The Renal System (eBook)

Ian Peate (Autor)

eBook Download: EPUB

2025
Wiley (Verlag)
9781394252459 (ISBN)

Infos

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

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.

Textauszug

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...

Produkt-Details

• Erscheint lt. Verlag: 9.1.2025
• Reihe/Serie: Peate's Body Systems
• Sprache: englisch
• Themenwelt: Medizin / Pharmazie ► Medizinische Fachgebiete
• Themenwelt: Naturwissenschaften ► Biologie
• Schlagworte: dialysis nursing • dialysis nursing book • illustrated dialysis nursing • kidney nursing • Renal nursing • renal nursing book • renal nursing illustrated • renal system illustrations • renal system nursing • renal system nursing book
• ISBN-13: 9781394252459 / 9781394252459