Renal Physiology Chapter 26 PDF

Because learning changes everything. ® Chapter 26 Urinary System Seeley’s ANATOMY & PHYSIOLOGY Thirteenth Edition Cinnamon VanPutte, Jennifer Regan, Andrew Russo © 2023 McGraw Hill, LLC. All rights reserved. Authorized only for instructor use in the classroom....

Because learning changes everything. ® Chapter 26 Urinary System Seeley’s ANATOMY & PHYSIOLOGY Thirteenth Edition Cinnamon VanPutte, Jennifer Regan, Andrew Russo © 2023 McGraw Hill, LLC. All rights reserved. Authorized only for instructor use in the classroom. No reproduction or further distribution permitted without the prior written consent of McGraw Hill, LLC.  Lecture Outline: Do not remember, review them ASAP Names (terms) used in renal physiology. Filtration, Filtrate Reabsorption Secretion Nephron Afferent, Efferent Gradient (pressure & concentration) Diffusion and active transport, osmosis Access the text alternative for slide images. © McGraw Hill, LLC 2  26.1 Functions of the Urinary System Urinary system is major excretory system of the body. The kidneys filter a large volume of plasma to remove wastes that form urine. Urine consists of excess water, excess ions, metabolic wastes (including urea, a protein by-product), and toxic substances. filter Renal artery Afferent arteriole Kidney © McGraw Hill, LLC 3  Filtration: cleaning © McGraw Hill, LLC 4  Filtration: cleaning (figure is an unreal example) Determined by pore size Blood RBC Prot Urine Plasma H2O WBC Small molecules © McGraw Hill, LLC 5  Functions of the Kidneys Excretion of waste products from the blood; 21% of cardiac output is filtered per minute. Regulation of blood volume and pressure by controlling extracellular fluid volume (plasma). Regulation of blood solute concentrations of the major ions, including Na+ and K+. Regulation of extracellular fluid pH by secreting H+ and bicarbonate © McGraw Hill, LLC 6  Kidney’s blood vessels, tubules, and urine flow Tubules? Capillaries Renal artery Renal pelvis Access the text alternative for slide images. © McGraw Hill, LLC 7  Structure of a Nephron, the kidney’s functional unit Nephron: functional unit of the kidney. Regions of the nephron: 1. Renal corpuscle (glomerulus and Bowman’s capsule). 2. Proximal convoluted tubule. 3. Nephron Loop (Loop of Henle). It will not be discussed in the lectures. 4. Distal convoluted tubule. © McGraw Hill, LLC 8  Functional Unit of the Kidney – the Nephron Blood vessels Tubules Cortex Medulla Access the text alternative for slide images. © McGraw Hill, LLC 9  Components of the Nephron Capsule 2. Tubular 1. Vascular Capsule Two arterioles PCT Afferent Loop of Henle Efferent DCT Two capillaries CD Glomerulus Peritubular Access the text alternative for slide images. © McGraw Hill, LLC 10  Characteristics of the Renal Corpuscle for Filtration Glomerulus High permeability for small molecules and water; large proteins and blood cells cannot pass through. © McGraw Hill, LLC 11 Renal Corpuscle: Glomerulus and Capsule Glomerular capsule Afferent arteriole Filtration Membrane Efferent arteriole © McGraw Hill, LLC 12 Filtration Membrane has 2 main components H2O + Small molecules Glomerular capsule 2. Capsule epithelium 1. Capillary endothelium Protein Red Blood Cells Plasma © McGraw Hill, LLC 13  Regulation of Glomerular Filtration Rate 2 Extrinsic mechanisms: sympathetic nervous system and hormones. Sympathetic simulation constricts small arteries and afferent arterioles, decreasing renal blood flow and filtrate formation. © McGraw Hill, LLC 14  Filtration and filter Peritubular capillary Glomerular capsule Do not cross the filtration membrane Efferent arteriole Filtrate PCT Filtrate Glucose Amino acids Afferent arteriole © McGraw Hill, LLC 15 Renal Corpuscle: Glomerulus and Capsule Proximal convoluted tubule Glomerular capsule Afferent arteriole te tra Fil Glomerular capillary Glomerulus Efferent arteriole Peritubular capillaries © McGraw Hill, LLC 16  Movement of solutes and water through epithelial cells Bowman’s capsule ell Peritubular capillary l c elia it h Ep Proximal Convolute Tubule Filtrate  Tubular Reabsorption: Overview Tubular reabsorption: transport of water and solutes from filtrate (lumen of tubule) into the blood of peritubular capillaries. Substances reabsorbed into peritubular capillaries: sodium, potassium, calcium, bicarbonate (overall 99% of filtrate is reabsorbed). Portion not reabsorbed ends up in urine. © McGraw Hill, LLC 18  Reabsorption of Solutes In the Proximal Convoluted Tubule Filtrate Bowman’s capsule Proximal Convolute Tubule Peritubular capillary Magnifying Glass © McGraw Hill, LLC 19 Reabsorption of Solutes In the Proximal Convoluted Tubule Facilitated diffusion Primary Active transport Peritubular capillary Solutes and water Peritubular capillary move into the extracellular fluid and then into Extracellular fluid the peritubular capillaries. K+ H2O ATP Osmosis Primary K+ Facilitated ADP Active diffusion transport Epithelial Epithelial cell cell Tubule cell Diffusion Glucose Amino acids H2O Na+ Na+ Na+ Osmosis Na+ Glucose Lumen of tubule Filtrate flow Amino acids containing filtrate Access the text alternative for slide images. Solutes and water Water move to loop and distal convolute tubule. © McGraw Hill, LLC 20  FILTRATION: K+ Glucose H+ Amino acids Na+ H2O Exchanges: Proximal Convoluted Tubule: REABSORPTION: secretion and reabsorption Glucose Na+ Amino acids HCO3 Distal Na+ H2O Convoluted Tubule Collecting Duct © McGraw Hill, LLC 21  Reabsorption of Solutes In the Proximal Convoluted Tubule 2 1. Reabsorption of most solutes is linked to the diffusion of Na  into the cells of the proximal convoluted tubule. There is a steep concentration gradient for Na  from the filtrate into the cytoplasm of the cells of the proximal convoluted tubule. This concentration gradient is established by active transport of Na  across the basal membrane of the cells of the proximal convoluted tubule. The Na   K + pump actively transports Na+ out of the epithelial cells and to the extracellular fluid. Na+ moved by facilitated diffusion from the filtrate into the cytoplasm of the cells of the proximal convoluted tubule. This movement of Na  into these cells is responsible for the secondary active transport of many other solutes from the lumen of the proximal convoluted tubule into the cytoplasm of the tubule cells. © McGraw Hill, LLC 22  Reabsorption of Solutes In the Proximal Convoluted Tubule 3 2. Carrier proteins that transport amino acids and glucose are located within the apical (next to the lumen) membrane, which separates the lumen from the cytoplasm of the cells of the proximal convoluted tubule. Each of these carrier proteins binds specifically to one of those substances to be transported and to sodium Na . The concentration gradient for Na  provides the energy that moves both the Na  and the other molecules or ions from the lumen into the tubule cell. Once glucose and amino acids are inside the cell, they cross the basal (outer or external) membrane of the cell by facilitated diffusion. The number of carrier proteins limits the amount of substance that can be transported. For example, the high blood glucose in someone with untreated diabetes mellitus can lead to such high glucose levels in the filtrate that not all of it can be removed by the glucose transport proteins. The excess glucose remains in the filtrate and becomes part of the urine. © McGraw Hill, LLC 23  Reabsorption of Solutes In the Proximal Convoluted Tubule 4 3. Some solutes also diffuse from the lumen of the proximal convoluted tubule to the extracellular fluid by moving between the cells across their lateral surfaces. As other solutes are transported out of the lumen, through the proximal convoluted tubule cells, and into the extracellular fluid, water follows the solutes by osmosis. As solute molecules are transported out of the filtrate, water also moves by osmosis out of the filtrate. By the time the filtrate has reached the end of the proximal convoluted tubule, its volume has been reduced by approximately 65%. © McGraw Hill, LLC 24  Reabsorption in the Distal Convoluted Tubule and Collecting Duct Water moves by osmosis from distal tubule and collecting duct under the influence of A DH. Permeability of wall of distal tubule and collecting ducts have variable permeability to water. K are  and H+ not absorbed until further in the DCT or collecting ducts and are under hormonal control depending on body conditions. Urine can vary in concentration from low volume of high concentration to high volume of low concentration. © McGraw Hill, LLC 25  Tubular Secretion Tubular secretion is the movement of nonfiltered substances from the blood into the filtrate. K+ and H+ are secreted into the distal convoluted tubule in exchange of Na+ and HCO3, respectively © McGraw Hill, LLC 26  Na+ and K+ exchange in Distal Convoluted Tubule Reabsorption From glomerulus K+ Peritubular capillary H+ K+ Potassium ion= Extracellular K+ Sodium ion= fluid Na+ ADP Primary ATP Active Na+ transport K+ Tubule Epithelial Cells Na+ From PCT & LH H2O ? Lumen Filtrate H2O Na+ Secretion HCO3- Other solutes © McGraw Hill, LLC 27  H+ and HCO3 exchange in Distal Convoluted Tubule From glomerulus Peritubular capillary H + H+ Hydrogen ion= Extracellular H+ Bicarbonate= fluid HCO3− ADP HCO3– Tubule Epithelial Cells From PCT & LH HCO3– Lumen Filtrate To collecting ducts © McGraw Hill, LLC 28  The Collecting Ducts Distal convoluted tubule H2O Collecting duct Collecting Duct Cell Collecting duct H2O Water Aquaporin Water Lumen of Collecting Duct Filtrate Blood to systemic circulation Water Urine into Renal Pelvis © McGraw Hill, LLC 29  Absorptive Capabilities of Renal Tubules and Collecting Ducts Distal Convoluted Tubule reabsorbs: – Na+ and water – HCO3 Distal Convoluted Tubule secretes: – K+ – H+ Collecting duct reabsorbs: – Water  600 mL 1500 mL 150 mL Plasma White blood cells Red blood cells  Homeostasis: Keep the normal blood volume 5 Liters Volume flowing out © McGraw Hill, LLC 32  Homeostasis: Keep the normal blood volume Close the faucet Leak 3 Liters Volume flowing out © McGraw Hill, LLC 33  Homeostasis: Keep the normal blood volume Open the faucet 7 Liters Volume flowing out © McGraw Hill, LLC 34 Components of the Nephron Afferent arteriole Distal CT Collecting duct © McGraw Hill, LLC 35 Blood to systemic circulation & urine to bladder Renal vein Ureter Urinary bladder  Filtration Pressure Gradient (P) between glomerulus & capsule Glomerular Capillary Glomerular Capsule (50 mmHg) (40 mmHg) R Ar ena te l ry Afferent arteriole Net filtration pressure (10 mm Hg) Blood flow Filtrate To proximal convoluted tubule Efferent arteriole To peritubular capillary © McGraw Hill, LLC 37  Dehydration & bleeding: ↓ in blood (plasma) volume ↓ blood (plasma) volume © McGraw Hill, LLC  Dehydration: Low blood volume causes sympathetic vasoconstriction Glomerular Capillary Glomerular Capsule (45 mmHg) (40 mmHg) R Ar ena te l ry Afferent arteriole NE Net filtration pressure (5 mm Hg) ↓Blood flow ↓Filtrate To proximal convoluted tubule Efferent arteriole To peritubular capillary © McGraw Hill, LLC 39  Na+ and K+ exchange in Distal Convoluted Tubule Reabsorption From glomerulus K+ Peritubular capillary H+ K+ Potassium ion= Extracellular K+ Sodium ion= Hormone fluid Na+ Primary Active transport ADP ATP Na+ K+ Tubule Epithelial Cells Na+ From PCT & LH H2O Lumen Filtrate H2O Na+ HCO3- Other solutes © McGraw Hill, LLC 40  The Collecting Ducts Distal convoluted tubule H2O Collecting duct Collecting Duct Cell Collecting duct H2O Water Aquaporin Water Lumen of Collecting Duct Filtrate Blood to systemic circulation Water Urine into Renal Pelvis © McGraw Hill, LLC 41  Dehydration → Concentrated urine↑Reabsorption Na+ ↓Filtration Sympathetic-mediated Vasoconstriction on afferent arteriole ↑Reabsorption  Concentration Solutes in Water out Concentrated Normal concentration Concentrated  Dehydration ↑ water or blood loss Volume produces pressure ↑ Sympathetic ANS? activity ↑ vasoconstriction in arterioles and arteries © McGraw Hill, LLC  Response to dehydration leads to normal blood volume H2O ↑ Plasma volume to normal Collecting Duct Volume produces pressure ↑ blood pressure to normal Drink just enough © McGraw Hill, LLC  Overhydration: Increase in blood volume Frequent visits to © McGraw Hill, LLC  Overhydration ↑ water or blood intake ↑ increased blood volume Volume produces pressure ↑ increased blood pressure ↓Sympathetic ANS? activity ↓ vasoconstriction in arterioles and arteries © McGraw Hill, LLC ↓Sympathetic activity increases filtration Pressure Gradient Glomerular Capillary Glomerular Capsule (55 mmHg) (40 mmHg) R Ar ena te l ry Afferent arteriole ↓vasoconstriction NE P Net filtration pressure (15 mmHg) ↓Blood flow ↑Filtrate To proximal convoluted tubule Efferent arteriole To peritubular capillary © McGraw Hill, LLC 48  Overhydration → Diluted urineReabsorption is ↓ ↑Filtration Collecting Duct ↓ Reabsorption  Dilution Diluted concentration Normal concentration Diluted concentration Response to overhydration leads to normal blood volume Volume produces pressure Normal blood flow, filtration, and urine volume © McGraw Hill, LLC  End of Main Content Because learning changes everything. ® www.mheducation.com © 2023 McGraw Hill, LLC. All rights reserved. Authorized only for instructor use in the classroom. No reproduction or further distribution permitted without the prior written consent of McGraw Hill, LLC.