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RENAL ANATOMY Kevin Kuan & Renee ChanStructure for today Learning Outcomes 1. Quick recap on kidney function 2. Anatomy of the kidney (location, relations, supply) 3. Structure and function of the glomerulus 4. Location of different transport systems 5. Organogenesis of the kidney and lower urinary tract 6. Structure and function the lower urinary tract MCQs throughout!Quick recap - functions of the kidney A WET BED A - acid base balance W - water balance E - electrolyte balance T - removes toxins B - blood pressure control E - erythropoietin synthesis D - vitamin D metabolismAnatomy of the kidney - OVERVIEWQ1 - Where are the kidneys located in relation to each other? A.right is 1 cm lower B.left is 1 cm lower C. right is 2 cm lower D. left is 2 cm lower E.they are at the same level, side by sideQ1 - Where are the kidneys located in relation to each other? A.RIGHT IS 1 CM LOWER B.left is 1 cm lower C. right is 2 cm lower D. left is 2 cm lower E.they are at the same level, side by sideAnatomy of the kidney - LOCATION - retroperitoneal organs - lie on the posterior abdominal wall, below the diaphragm - kept in place by renal vessels and fascia - between the upper borders of T12 and L3 vertebrae - right kidney is 1 cm inferior (under the liver) - the right kidney and liver are separated by Morisons pouch - kidneys may descend 1-2 cm with deep inspirationAnatomy of the kidney - ANTERIOR RELATIONS - superiorly: adrenal glands - anterior to the L kidney: spleen, stomach, pancreas, left colic flexure and jejunum - anterior to the R kidney: liver, duodenum and right colic flexureAnatomy of the kidney - POSTERIOR RELATIONS - posterior to both R & L kidneys: - diaphragm - 3 muscles: psoas major, quadratus lumborum, and transversus abdominis - 3 nerves: subcostal, iliohypogastric, and ilioinguinal - L kidney: 11th and 12th ribs - R kidney: 12th rib (1 cm lower)Q2 - What is B? A.paranephric fat B. perinephric fat C. renal fascia D. renal capsule E. renal pouchQ2 - What is B? A.paranephric fat B. perinephric fat C. RENAL FASCIA D. renal capsule E. renal pouchAnatomy of the kidney - PROTECTION From the inside out - 4 layers of protection: 1. renal/fibrous capsule - tough and fibrous, directly envelops the kidney 1. PERInephric/perirenal fat 2. renal fascia 3. PARArenal fatQ3 - From anterior to posterior, what is the order of the structures leaving the hilum? A.renal artery, renal vein, renal pelvis B. renal artery, renal pelvis, renal vein C. renal vein, renal pelvis, renal artery D. renal vein, renal artery, renal pelvis E. renal pelvis, renal artery, renal veinQ3 - From anterior to posterior, what is the order of the structures leaving the hilum? A.renal artery, renal vein, renal pelvis B. renal artery, renal pelvis, renal vein C. renal vein, renal pelvis, renal artery D. RENAL VEIN, RENAL ARTERY, RENAL PELVIS E. renal pelvis, renal artery, renal veinAnatomy of the kidney - HILUM Anterior to posterior: (VAP) 1. renal vein (exiting the kidney, draining blood to the IVC) 2. renal artery (supply blood to the kidney, from the descending aorta) 3. renal pelvis (superior portion of the ureters, brings urine to the bladder)Anatomy of the kidney - INTERNAL STRUCTURE - renal cortex (outer - pink) - renal medulla (inner - red) - renal columns - extensions of the renal cortex - renal pyramids - pyramid-shaped sections (divided by renal columns) - renal papilla (pyramid apex) - this is where urine is excreted - minor calyx - major calyx - renal pelvis - ureterQ4 - At what level do the renal arteries branch off the abdominal aorta? A.T11/T12 B.T12/L1 C.L1/L2 D.L2/L3 E.L3/L4Q4 - At what level do the renal arteries branch off the abdominal aorta? A.T11/T12 B.T12/L1 C.L1/L2 D.L2/L3 E.L3/L4Anatomy of the kidney - BLOOD SUPPLY (ART) - abdominal aorta - renal arteries (L1/L2, below the superior mesenteric a.) - right renal a. slightly longer - cross IVC posteriorly - renal arteries divide into segmental arteries - each supply a different renal segmentAnatomy of the kidney - BLOOD SUPPLY (VEN) - blood leaves via the renal veins, drains to the IVC - the R renal vein exclusively drains the R kidney - the L renal vein receives additional tributaries from: - L inferior phrenic, L suprarenal, and L gonadal veins - then passes anterior to the abdominal aorta, posterior to the superior mesentericNow onto the nephron and structures inside the kidney that produce urine! Any questions so far?Anatomy of the kidney - NEPHRON & GLOMERULUS - nephron = renal corpuscle + renal tubule - renal corpuscle - glomerulus - bowman’s capsule - glomerulus - supplied by the afferent arterioles - blood carried away by the efferent arterioles - (thinner = hyperfiltration)Anatomy of the kidney - NEPHRON & GLOMERULUS - blood enters the glomerulus, starts to get filtered, through the 3 layers of the capillary - endothelial lining of the capillary - basement membrane - podocytes wrap around the basement membrane and have filtration slits between them - epithelium of the nephron (podocytes) - enters Bowman’s space = filtrateAnatomy of the kidney - JUXTAGLOMERULAR COMPLEX - job = regulate BP and GFR - located between the afferent arteriole and DCT - 3 types of cells: - juxtaglomerular cells - extraglomerular mesangial cells - macula densa cells - macula densa cells detect low BP (low Na + Cl) - send signal to juxtaglomerular cells - juxtaglomerular cells can also detect low BP - secrete renin - inc sodium reabsorption, raise blood volume, constrict vessels, raise BPAnatomy of the kidney - RENAL TUBULE & URINE PRODUCTION 1. proximal convoluted tubule 2. the loop of henle - thin descending limb - thin ascending limb - thick ascending 1. distal convoluted tubule 2. collection duct 3. minor calycesKidney Development •Renal + genital systems ⟶ from mesoderm •Drain into the cloaca (primitive common sewer) •3 stages of kidney development along mesonephric duct •Pronephros + Mesonephros + MetanephrosKidney Development (2)Kidney Development (3) •Ureteric bud invades metanephros & forms renal pelvis •Ureteric bud induces metanephric blastema to form tubules at its ends •Capillaries invaginate ends of tubules ⟶ glomerulus •Thus Nephrons form and the permanent kidney developsUreter ● Muscular tube ● Moves urine by peristalsis + gravity Constriction points ● Ureteropelvic junction (junction of ureter + renal pelvis) ● Pelvic brim (crossing external iliac artery just beyond common iliac artery bifurcation) ● Ureterovesical junction (passing through bladder wall)Open Q: Why would areas of constriction be clinically important? - Obstruction at these sites such as nephrolithiasis (kidney stones) Fun fact: ureteropelvic junction is most common site of obstruction in fetal kidney -> hydronephrosisUreter - blood supply & venous drainage Blood supply ● Renal arteries ● Gonadal arteries ● Abdo aorta Venous drainage ● Renal veins ● Gonodal veinsUreter - histology ● Transitional epithelium (pear-shaped cells) Histological layers - from deep to superficial ● Transitional epithelium ● Lamina propria ● Muscularis externaBladder ● Hollow muscular organ ● Urine storage (empty ⟶ lesser pelvis, full ⟶ greater pelvis) ● Extraperitoneal, peritoneum lies on its top (so you can get intra- or extra- peritoneal bladder perforation) Elements ● Smooth muscle – detrusor (thicker in men – can push urine through BPH) ● Trigone – smooth part of detrusor ● Apex (connected to umbilicus by medial umbilical ligament – remnant of urachus) ● Fundus ● Neck ● Internal urethral orifice (sphincter)Bladder - blood supply & innervation Blood supply ● Superior vesical arteries (anterior & superior parts of the bladder) ● Inferior vesical arteries (males) (fundus & neck) ● Vaginal arteries* (females) (fundus & neck) * branches of internal iliac Nerve supply ● Sympathetic -> T10 – L2 via pelvic ganglia ○ These relax the detrusor & contract bladder neck ● Parasympathetic -> sacral level of spinal chord ● Sensory - pelvic + hypogastric + pudendal nervesQ5 - Cauda equina A 55 year old patient complains of changes in lower limb sensations and weakness (bilaterally). Spinal MRI confirms the diagnosis of cauda equina syndrome (compression of the lower nerve roots). What type of symptoms may this patient present with?: a) Urinary retention b) Changes in genital sensation c) Impotence (erectile dysfunction) d) Urinary incontinenceBladder - histology ● Transitional epithelium, also known as urothelium (pear- shaped cells) Histological layers – from deep to superficial ● Mucosa (transitional epithelium) ● Lamina propria (basement membrane) ● Smooth muscle (muscularis propria) ● Interwoven smooth muscle in 3 layersOpen Q: What is the function of transitional epithelium? Allows bladder to stretch! Bladder Development •Bladder derived from the cloaca •Cloaca divided into 2 parts by urorectal septum (week 4-7): •The urogenital sinus •Anal Canal •The upper part of the urogenital sinus forms the bladder •Initially drains into the allantois (connected to umbilical cord)Urethra ● Fibromuscular tube ● Extends from bladder to external urethral orifice Male ● 20 cm ● 4 parts (pre-prostatic*, prostatic, membranous, spongy) *some textbooks don’t recognise pre-prostatic urethra Female ● 3-4 cm ● Terminates b/w clitoris & vaginal orificeUpper Urethral Development •Develops from the lower part of the urogenital sinus (cloaca) •In males: pelvic and phallic part of the urogenital sinus. •In females: the pelvic part of the urogenital sinus Lower Urethral Development ● Genital tubercle develops at the superior end of the cloacal membrane (week 4) ● Two urethral folds develop on either side of cloaca ● Laterally, two labioscrotal folds form on either side of urethral folds ● In males, urethral folds fuse to form penile urethra ● In females they remain separate to form labia minoraFeedback Please take a minute now before you leave to fill in a quick feedback form: https://app.medall.org/training/feedback/anon ymous?organisation=accessibility-in- medicine&keyword=5b4828aa51b577c5c9a36d0b AIM Facebook Page ▶ Give our Facebook page a like for updates and opportunities,just search @AIMEdinburgh Thank you for coming! ▶ If you have any more questions, feel free to email me at ▶Renee - s2134683@ed.ac.uk ▶Kevin - s2271119@ed.ac.uk ▶ or email accessibilityinmedicine@gmail.com