Human Excretory System for Class 4 Science
- Excretion is the process of eliminating the waste produced in our bodies.
- The major waste produced in our bodies is carbon dioxide and uric acid. Uric acid is eliminated from the body in the form of urine.
- The Human excretory system helps in the process of excretion.
- The main organs of the excretory system are the kidneys, ureters, urinary bladder, and urethra.
- Kidneys are bean-shaped organs, also called the filters of our bodies.
Excretory System’s Function
What Kind of Wastes Are Eliminated by the Kidneys?
- Mainly toxins from the blood are eliminated, such as ammonia, urea and uric acid.
- Excess salt and sugar are eliminated to maintain proper water and salt balance inside the body.
- The kidneys also eliminate drugs taken in the form of medicines.
Why Are Nephrons Called the Structural and Functional Units of the Kidney?
- The nephrons are called the structural units of the kidney because many nephrons combine to form a kidney.
- Each nephron is specialised for the key steps of blood purification, i.e. filtration, reabsorption and secretion, hence called the functional unit.
What Is the Path of Excretion of Urine Through the Excretory System?
The path of urine through the excretory system is-
Briefly Describe the Steps of Urine Formation.
The process of urine formation can be divided into the following steps:
- Filtration by the nephrons
- Reabsorption by the nephrons
- Secretion by the nephrons
Why Do We Feel the Urge To Pee?
- The urinary bladder is a balloon-like organ that stores urine inside it temporarily.
- When it fills with urine, it expands and increases the pressure on the bladder muscles.
- When the bladder exceeds its limit of storing urine, the urge to urinate is triggered.
Healthy Habits Related to Excretion
How Does the Weakening of Bones Be Related to Kidney Diseases?
- Kidneys play a vital role in keeping the level of phosphorus balanced in our bodies.
- A balanced phosphorus level is necessary for balancing Vitamin D in our body. Vitamin D is essential for the absorption of calcium in the body.
- An increase in phosphorus levels does not allow calcium to get absorbed into the body, leading to weakening bones.
Explain How Kidney Stones Are Formed.
- An increase in the concentration of uric acid and calcium salts in the blood may lead to the formation of kidney stones.
- This is because the kidney cannot filter these substances efficiently when their level increases, and they start depositing inside the kidneys in the form of kidney stones.
What is Dialysis?
- Dialysis is an artificial method to purify blood in case of kidney failure.
- It is done using an artificial machine which functions like a kidney.
- The frequency of the dialysis depends on an individual's age, diet and medical condition.
Name the Blood Vessels Which Carry Blood to the Kidneys.
- Renal veins and arteries carry blood to the kidneys.
- The renal artery carries the unfiltered blood from body parts to the kidneys for filtration.
- The blood, once filtered, is sent back to the body parts with the help of the renal vein.
How Is the Flow of Urine From the Urinary Bladder Regulated?
- The sphincter muscles regulate the flow of urine from the urinary bladder.
- They contract to allow the urine to pass to the urethra and relax to allow the urinary bladder to hold the urine.