GROSS ANATOMY OF KIDNEY, URETER AND SUPRA RENAL GLAND
Professor Dr. Mario Edgar Fernández.
Kidneys: Gross Anatomy
Lie in retroperitoneal, superior lumbar region Extend from T11 or T12 to L3 Laterally convex, medially concave Hilus Where blood vessels, ureters, and nerves enter and leave kidney Adrenal gland On superior portion Kidney: Gross Anatomy
Lateral margin. Convex. Medial margin. Concave at the hilum. Renal hilum. Site of entry and exit of blood vessels & ureter. Renal sinus. Cavity at the medial border for the renal hilum. Anterior surface. Facies anterior. Curved. Posterior surface. Facies posterior. Nearly flat. Upper pole. Extremitas superior Lower pole. Extre,itas inferior Projections Kidneys: Gross and Sectional Anatomy
Right kidney ~ 2cm lower than left Adrenal gland on superior pole
KIDNEYS Its main function is to excrete most of the waste products of metabolism
It control the water and electrolyte balance of the body
It maintain acid-base balance of the blood
The waste products leave the kidneys as urine, which passes down the ureters to the urinary bladder
The urine leaves the body through the urethra KIDNEYS Kidneys are reddish brown in color Lie behind the peritoneum of the posterior abdominal wall It lie high up on either side of the vertebral column
Are largely under cover of the costal margin
The right kidney lies slightly lower than the left due to the large size of right lobe of the liver With contraction of the diaphragm during respiration, KIDNEYS both kidneys move downward in a vertical direction as much as 2.5 cm
On the medial border of each kidney is a vertical slit called the hilum
The hilum extends into a large cavity called the renal sinus
The hilum transmits the renal vein, two branches of renal artery, ureter, and the third branch of renal artery from the front backward (V.A.U.A.) 1- Fibrous capsule: It surrounds the kidney COVERINGS 2- Perirenal fat: It covers the fibrous capsule
3- Renal fascia: it is a condensation of connective tissue that encloses the kidneys and suprarenal glands, it is continuous laterally with the fascia transversalis 4- Pararenal fat: it lies external to the renal fascia, and forms part of the retroperitoneal fat Each kidney has a dark brown outer cortex and a Renal Structure light brown inner medulla
Medulla is composed of about a dozen renal pyramids
Each pyramid having its base directed laterally toward the cortex, and its apex, (the renal papilla), projecting medially
The cortex extends into the medulla between adjacent pyramids as the renal column
Extending from the bases of the renal pyramids into Renal Structure the cortex are striations known as medullary rays
The renal sinus within the hilum, contains the upper expanded end of the ureter, the renal pelvis
Renal pelvis divides into two or three major calyces, which divides into two or three minor calyces
NEPHRON – THE FUNCTIONAL UNIT OF KIDNEY
Nephron consists of: Renal corpuscle Renal tubule: Proximal convoluted tubule (PCT) Loop of Henle Distal convoluted tubule (DCT) Nephron empties tubular fluid into a system of collecting ducts and papillary ducts
RENAL CORPUSCLE Consists of: Glomerulus – tuft of fenestrated capillaries Glomerular (Bowman’s) capsule Parietal layer – simple squamous epithelium Visceral layer – consists of podocytes Blood travels from efferent arteriole to peritubular capillaries Blood leaves the nephron via the efferent arteriole RENAL CORPUSCLE AND THE FILTRATION MEMBRANE
Figure 23.6a GLOMERULUS ANATOMY
Podocytes cover lamina densa of capillaries Project into the capsular space Pedicels of podocytes separated by filtration slits TWO TYPES OF NEPHRON Cortical nephrons ~85% of all nephrons Located in the cortex Juxtamedullary nephrons Closer to renal medulla Loops of Henle extend deep into renal pyramids Nephron Proximal convoluted tubule (PCT) Actively reabsorbs nutrients, plasma proteins and ions from filtrate Released into peritubular fluid Loop of Henle Descending limb Ascending limb Each limb has a thick and thin section NEPHRON Distal convoluted tubule (DCT) Actively secretes ions, toxins, drugs Reabsorbs sodium ions from tubular fluid COLLECTING TUBULES (COLLECTING DUCTS) Collecting tubules - Receive urine from distal convoluted tubules
Figure 23.8 Uriniferous Tubule
Figure 23.5a Types Of Capillary Beds In Nephron
Glomerulus - Fed and drained by afferent and efferent arterioles Peritubular capillaries Arise from efferent arterioles Low-pressure, porous capillaries Absorb solutes Vasa recta Thin-walled looping vessels Part of the kidney’s urine- concentrating mechanism
Mechanisms of Urine Production Filtration - filtrate of blood leaves kidney capillaries Reabsorption – most nutrients, water, and essential ions reclaimed Secretion - active process of removing undesirable molecules Microscopic Anatomy of the Kidney Juxtaglomerular apparatus Functions in the regulation of blood pressure Juxtaglomerular cells – secrete renin Macula densa A portion of distal convoluted tubule Tall, closely packed epithelial cells Act as chemoreceptors SUMMARY OF NEPHRON FUNCTION
Each segment of nephron and collecting system contribute Glomerulus PCT Descending limb Thick ascending limb DCT and collecting ducts Concentrated urine produced after considerable modification of filtrate Nephrons The functional filtration unit in the kidney. Consists of the following: Renal corpuscle Glomerulus Glomerular capsule (Bowman’s capsule) Proximal convoluted tubule (PCT) Nephron loop (loop of Henle) Ascending loop of Henle Descending loop of Henle Distal convoluted tubule (DCT) collectively called the renal tubule In both kidneys: approximately 2.5 million nephrons. Are microscopic: measure about 5 centimeters in length. Two Types of Nephrons
Cortical nephrons (85%) shorter, mostly in cortex of kidney, produce "standard" urine Juxtamedullary nephrons (15%), "juxta-next-to" the medulla - responsive to ADH, can concentrate urine RIGHT KIDNEYANTERIOR RELATIONS Suprarenal gland Liver, OF THE KIDNEYS Second part of the duodenum, Right colic flexure Coils of small intestine
LEFT KIDNEY Suprarenal gland, Spleen, Stomach, Pancreas (body), Left colic flexure, Descending colon Coils of jejunum
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RIGHT KIDNEY POSTERIOR RELATIONS Diaphragm, OF THE KIDNEYS Costodiaphragmatic recess of the pleura, Twelfth rib & last intercostal space, Psoas major Quadratus lumborum, Transversus abdominis muscle Subcostal nerve (T12) Iliohypogastric nerve (L1) Ilioinguinal nerve (L1)
LEFT KIDNEY Same as the right except it is higher it reaches up to the 11th rib.
Blood Supply
The renal artery arises from the aorta at the level of the second lumbar vertebra
Each renal artery divides into five segmental arteries that enter the hilum of the kidney, four infront and one behind the renal pelvis
Lobar artery arise from each segmental artery, one for each renal pyramid Each lobar artery gives two or three interlobar arteries Blood Supply The interlobar arteries run toward the cortex on each side of the renal pyramid
Interlobar arteries give the arcuate arteries at the junction of the cortex and medulla
The arcuate arteries give several interlobular arteries
Afferent glomerular arterioles arise as branches of interlobular arteries
Veins, Lymph, Nerve Supply Renal vein emerges from the hilum in front of the renal artery and drains into the IVC Left renal vein is longer than the right renal vein Lateral aortic lymph nodes lie around the origin of the renal artery
Renal sympathetic plexus: afferent fibers that travel through the renal plexus enter the spinal cord in the 10th, 11th, and 12th thoracic nerves
The two ureters are muscular tubes that extend from the URETERS kidneys to the posterior surface of the urinary bladder
The urine is propelled along the ureter by peristaltic contractions
Each ureter measures about 25 cm long
Each ureter has three constrictions along its course, 1- Where the renal pelvis joins the ureter, 2- As it crosses the pelvic brim, 3- Where it pierces the bladder wall ( intra-mural part) Ureter The renal pelvis is the funnel-shaped expanded upper end of the ureter
It lies within the hilum of the kidney and receives the major calyces
It enters the pelvis by crossing the bifurcation of the common iliac artery in front of the sacroiliac joint
It runs downward & forward on the lateral wall of the pelvis to enter the lateral angle of the bladder Anterior: RELATIONS Duodenum, RIGHT URETER Terminal part of the ileum, Right colic vessels, Iliocolic vessels, Right testicular or ovarian vessels, and the Root of the mesentery. Posterior: Right psoas muscle, Bifurcation of the right common iliac artery RELATIONS LEFT Anterior: Sigmoid colon, URETER Sigmoid mesocolon, Left colic vessels, Left testicular or ovarian vessels
Posterior: Left psoas muscle, Bifurcation of left common iliac artery Histology of Ureter
Mucosa – transitional epithelium Muscularis – two layers Inner longitudinal layer Outer circular layer Adventitia – typical connective tissue Upper end is supplied BLOOD SUPPLY by the renal artery
Middle portion by (gonadal) testicular or ovarian artery
In the pelvis is supplied by the superior vesical artery The lymph drains to the lateral aortic nodes and the iliac nodes Nerve Supply Renal, testicular (or ovarian), and hypogastric plexus (in the pelvis)
Afferent fibers travel with the sympathetic nerves and enter the spinal cord in the first and second lumbar segments ADRENAL GLAND
Lie on the upper medial surface of the kidney Within renal fascia & adipose capsule Triangular shape Contacts Right gland – liver Left gland – stomach, pancreas, spleen Blood supply A. suparenalis superior A. suparenalis media A. suparenalis inferiorr The two suprarenal glands are yellowish SUPRARENAL GLANDS retroperitoneal organs that lie on the upper poles of the kidneys
They are surrounded by the renal fascia
Separated from the kidneys by the perirenal fat
Each gland has a yellow cortex and a dark brown medulla The cortex secretes SUPRARENAL hormones include: Mineral corticoids, GLANDS which control fluid and electrolyte balance. Glucocorticoids, which control carbohydrates, fats, and proteins. Sex hormones, which probably play a role in the prepubertal development of the sex organs The medulla secretes the catecholamine, epinephrine and norepinephrine LEFT SUPRARENAL Left suprarenal gland is GLANDS crescentic in shape Extends along the medial border of the left kidney from the upper pole to the hilum It lies behind the: The pancreas, The lesser sac, The stomach It rests posteriorly on the diaphragm RIGHT SUPRARENAL The right suprarenal GLANDS gland is pyramidal in shap and caps the upper pole of the right kidney
It lies behind the right lobe of the liver and extends medially behind the IVC
It rests posteriorly on the diaphragm Arteries: Blood Supply Three arteries supplying each gland, 1- Superior suprarenal artery: from inferior phrenic artery 2- Middle suprarenal from aorta. 3- Inferior suprarenal from renal. Veins: A single vein emerges from the hilum of each gland: The right suprarenal vein drains into the IVC . The left suprarenal vein drains into the left renal The suprarenal glands of the human fetus are 10 to 20 times larger than the adult glands relative to body weight, and are large compared with the kidneys. These large glands result from the extensive size of the fetal cortex.
49 Dr. L. Tchakarov