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Urinary System

 Xenotransplantation – The last cure for renal failure Xenotransplantation – The last cure for renal failure Xeno refers to ‘new’. Kidneys were the first organs to be successfully transplanted. Renal transplantation is the organ transplant of a kidney into a patient with end–stage renal disease. Kidney transplants have a high success rate, although recipients do need to take immune–suppressant drugs for the rest of their life to prevent rejection. The donor kidney may come from a living or recently deceased donor and can be kept viable outside of the body for several days. Let’s learn the basic structure and function of human renal system and its associated disorders.

Learning Objectives

After completing the topic, the student will be able to:

  • Describe the morphology and anatomy of human kidney and explore its functions.
  • Illustrate how kidneys maintain acid–base concentration.
  • Discuss and understand how kidneys influence blood pressure.
  • Systematize the sequential steps involved in the formation of urine.
  • List the hormones that are secreted from the kidneys and explore their key roles.
  • Identify the risk factors that are associated with kidney disease.
  • List some of the kidney disorders.
  • Define “diuretics” and explore how they operate to increase urine flow.
  • Discuss and explore the different treatment options available till date for renal failure.
The Human Urinary System Image Description: The urinary system - also known as the renal system - produces stores and eliminates urine, the fluid waste excreted by the kidneys.

The urinary system consists of two kidneys, two ureters, one urinary bladder, and one urethra. The main function of this system is to regulate the volume, pressure, and composition of the blood. The kidneys are the organs of the urinary system that accomplish this task by regulating the amount of water and dissolved substances that are added to or removed from the blood. Wastes and excess materials removed from the blood form urine, the yellowish fluid produced by each kidney.

Urine from the kidneys travels down tube like organs called ureters to the urinary bladder. The urinary bladder is a muscular organ that temporarily stores urine until it is excreted from the body. Urine leaves the body through the urethra, a muscular tube that transports urine from the urinary bladder to the outside of the body through an external opening. The female urethra transports only urine. The male urethra, however, carries urine and reproductive fluids (but not simultaneously). The reproductive function of the male urethra is discussed in Reproductive system in detail.

Components of the urinary system and their functions
Kidneys Kidneys- Filtration units of our body The kidneys maintain water volume and balance as well as regulate blood composition.
Structure of urinary system

Kidneys are two bean – shaped organs, each about the size of your fist,10 cm long and 6 cm wide, located on either side of the backbone, just below the rib cage and protected by the last two ribs. Kidneys weigh about 0.5 percent of total body weight. The right side kidney is at a slightly lower level than the left one. Kidneys receive the blood from the renal artery, process it, return the processed blood to the body through the renal vein and remove the wastes and other unwanted substances in the urine.

A tube, the ureter, arises from the notch (hilum) in the median surface of each kidney and connects behind with the urinary bladder in the lower part of the abdomen. The front end of the ureter is somewhat expanded into the kidney and is called the pelvis. Urine flows from the kidneys through the ureters to the urinary bladder. In the bladder, the urine is stored until it is excreted from the body through the urethra. The kidney is the only organ of the body in which two capillary beds, in series, connect arteries with veins. This arrangement is important for maintaining a constant blood flow through and around the nephron despite fluctuations in systemic blood pressure.

Structure of Kidney:
A longitudinal section of the kidney shows the following parts:

  1. Renal capsule: a thin, outer membrane that helps protect the kidney.
  2. Cortex: a lightly colored outer region.
  3. Medulla: a darker, reddish – brown, inner region composed of a finely striped substance arranged in several pyramids. The apex of each pyramid (papilla) projects into the pelvis of the kidney.
  4. Renal pelvis: a flat, funnel shaped cavity that collects the urine into the ureters.
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