Functions of the KIDNEY
REMOVAL OF WASTES
One of the main tasks of the kidney is to rid the body wastes and excess fluids. These are excretory functions by making urine that is high level of waste products. The waste is from foods that are digested and metabolized. Other waste includes drugs, toxins and acids.
ABSORPTION OF NUTRIENTS
The kidneys reabsorbs nutrients from the blood and transport them to where they would best support health. It also maintains homeostasis.
MAINTANING pH
The acceptable pH level is between 7.38 and 7.42 below this boundary, the body enters a state of acidemia, and above it, alkalemia. The kidneys manage the pH through two processes:
- Reabsorbing and regenerating bicarbonate from urine: Bicarbonate helps neutralize acids. The kidneys can either retain itif the pH is tolerable or release it if acid levels rise.
- Excreting hydrogen ions and fixed acids: Fixed or nonvolatile acids are any acids that do not occur as a result of carbon dioxide. They result from the incomplete metabolism of carbohydrates, fats, and proteins. They include lactic acid, sulfuric acid, and phosphoric acid.
OSMOLALITY
Is a measure of the body’s electrolyte-water balance, or the ratio between fluid and minerals in the body. Dehydration is a primary cause of electrolyte imbalance.
REGULATING BLOOD PRESSURE
The kidneys regulate blood pressure when necessary, but they are responsible for slower adjustments. They adjust long-term pressure in the arteries by causing changes in the fluid outside of cells.
- These fluid changes occur after the release of a vasoconstrictor called angiotensin II. Vasoconstrictors are hormones that cause blood vessels to narrow.
- They work with other functions to increase the kidneys’ absorption of sodium chloride, or salt. This effectively increases the size of the extracellular fluid compartment and raises blood pressure.
- Anything that alters blood pressure can damage the kidneys over time, including excessive alcohol consumption, smoking, and obesity.
SECRETIONS OF OTHER COMPOUNDS
The kidneys release a number of important compounds, including:
- Erythropoietin: This controls erythropoiesis, or the production of red blood cells. The liver also produces erythropoietin, but the kidneys are its main producers in adults.
- Renin: This helps manage the expansion of arteries and the volume of blood plasma, lymph, and interstitial fluid. Lymph is a fluid that contains white blood cells, which support immune activity, and interstitial fluid is the main component of extracellular fluid.
- Calcitriol: This is the hormonally active metabolite of vitamin D. It increases both the amount of calciumthat the intestines can absorb and the reabsorption of phosphate in the kidney.