Although kidneys are relatively small organs compared to the heart and brain, they are important to the process of removing water and waste from the bloodstream. The fact that the body constantly produces waste as a byproduct of metabolism means that the kidneys have to work around the clock to protect the body from potentially harmful effects that excessive amounts of water and waste cause. Can cause. People suffering from kidney damage lose their ability to remove these particles from the blood for a long time and depend on a machine to filter the blood. When more than 80% of the filtration capacity is lost, kidney transplantation or dialysis may become the only option for survival. Unfortunately, the number of people suffering from end-stage renal failure has increased in recent years and it has become more important than ever for dialysis professionals to educate the public about kidney structure, function, and health. is.
In most cases, the average human has two kidneys on either side of the body in the lower part of the abdominal cavity. Each kidney is protected to some degree from external damage by the ribs underneath. Within the kidney, there are several structures called nephrons that contain the structural components necessary to selectively remove particles from the blood. The renal arteries carry blood to the nephron where they pass through a collection of capillaries known as glomerulus. These tiny blood vessels are so small that they only allow red blood cells to pass in one file. Each glomerulus resides in a cup-shaped cell called the Bowman capsule. This capsule has a permeable membrane that simply has holes to pass through the collection tubes for small particles such as water and waste. These channels carry the filtrate through a series of loops that allow the body to absorb nutrients that can still be used and exclude particles that were not initially filtered. The fluid that remains in the tubes is sent to the bladder where it is stored as urine until it can be excreted.
The kidney is able to remove water and waste from the bloodstream without expending energy thanks to a number of simple scientific principles that describe the movement of solutes and solvents. The first principle is known as diffusion and states that solutes (particles that dissolve in water) move a permeable membrane from areas of high concentration to areas of low concentration until the particle concentrations are equal on both sides. . This is the process that takes place when the waste in Bowman’s capsule is filtered from the bloodstream. Because the collecting ducts in the kidney continuously filter out of the glomerulus, the gradient always persists and the waste vessels go out.
The second important principle in kidney filtration is known as osmosis and it states that solvents such as water move from areas of low particle concentration to areas of high particle concentration to maintain equilibrium across the permeable membrane. Basically, water follows solutes through the membrane in an attempt to maintain the equilibrium of the particle concentration on both sides of the membrane. Although the kidneys often filter more water than is necessary to prevent an unhealthy build-up in the body, the salt gradient in the bladder path allows the body to absorb water from the filtrate it can still use. The act of regulating the amount of water taken from the blood is the process used to concentrate and dilute the urine.
Individuals with end-stage renal failure are often unable to filter potentially harmful particles from the blood and often rely on a procedure called dialysis to keep them alive. Dialysis uses a machine outside the body to remove water and waste that is normally filtered by the kidneys. Dialysis machines are designed to filter blood according to the same scientific principles used in the body. While dialysis cannot completely compensate for kidney failure, it extends lifespan and can dramatically improve health outcomes for individuals suffering from end-stage renal failure.