The Renal System
Description
PEATE'S BODY SYSTEMS THE RENAL SYSTEM
A CONCISE, ILLUSTRATED, AND ACCESSIBLE GUIDE TO THE RENAL SYSTEM
Each of the twelve volumes in Peate's Body Systems series is rooted in the belief that a deep and thorough understanding of the human body is essential for providing the highest standard of care. Offering clear, accessible and up-to-date information on different body systems, this series bridges the gap between complex scientific concepts and practical, everyday applications in health and care settings. This series makes for an invaluable resource for those committed to understanding the intricacies of human biology, physiology and the various systems that sustain life.
The Renal System is the perfect companion for students and newly registered practitioners across nursing and allied health fields with an interest in renal care, providing a comprehensive yet easy-to-digest guide for both academic and clinical application.
- Equips healthcare students and practitioners with the necessary information to provide safe and competent care
- Features colourful illustrations to aid comprehension, clarify complicated concepts, and render content more engaging and accessible
- Empowers readers to adapt to a rapidly evolving healthcare landscape, preparing them for the future of healthcare delivery
- Contains information necessary for effective patient care of those with chronic and acute kidney disease, urinary tract infection, and other renal diseases and conditions
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Person
IAN PEATE is a Visiting Professor at Northumbria University, a Senior Clinical Fellow at the University of Hertfordshire, and a Professorial Fellow at the University of Roehampton. He is also the Editor-in-Chief of the British Journal of Nursing and the Consultant Editor of the Journal of Paramedic Practice and the International Journal of Advancing Practice.
Content
Preface viii
Acknowledgements x
1 Anatomy and Physiology: The Renal System 1
Renal System 1
Kidneys (External) 1
Kidneys (Internal) 2
Nephrons 3
The Functions of the Kidney 7
Kidney Blood Supply 8
Urine Formation 9
Hormonal Control of Tubular Reabsorption and Secretion 10
Composition of Urine 12
Ureters 13
Urinary Bladder 14
Urethra 15
Male Urethra 15
Female Urethra 17
Micturition 17
Conclusion 17
Glossary of Terms 18
Multiple Choice Questions 19
References 20
2 Renal System Assessment 21
Assessing Needs 21
History Taking 22
Effective Communication 22
The Health History 24
Application of the Patient History to Renal System Conditions 26
Introduction and Establishing Rapport 26
Chief Complaint and Presenting Symptoms 26
History of Present Illness 26
Pain Assessment 26
Past Medical History 27
Medication History 27
Allergy History 27
Family History 28
Dietary Habits, Including Salt and Fluid Intake 28
Social History 28
Occupational History 28
Review of Systems 28
Urinary Habits 29
Fluid Intake and Output 29
Weight 29
Fluid Balance Charts 30
Psychosocial History 30
Patient Concerns and
Expectations 30
Patient Education Needs 30
The Physical Examination 30
Specific Gravity 32
Additional Factors 33
Conclusion 35
Glossary of Terms 36
Multiple Choice Questions 37
References 38
3 Pyelonephritis 39
Pathophysiological Changes Associated with Pyelonephritis 39
Epidemiology 42
Risk Factors 43
Clinical Presentation 44
Clinical Investigations and Diagnosis 46
Clinical Investigations 48
Management 50
Health Teaching 52
Conclusion 53
Glossary of Terms 53
Multiple Choice Questions 54
References 55
4 Acute Kidney Injury 57
Pathophysiological Changes Associated with Acute Kidney Injury 57
Categorisation of Acute Kidney Injury 58
Epidemiology 58
Risk Factors 61
Clinical Presentation 64
Clinical Investigations and Diagnosis 67
The History 67
Physical Examination 68
Investigation and Tests 70
Laboratory Tests 70
Urinalysis 70
Electrolyte and Acid-Base Balance 70
Full Blood Count 70
Inflammatory Markers 71
Imaging Studies 71
Renal Biopsy 71
Management 71
Health Teaching 73
Conclusion 73
Glossary of Terms 74
Multiple Choice Questions 74
References 76
5 Chronic Kidney Disease 77
Acute Kidney Injury 77
Pathophysiological Changes Associated with Chronic Kidney Disease 78
Epidemiology 80
Risk Factors 80
Clinical Presentation 80
Clinical Investigations and Diagnosis 82
Categorisation of Chronic Kidney Disease 82
Medical History and Physical Examination 83
Investigations and Tests 86
Management 87
Health Teaching 88
Conclusion 89
Glossary of Terms 89
Multiple Choice Questions 90
References 91
6 Renal Calculi 93
Pathophysiological Changes Associated with Renal Calculi 94
Typical Sites of Stone Impaction in the Urinary Tract 96
Epidemiology 98
Risk Factors 98
Clinical Presentation 99
Clinical Investigations and Diagnosis 101
Physical Examination 103
Clinical Investigations 104
Management 106
Health Teaching 108
Conclusion 108
Glossary of Terms 108
Multiple Choice Questions 109
References 111
7 Bladder Cancer 112
Pathophysiological Changes Associated with Bladder Cancer 114
Epidemiology 115
Risk Factors 116
Clinical Presentation 116
Clinical Investigations and Diagnosis 117
History Taking 118
Physical Examination 118
Staging of Bladder Cancer 119
Bladder Cancer Grading 121
Management 122
Treating Non-muscle-invasive Bladder Cancer 123
Treating Muscle-invasive
Bladder Cancer 123
Health Teaching 123
Conclusion 124
Glossary of Terms 125
Multiple Choice Questions 125
References 127
8 Urinary Tract Infection 128
Pathophysiological Changes Associated with Urinary Tract Infection 129
Epidemiology 130
Risk Factors 130
Clinical Presentation 132
Clinical Investigations and Diagnosis 132
Obtaining a Midstream Specimen of Urine 136
Management 137
Recurrent Urinary Tract Infection 139
Health Teaching 140
Conclusion 141
Glossary of Terms 142
Multiple Choice Questions 142
References 144
MCQ Answers 145
Index 146
Chapter 1
Anatomy and Physiology: The Renal System
The renal system is also known as the urinary system; it plays a crucial role in maintaining homeostasis within the body. Comprising the kidneys, ureters, bladder and urethra, this system is responsible for filtering and eliminating waste products from the blood while regulating fluid and electrolyte balance.
The body is an intricately designed collection of systems and organs, relying on the precise coordination of various functions to maintain equilibrium. At the epicentre of this physiological coordination is the renal system, which is a complex network responsible for filtering blood, regulating fluid balance and arranging the expulsion of waste. This chapter explores the renal system, the anatomy, functions and mechanisms that define its role in sustaining the delicate balance of internal homeostasis.
The renal system is located in the lower back, where the two bean-shaped organs house nephrons, the microscopic components of urine formation. The intricate structures and functions of the kidneys are responsible for selective filtration, reabsorption and secretion taking place within these vital organs.
The ureters, bladder and urethra are also key components of the renal system. Together, these components form a dynamic group that facilitates the storage and expulsion of urine, contributing to the body's fluid and electrolyte balance.
The renal system is responsible for a number of regulatory functions. From the delicate regulation of blood pressure to the adjustment of acid-base balance, the renal system ensures that the internal environment remains finely tuned for optimal cellular function.
Renal System
The renal system, also known as the urinary system, consists of:
- Two kidneys, which filter the blood to produce urine.
- Two ureters, which convey urine to the bladder.
- One urinary bladder, a storage organ for urine until it is eliminated.
- One urethra, which conveys urine to the exterior.
The organs of the renal system are depicted in Figure 1.1.
Figure 1.1 The renal system and female abdominal cavity
Kidneys (External)
There are usually two kidneys, one on each side of the spinal column (located in the posterior abdomen, retroperitoneally). They are approximately 11 cm long, 5-6 cm wide and 3-4 cm thick. The adrenal glands sit immediately superior to the kidneys. The kidneys are said to be bean-shaped organs where the outer border is convex; the inner border is known as the hilum (or hilus) and at this point, the renal arteries, renal veins, nerves and ureters enter and leave the kidneys (Figure 1.1). The renal artery transports blood to the kidneys and once the blood has been filtered, the renal vein takes the blood away. The right kidney is in contact with the liver's large right lobe and, as such, the right kidney is approximately 2-4 cm lower than the left kidney. There are three layers that cover and support the kidneys:
- Renal fascia
- Adipose tissue
- Renal capsule
The renal fascia provides the outer layer and consists of a thin layer of connective tissue that anchors the kidneys to the abdominal wall and the surrounding tissues. The middle layer is called the adipose tissue and surrounds the capsule. It cushions the kidneys from trauma. The inner layer is called the renal capsule. It consists of a layer of smooth connective tissue that is continuous with the outer layer of the ureter. The renal capsule protects the kidneys from trauma and maintains their shape (see Figure 1.2).
Figure 1.2 The external layers of the kidney
Kidneys (Internal)
Inside the kidney, there are three distinct regions. They are:
- Renal cortex
- Renal medulla
- Renal pelvis
The outermost part of the kidney is the renal cortex. The renal cortex forms a continuous, smooth outer portion of the kidney with a number of projections (the renal columns) extending down between the pyramids. The renal column is the medullary extension of the renal cortex; it is reddish in colour and has a granular appearance, which is due to the capillaries and the structures of the nephron. The medulla is lighter in colour with an abundance of blood vessels and tubules of the nephrons. The medulla is made up of approximately 8-12 renal pyramids. Figure 1.3a shows the frontal section of the right kidney and Figure 1.3b the path of blood flow. The renal pyramids, also called malpighian pyramids, are the cone-shaped sections of the kidneys. The wider portion of the cone faces the renal cortex, with the narrow ends pointing internally, and this section is known as the renal papilla. Urine formed by the nephrons flows into cup-like structures, called calyces, via papillary ducts. Each kidney contains approximately 8-18 minor calyces and two or three major calyces. The minor calyces receive urine from the renal papilla, which conveys the urine to the major calyces. The major calyces unite to form the renal pelvis, which then conveys urine to the bladder (see Figure 1.4). The renal pelvis forms the expanded upper aspect of the ureter, which is funnel-shaped, and it is in the region where two or three calyces converge.
Figure 1.3 (a and b) The internal structures.
Source: Tortora and Derrickson (2009). Reproduced with permission from John Wiley & Sons.
Figure 1.4 The internal structures showing blood vessels.
Source: Tortora and Derrickson (2009). Reproduced with permission from John Wiley & Sons.
Nephrons
The nephrons are small structures that form the functional units of the kidney. The nephron consists of a glomerulus and a renal tubule (see Figure 1.5). There are around one million nephrons in each kidney. It is within these structures that urine is formed. The nephrons:
- Filter blood
- Perform selective reabsorption
- Excrete unwanted waste products from the filtered blood
Figure 1.5 Nephron.
Source: Tortora and Derrickson (2009). Reproduced with permission from John Wiley & Sons.
The nephron plays a key part in homeostasis. This system helps to regulate the amount of water, salts, glucose, urea and other minerals in the body. The nephron is a filtration system situated in the kidney and is responsible for the reabsorption of water and salts. The nephron is divided into several sections:
- Bowman's capsule
- Proximal convoluted tubule
- Loop of Henle
- Distal convoluted tubule (DCT)
- Collecting ducts
Each section carries out a different function; these are discussed in the following sections.
Bowman's Capsule
Also known as the glomerular capsule (see Figure 1.6), Bowman's capsule is a cup-like sac and is the first portion of the nephron. Bowman's capsule is part of the filtration system in the kidneys. When blood reaches the kidneys for filtration, it first enters Bowman's capsule, with the capsule separating the blood into two components: a filtrated blood product and a filtrate that is moved through the nephron, another structure in the kidneys. The glomerular capsule consists of visceral and parietal layers. Epithelial cells, known as podocytes, line the visceral layer, while the parietal layer is lined with simple squamous epithelium; it is in Bowman's capsule that the network of capillaries called the glomerulus (Marieb and Hoehn 2019) is found. Filtration of blood takes place in this portion of the nephron.
Figure 1.6 Bowman's capsule.
Source: Tortora and Derrickson (2009). Reproduced with permission from John Wiley & Sons.
Proximal Convoluted Tubule
From the Bowman's capsule, the filtrate drains into the proximal convoluted tubule (see Figure 1.6). The surface of the epithelial cells of this segment of the nephron is covered with densely packed microvilli, which increase the surface area of the cells, thus facilitating their resorptive function. The infolded membranes forming the microvilli are the site of numerous sodium pumps. Resorption of salt, water and glucose from the glomerular filtrate occurs in this section of the tubule; at the same time, certain substances, including uric acid and drug metabolites, are actively transferred from the blood capillaries into the tubule for excretion.
Loop of Henle
The proximal convoluted tubule bends into a loop known as the loop of Henle (see Figure 1.5). The loop of Henle dips or 'loops' from the cortex into the medulla (descending limb) and then returns to the cortex (ascending limb). The ascending loop of Henle is much thicker than the descending portion. The main function of the loop of Henle is to generate a concentration gradient creating a region of a high concentration of sodium in the medulla of the kidney. The descending portion of the loop of Henle is highly permeable to water with low permeability to ions and urea. The ascending loop of Henle is permeable to ions but not to water. When required, urine is concentrated in this portion of the nephron. This is possible because of the high concentration of solute in the substance or interstitium of the medulla. Different sections of the loop of Henle have different actions:
- The descending loop of Henle is relatively...
