Problem 65 - Objective Biology for NEET

Question

How much amount of blood is filtered out by kidney's/min? (a) \(500 \mathrm{ml}\) (b) \(1100-1200 \mathrm{ml}\) (c) \(1500 \mathrm{ml}\) (d) \(125 \mathrm{ml}\)

Step-by-Step Solution

Answer

The kidneys filter out approximately \(1100-1200 \mathrm{ml}\) of blood per minute.

Step 1: Renal Blood Filtration Rate

The kidneys filter approximately 20% of the blood. The blood total volume of blood a heart pumps per minute i.e, Cardiac output is about \(5-6 \mathrm{Liters/min}\), which is same as \(5000-6000 \mathrm{ml/min}\). So \(20\%\) of \(5000 - 6000 \mathrm{ml/min}\) blood is filtered by kidneys in a minute. That'll be \(1000 - 1200 \mathrm{ml/min}\)

Step 2: Choosing the correct answer

Based on the information above, we can rule out responses (a), (c), and (d) as the amount of blood filtered by the kidneys per minute. The volume is between \(1100-1200 \mathrm{ml}\) which is answer (b).

Key Concepts

Kidneys

The kidneys are vital organs responsible for filtering blood and removing waste products from the body. They are part of the urinary system and help maintain overall body fluid balance. Situated just below the rib cage on either side of the spine, the kidneys perform multiple crucial functions:

• Removing waste products and excess substances from the bloodstream.
• Regulating water and electrolyte balance in the body.
• Controlling blood pressure by releasing hormones.
• Stimulating red blood cell production through erythropoietin hormone.

Each kidney contains around a million filtering units called nephrons. Nephrons play a pivotal role in blood filtration, ensuring waste is excreted while valuable substances like glucose and amino acids are reabsorbed into the bloodstream.
The efficiency of the kidneys' filtration process is key to maintaining health and preventing the buildup of harmful substances in the body.

Cardiac Output

Cardiac output is a term that defines the volume of blood the heart pumps per minute. This measurement is essential for understanding the blood supply reaching various body parts, including the kidneys.
The heart's output is calculated by multiplying the heart's rate (beats per minute) by the volume of blood pumped with each beat (stroke volume). Typically:

• An average resting cardiac output is about 5-6 liters per minute.
• Factors such as physical activity, stress, and health conditions can alter the cardiac output significantly.

Understanding cardiac output helps nephrologists and healthcare providers determine how efficiently the kidneys receive and filter blood. Adequate cardiac output ensures the kidneys function properly by receiving enough blood to filter, which can range from 1000 ml to 1200 ml per minute.

Blood Filtration

Blood filtration is a critical process performed primarily by the kidneys. It involves cleaning the blood of impurities and waste products while retaining necessary nutrients and substances. This process systematically occurs in the nephrons of the kidneys, which filter about 20% of the blood that circulates through them.
The blood filtration process comprises several steps:

• Glomerular filtration: Blood enters the nephron and passes through a cluster of small blood vessels known as the glomerulus.
• Tubular reabsorption: Useful substances like water, glucose, and certain ions are reabsorbed back into the bloodstream.
• Tubular secretion: Additional wastes are secreted into the tubules from the blood.
• Excretion: The final filtrate leaves the kidneys as urine.

The kidneys usually filter 1100-1200 ml of blood every minute, highlighting their critical role in maintaining homeostasis and preventing toxin accumulation in the body.

Nephrology

Nephrology is the specialized field of medicine that focuses on the kidneys and their functions. This branch of medicine deals with diagnosing and treating kidney diseases, disorders, and inefficiencies.
Nephrologists or kidney doctors address a wide range of conditions, including:

• Chronic and acute kidney diseases.
• Kidney stones and infections.
• Hypertension related to kidney function.
• Dialysis and kidney transplantation.

The understanding of kidney functions and conditions in nephrology goes beyond symptom management and involves in-depth knowledge of the physiological and biochemical processes of the kidneys. This knowledge helps healthcare professionals develop appropriate treatment plans for individuals facing kidney issues, focusing both on the restoration of kidney function and prevention of further damage.