Earth Science: Biology – Humans – Water and the Kidneys
Water in the body serves as a means of transportation and a dissolving agent, and it helps to regulate body temperature. The kidneys play a major role in maintaining the water balance in the body and removing toxins.
The human body contains between 65 and 75 percent water, depending on the sex and age of the person. The amount of water taken in, produced, and lost remains constant (water balance). Liquids are mainly taken in by drinking and, to a certain extent, by food intake; water is lost through the kidneys (urination), the sweat glands, and a small amount through respiration.
If water is lost at a higher rate, for example, through heavy sweating, more water must be drunk in order to prevent dehydration. The consequences of dehydration can be serious and include fainting and dizziness, vision loss, extreme sleepiness, decreased urine output, and if left untreated, death.
Symptoms usually begin if approximately 2 percent of the body’s water is lost; losses of over 15 percent are usually fatal.
Kidneys
The kidneys are important organs that regulate the water cycle and remove waste products from the human body. These waste products usually reach the kidneys via the blood flow through the liver. After they pass the kidneys, they leave the body through urination. Kidneys come in pairs and look like approximately four-inch (ten-cm)-long beans.
They are located alongside the 12th vertebra of the chest, on either side of the spine. The organs are composed of a renal capsule that surrounds the renal cortex and medulla. The medulla contains 16 to 20 renal pyramids, whose tips point inward and have many openings for excreting urine.
The opposite ends of the pyramids extend from the medulla into the renal cortex and contain about a million nephrons, which are responsible for urine production. Each nephron consists of several renal corpuscles that are surrounded by capillary blood vessels and are connected to a convoluted renal tubule that forms a U-shape in the medulla.
The renal corpuscles take in waste products from the blood and transfer these into the tubules to produce primary urine. While passing through the tubules, essential substances and, moreover, most of the liquid is taken out again, which results in concentrated urine being excreted via the ureter.
SPORTS AND HYDRATION
It Is essential for everybody to drink enough and stay well hydrated This is especially important during exercise, when the body loses a lot of liquids through sweating.
If the lost water is not replaced in time, the blood viscosity, or blood thickness, is reduced. This means that the blood cannot flow quickly enough to provide the muscle cells with enough oxygen and nutrients.
This may result in dizziness, vomiting, and cramping of the muscles.
ISSUES TO SOLVE
KIDNEY TRANSPLANTS are relatively successful in case of kidney failure.
The greatest problem is the limited number of people willing to donate their organs after they have died.