Urinary System Part 1 2020 PDF

Urinary System: Part 1 Gross Anatomy Microanatomy of the Nephron Filtration of Blood Anatomy & Physiology II BIOL2220 Version 1 1 The Urinary System Functional Significance Major Functions of the Kidneys...

Urinary System: Part 1 Gross Anatomy Microanatomy of the Nephron Filtration of Blood Anatomy & Physiology II BIOL2220 Version 1 1 The Urinary System Functional Significance Major Functions of the Kidneys The Kidneys: -are “retroperitoneal”, in the upper posterior 1. Regulation of: abdominal wall, at the level of T11-T12 -are asymmetrical, with the right slightly lower Body fluid osmolarity and volume than the left Electrolyte balance -Are shaped like a ‘kidney bean”, with a lateral Acid-base balance surface that is convex, and a medial surface that it Blood pressure concave - -this concavity is called the hilum - -the hilum contains the 2. Excretion of: following: - The renal vein Metabolic products - Two branches of the Foreign substances (pesticides, chemicals ,etc.) renal artery Excess substance (water, etc) - The ureter - Lymphatic vessels - Sympathetic nerve fibers 3. Secretion of: Erythropoietin-Made in Fibroblasts 1,25-dihydroxy vitamin D3 (vitamin D activation)- Synthesis completed in Tubule cells Renin-Made in JG cells 2 The Urinary System Kidney Gross Anatomy Outer cortex Inner medulla 3 The Urinary System Ureters & Urinary Bladder Gross Anatomy 4 The Urinary System Urethra Gross Anatomy 5 The Urinary System Renal Blood Flow Aorta Inferior Vena Cava Renal Artery Renal Vein Segmental Artery Interlobar Vein Interlobar Artery Arcuate Vein Arcuate Artery Cortical Radiate Vein Cortical Radiate Artery Peritubular Capillaries Afferent Arteriole Glomerulus Efferent Arteriole 6 6 The Urinary System Microanatomy of the Kidney-The Nephron Cortical nephron – glomeruli in outer cortex & short loops of Henle that extend only short distance into medulla-- blood flow through cortex is rapid – majority of nephrons are cortical Juxtamedullary nephron – glomeruli in inner part of cortex & long loops of Henle which extend deeply into medulla.– blood flow through vasa recta in medulla is slow – medullary interstitial fluid is hyperosmotic – this nephron maintains osmolality Collecting Duct in addition to filtering blood and Not part of “technically” part of maintaining acid-base balance nephron Collects urine from distal convoluted tubules of many nephrons Opens at tip of pyramid Urine drains into minor calyx 7 The Urinary System Outline of the Nephron Physiology-Nephron Overview EFF ART Peritubular Capillaries CT Capsule & JGA Glomerulus PCT DCT (Renal Corpuscle) TO CORTICAL U RADIATE VEIN R D I AFF ART A N L L E TO LOOP C A L Y Vasa Recta C E S 8  The Urinary System Cortex Microanatomy of the Kidney Peritubular Capillary Distal Convoluted Tubule Juxtaglomerular Apparatus Glomerulus 1. Peritubular Capillary 2. Distal Convoluted Tubule 3. Juxtaglomerular Apparatus 4. Glomerulus with Bowman’s Capsule 5. Proximal Convoluted Tubule Proximal Convoluted Tubule Bowman’s Capsule 9 The Urinary System Medulla Microanatomy of the Kidney Descending Limb Ascending Limb 1 2 3 4 1. Ascending Limb of the Loop Vasa Recta Capillary 2. Descending Limb of the Loop Collecting Duct 3. Vasa Recta Capillary 10 4. Collecting Duct  Key Points: Glomerular Blood Pressure Drives Glomerular Filtration, and the Filtration Barrier is Two Cells Thick: Squamous Cell of the Capillary The Urinary System & The Podocyte Microanatomy of the Kidney-The Renal Corpuscle FYI: This is Gross filtrate where Renin is released. Note: Podocytes provide an extra filtration barrier for things like cells and large proteins. Note: Blood pressure in the glomerulus is at an arterial level…much higher than pressure in typical 11 11 capillaries. The Urinary System Physiology of the Nephron-The 4 Important Processes Reabsorption Secretion Filtration Excretion – Filtration: – Reabsorbtion: Process of – Secretion: – First step in urine formation returning filtered – Material added to lumen – Bulk transport of fluid from material to of kidney from blood blood to kidney tubule bloodstream – Active transport (usually) » Isosmotic filtrate 99% of what is of toxins and foreign filtered substances (Saccharine, » Blood cells and Penicillin), but may also proteins don’t filter May involve include ions (H+, K+). – Result of hydraulic pressure transport protein(s) – Excretion: – GFR = 180 L/day Normally glucose – Loss of fluid from body in is totally form of urine 12 reabsorbed The Urinary System Key Point : Aff Art Dilation and Constriction Is the Glomerular Filtration way to Change GFR Glomerulus Bowman’sCapsule Afferent arteriole Efferent arteriole Glomerular Filtrate VC AffArtàê Q AffArtà êGBFàê GBPà êGFR VD AffArtà éQ AffArtà éGBFà éGBPà éGFR 13 The Urinary System GFR: Functional Significance of the JGA/Tuboglomerular Feedback êNa+ in ê Na+ in é NO VD of é GBF éGBP éGFR êGFR DCT Macula Afferent release Arteriole éNa+ in éNa+ in éAdenosine VC of êGBF êGBP éGFR êGFR DCT Macula release Afferent Arteriole The Urinary System GFR: Response to Severe Drop in Blood Pressure êêGFR êêNa+ in êêNa+ in DCT Macula cells Macula Densa éBP Juxtaglomerular Apparatus Mesangial Cells éVC @ TPRs Regulates the Juxtaglomerular function Cells (granular cells) éRenin éRAS éAgII of each nephron éVC @ êêêGFR AFF ART 15 The Urinary System Operation of the Nephron Physiology-Nephron Overview EFF ART ▲ BP ▲ RAS ADH Aldo TGF PTH CT Capsule & JGA Glomerulus PCT DCT (GFR) Na+ Concentration K+ & H+ U in DCT Fluid, R SNS, Prostaglandins I H2O NaCl N AFF ART E VC: Ag II, NE, UREA ADH/AVP, Adenosine TO VD: ANP, NO RESORB: LOOP C Na+ Na+ K+ A Ca++ L Glu H2 O H2O Y The AA Countercurrent C Multiplier E S 1 PERITUBULAR CAPILLARIES & 16 VASA RECTA  The Urinary System Glomerular Filtration Rate (GFR) Amount of filtrate produced in the kidneys each minute: 125mL/min = 180L/day Factors that alter GFR include: – Increased Glomerular Capillary Q --> Increased GFR – Decreased Glomerular Capillary Q --> Decreased GFR So, How do you regulate“Glomerular Capillary Q”? GFR is regulated using three mechanisms 1. Renal Autoregulation/Tuboglomerular Feedback (previously diagrammed) 2. Neural regulation 3. Hormonal regulation All three mechanisms adjust renal blood pressure and blood flow 17 The Urinary System Key Point : Aff Art Dilation GFR: Neural & Hormonal Regulation and Constriction Glomerulus Afferent arteriole Efferent arteriole ñGFR òGFR Glomerular filtrate Eff. Art. Aff. Art. Eff. Art. dilation Aff. Art. dilation constriction constriction ANP, NO Angiotensin II Ag II (high level), Angiotensin II (low level) Epi/NE(SNS), ADH/AVP. blockade Adenosine 18