Brain and Kidney Crosstalk (Physiology in Clinical Neurosciences – Brain and Spinal Cord Crosstalks)

Description

This book discusses normal brain physiology and renal physiology, as well as the interactions between the two. The physiology of the brain can easily be affected by any changes to the physiology of other systems, which in turn may compromise cerebral blood flow and oxygenation. Together the brain and the renal system help our body systems to function automatically.  The book addresses the basic aspects of neurophysiology and renal physiology in three broad sections, the first of which covers the basic principles of cerebral physiology and neural regulation of the renal system. The second part reviews the normal physiology of the renal system, including the mechanism of action, while the last section summarizes the correlation between the brain and kidney. Highly informative and clearly structured, the book provides essential insights for anyone with an interest in physiology and medicine. Preface Acknowledgement Contents About the Editors 1: Neurophysiology and Renal System 1.1 Basics of Cerebral Physiology 1.1.1 Cerebral Blood Flow and Autoregulation 1.1.1.1 Cerebral Blood Flow 1.1.1.2 Cerebral Autoregulation 1.1.2 Blood Cerebrospinal Fluid and Blood–Brain Barrier 1.1.3 Role of Brain in Body Fluid Dynamics 1.2 Neural Regulation of Renal System 1.2.1 Efferent Signals from Central Nervous System to Kidneys 1.2.1.1 Neural Control of the Renal Circulation 1.2.1.2 Neural Control of Renal Tubular Function 1.2.1.3 Neural Control of Renal Hormonal Secretion 1.2.2 Afferent Signals from Kidneys to Central Nervous System 1.2.2.1 Renorenal Reflex Control of Renal Function 1.2.2.2 Mechanisms of Activation of Renal Sensory Nerves 1.3 Role of Renal Sympathetic Nerves in Pathophysiological States 1.3.1 Hypertension 1.3.2 Chronic Sodium-Retaining Edema-Forming States 1.4 Brain–Gut–Kidney Axis 1.5 Conclusion References 2: Normal Physiology of Renal System 2.1 Structure and Function of Kidney 2.1.1 Gross Structure 2.1.1.1 Location 2.1.1.2 Cortex and Medulla 2.1.2 Functional Unit: The Nephron 2.1.2.1 Renal Corpuscle 2.1.2.2 Renal Tubule 2.1.3 Types of Nephrons 2.1.4 Juxtaglomerular Apparatus 2.1.5 Vascular Supply and Innervation of Kidney 2.1.5.1 Vascular Supply 2.1.5.2 Innervation of Kidney 2.1.6 Functions of Kidney 2.1.7 Recent Advances 2.2 Glomerular Filtration Rate (GFR) 2.2.1 Mechanism of Generation of GFR 2.2.1.1 Pressure Gradients 2.2.1.2 Filtration Coefficient 2.2.2 Factors Effecting Glomerular Filtration Rate: (Bhaskar and Oommen 2018) 2.2.3 Regulation of Glomerular Filtration Rate 2.2.4 Effect of Vasoconstrictors and Vasodilators (Hall and Brands 2012) 2.2.5 Measurement of GFR (Gaspari et al. 1997) 2.2.5.1 Filtration Markers 2.2.5.2 Renal Clearance 2.2.5.3 Creatinine Clearance Test Estimated Creatinine Clearance 2.2.5.4 SNGFR Estimation Technique (Moore 1984) 2.3 Transport of Solute Across Kidneys 2.3.1 Active Transport 2.3.2 Passive Transport 2.3.3 Proximal Tubule (Curthoys and Moe 2014) 2.3.3.1 Sodium Reabsorption 2.3.3.2 Water Reabsorption 2.3.3.3 Glucose Reabsorption (Mather and Pollock 2011) 2.3.4 Loop of Henle 2.3.5 Distal Convoluted Tubule 2.3.6 Collecting Duct 2.3.6.1 Reabsorption of Solutes 2.3.6.2 Reabsorption of Water 2.4 Urine Concentration and Dilution 2.4.1 Why Is There a Need for Urine Concentration? 2.4.1.1 How Is Urine Concentration Achieved? The Solute and Water Permeability Characteristics of Each Tubule Segment (Table 2.4) The Osmotic Gradient Between the Tubule Lumen and Its Surrounding Interstitium (Knepper and Stephenson 1986) Corticomedullary Osmolality Gradient (Boron and Boulpaep 2016) (Fig. 2.28) 2.4.2 Countercurrent Multiplication (Pallone et al. 2003) 2.4.2.1 Prerequisites for Countercurrent Flow 2.4.2.2 Countercurrent Multiplication (Sands and Layton 2009) 2.4.3 Countercurrent Exchange (Zimmerhackl et al. 1987) 2.4.4 Role of the Collecting Duct 2.4.4.1 Role of Urea 2.5 Regulation of Acid–Base Balance 2.5.1 Basic Concepts 2.5.1.1 Importance of Henderson–Hasselbalch Equation 2.5.2 Blood pH Regulation 2.5.3 Physiological Buffering 2.5.4 Renal Regulation of Plasma Bicarbonate Concentration 2.5.4.1 Role of Proximal Tubule in Acid–Base Balance 2.5.4.2 Role of Distal Segments of Nephron in Acid–Base Balance 2.5.4.3 Conversion of Alkaline Phosphate to Acid Phosphate 2.5.4.4 Ammonia Secretion 2.5.4.5 Summary of the Renal Contribution to Acid–Base Balance 2.5.5 Factors Influencing Renal Excretion of Hydrogen Ions 2.5.5.1 Decrease in Intracellular pH 2.5.5.2 Changes in Arterial Partial Pressure of Carbon Dioxide 2.5.5.3 Carbonic Anhydrase Activity 2.5.5.4 Increased Sodium Reabsorption 2.5.5.5 Changes in Plasma Potassium Concentration 2.5.5.6 Aldosterone 2.5.5.7 High Transepithelial pH Gradient 2.5.6 Simple Acid–Base Balance Disorders 2.6 Control of Blood Volume and Composition 2.6.1 Sensors of Blood Volume 2.6.1.1 Cardiopulmonary Volume Sensors Atrial Sensors Mechanism of Action Neural Pathways Humoral Pathways Ventricular and Pulmonary Sensors 2.6.1.2 Arterial Sensors 2.6.1.3 Central Nervous System Sensors 2.6.1.4 Hepatic Receptors 2.6.2 Efferent Limb: Effectors for Blood Volume Homeostasis 2.6.2.1 Glomerular Filtration Rate 2.6.2.2 Intrarenal Physical Factors Peritubular Factors Luminal Factors in Glomerular-Tubular Balance 2.6.2.3 Humoral Effector Mechanisms Renin–Angiotensin–Aldosterone System Actions of Angiotensin II Actions of Aldosterone Anti-diuretic Hormone Prostaglandins Natriuretic Peptides Endothelium-Derived Factors Nitric Oxide Endothelin 2.6.2.4 Renal Nerves 2.6.3 Integrated Response to Volume Expansion 2.6.4 Integrated Response to Volume Contraction 2.7 Endocrine Function of Kidneys 2.7.1 Hormone Production 2.7.1.1 Renin Secretion Function Importance 2.7.1.2 Erythropoietin Secretion Function Importance 2.7.1.3 Urodilatin Secretion Function Importance 2.7.1.4 Klotho Secretion Function Importance 2.7.1.5 Thrombopoietin Secretion Function Importance 2.7.2 Hormone Activation 2.7.2.1 Vitamin D Activation Function Importance 2.7.3 Hormone Metabolism 2.7.3.1 Prostaglandin Metabolism Function Importance 2.7.3.2 Insulin Metabolism Importance 2.7.3.3 Gastrin Metabolism Function Importance 2.7.3.4 Parathyroid Hormone Function Importance 2.7.4 Miscellaneous 2.7.4.1 Gluconeogenesis Metabolism Function Importance 2.8 Physiology of Micturition 2.8.1 Functional Anatomy 2.8.2 Innervation 2.8.3 Mechanics of Micturition 2.8.3.1 Filling of the Bladder 2.8.3.2 Emptying of the Bladder 2.8.4 Neural Mechanism of Micturition 2.8.4.1 Supra-spinal Centres for Bladder Control 2.8.4.2 Overall Scheme of Bladder Control 2.8.5 Micturition Disorders 2.8.5.1 Atonic Bladder 2.8.5.2 Automatic Bladder 2.8.5.3 Neurogenic Bladder References 3: Brain and Kidney Crosstalk 3.1 Introduction 3.2 Brain-Kidney Crosstalk in Disorders of Sodium and Water Regulation 3.2.1 Hyponatremia in Patients with Acute Brain Injury 3.2.1.1 Pathophysiological Mechanisms for Cerebral Edema and Osmotic Demyelination 3.2.2 Hypernatremia in Patients with Acute Brain Injury 3.2.2.1 Pathophysiological Mechanisms for Brain Cell Injury in Hypernatremia 3.3 Brain-Kidney Crosstalk in Chronic Kidney Disease 3.3.1 Neurological Complications in Chronic Kidney Disease 3.3.2 Proposed Mechanisms for Dysregulated Brain-Kidney Crosstalk in Chronic Kidney Disease 3.4 Brain-Kidney Crosstalk in Acute Kidney Injury 3.4.1 Neurological Complications in Acute Kidney Injury 3.4.2 Proposed Mechanisms for Dysregulated Brain-Kidney Crosstalk in Acute Kidney Injury 3.4.2.1 Activation of Systemic Inflammation 3.4.2.2 Acute Uremic State 3.4.2.3 Neurotransmitter Derangement and Brain Injury 3.4.2.4 Transcriptional Dysregulation 3.4.2.5 Alterations in Drug Pharmacokinetics 3.4.3 Renal Insult in Acutely Brain-Injured Patients 3.4.4 Proposed Mechanisms for Renal Injury in Acutely Brain-Injured Patients 3.5 Brain-Kidney Crosstalk During Renal Replacement Therapy 3.5.1 Neurological Complications During Renal Replacement Therapy 3.5.2 Proposed Mechanisms of Brain-Kidney Crosstalk During Renal Replacement Therapy 3.6 Conclusion References