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

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