This was done as a Student presentation on the kidney.
Here following topics are covered.
Macroscopic structure of the urinary system
Microscopic anatomy of the urinary system
Functions of the nephron
Renal blood supply
Kidneys and blood pressure regulation
Structure of ureters and urinary bladder to perform its function
Renal failure
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The kidney
1. Kidney Excretion & Reproduction Module Student presentation 2007/08 Batch Faculty of Medicine University of Peradeniya All what you have to know about the kidney
2. Sub topics…. 1.2.Macroscopic structure of the urinary system 3.4.5.Microscopic anatomy of the urinary system 6.7.8.Functions of the nephron 9.10.11.Renal blood supply 12,13,14.Kidneys and blood pressure regulation 15,16,17.Structure of ureters and urinary bladder to perform its function 18,19,20.Renal failure
5. KIDNEYS Size – 3 x 6 x 12 cm Weight – 130 g Shape – Bean shaped Location – Lie on the posterior abdominal wall, retroperitoneally. T12 – L3 vertebral level Right is slightly below than the left.
6. RELATIONS RIGHT KIDNEY Superiorly - Right adrenal gland Anteriorly - Right lobe of the liver, Second part of the duodenum, Hepatic flexure of the colon Posteriorly – Posterior abdominal wall muscles. (Psoas major, Quadratus lumborum, Transversus abdominis)
7. RELATIONS LEFT KIDNEY Superiorly – Left adrenal gland Anteriorly – Spleen, Stomach, Pancreas, Jejunum, Splenic flexure of the colon. Posteriorly – Diaphragm, Posterior abdominal wall muscles. (Psoas major, Quadratus lumborum, Transversus abdominis)
8. External Features Each kidney is enclosed by (from inside to outside respectively), Renal capsule – fibrous connective tissue Perirenal fat Renal fascia - fibroelastic connective tissue
9. External Features Hilum of the kidney, Concave medial border of the kidney Structures enter / leave through the hilum (from anterior to posterior), Renal vein Renal artery Ureter and Renal nerves and Lymphatics.
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12. URETER 25 – 30 cm long and 3 mm in diameter Continuous with renal pelvis In abdominal cavity, lies on psoas major muscle Enters the pelvic cavity anterior to the sacroiliac joint Passes obliquely through the posterior wall of the bladder and penetrates it
13. Narrowest parts of the ureter At the junction between the pelvis and abdominal part of the ureter At the pelvic brim At the ureteric orifice of the bladder
14. BLADDER Empty bladder lies entirely in the pelvic cavity It has a shape of a flattened 3 sided pyramid.
15. Areas & surfaces Apex – sharp, pointed forward to the top of pubic symphysis. Base – triangular posterior surface facing backward in front of rectum or vagina. Trigone – lowest area of the base lies between 2 ureteral orifices and internal urethral orifice. Neck – urethral opening. Two inferolateral surfaces and superior surface.
24. Kidney is made up of 10-18 lobes Lobes are made up of medullary pyramids. Bases of pyramids are enveloped by cortex. Cortex contain renal corpuscles , proximal & distal parts of tubules. Apices of renal pyramids are known as renal papilla. Renal papilla open to the renal pelvis via a branch of a renal pelvis called a calyx. Renal sinus-fatty supporting tissue between medullary pyramids
30. BOWMAN’S CAPSULE Single layer of flattened cells resting on a basement membrane. GLOMERULUS Globular network of anastomosing capillaries. Glomerular capillaries are invested by visceral layer of Bowman’s capsule. These cells are called Podocytes. They have finger like projections .
33. RENAL TUBULES Extend from Bowmen’s capsule to collecting duct. PCT Loop of Henle DCT
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35. PROXIMAL CONVOLUTED TUBE Longest , most convoluted tube. Found in renal cortex. Simple cuboidal epithelium. Brush border fills the lumen in a section. Cytoplasm pink stained due to mitochondria. Less cells in a section than DCT
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38. Loop of Henle is closely associated with parallel capillary loops-vasa recta, peritubular capillaries
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42. DCT SHRTER Less convoluted Found in cortex No brush border Large lumen comparing to PCT Small cells. More cells in a section
46. COLLECTING DUCT Descend through the cortex in parallel bundles called medullary rays. Lined by columnar epithelium. Pale stained. No brush border Consist of 2 cell types intercalated cells(I cells) principal cells
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48. principal cells pale cytoplasm. Short microvillus actively reabsorb Na+ ,K+ ,H2O Intercalated cells dark cytoplasm due to concentrated mitochondria ribosome & vesicles. secrete H+ & reabsorb HCO-3 .maintain acid base homeostasis
67. Parts of the nephron Distal Convoluted tubule Bowman’s capsule Collecting tubules Proximal Convoluted tubule Glomerulus Thick ascending limb of Loop of Henle Collecting duct Thin descending limb of Loop of Henle Thin ascending limb of Loop of Henle Hairpin bend of Loop of Henle To bladder
69. Bowman’s capsule Glomerular Filtration The capsular epithelium(podocytes) surrounding the outer surface of the capillary basement membrane forms a part of the glomerular filtration membrane.
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71. Podocytes are also involved in regulation of glomerular filtration rate (GFR).
72. When podocytes contract, they cause closure of filtration slits. Decreases the GFR(by reducing the surface area available for filtration)
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76. Tubular Secretion of Organic acids and bases Metabolic products such as Bile salts, Oxalate,Urate and Catecholamines are rapidly removed from the body by the PCT. In addition, the PCT secretes harmful drugs or toxins. Eg: Penicillin, Salicylates
77. Cortex H20 300 mOsm/L 20% of water is reabsorbed H20 Medulla 1200 mOsm/L Loop of Henle-Descending limb
94. RENAL ARTERIES The aorta gives 2 branches at the L2 vertebral level, which supply kidneys. Left renal artery Right renal artery
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96. SEGMENTAL BLOOD SUPPLY According to blood supply, each kidney is divided into 5 vascular segments. Each segment is supplied by one segmental artery. Segmental arteries do not anastomose with each other. Obstruction of a segmental artery leads to necrosis of that particular segment.
97. Segmental artery Lobar artery Interlobar artery Arcuate artery Interlobular artery Afferent glomerular arteriole DISTRIBUTION OF INTRARENAL ARTERIES
99. Afferent glomerular artery Glomerular capillary network Efferent glomerular arteriole GLOMERULAR CAPILLARIES Glomerulus is a special capillary network between 2 arterioles.
100. VASA RECTA & PERITUBULAR CAPILLARIES There are two types of nephrones. Cortical nephrones. Juxtamedullary nephrones. In cortical nephrones efferent arteriole gives rise to peritubular capillaries. In juxtamedullary nephrones it gives rise peritubular capillaries and vasa recta.
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104. There are 3 types of capillary networks in kidney. Glomerular capillary plexus Peritubular capillary plexus Vasa recta
105. VENOUS DRAINAGE OF NEPHRONS Interlobular veins Arcuate veins Interlobar veins Intrarenal vein Renal vein INFERIOR VENA CAVA Peritubular capillaries drain into inter lobular veins. Ascending vasa recta can be drained into interlobular or arcuate veins.
110. How the body regulates the blood pressure ? Two major parameters of Blood Pressure control 1. Total peripheral resistance 2. Cardiac output Arterial Blood Pressure = Cardiac Output X Total Peripheral Resistance
111. Mechanisms of controlling Blood Pressure Rapid Control Baroreceptor CNS ischemic mechanism Chemoreceptors Combine to cause venoconstriction, increasing venous return, increase heart rate and contractility, arteriolar constriction Intermediate Control (during this time nervous mechanisms usually fatigue and become less important) Long-Term Control (Renal-body fluid pressure control mechanism -hours to days) RAAS interaction with aldosterone – Regulating ECF volume
114. How RAAS affect blood pressure regulation ? Increase in Blood volume Increase in venous return Increase in cardiac output BP = CO X TPR Increase in blood pressure
115. Vasoconstriction Resistence = 1 (radius)4 Increase Total Peripheral Resistance BP = CO X TPR Increase blood pressure
116. How the Renin is formed ? Juxtaglomerular Apparatus
117. Stimulations for Renin release 1. Low renal blood flow Stimulate intrarenal baroreceptors 2. Increased sympathetic activity 3. Low concentration of Na+ and Cl- in macula densa
124. Arterial Volume receptors and Hypothalamic osmoreceptors Increase pressure due to Decrease osmotic pressure Increase in blood volume Distension of the atrial walls Hypothalamus Stimulation of receptors Decrease ADH secretion Dilatation of renal arterioles Decrease water reabsorption from the kidney More filtration of fluid in the kidneys Bring the Volume and BP back to normal
126. Structure of ureters and urinary bladder to perform its function Groups-15,16,17
127. Ureters….. A .begin as a continuation of the renal pelvis B .run retroperitoneally C .just medial to tips of transverse processes of lumbar vertebrae towards the urinary bladder D. join the urinary bladder trigone at its posterolateral corners (behind the urinary bladder)
128. Ureters can pass urine from pelvicalyceal system to urinary bladder because it is a hollow tube macroscopicstructure and its function Ureter 25cm long , A Hollow muscular tube Function!!!
129. There is a very narrow and acute angle at the point where the ureters connect with the bladder Function!!! The acute angle between the ureter and bladder prevents back flow of urine to ureters from the bladder.
134. Wall of the ureter Consists of; Urothelium Lamina propria Two smooth muscle layers (in upper 2/3 ) -inner longitudinal layer -outer circular layer Lower 1/3 has also a outermost longitudinal layer
135. Muscle layers-wall of the ureter Outer circular layer Inner longitudinal layer Transitional epithelium
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139. Urinary bladder Microscopic structure Mainly relates with its epithelium and wall Epithelium-Transitional epithelium Several cell layers (stretchable) Outer round cell layer (umbrella cells)
140. Structure of the wall of the bladder a. mucosa - transitional epithelium b. submucosa c. muscularis (called detrusor muscle) - 3 layers of smooth muscle -inner longitudinal layer -middle circular layer -outer longitudinal layer d. adventitia
159. Accidents, injuries or complications from surgery (where the kidneys are deprived of normal blood flow for an extended period of time.) e.g.- heart-bypass surgery.
184. INVESTIGATION Chronic kidney failure is measured in five stages, which are calculated using a patient’s GFR, or glomerular filtration rate
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189. Peritoneal dialysis uses the peritoneal membrane, the lining of the abdomen, to remove excess water, wastes, and chemicals from the body.10 A dialysate passes through the abdomen via a surgically placed catheter. Fluid, wastes, and chemicals pass from capillaries in the peritoneal membrane into the dialysate. After several hours, the waste-carrying dialysate is drained from the abdomen.