urinarysystemppt.pdf

Overview of the Urinary System October 6, 2023 Dr. O. Oyedele UBC Faculty of Medicine, Southern Medical Program [email protected] “Thi...

Overview of the Urinary System October 6, 2023 Dr. O. Oyedele UBC Faculty of Medicine, Southern Medical Program [email protected] “This copy is made solely for your personal use for research, private study, education, parody, satire, criticism or review only. Further reproduction, fixation, distribution, transmission, dissemination, communication, or any other uses, may be an infringement of copyright if done without securing the permission of the copyright owner. You may not distribute, email or otherwise communicate these materials to any other person.” (Full statement from http://copyright.ubc.ca/faq/digital- classroom/) No conflicts to disclose  Lecture Objectives 1. Describe and identify the key histological structures of the kidney specifically, its functional unit, the uriniferous tubule. 2. Explain how the structure & ultrastructure of the kidney relate to glomerular filtration, tubular processing and concentration of urine. 3. Outline the role of the JGA in the regulation of blood pressure. 4. Describe the histology of the ureters and relate this to their function. 5. Describe the histology of the urinary bladder and relate this to its function.  Overview & histology of uriniferous tubule Objective #1 Describe and identify the key histological structures of the kidney specifically, its functional unit, the uriniferous tubule.  Kidney Anatomy Fig. 26-1 & 26-2 From Pocket Companion to Guyton & Hall Textbook of Medical Physiology Copyright © 2021 by Elsevier, Inc. All rights reserved. Corticomedullary junction Kidney Histology Arcuate vessels General organization of kidney: structure reflects function medulla  medulla General General organization organization of kidney of kidney: Inner structure medulla reflects function LOH…..later Outer medulla Arc. Vsl Arc. Vsl Arc. Vsl Arc. Vsl cortex  General organization of kidney (contd.) Cortical labyrinth Renal lobule Functional Unit of Kidney: defining the uriniferous tubule Renal corpuscles & Renal tubules Slide #312 Rabbit Kidney  Uriniferous tubule (contd.) Image by Fran Barreto from Pixabay https://pixabay.com/users/franknowledge7-3016758/?utm_source=link- attribution&utm_medium=referral&utm_campaign=image&utm_content=5919647  Uriniferous tubule (contd.) “Uriniferous” means “urine bearing” or “urine Renal conveying” corpuscle Uriniferous tubule = nephron + collecting tubule (duct) Fig. 26-2 From Pocket Companion to Guyton & Hall Textbook of Medical Physiology Copyright © 2021 by Elsevier, Inc. All rights reserved.  Kidney structure & ultrastructure Objective # 2 Explain how the structure & ultrastructure of the kidney relate to glomerular filtration, tubular processing and concentration of urine  Histological basis of glomerular filtration Renal corpuscle Fig. 26-2 From Pocket Companion to Guyton & Hall Textbook of Medical Physiology Copyright © 2021 by Elsevier, Inc. All rights reserved. Histology of the renal corpuscle The capillary network is called the glomerulus Bowman’s capsule is a double layered epithelial ‘cup’ Urinary space  Renal Corpuscle Vascular Pole Bowman capsule Visceral layer Mesangial cells (podocytes) Parietal layer (squamous cells) Slide #312 Rabbit Kidney Bowman’s space (urinary space) Urinary Pole  Renal Filtration Barrier (EM) UBC Faculty of Medicine – Histology EM Magnifier Glomerular capillary lumen Urinary Slide #312 Rabbit Kidney space  Renal Filtration Barrier (EM) contd. Fenestrated capillary endothelium. Capillary basement Glomerular membrane. capillary lumen Podocytes, podocyte process with pedicels Filtration slits between pedicels, bridged by slit membranes. UBC Faculty of Medicine – Histology EM Magnifier  Renal Filtration Barrier (SEM) Slide #312 Rabbit Kidney You are here UBC Faculty of Medicine – Histology EM Magnifier Renal Filtration Barrier (molecular structure, FYI only) (pedicel) Fig. 20.14. Histology : a text and atlas : with correlated cell and molecular biology. 8th Ed / Wojciech Pawlina, Michael H. Ross. © 2020 Wolters Kluwer. All Rights Reserved  Kidney structure & ultrastructure Objective # 2 Explain how the structure & ultrastructure of the kidney relate to glomerular filtration, tubular processing and concentration of urine Fig. 26-2 From Pocket Companion to Guyton & Hall Textbook of Medical Physiology Copyright © 2021 by Elsevier, Inc. All rights reserved. Proximal Convoluted Tubule (PCT)‐ histology More numerous in cross section Cuboidal cells Granular appearance of cytoplasm (lots of mitochondria) Eosinophilic Indistinct cell boundary (due to interdigitations) ‘Dirty’ lumen – due to abundant microvilli (brush border) Slide #312, Rabbit kidney Distal Convoluted Tubule (DCT) Fewer in cross section Smaller cuboidal cells Less eosinophilic Indistinct cell boundary Wider lumen – due to absence of brush border (microvilli) Slide #312, Rabbit kidney  Comparing PCT vs DCT Slide #121, Kidney, Basement Membrane PAS stain  Comparing PCT vs DCT Ultrastructure A B Courtesy Dr. P Nahirney Loop of Henle (thick & thin limbs)  The arrangement of the peritubular capillaries surrounding the loops of Henle facilitates urine concentration Fig. 26-2 From Pocket Companion to Guyton & Hall Textbook of Medical Physiology Copyright © 2021 by Elsevier, Inc. All rights reserved. Briefly about function.....  s f l a o s w t e e r r https://pixabay.com/photos/go-kart-track-kart-go-kart- 187490/  Loop of Henle concn concn https://pixabay.com/photos/go-kart-track-kart-go-kart-187490/  The selective permeability of different segments of the LOH to water or solutes and arrangement of the peritubular capillaries around the loops of Henle facilitates urine concentration – ‘countercurrent mechanism’ Fig. 26-2 From Pocket Companion to Guyton & Hall Textbook of Medical Physiology Copyright © 2021 by Elsevier, Inc. All rights reserved. Loop of Henle: thick & thin limbs The uriniferous tubule p. 360 Netter’s Essential Histology 2nd ed. by WK Ovalle and PC Nahirney 2013 © Elsevier Saunders PA Used by Permission. All rights reserved.  medulla General organization of kidney: Loop of Henle Inner structure medulla reflects function LOH Outer medulla Arc. Vsl Arc. Vsl Arc. Vsl Arc. Vsl cortex  Loop of Henle Thick limb Thin limb  Loop of Henle Cap Thn C Thk Thk Cap Thn Thn Thk Thn Thk Thk Thn Cap  Loop of Henle – long. orientation Thick limbs resemble DCTs but are located in the medulla, as opposed to actual DCTs which are mostly found in the renal cortex.  Loop of Henle – long. orientation Thin limbs, also in the medulla, have a simple squamous epithelium. They are differentiated from the surrounding capillaries by the absence of RBCs in their lumen. Collecting tubules  Histology of Collecting Tubules Slide #312, Rabbit kidney Wide lumen; pale‐staining cytoplasm; distinct intercellular outlines, central nucleus, perinuclear halo; cells vary from cuboidal to low columnar.  Collecting Tubules Distinct cell boundary Perinuclear halo Perinuclear halo represents areas where glycogen has been lost / “washed out” during histological preparation Juxtaglomerular apparatus Objective #3 Outline the role of the JGA in the regulation of blood pressure.  The arrangement of the peritubular capillaries surrounding the loops of Henle facilitates urine concentration Fig. 26-2 From Pocket Companion to Guyton & Hall Textbook of Medical Physiology Copyright © 2021 by Elsevier, Inc. All rights reserved. Juxtaglomerular apparatus (JGA) The JGA is a mechanism by which the kidneys regulate arterial blood pressure and control glomerular filtration rate  Juxtaglomerular apparatus DCT Macula densa Afferent arteriole (JG cells) Extraglomerular mesangial cells (lacis cells) – not resolved by LM Slide #312, Rabbit kidney Juxtaglomerular apparatus (schematic) Schematic UBC Faculty of Medicine – Histology EM Magnifier Juxtaglomerular apparatus (EM)  Juxtaglomerular apparatus (EM) contd. Mesangial UBC Faculty of Medicine – Histology EM Magnifier cell DCT lumen Macula densa (detect Na+) AA JG cell lumen nucleus Na Low Aldosterone Na Angiotensin II Renin Angiotensinogen > Angiotensin I ACE Type II pneumocytes Ureters & Urinary bladder Objectives #4 & 5 Describe the histology of the ureters and relate this to their function Describe the histology of the urinary bladder and relate this to its function  Ureter has four histological layers 4 3 2 1 Slide #313, Ureter 1. Epithelium 2. Lamina propria 3. Muscularis 4. Adventitia  2 1 3 Transitional epithelium/Urothelium Lines urinary system from minor calyx to most of urethra. Impermeable to contents of ** urine. 3‐8 cell layers, depending on state of distension. Surface cells are dome‐ shaped ‘umbrella cells’ **. EM shows that plasma membrane of umbrella cells full bladder have rigid plaques, absent at interplaque regions. Hence epithelium can fold at empty bladder interplaque hinge points. Urinary Bladder Histology (very similar to ureter) lumen IL LP urothelium OL OC adventitia Slide #123A Urinary Bladder (Human) Ureter vs. Urinary Bladder  Review of Lecture Objectives 1. Describe and identify the key histological structures of the kidney specifically, its functional unit, the nephron. 2. Explain how the structure & ultrastructure of the kidney relate to glomerular filtration, tubular processing and concentration of urine. 3. Outline the role of the JGA in the regulation of blood pressure. 4. Describe the histology of the ureters and relate this to their function. 5. Describe the histology of the urinary bladder and relate this to its function.