Msc zoology fourth semester Day 20 - The Nephron.pptx

Science notes

1. Urinary System: Outcome: I can describe the specific filtration process kidneys use for blood. Drill: What are the four main structures/organs in the urinary system?

2. © 2015 Pearson Education, Inc. Overview of a nephron and the collecting system Slide 1 Figure 24.4 1 – 2 Ascending limb Descending limb Renal tubule Proximal Convoluted Tubule Afferent arteriole Glomerular capsule Efferent arteriole Renal Corpuscle Nephron Loop Distal Convoluted Tubule Ascending limb of loop ends Descending limb of loop begins KE Y Papillary Duct Collecting Duct Nephron Collecting System Capsular space Glomerulu s Filtrate Water reabsorption Variable water reabsorption Solute reabsorption or secretion Variable solute reabsorption or secretion 4 2 1 3 5 6

3. © 2015 Pearson Education, Inc. © 2015 Pearson Education, Inc. Types of nephrons and their location Figure 24.3 3 Cortical nephron Juxtamedullary nephron Renal cortex Renal medulla Minor calyx

4. Segments of a Nephron Nephron components Two components Renal corpuscle Blood pressure forces water and solutes out of the glomerular capillaries in a process called filtration Produces filtrate (protein-free solution, similar to blood plasma) Renal tubule Tubular passageway Receives filtrate and modifies it to create urine © 2015 Pearson Education, Inc.

5. Segments of a Nephron Nephron segments Renal corpuscle Glomerular capsule (cup-shaped chamber) Capillary network ( glomerulus ) Proximal convoluted tubule ( PCT ) Reabsorbs nutrients from the filtrate (now called tubular fluid ) © 2015 Pearson Education, Inc.

6. Segments of a Nephron Nephron segments (continued) Nephron loop (Loop of Henle ) Establishes osmotic gradient for water reabsorption Each limb contains a thin segment and a thick segment Distal convoluted tubule ( DCT ) Adjusts tubular fluid composition by reabsorption and secretion © 2015 Pearson Education, Inc.

7. © 2015 Pearson Education, Inc. © 2015 Pearson Education, Inc. Parts of a nephron Figure 24.4 1 Ascending limb Descending limb Renal tubule Proximal Convoluted Tubule Afferent arteriole Glomerular capsule Efferent arteriole Renal Corpuscle Nephron Loop Distal Convoluted Tubule Ascending limb of loop ends Descending limb of loop begins KE Y Nephron Capsular space Glomerulu s Filtrate Water reabsorption Variable water reabsorption Solute reabsorption or secretion Variable solute reabsorption or secretion 4 2 1 3

8. Circulation Patterns in the Kidney Blood flow around a nephron Afferent arteriole Supplies blood to each individual nephron Glomerulus (FILTRATION OCCURS HERE) Efferent arteriole Carries blood from the glomerulus to the peritubular capillaries Peritubular capillaries (in Cortical Nephron ) Vasa Recta (in Juxtmedullary Nephron ) Surround the entire renal tubule Collect water and solutes absorbed by the nephron Deliver other solutes to the nephron for secretion Drain into cortical radiate veins © 2015 Pearson Education, Inc.

9. © 2015 Pearson Education, Inc. © 2015 Pearson Education, Inc. Cross-sectional view of the visceral layer of the glomerular capsule Figure 24.8 1 Initial segment of renal tubule Parietal layer Visceral layer Glomerular capsule Efferent arteriole Juxtaglomerular complex Afferent arteriole Visceral layer Glomerular endothelial cell Filtration slits Pedicels Podocyte Mesangial cells Capsular space RBC DCT Capsular space – 2

10. © 2015 Pearson Education, Inc. © 2015 Pearson Education, Inc. Peritubular capillaries in a cortical nephron Figure 24.5 2 To the cortical radiate vein Glomerulus in renal corpuscle Peritubular capillaries Efferent arteriole Afferent arteriole

11. © 2015 Pearson Education, Inc. © 2015 Pearson Education, Inc. Vasa recta in a juxtamedullary nephron Figure 24.5 3 Peritubular capillaries Efferent arteriole Afferent arteriole To cortical radiate vein Capillaries of the vasa recta

12. © 2015 Pearson Education, Inc. © 2015 Pearson Education, Inc. Locations of filtration, reabsorption, and secretion in the nephron and collecting system Figure 24.7 1 Glomerulus Proximal convoluted tubule (PCT) Nephron loop Distal convoluted tubule (DCT) KEY Collecting duct Glomerular capsule Urine storage and elimination Filtration Water reabsorption Variable water reabsorption Solute reabsorption Variable solute reabsorption or secretion

13. Glomerular Filtration Rate Glomerular filtration rate ( GFR ) Amount of filtrate produced by the kidneys each minute Each kidney has ~6 m 2 (64 sq. ft.) of filtration surface GFR averages 125 mL/min (180 L/day) ~99 percent is reabsorbed © 2015 Pearson Education, Inc.

14. Urinary System: Exit Ticket: Describe the pathway of blood flow into the kidney. What arteries are being pass through (in order)?