>> Welcome to another anatomy and physiology SmartArt video where we guide you through an important piece of art. After watching this video, you should be able to describe the structure and function of a nephron, the functional unit of the kidney. Each kidney contains approximately 1.25 million nephrons. A nephron consists of a renal corpuscle and a renal tubule. Let's look closer and begin at the renal corpuscle. A renal corpuscle is made of two structures, a glomerular capsule, also called a Bowman's capsule, and a capillary network called the glomerulus. The first step in urine formation occurs here, as blood pressure forces plasma, consisting of water and dissolved solutes, out of the glomerulus and into the capsular space. The capsular space is between the glomerulus and the glomerular capsule. This process is called filtration, because it passes liquid through a filter. During filtration, a substance called filtrate is produced, a protein-free solution similar to blood plasma. This fluid is modified as it travels through the tubules<br>three segments. Substances, such as water <br>and various solutes, are reabsorbed into the capillary surrounding the renal tubule, or secreted from <br>the surrounding capillaries into the tubule. The first segment closest to it the renal corpuscle is<br>the proximal convoluted tubule. Nutrients from the filtrate are reabsorbed here, and the resulting product is called tubular fluid. The next segment is the nephron loop, also known as the loop of Henle, and the third segment is the distal convoluted tubule. Tubular fluid now moves into the collecting system, a network of tubes that carry tubular fluid away from the nephron, while also making final adjustments in volume and composition to what is now called urine. The urine will then empty into a minor calyx and flow into a major calyx, then into the renal pelvis, before exiting the kidney through the ureter to the urinary bladder. The urinary bladder stores the urine. In summary, the nephron is the functional unit of the kidney, and each nephron is made of a renal corpuscle and a renal tubule. At the renal corpuscle, fluid is forced out of the glomerulus and into the capsular space before traveling into the renal tubule. The renal tubule modifies this tubular fluid as it passes along the proximal<br>convoluted tubule, nephron loop, and distal convoluted tubule<br>by either reabsorption into or secretion from the<br>surrounding capillaries. The resulting fluid then enters the collecting system where it is further modified and then passes from the kidney as urine. So what? Why is it important to understand the structure and function of the nephron? Well, this information is crucial to understanding renal failure, a life-threatening disease, often as a result of nephron damage from high blood pressure, vascular disease, or diabetes, filtration formation at the renal corpuscle drops significantly. As a result, urine production drops, metabolic wastes and blood are not eliminated, and blood becomes increasingly toxic. This life-threatening situation can be treated with hemodialysis. In this treatment, a patient's blood flows past an artificial membrane with special fluid on the other side. Toxins and wastes cross the membrane, filtering them out of the blood, and this cleaner blood is returned to the patient. In effect, hemodialysis substitutes artificial filtration for the natural filtration the nephrons can no longer perform. However, waste products immediately start accumulating again in the patient's blood, so hemodialysis must be done on a regular basis. Patients with renal failure often require a kidney transplant, where a living or deceased donor donates a kidney that is surgically implanted into a recipient. Kidney transplantation often eliminates or decreases the need for dialysis for many years, and improves the patient's quality of life. Unfortunately, the waiting list to receive a kidney transplant can be anywhere from five to ten years. As people live longer and diseases, such as diabetes and hypertension increase, renal failure is a condition that will continue to challenge healthcare professionals.