lobe of liver
  • 2 part of duodenum
  • right colic flexure
  • coils of ileum

  
• Anterior aspect of left kidney is related to

  • Left suprarenal
  • stomach and lesser omentum
  • spleen and splenic vessels
  • body and tail of pancreas
  • left colic flexure and descending colon
  • coils of jejunum

  
• Arterial supply of kidneys

  • each kidney is supply by renal artery
  • Renal arteries are lateral branches of abdominal aorta arise at l1 level
  • right renal artery is longer and lower than left and passes posterior to IVC
  • each renal artery divides close to hilum into anterior branch which then divides into segmental branches and posterior branch which continues as the 5 segmental brancg. These segmental branches are end arteries

  
• relation of kidney

  
• Vascular renal segments : Each renal artery divides into

  1. Anterior branch  which gives 4 segmental end arteries to apical ( superior ) , anterior superior , anterior inferior and inferior renal segments .

  2- Posterior branch which continue as posterior segmental artery .
• Kidney anterior relations

  
• The kidneys are bilateral organs placed retroperitoneally in the upper left and right abdominal quadrants and are part of the urinary system
• • Maintaining ACID-base balance
  • Maintaining WATER balance
  • ELECTROLYTE balance
  • TOXIN removal
  • BLOOD Pressure control
  • Making ERYTHROPOIETIN
  • Vitamin D metabolism
• The posterior surfaces of both kidneys are related to certain neurovascular structures and muscles:

  • 1 Artery: subcostal artery
  • 2 Bones: 11th and 12th ribs
  • 3 Nerves: subcostal, iliohypogastric, and ilioinguinal nerves
  • 4 Muscles: diaphragm, psoas major, quadratus lumborum, transversus abdominis
• Margins of the kidneys

  Each kidney has two margins (borders) :

  • lateral margin : convex .
  • medial margin : concave, containing a vertical cleft (the renal hilum) .
  • renal hilum: structures entering and existing kidney: renal vein anterior, renal artery middle and renal pelvis posterior.

  
• Renal sinus is an area around the renal hilum that contains fatty tissue, blood vessels, lymphatic channels, and nerve fibers.
• Renal internal structure(parenchyma of kidney) consists of

  1. Renal cortex: outer portion of kidney just beneath capsule
  2. contains: renal corpucles (glomerulus + bowman’s capsule); proximal convulated tubuled and distal convulated tubules

  
• Kidneys

  • Pair excretory organs situated on posterior abdominal wall one on each side of vertebral column
  • on average 150g
• Parenchyma of kidney shows

  • Outwr reddish bomrown cortex
  • inner pale medulla
  • renal sinus
• Renal medulla

  • Inner portion of the kidney, beneath the cortex.
  • contains renal pyramids, loops of henle and collecting duct.
  • main unit of medulla is renal pyramid. 8-18 renal pyramids in each kidneys that look triangular on cororanal section, with base direct towwrds cortex and apex towards hilum. Apex is called renal papilla and it open into a minor calix.
  • several minor calix joins to form major calix, which is ussually 2-3, which later join to form renal pelvis.
  • pyramids are separated by renal columns.

  
• Functional unit of kidney

  • Nephron.
  • it consist of glomerulus within cortex and tubules within medulla. The later drains to a collecting duct which opens onto surface of renal papilla into minor calyx.

  
• • Each nephron contains: renal corpuscles which filters blood and renal tubules that processes and carries filtered blood to system of calices
  • renal corpuscle: glomerulus (tuft capillaries where blood filtration begins; supplied by afferent and efferent arteriole) + bowman capsule (double layer capsule surrounding glomerulus collecting filtrate that passes through glomerular capillaries)
• Renal tubules

  • PCT: Continuation of Bowman's capsule; responsible for reabsorption of h2o, ions, nutrients.
  • Loop of Henle: Descends into medulla and then ascends back to cortex; important concentrating urine.
  • Descending Limb: Permeable to h2o, allows h2o to be reabsorbed into medulla.
  • Ascending Limb: Impermeable to h2o, actively transports ions out of filtrate, contributing to osmotic gradient in medulla.
  • DCT: in cortex; involved in selective reabsorption and secretion.
  • CD: Receives filtrate from multiple DCTs; passes through medulla to renal papilla, where urine is collected by minor calyces.

  
• Nephron functional unit of kidney

  
• Arterial supply of kidney

  • Renal Artery: Branches from abdominal aorta and enters the kidney at hilum.
  • Segmental Arteries: Branch from the renal artery within kidney.
  • Inter lobar Arteries: Travel between the renal pyramids.
  • Arcuate Arteries: Arch over the bases of the renal pyramids.
  • Interlobular Arteries: Extend into the cortex, giving rise to afferent arterioles.
  • Afferent Arterioles: Supply blood to the glomeruli.

  
• Venous drainage of kidney

  • Efferent Arterioles: Drain blood from glomeruli, forming peritubular capillaries and vasa recta.
  • Peri tubular Capillaries: Surround renal tubules, involved in reabsorption and secretion.
  • Vasa Recta: Capillaries that follow the loop of Henle, crucial for maintaining osmotic gradient in medulla.
  • Interlobular Veins: Drain peritubular capillaries.
  • Arcuate Veins: Collect blood from interlobular veins.
  • Inter lobar Veins: Drain Arcuate veins.
  • Renal Vein: Formed by the convergence of interlobar veins; exits the kidney at hilum and drains into IVC

  
• Blood supply and venous drainage


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• Longitudinal disposition of renal fascia

  • Superior encloses kidney extends superior covering suprarenal gland and becomes continuous with inferior fascia of diaphragm (suspensory ligament of suprarenal gland)
  • inferior it continuous downward, covers ureter