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What is the primary function of the excretory system in humans regarding blood purification?
To filter nitrogenous waste from the blood
To absorb glucose from the blood
To produce red blood cells
To regulate blood pressure
To filter nitrogenous waste from the blood
The human excretory system, primarily through the kidneys, functions to filter blood by removing metabolic nitrogenous waste products like urea, uric acid, and creatinine. This process maintains the body's internal chemical balance and prevents the accumulation of toxic substances in the bloodstream.
The human excretory system, primarily through the kidneys, functions to filter blood by removing metabolic nitrogenous waste products like urea, uric acid, and creatinine. This process maintains the body's internal chemical balance and prevents the accumulation of toxic substances in the bloodstream.
Think of the kidney as a sophisticated water purification filter in a house; it lets the clean water pass through for use while trapping the dirt and debris to be flushed out into the drain.
FUN (Filtration, Ultrafiltration, Nitrogenous-waste removal)
Excretion=FiltrationтИТReabsorption+Secretion
The process occurs via the nephrons, the structural and functional units of the kidney. Blood enters the glomerulus under high pressure, leading to ultrafiltration where water and small solutes are forced into Bowman's capsule. Subsequently, the renal tubules selectively reabsorb useful substances while secreting additional waste into the filtrate to form urine.
Urea is the primary nitrogenous waste produced in the liver via the urea cycle.
The glomerulus acts as a mechanical filter driven by hydrostatic pressure.
Homeostasis is achieved by balancing electrolytes and water content alongside waste removal.
Maintains blood pH and osmolality.
Regulates blood volume through water retention or excretion.
Dialysis for patients with renal failure.
Urinalysis as a diagnostic tool for systemic diseases.
The normal GFR (Glomerular Filtration Rate) in a healthy adult is approximately 125┬аmL/min.
Option B is incorrect because nutrient absorption occurs primarily in the small intestine, not the kidneys. Option C is incorrect because red blood cell production (erythropoiesis) occurs in the bone marrow. Option D is incorrect because although kidneys regulate blood pressure, it is a secondary regulatory function, not the primary mechanism of blood purification.
A is correct тАФ The primary function of the excretory system is the filtration of metabolic nitrogenous waste from the blood.
Remember that kidneys do not produce red blood cells but do release the hormone erythropoietin which stimulates the bone marrow to produce them; linking biology topics helps avoid confusion.