The kidney

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

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

3. MACROSCOPIC STRUCTURE OF THE URINARY SYSTEM Group No 1-2

4. URINARY SYSTEM Urinary system consists of Two kidneys Two ureters Bladder Urethra

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.

10. Internal features Cortex A reddish, brown, layer of tissue immediately below the capsule and outside the pyramids. Medulla The innermost layer consisting of pale conical shape striations - Renal pyramids In between renal pyramids – Renal columns.

11. Internal features Pyramids Papillae Renal pelvis Major calyces Minor calyces

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.

16. URETHRA It lies in the perineum. In males, it consists of 3 parts: Prostatic urethra. Membranous urethra. Penile urethra. But in female urethra, there are no such divisions and it is shorter than the male urethra.

17. Male & Female urethra

18. MICROSCOPIC ANATOMY OF THE URINARY SYSTEM Group 3,4,5

19. CONTENT Kidney 1, histology 2, nephron 3, collecting duct 4, vasculature 5, juxtaglomerular apparatus Ureter Urinary bladder Urethra

20. THE URINARY SYSTEM-COMPRISES TWO KIDNEYS TWO URETERS URINARY BLADDER URETHRA

21. HISTOLOGY OF THE KIDNEY

22. 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

23. PELVICALYCEAL SYSTEM Whole urinary collecting system within the kidney

24. NEPHRON

25. NEPHRON Renal corpuscle Renal tubules

26. RENAL CORPUSCLE GLOMERULUS BOWMAN’S CAPSULE

27. 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 .

28. GLOMERULAR FILTRATION BARRIOR Glomerular endothelium Basement bembrane Podocytes

29. RENAL TUBULES Extend from Bowmen’s capsule to collecting duct. PCT Loop of Henle DCT

30. 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

31. LOOP OF HENLE Descending limb (thin limb, concentrating limb) Simple squamous epithelium. Hairpin loop Simple squamous epithelium Ascending limb Thin ascending limb- simple squamous epithelium. Thick ascending limb- simple cuboidal epithelium

32. Loop of Henle is closely associated with parallel capillary loops-vasa recta, peritubular capillaries

33. DCT SHRTER Less convoluted Found in cortex No brush border Large lumen comparing to PCT Small cells. More cells in a section

34. COLLECTING TUBULES Terminal part of DCT. Several get together & form a Collecting duct

35. 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

36. principal cells pale cytoplasm. Short microvillus actively reabsorb Na + , K + ,H 2 O Intercalated cells dark cytoplasm due to concentrated mitochondria ribosome & vesicles. secrete H + & reabsorb HCO - 3 . maintain acid base homeostasis

37. RENAL VASCULATURE

38. JUXTAGLOMERULAR APPARATUS

39. Juxtaglomerular cells smooth muscle cells of afferent arteriole sensitive to blood pressure in afferent arteriole Release enzyme renin Macula densa modified DCT epithelium sensitive to [Na + ] within DCT low [Na + ] stimulate release of renin from juxtaglomerular cells

40. Lasis cells extra glomerular mesengial cells release erythropoitin

41. URETER Transitional epithelium (urothelium) Muscular tube inner longitudinal muscle layer outer circular muscle layer Impermeable to urine. Prevent water leaking toward concentrated urine.

42. URINARY BLADDER Transitional epithelium Wall has 3 muscle layers (Detrusor muscles)

43. URETHRA In male 3 parts Prostatic urethra urothelium Membranous urethra stratified squamous epithelium Spongy urethra (penile urethra) stratified epithelium or pseudostratified columnar epithelium

44. Acknowledgments Wheater’s functional histology (fifth edition) www.ELSEVIR.com academic.kellogg.cc.mi.us http://biology.clc.uc.edu/Fankhauser/Labs/Anatomy_&_Physiology

45. Functions of different parts of the nephron Groups 6,7,8

46. The functional unit of the kidney NEPHRON (Site of urine formation)

47. To bladder Glomerulus Bowman’s capsule Proximal Convoluted tubule Hairpin bend of Loop of Henle Thick ascending limb of Loop of Henle Distal Convoluted tubule Collecting tubules Collecting duct Thin descending limb of Loop of Henle Parts of the nephron Thin ascending limb of Loop of Henle

48. Glomerular Filtration Renal processes Tubular Reabsorption Tubular Secretion Excretion

49. 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.

50. Small molecules such as water, glucose, and ionic salts except for plasma proteins are able to pass through the slits and form an ultra filtrate . Podocytes are also involved in regulation of glomerular filtration rate (GFR). When podocytes contract, they cause closure of filtration slits. Decreases the GFR (by reducing the surface area available for filtration)

51. Proximal Convoluted Tubule(PCT) Proximal Tubular Reabsorption Fluid in the filtrate entering the proximal convoluted tubule is reabsorbed into the peritubular capillaries . This is driven by sodium transport from the lumen into the blood by the Na + /K + ATPase in the basolateral membrane of the epithelial cells.

52. Substance % of filtrate reabsorbed Mechanisms Salt and water approximately two-thirds(60 -70 %) Passively across the luminal membrane via transcellular transport , which is then actively reabsorbed across the basolateral membrane via the Na/K/ ATPase pump. Organic solutes (primarily glucose and amino acids )and inorganic phosphate 100% Reabsorbed via secondary active transport through cotransport channels driven by the sodium gradient out of the PCT epithelial cells. Potassium(K + ) approximately 65% Reabsorbed by paracellular mechanisms.

53. Substance % of filtrate reabsorbed Mechanisms Urea approximately 50% As water leaves the lumen, the concentration of urea increases which facilitates diffusion in the late proximal tubule. Phosphate(HPO 4 2- ) approximately 80% Reabsorbed via secondary active transport mechanisms and exit across the basolateral membrane by facilitated diffusion. Chloride(Cl - ) Lesser than 65% The higher concentration of chloride in the late PCT favors simple diffusion from the tubular lumen into the renal interstitium through tight junctions. Bicarbonate(HCO 3 - ) approximately 80% Via counter transport mechanisms.

54. 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

55. Cortex Medulla 300 mOsm/L 1200 mOsm/L H 2 H 2 20% of water is reabsorbed Loop of Henle- Descending limb

56. Na + , K + , Cl - , Ca +2 , HCO3 - , Mg +2 Thick Thin Loop of Henle- Ascending limb

57. Tubular Lumen 3Na+ 2K+ Na + K + 2Cl - Na + H + Ca +2 , Mg +2 ( Paracellular pathway) Basolateral membrane

58. NaCl (5%) Impermeable to water and urea K + Dilutes the tubular fluid Early Distal Convoluted Tubule(DCT)

59. Late Distal Tubule Two types of cells Principal cells Secretes K + and Reabsorbs Na + 3Na 2K Na K Lumen

60. 2. Intercalated Cells H + Secretion and HCO3 - Reabsorption ( H + facilitates HCO3 - reabsorption ) The H + / ATPase pump can secrete H + against a very high conc. gradient. CA HCO3 - + H + H2CO3 H2O + CO2 CA=Carbonic Anhydrase

61. Action of Vasopressin(ADH) H 2 O

62. Permeability of late distal tubular cells to water depends on the ADH. ADH stimulates the binding of Aquaporin-2 channels to the luminal membrane.

63. Collecting tubule(CT) Impermeable to urea. Reabsorb s Na + from the lumen & secrete K + ions. The permeability of the CT& collecting duct for water is controlled by the level of ADH .

64. Principal cells of CT Reabsorbs Na + ions and water Secrete K + ions. Intercalated cells of CT Secrete hydrogen ions by an active H + /ATPase mechanism. Depending on the Na + /K + ATPase pump activity.

65. High level of ADH ( Ant diuretic hormone-Vasopressin) Increases water reabsorption Concentrates the solutes in urine

66. Summary

67. RENAL BLOOD SUPPLY -ANATOMY- Group 9,10,11

68. RENAL ARTERIES The aorta gives 2 branches at the L2 vertebral level, which supply kidneys. Left renal artery Right renal artery

69. 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.

70. DISTRIBUTION OF INTRARENAL ARTERIES Segmental artery Lobar artery Interlobar artery Arcuate artery Interlobular artery Afferent glomerular arteriole

71. Arcuate artery Interlobar arteries Interlobular arteries BLOOD SUPPLY TO THE NEPHRONS

72. GLOMERULAR CAPILLARIES Glomerulus is a special capillary network between 2 arterioles. Glomerular capillary network Afferent glomerular artery Efferent glomerular arteriole

73. 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.

74. Peritubular capillaries Arise from efferent arteriole Surround PCT & DCT in the cortex. Vasa recta Arise from efferent arteriole. Wide parallel capillary loops which are associated with limbs of loops of Henle of juxtamedullary nephrones.

75. Efferent arteriole continues as descending vasa recta. Descending vasa recta give rise to capillaries around loops of Henle. Venous ends of capillaries converge to form ascending vasa recta.

76. There are 3 types of capillary networks in kidney. Glomerular capillary plexus Peritubular capillary plexus Vasa recta

77. VENOUS DRAINAGE OF NEPHRONS Peritubular capillaries drain into inter lobular veins. Ascending vasa recta can be drained into interlobular or arcuate veins. Interlobular veins Arcuate veins Interlobar veins Intrarenal vein INFERIOR VENA CAVA Renal vein

78. VENOUS DRAINAGE OF KIDNEYS Interlobular veins Arcuate veins Interlobar veins Intrarenal vein INFERIOR VENA CAVA Renal vein

79. RENAL VEINS

80. SUMMARY.

81. Kidneys And Blood Pressure Regulation Groups - 12, 13, & 14

82. 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

83. 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

84. Renin Angiotensin Aldosterone System (RAAS)

85. 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

86. Vasoconstriction Resistence = 1 (radius) 4 Increase Total Peripheral Resistance BP = CO X TPR Increase blood pressure

87. How the Renin is formed ? Juxtaglomerular Apparatus

88. 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

89. Formation of Angiotensin 11

90. Action of Angiotensin 11

91. Action of Aldosterone

92. ADH (Vasopressin) and Blood Volume Anterior Pituitary Posterior Pituitary Hypothalamus Maxillary Body Optic chiasma Ang II receptors Osmo receptors Increased osmolarity ADH Atrial volume receptors Vagal afferents SON PVN H 2 O H 2 O H 2 O Volume Retention  TPR

93. Action of ADH

94. 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

95. Action of ANP ( Atrial Natriuretic Peptide)

96. Structure of ureters and urinary bladder to perform its function Groups-15,16,17

97. D. join the urinary bladder trigone at its posterolateral corners (behind the urinary bladder) 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

98. macroscopic structure and its function Ureter 25cm long , A Hollow muscular tube Ureters can pass urine from pelvicalyceal system to urinary bladder because it is a hollow tube Function!!!

99. The acute angle between the ureter and bladder prevents back flow of urine to ureters from the bladder. There is a very narrow and acute angle at the point where the ureters connect with the bladder Function!!!

100. Ureter microscopic structure and its function Transitional epithelium (Urothelium) Outer round cell layer-umbrella cells Umbrella cells urothelium is stratified (stretchable) Comprising 3 – 6 layers of cells. Surface cells are often called Umbrella cells

101. Functions!!! Umbrella cells- impermeable to urine even when it is in full stretch Prevent water entering to hypertonic urine from epithelium

102. Transitional epithelium- functions: Allow to stretch the bladder and the ureter by compressing the number of cell layers It is thrown up in to folds in the relaxed state to allowing the ureter to dilate during passage of bolus of urine Mucosal folds

103. 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

104. Outer circular layer Transitional epithelium Inner longitudinal layer Muscle layers-wall of the ureter

105. Functions? Because of the presence of smooth muscles layers it can propel urine by peristaltic movements. Mucus secreted by mucosa of ureter prevents the cells from coming into contact with urine.

106. . Urinary bladder A distensible/stretchable organ It can hold about 250ml of urine before we feel to pass them out. is like a collapsible bag Macroscopic structure and function A hollow muscular organ Functions !!! 1. to serve as a reservoir for urine .(Without the bladder, you would just have a constant urine coming out all the time as your kidneys are constantly processing new urine. Needless to say, that would make you inconvenient ) 2.Internal urethral orifice contributes to accumulate urine in the bladder

107. Urinary bladder Microscopic structure Mainly relates with its epithelium and wall Epithelium-Transitional epithelium Several cell layers (stretchable) Outer round cell layer (umbrella cells)

108. Structure of the wall of the bladder d. adventitia c. muscularis (called detrusor muscle) - 3 layers of smooth muscle -inner longitudinal layer -middle circular layer -outer longitudinal layer a. mucosa - transitional epithelium b. submucosa

109. Microscopic structure of the wall of the urinary bladder Smooth muscle layers

110. Urinary bladder-How the functions Relate with its microscopic structure Ability to stretch because presence of transitional epithelium. By contracting smooth muscle layers urine is expelled with the help of the urethra

111. Groups 18, 19, 20 RENAL FAILURE

112. Renal failure or kidney failure is a situation in which the kidneys fail to function adequately

113. Renal failure can broadly be divided into two categories: Acute renal failure Chronic renal failure

114. The type of renal failure is determined by the trend in the serum creatinine . Other factors which may help differentiate acute and chronic kidney disease include the presence of anemia and the kidney size on ultrasound . Chronic kidney disease generally leads to anemia and small kidney size.

115. ACUTE RENAL FAILURE Acute renal failure (ARF) is a rapidly progressive loss of renal function , generally characterized by oliguria (decreased urine production); b ody water and body fluids disturbances;and electrolyte derangement. ARF can result from a large number of causes.

116. Decrease urine output (70%) Edema, esp. lower extremity Mental changes Heart failure Nausea, vomiting Pruritus Anemia Tachypenia Cool, pale, moist skin Symptoms of ARF

117. Causes of acute renal failure Sudden interruption in the blood supply to the kidney, Toxic overload of the kidneys. 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. Drug overdoses, such as antibiotics or chemotherapy,

118. Chronic kidney disease Chronic Kidney Disease (CKD) can develop slowly and show few initial symptoms, be the long term result of irreversible acute disease or be part of a disease progression

119. CRF Symptoms Malaise Weakness Fatigue Neuropathy Anorexia Nausea Vomiting Seizure Constipation Peptic ulceration Diverticulosis Anemia Pruritus Jaundice Abnormal hemostasis

120. CHRONIC RENAL FAILURE CAUSES Diabetes mellitus (main cause) Hypertension Polycystic kidney disease Overuse of some common drugs, such as aspirin, ibuprofen, cocaine and acetaminophen Glomerulonephritis HIV nephropathy Reflux nephropathy in children Kidney infections & obstructions

121. Polycystic kidney disease

122. Polycystic kidney disease

123. INVESTIGATION Chronic kidney failure is measured in five stages, which are calculated using a patient’s GFR, or glomerular filtration rate

124. MEDICATIONS Unlike in chronic kidney disease, the kidneys can often recover from acute failure, allowing the patient to resume a normal life. People suffering from acute failure require supportive treatment until their kidneys recover function, and often remain at an increased risk of developing future kidney failure

125. Medications used in acute or chronic kidney failure may include Diuretics – to flush out the kidneys, increase urine flow, and rid the body of excess sodium ( eg , furosemide , mannitol ) Dopamine, atrial natriuretic peptide (ANP) – to dilate blood vessels in the kidneys, increase urine flow, flush out sodium

126. Blood pressure medications ( eg , ACE inhibitors) Sodium polystyrene sulfonate or insulin in dextrose – to control high potassium levels Calcium acetate – to control high phosphorus levels

127. 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.

128. Kidney transplant

129. REFERENCE Davidson’s Clinical Medicine – 20 th Edition (pg.491 – 496) http://www.wikipedia.com http://www.kidney.org http://www.umm.edu/ency/article/000471.htm http://www.fpnotebook.com/REN38.htm http://www.paems.org/eWebquiz/renal%20failure/Dialysis%20CEU.pdf http://www.loyolaems.com/sop/4med.htm#med8 http://www.chpnet.org/BIEM_Res/lectures.asp http://www.emedicine.com/emerg/topic501.htm http:// http://www.medonline.com.br/med_ed/med1/iranejm.htm www.auburn.edu/~deruija/renal_part3/sld001.htm