Macroscopic Anatomy of the Urinary Tract VETS2007/2008 PDF

Macroscopic Anatomy of the Urinary System VETS2007/2008 School of Veterinary Medicine and Science Learning Outcomes Compare and contrast the macroscopic anatomy of the kidneys in horses, cows, dogs, cats, pig and small ruminants Describe the topographical anat...

Macroscopic Anatomy of the Urinary System VETS2007/2008 School of Veterinary Medicine and Science Learning Outcomes Compare and contrast the macroscopic anatomy of the kidneys in horses, cows, dogs, cats, pig and small ruminants Describe the topographical anatomy and peritoneal associations of all parts of the urinary system in common domestic species Describe the innervation and vascularisation of the urinary system (including species variation in the internal renal portal system) Recognise kidneys of different veterinary species and the structure of the bladder wall Explain the concept of end-arteries and their relevance to renal function School of Veterinary Medicine and Science  Overview ▪Please read before the lecture School of Veterinary Medicine and Science Anatomy of the Urinary Tract ▪ Kidney ▪ Ureter ▪ Bladder ▪ Urethra School of Veterinary Medicine and Science The Kidney School of Veterinary Medicine and Science Urinary System Urine producing organ: ▪ Kidney – nephron Urine transporting, storing and excreting organs: ▪ Renal pelvis ▪ Ureter ▪ Urinary bladder ▪ Urethra (sex specific differences) School of Veterinary Medicine and Science  Location of the Kidneys ▪Please read before the lecture. ▪Dog and cat, but similar elsewhere School of Veterinary Medicine and Science  The Kidneys ▪ Paired organs ▪ Lie retro-peritoneally ▪ Positioned in the dorsal abdomen ▪ Positioned in the ventral lumbar region with limited mobility (except cat) ▪ Right kidney is most cranial (except pig) ▪ Lies in a small fossa of the caudate liver lobe ▪ Left kidney is most mobile School of Veterinary Medicine and Science Position of Kidneys – Dog & Cat School of Veterinary Medicine and Science The Kidney R L School of Veterinary Medicine and Science  Anatomical Landmarks of the Left Kidney (1) ▪ Cranial pole contacts the greater curvature of the stomach ▪ Dorsomedial aspect of the cranial pole contacts the spleen laterally ▪ Often the spleen is located ventral to the kidney making a useful acoustic window ▪ Cranially the left kidney may contact the left limb of the pancreas School of Veterinary Medicine and Science  Anatomical Landmarks of the Left Kidney (2) ▪ Medially the cranial pole contacts the left adrenal gland ▪ Caudally there is small intestine and descending colon ▪ The ovary if present is located caudally and ventrally School of Veterinary Medicine and Science  Anatomical Landmarks of the Right Kidney (1) ▪ Cranial pole is located within the renal fossa of the caudate lobe of the liver ▪ Medially is the caudal vena cava (CVC) ▪ Dorsolateral to the CVC close to the medial aspect of the right kidney is the right adrenal gland School of Veterinary Medicine and Science  Anatomical Landmarks of the Right Kidney (2) ▪ Ventrally is the descending duodenum ▪ Ventrally and medially is the right pancreatic limb ▪ The ovary if present is caudoventral to the right kidney School of Veterinary Medicine and Science Laparotomy approach requires gut retraction Retract mesocolon on LHS to see left kidney. Retract mesoduodenum on RHS to right kidney. School of Veterinary Medicine and Science ▪ Hopefully you have read to here! ▪ Lecture delivery starts at next slide. School of Veterinary Medicine and Science  Renal Terminology ▪ Renal or nephros School of Veterinary Medicine and Science  The Kidney Basic components: ▪ Outer fibrous capsule ▪ Renal cortex ▪ Renal medulla School of Veterinary Medicine and Science  Basic Terminology - 1 ▪ Described as bean-shaped ▪ Dog, cat, sheep, goat ▪ Terminology ▪ Lateral and medial border ▪ Dorsal and ventral surface ▪ Cranial and caudal pole ▪ Renal hilus (=hilum) is medial (artery(s), vein, ureter) School of Veterinary Medicine and Science Basic Terminology - 2 Cortex+pyramid+papilla of one functional unit is a renal lobe. Blood vessels travel in the renal columns Each minor calyx is fixed to one papilla School of Veterinary Medicine and Science  Overall Shape ▪ Comparative Anatomy School of Veterinary Medicine and Science  Kidney Beans! ▪ Described as bean-shaped ▪ Dog, cat, sheep, goat Renal crest Lamb kidney School of Veterinary Medicine and Science  Equine Kidneys ▪ Equine kidneys are more triangular in shape ▪ Right described as ‘heart-shaped’ ▪ Left described as ‘pyramidal’ Right Left School of Veterinary Medicine and Science  Porcine Kidneys ▪ Porcine kidneys are more flattened in shape ▪ “Long and flat” School of Veterinary Medicine and Science  Bovine Kidneys ▪ Bovine kidneys are more oval and irregular in shape ▪ Obvious lobules = reniculate ▪ Similar to aquatic mammals ▪ Dolphins ▪ Seals ▪ Otters ▪ Also bears and elephants ☺ School of Veterinary Medicine and Science Unilobar or Multilobar? School of Veterinary Medicine and Science  Kidney – Cortex, Medulla and Lobes C Cortex (Cortex renis) External (outer) zone M Internal (inner) zone [described as juxtamedullary] RL Glomeruli and convoluted tubules Medulla (Medulla renis) [M] Medullary pyramids Loops of Henle and collecting ducts Outer part = base of pyramid Inner part = renal papilla (only has collecting ducts) Renal lobes [RL] Section of kidney Cortex+medulla that work together School of Veterinary Medicine and Science  Unilobar Kidneys Rodents and lagomorphs. ▪ Single renal lobe. ▪ Single pyramid. ▪ Single papilla. ▪ Papilla may extend through hilus in desert-adapted species. ▪ Rats, mice, hamsters, gerbils, jerboa, guinea pigs, beavers, squirrels, capybara. ▪ Bunnies and hares. School of Veterinary Medicine and Science  Multilobar Kidneys Cow, elephant, bear, Pig, primate. Dog, cat, sheep, horse. aquatic mammals Fused cortex Fused cortex Separate cortices Separate medullae Fused medullae Separate medullae Lobes still seen internally. Pyramids partially merged. Obvious pyramids. Papillae merged to form Multiple renal papillae. renal crest. Multiple lobes/pyramids. Multiple calices. No calices Multiple renal papillae. Branched pelvis. Single pelvis. Multiple calices. Smooth surface. Smooth surface. No pelvis. Lobulated surface. School of Veterinary Medicine and Science  Lobation v Species Species Rodents Dogs/cats Pigs Large bovids Lagomorphs Equids Primates Elephants Small bovids Aquatic mammals Surface Globate Globate Globate Reniculate Description Unilobar Multilobar Multilobar Multilobar Cortices Single Fused Fused Multiple Pyramids Single Fused Multiple Multiple Papillae Single Fused into renal Multiple Multiple crest Calices No No Multiple Major and minor Pelvis Yes Yes Yes No School of Veterinary Medicine and Science  Renal Pelvis and Calices ▪ Comparative Anatomy School of Veterinary Medicine and Science  Calices versus Pelvis The urine drains from the tip of the pyramids. Cattle, pigs, primates: there are separate pyramids, then each has a “funnel” attached to collect the urine = minor calyx. 2-3 Minor calices drain into a major calyx. Major calices drain directly into the ureter in cattle. In pigs and primates the major calices drain into a space = renal pelvis. This then drains into the ureter. In dogs, cats, sheep, horses the medullary cones are fused = renal crest. No calices. The renal crest drains into the renal pelvis. School of Veterinary Medicine and Science The Renal Pelvis – Dogs and Cats ▪ The medullary pyramids are fused = renal crest ▪ Urine drains into a space = renal pelvis ▪ The renal pelvis is located within the renal sinus Renal pelvis – Renal pelvis – corrosion cast excretory urogram School of Veterinary Medicine and Science  The Renal Pelvis and Calices – Comparative (1) ▪ The renal pelvis differs between species: ▪ Large irregular structure with broad finger-like processes called recesses in single lobe species ▪ In the horse there are only 2 recesses ▪ Smaller irregular structure with short stems ending in a dilated region called calyces in pigs and primates ▪ Divided proximal ureter leading to multiple calyces in cattle (no pelvis) Dog/cat – pelvis and recesses Pig – pelvis and calyces Cow – calyces and ureter School of Veterinary Medicine and Science The Renal Pelvis and Calices – Comparative (2) Pigs and People School of Veterinary Medicine and Science Internal Renal Vasculature School of Veterinary Medicine and Science  Overview of Renal Blood Flow Kidneys represent 1% of body mass but receive 20-25% of cardiac output. Basic flow is from hilus to cortex, then to cortex and medulla. Venous drainage is from medulla back to cortex to join cortical venous drainage. Arterial and venous patterns the same for large intra-renal vessels. Intra-renal portal system. Outflow via hilus (carnivores have extra cortical drainage). Glomerular blood flow is closely regulated to control GFR. The detail of the flows is important in order to understand renal function. School of Veterinary Medicine and Science  Vasculature of the Kidney -interlobulary a -interlobulary v. -arcuate a. -arcuate v. -interlobar a. -interlobar v. -renal a. -renal v -Aorta -caudal VC School of Veterinary Medicine and Science  Renal Blood Flow Circuit Aorta -> -> renal artery -> inter-lobar artery -> arcuate artery -> inter-lobular artery -> afferent glomerular artery -> GLOMERULUS -> efferent glomerular artery -> renal tubule plexus -> inter-lobular vein -> arcuate vein -> inter-lobar vein -> renal vein -> caudal vena cava School of Veterinary Medicine and Science Microvascular Anatomy -afferent arteriole -glomerulus -efferent arteriole -capillary networks: -from cortical glomeruli: => peritubular capillaries in the cortex -from juxtamedullary glomeruli, two separate flows: => peritubular capillaries in the cortex (90% of flow) => vasa recta in the medulla (10% of flow) -venules drain the peritubular capillaries and vasa recta, then drain to either arcuate or interlobulary vv., but do not re-enter Bowman’s capsule. School of Veterinary Medicine and Science Internal Renal Portal System ▪ Within the kidney there is an arterial portal system, in which efferent glomerular arterioles receive blood from the capillaries of the renal glomeruli and carry it to the peritubular capillary plexus surrounding the proximal and distal convoluted tubules. School of Veterinary Medicine and Science  Blood Flow in Juxta-Medullary Nephrons Afferent arteriole For juxta-medullary nephrons: The afferent arteriole firstly enters Bowman’s capsule, then the efferent arteriole exits. The efferent vessel splits and supplies: Efferent (a) the peritubular capillaries around the PCT arteriole & DCT, then drains to veins in the cortex. (b) the vasa recta around the LoH then drains to the arcuate veins. Note this is a parallel supply – blood does not go from convoluted tubules to the LoH. This is so that the venous blood carrying a.a., glucose etc reabsorbed from the PCT is not delivered to the medulla. School of Veterinary Medicine and Science Blood Flows in Two Routes Peritubular vessels reabsorb many solutes – needs to be a different pathway otherwise osmotic solutes would be sent to the renal medulla In vasa recta, mostly: Water, Na, K, Cl, urea School of Veterinary Medicine and Science  Renal Arteries are…...End arteries What does this mean? What is significance? School of Veterinary Medicine and Science  Some Species Differences All carnivores have an extra cortical venous drainage which flows through the cortex to the hilum and joins the renal vein. But in cats these veins run over the cortex, hence are called subcapsular veins. These also run towards the hilum of the kidney and are a distinctive feature of feline kidneys. School of Veterinary Medicine and Science The Ureters and Bladder School of Veterinary Medicine and Science  Urothelium (prev. transitional epithelium) Walls of ureters and bladdder made up from: ▪ Mucous membrane - Urothelium (prev. transitional epithelium) - Apical cellular protection against urine due to tight junctions - Urothelial cells tolerate stretching as bladder fills ▪ Lamina propria ▪ Muscular layer ▪ Adventitia School of Veterinary Medicine and Science The Ureters (1) From the kidneys to the bladder. School of Veterinary Medicine and Science The Ureters (2) ▪ Bilateral muscular tubes which pass within the retroperitoneal space ▪ Abdominal portion ▪ Pelvic portion ▪ Here it is directed medially through either the broad ligament (female) or mesoductus (male) ▪ There is a risk for inclusion in ligatures at the time of ovario- hysterectomy ▪ Ureter ends on the dorso-lateral bladder surface (within the lateral ligament of the bladder) School of Veterinary Medicine and Science The Ureters (3) ▪ The ureter enters the bladder obliquely and runs intramurally between the muscular layer and mucosa before opening through two slits often on a slightly raised ‘hillock’ Dog ultrasound showing the two ureteral hillocks on the dorso-lateral Dog urethrocystoscopy bladder showing urine entering bladder School of Veterinary Medicine and Science  The Bladder (1) ▪ A hollow muscular-membranous organ ▪ Varies in size and position depending on degree of filling ▪ Divided into ▪ Cranial pole ▪ Intermediate body ▪ Caudal neck ▪ Lining cells are endoderm-derived ▪ Urothelium ▪ Designed to be stretchy and tolerant of distortion ▪ Other body cells die when distorted ▪ Special anti-urine junctions between cells School of Veterinary Medicine and Science The Bladder (2) ▪ Degree of filling has significant impact upon appearance ▪ Has wrinkled appearance when empty ▪ Folds disappear when distended ▪ Wall thinner when distended Bladder lumen Bladder wall Non-distended Distended School of Veterinary Medicine and Science  The Bladder (3) ▪ Two folds (ureteric folds) extend from the ureteral openings to the neck of the bladder where they fuse to become the urethral crest. School of Veterinary Medicine and Science The Bladder (4) ▪ Two lateral ligaments of the bladder insert in the dorsal abdominal wall ▪ Within them are the residual umbilical vessels ▪ The median ligament connects the bladder to the pelvic floor and linea alba School of Veterinary Medicine and Science Female Urethra School of Veterinary Medicine and Science  The Female Urethra ▪ Female ▪ Empties (at the external urethral orifice) onto the ventral wall of the vagina at the vestibulo-vaginal junction ▪ (Note the vagina becomes the vestibule at this point) ▪ Conveys urine only ▪ Length and diameter vary considerably between species ▪ Short and wide in mare ▪ Bordered by two fossae in bitch ▪ Sow and cow have significant sub-urethral diverticulum* * School of Veterinary Medicine and Science Male Urethra School of Veterinary Medicine and Science  The Male Urethra (1) ▪ Male ▪ Empties at the tip of the penis ▪ Divided into ▪ Pre-prostatic ▪ From bladder neck to seminal hillock Pelvic portion ▪ Prostatic portion ▪ Includes openings of deferent, vesicular and prostatic ducts ▪ Penile portion ▪ From ischial arch to penile tip School of Veterinary Medicine and Science The Male Urethra (2) ▪ Canidae ▪ Simple urethra ▪ Os penis (what is the clinical relevance?) ▪ Felidae ▪ Sigmoidal urethra (think about catheterisation technique) ▪ Small os penis ▪ Glans penis has many small barbs (regress when neutered) ▪ Equidae ▪ Urethra is inside the urethral fossa of the glans ▪ Porcidae ▪ Simple urethra ▪ Bovidae ▪ Urethra exits at the end of a spiral groove in the glans ▪ Ovidae and capridae ▪ Urethra extends 3 – 4 cm beyond the glans penis School of Veterinary Medicine and Science  External Renal Vasculature ▪ Arteries, Veins and Lymphatics School of Veterinary Medicine and Science  Blood Supply - Overall ▪ Renal ▪ Internal iliac ▪ Umbilical ▪ Cranial vesicular ▪ Urogenital ▪ Artery of ductus deferens ▪ Caudal vesicular ▪ Prostatic / vaginal artery ▪ Urethral artery ▪ External iliac ▪ Caudal abdominal ▪ Deep femoral ▪ Middle vesicular School of Veterinary Medicine and Science Renal Blood Vessels ▪ The renal arteries originate from the lateral aspect of the aorta and in the dog measure 3 - 4 mm in diameter ▪ Arteries often divide into a dorsal and ventral branch before entering the kidney ▪ In 20% of dogs the renal arteries may be double particularly to the left kidney School of Veterinary Medicine and Science  Left Renal Blood Vessels ▪ Left renal artery originates 2 cm caudal to the right renal artery ▪ Left renal artery is 3 cm in length ▪ Left renal vein is immediately ventral to the artery ▪ Left renal vein approximately 3 - 4 cm in length ▪ Left gonadal vein enters left renal vein School of Veterinary Medicine and Science  Right Renal Blood Vessels ▪ Right renal artery arises 4 cm caudal to the cranial mesenteric artery ▪ Traverses dorsal to the caudal vena cava ▪ Approximately 4 - 5 cm in length ▪ Right renal vein is immediately ventral to the renal artery ▪ Right renal vein approximately 4 - 5 cm in length ▪ Right gonadal vein enters the caudal vena cava School of Veterinary Medicine and Science  Male dog: on the left side the peritoneum and retroperitoneal fat has been removed Right testicular vein (opens directly into caudal vena cava) Right ureter (covered by peritoneum) Right kidney (closely associated with right lobe of the liver) Bladder Liver Caudal vena cava Aorta Colon External iliac lymph node Left adrenal gland (crossed by phrenico-abdominal vein) Renal artery and vein Left ureter Left kidney (slightly further caudal than the right) Left testicular artery Left testicular vein (opens into left renal vein)School of Veterinary Medicine and Science  Female dog: on the left side the peritoneum and retroperitoneal fat has been removed Right ovarian vein Right kidney (closely associated with right lobe of the liver) Bladder Right and left (caudally reflected) ovarian arteries Uterus Liver Caudal vena cava Colon Left adrenal gland (crossed by phrenico-abdominal vein) Left ureter Left renal vein (the artery is lying dorsally) Left ovarian vein Aorta (covered by a plexus of sympathetic nerve fibers) School of Veterinary Medicine and Science Blood Supply to Ureters, Bladder and Reproductive Organs School of Veterinary Medicine and Science Blood Supply – Bladder and Urethra Bladder ▪ Caudal vesicular artery Urethra ▪ Urethral artery School of Veterinary Medicine and Science Female Bladder and Uterine Blood Supplies School of Veterinary Medicine and Science Male Bladder, Prostatic and Penile Blood Supplies School of Veterinary Medicine and Science Lymphatic drainage Kidney ▪ Renal lymph nodes Ureter ▪ Lumbar lymph nodes Bladder ▪ Iliosacral lymph nodes School of Veterinary Medicine and Science Urinary System Innervation School of Veterinary Medicine and Science Innervation Kidney ▪ Sympathetic and parasympathetic fibres from solar plexus via renal arteries ▪ Sympathetic fibres form synapses in coeliac ganglion and cranial mesenteric ganglion Bladder ▪ Sympathetic via the hypogastric nerve from the caudal mesenteric ganglion ▪ Parasympathetic from the pudendal nerve School of Veterinary Medicine and Science Learning Outcomes Compare and contrast the macroscopic anatomy of the kidneys in horses, cows, dogs, cats, pig and small ruminants Describe the topographical anatomy and peritoneal associations of all parts of the urinary system in common domestic species Describe the innervation and vascularisation of the urinary system (including species variation in the internal renal portal system) Recognise kidneys of different veterinary species and the structure of the bladder wall Explain the concept of end-arteries and their relevance to renal function School of Veterinary Medicine and Science References ▪ Essential reading ▪ Konig and Liebich (2007). Urinary System. In Veterinary Anatomy of Domestic Species 3rd Edition, pp 391-405. ▪ Dyce, Sack and Wensing (2010). The Urogenital Apparatus. In Veterinary Anatomy 4th edition, pp 174-184, 192-195, 201-202. ▪ Additional reading ▪ Dyce, Sack and Wensing (2010). The Pelvis and Reproductive Organs (Chapters specific to species). In Veterinary Anatomy 4th edition, starting at pp 454, 563, 698 and 772. ▪ Further reading ▪ None School of Veterinary Medicine and Science