11/18/2013
Fall in a stream The Urinary System: Outline bed, far, far away… 1. Adaptation to Arid Environments 2. Urinary System Components and Functional Overview 3. Kidney Lobes and Lobules Gale Crater… Mars 4. The Nephron and Tubular Nomenclature 5. The Renal Corpuscle 6. The Glomerulus, Podocytes and the Filtration Barrier 7. The Proximal Tubule 8. The Loop of Henle 9. The Distal Tubule 10. Renal Circulation Joseph B. Delcarpio, Ph.D., Associate Dean; Professor, 11. The Juxtaglomerular Apparatus Cell Biology and Anatomy, LSUHSC All rights reserved.
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The Urinary System Adaptations to Arid Environments The Urinary System Adaptations to Arid Environments
The Cloudless Sulfur: Phoebis sennae Linnaeus The Kangaroo Rat : Dipodomys speciabilis
Microcell in wing scale is the site of uric acid crystal deposition.
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The Urinary System: Components The Urinary System: Functions
1. Paired Kidneys: 1. Waste Excretion/Water a. Left slightly Conservation higher than right 2. Acid/Base Regulation
2. Paired Ureters: 3. Endocrine functions: a. Exit Hilum a. Erythropoietin (90%- interstitial fibroblast in cortex) b. Insert into Trigone b. Renin (juxtaglomerular cells) 3. Single Urinary Bladder 4. Hydroxylation of Vitamin D 4. Single Urethra
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The Urinary System: The Kidney The Urinary System: The Kidney Structure: Fetal and Adult Kidney Lobes
Cortex
Papilla Cortex
Papilla Cortex
Medulla
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The Urinary System: The Kidney The Urinary System: The Kidney Structure: Lobule – Centered on Medullary Rays Structure: Lobule – Cortex
Medullary rays: straight tubules in the cortex, some of which are continuous with collecting tubules of the medulla
Figure 20.6 09/35 10/35
The Urinary System: The Kidney The Urinary System: The Kidney Structure: Lobule – Cortex Structure: Lobule – Medulla Kidney Lobule: Kidney Lobule: a. medullary ray at center a. medullary ray at b. one half adjacent cortical labyrinth center c. single medullary duct (next slide) b. one half adjacent cortical labyrinth c. single medullary duct d. consists of all nephrons associated with a single medullary duct. (Duct of Bellini) Figure 20.2 11/35 12/35
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The Urinary System: Nephron - 2 Types The Urinary System: Nephron
1. Juxtamedullary 2. Mid-Cortical 1. Renal Corpuscle 8. Distal Nephron: long Nephron: short 2. Proximal Convoluted loops of Henle loops of Henle Convoluted Tubule Tubule 9. Connecting 3. Medulla: divided 3. Proximal Tubule into – outer and 3.c. Inner Stripe: Straight Tubule inner medulla thick and thin 9*. Collecting a. Outer Medulla: tubular segments; 4. Descending Thin Tubule divided into outer outer medullary Limb 10. Cortical and inner stripes collecting ducts 5. Ascending Collecting Thin Limb Duct b. Outer stripe: only thick tubular 4. Inner Medulla: 6. Thick 11. Outer Medullary segments, outer thin segments; Ascending Limb Collecting Duct medullary inner medullary (Distal Straight collecting ducts collecting ducts Tubule) 12. Inner Medullary Collecting Duct Figure 20.2 7. Macula Densa Figure 20.2
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The Urinary System: Renal Corpuscle The Urinary System: Renal Corpuscle Structure: Renal Corpuscle – Development
Note: Glomerular Arterial “tuft” is surrounded by the renal tubule.
Note: Visceral layer of Bowman’s capsule thins. Note: Pale purple region represents Bowman’s space, or the urinary space. 15/35 16/35
The Urinary System: Renal Corpuscle The Urinary System: Renal Corpuscle Structure:Renal Corpuscle -Three Dimensional View
* The Mature Renal Corpuscle, Vascular components: Pole 1. The glomerular capillary tuft 2. Bowmans’ Capsule: visceral layer
parietal layer
The Urinary Pole Figure 20.7 17/35 18/35
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The Urinary System: Renal Corpuscle Renal Corpuscle: Podocytes – Visceral Layer Structure: Podocytes – Visceral Layer Bowman’s Capsule
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The Urinary System: Renal Corpuscle The Urinary System: Renal Corpuscle Structure: Podocytes – Visceral Layer Bowman’s Capsule Structure: Electron Microscopy of Renal Corpuscle
Podocyte Body Bowman’s Space Urinary Space
Note: 1O and 2O Podocyte processes
Pedicels branch from 2O Blocked area processes enlarged at right.
Figure 20.12b Figure 20.13 21/35 22/35
The Urinary System: Renal Corpuscle The Urinary System: Renal Corpuscle Structure: Glomerular Filtration Barrier – Components (3) Structure: Mesangial Cells – Functions
Filtration Slits (with diaphragms) Mesangial cells: provide mechanical Urinary Space 1. Podocyte Pedicels support
2. Glomerular Basement control GBM material Membrane (GBM): turnover Lamina rara externa regulate blood flow Lamina densa secrete vasoactive substances Lamina rara interna Capillary respond to Lumen angiotensin II 3. Capillary Endothelium
Fenestrations Figure 20.16
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The Urinary System: Renal Corpuscle The Urinary System: Proximal Tubule Structure: Urinary Pole – Proximal Tubule, pars convoluta Structure: Proximal Convoluted Tubules – Cytology Primary Cilia
Distal Cell Border Tubule. Afferent A. Extensive Microvilli: lateral Brush Border interdigitations
Proximal Tubule.
Figure 20.17 Plicae: lateral infolding Basal lamina
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The Urinary System: Loop of Henle The Urinary System: Distal Tubule Structure: The Kangaroo Rat and the Loop of Henle Structure: Distal Tubules: reabsorption of ~7% filtrate Concentrated Urine: Counter-Current Multiplier DTs: sensitive to Aldosterone - conserves water and Antiduretic Hormone - depends on length of the Loop of Henle Histology: low cuboidal cells; lateral and basal infoldings
Kangaroo Rats: - live in arid conditions and need to conserve water - therefore, have the longest Loop of Henle of all the mammals
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The Urinary System: Collecting Tubule The Urinary System: Collecting Tubule Structure: Cortical Collecting Tubules/ Medullary Ray Structure: Outer Medullary Collecting Tubules/Ducts Histology: Collecting Histology: low cuboidal epithelium, Tubules – low cuboidal cells central nuclei, lateral cell borders. Intercalated (Dark) & Principal cells (sensitive to Aldosterone). Vasa recta Thin Loop of Henle
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The Urinary System: Collecting Ducts The Urinary System: Blood Supply Structure: Inner Medullary Collecting Ducts of Bellini Structure: The Cortical and Medullary Vasculature G1 and G2 glomeruli: efferent arterioles give rise Papillary Collecting Ducts: to peritubular capillaries columnar cells (pc) clear cytoplasm lateral cell boundaries G3 glomeruli: efferent arterioles give rise to vasa recta capillaries (ARS, MP –medullary plexus) Note: Vasa recta with blood Arcuate aa. and vv.: elements in the lumen. boundary between cortex and medulla
Interlobular (IL) aa/vv.: Note: Thin loops of Henle give rise to stellate aa/vv (sv) with prominent nuclei in afferent arterioles the lumen. Figure 20.23 31/35 32/35
The Urinary System: The JG Apparatus The Urinary System: The JG Apparatus Structure: The Juxtaglomerular apparatus Function: The Juxtaglomerular apparatus
Vascular Pole of Renal Corpuscle The Juxtaglomerular Apparatus Function of the JGA: 1. Juxtaglomerular Components of the JGA: secrete renin cells react to stretch 1. Juxtaglomerular cells of the afferent arteriole 2. Extraglomerular Mesangial Cells 2. Macula Densa cells of modify activity of JG the Distal Tubule cells
3. Extraglomerular 3. Macula Densa cells Mesangial Cells (Lacis sense changes in Na cells) and regulate JG cells
Figure 20.7
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The Urinary System: Summary
1. The Function of the Urinary System is Carefully Tied to Its Structural Components. 2. The Kidney is divided into a Cortex, containing the filtering structures (Glomeruli) and a Medulla containing a collection system composed of tubular units (Collecting Ducts and Loops of Henle). 3. Loops of Henle within the Medulla are responsible for establishing an interstitial concentration gradient which is part of a Counter-current Multiplier. 4. The Kidney contains a unique circulation responsible for returning materials reabsorbed from the ultrafiltrate to general circulation and helping to maintain a hypertonic interstitial medulla necessary for developing a Concentrated Urine (Countercurrent Exchange System). 5. The Juxtaglomerular Apparatus is important in regulating both renal and systemic blood pressure. 35/35
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