Chapter 19. The Urinary System. Learning Objectives (1 of 2). Describe normal structure and functions of the kidneys Explain pathogenesis and clinical manifestations of glomerulonephritis, nephrosis, nephrosclerosis, and glomerulosclerosis
The Urinary System
A representation of fine structure of glomerular filter as visualized by electron microscopy. Segment of glomerular capillaries
A representation of fine structure of glomerular filter as visualized by electron microscopy. Cross-section through the center of the glomerulus.
The structure of the renal tubule, illustrating its relationship to the glomerulus and the collecting tubule.
© Courtesy of Leonard Crowley, M.D./University of Minnesota Medical School
Figure 21.21a, b
Figure 25.21c, d
Glomerulonephritis, also known as glomerular nephritis, is a renal disease (usually of both kidneys) characterized by inflammation of the glomeruli, or small blood vessels in the kidneys
Section of kidney revealing white urate deposits within renal pyramid and large urate deposit near tip of pyramid
Figure 25.18a, b
An epispadias is a rare type of malformation of the penis in which the urethra ends in an opening on the upper aspect (the dorsum) of the penis. It can also develop in females when the urethra develops too far anteriorly. It occurs in around 1 in 120,000 male and 1 in 500,000 female births
Posterior urethral valves is a congenital defect in males that results in obstruction of the bladder due to extra tissue that projects into the urethra. This excess tissue blocks urine from flowing freely from the bladder to the outside of the body. This blockage, if not corrected, can cause problems in all the organs in the urinary system including the kidneys, ureters, urethra and bladder.
Renal cell carcinoma (Clear Cell) is a kidney cancer that originates in the lining of the proximal convoluted tubule. RCC is the most common type of kidney cancer in adults, responsible for approximately 80% of cases. It is also known to be the most lethal of all the genitourinary tumors. Initial treatment is most commonly a radical or partial nephrectomy and remains the mainstay of curative treatment. Where the tumour is confined to the renal parenchyma, the 5-year survival rate is 60-70%, but this is lowered considerably where metastases have spread. It is resistant to radiation therapy and chemotherapy, although some cases respond to immunotherapy.
Wilms' tumor or nephroblastoma is cancer of the kidneys that typically occurs in children, rarely in adults. Its common name is an eponym, referring to Dr. Max Wilms, the German surgeon (1867–1918) who first described this kind of tumor.
Hemodialysis removes wastes and water by circulating blood outside the body through an external filter, called a dialyzer, that contains a semipermeable membrane. The blood flows in one direction and the dialysate flows in the opposite. The counter-current flow of the blood and dialysate maximizes the concentration gradient of solutes between the blood and dialysate, which helps to remove more urea and creatinine from the blood.
The dialysis solution has levels of minerals like potassium and calcium that are similar to their natural concentration in healthy blood. For another solute, bicarbonate, dialysis solution level is set at a slightly higher level than in normal blood, to encourage diffusion of bicarbonate into the blood, to act as a pH buffer to neutralize the metabolic acidosis that is often present in these patients
In peritoneal dialysis, wastes and water are removed from the blood inside the body using the peritoneal membrane of the peritoneum as a natural semipermeable membrane. Wastes and excess water move from the blood, across the peritoneal membrane, and into a special dialysis solution, called dialysate, in the abdominal cavity which has a composition similar to the fluid portion of blood.