Excretion

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:In Plants

, the process by which animals and plants rid themselves of waste products and of the nitrogenous by-products of Metabolism. Through excretion organisms control osmotic pressure—the balance between inorganic ions and water—and maintain acid-base balance. The process thus promotes homeostasis, the constancy of the organism’s internal Environment.

Plants have no special organs for removal of wastes. The waste products of Respiration and Photosynthesis are used as raw materials for each other. Oxygen gas produced as a by-product of photosynthesis is used up during respiration and carbon dioxide produced during respiration is used up during photosynthesis.

is carried out in the plants in the following ways:  

  • The gaseous wastes, oxygen, carbon dioxide and water vapour are removed through stomata of leaves and lenticels of stems.  
  • Some waste products collect in the leaves and bark of trees. When the leaves and bark are shed, the wastes are eliminated.  
  • Some waste products are rendered harmless and then stored in the plant body as solid bodies. Raphides, tannins, resins, gum, rubber and essential oils are some such wastes.

in animals

Many unicellular organisms like Amoeba throw out their wastes by diffusion from their body surface. Protozoan’s have no organs for excretion. As they live in an aquatic habitat, their wastes are eliminated by diffusion through the plasma membrane.

Simple multicellular organisms like Hydra throw out solid waste matter through their mouth. Higher multicellular organisms have well-defined specialized excretory organs. These organs could be simple tubular structures as in flatworms and leech.

The excretory organs of insects (e.g., grasshopper, cockroach and housefly) are also tubular. They remove nitrogenous wastes from the body fluid and help in maintaining the water balance in the body.  In vertebrates, the main organs of excretion and maintenance of water balance are the kidneys.

Excretory System in Human

Our excretory system consists of kidneys, blood vessels that join them, ureters, urinary bladder and urethra. They help produce and excrete urine.

There are two bean-shaped kidneys that lie in the abdominal cavity, one on either side of the vertebral column. The kidneys are reddish brown. Each of them is about 10 cm long and weighs about 150 g. Although they weigh less, they receive a lot of blood for filtration.

A volume of blood nearly equivalent to that in the whole body passes through the kidneys every four or five minutes. The kidneys produce urine to filter out the waste products, like urea and uric acid, from the blood.

Urine leaves each kidney through a tube called ureters. The ureters from both the kidneys are corrected to the urinary bladder that collects and stores urine. Ureters carry urine from the kidneys into the urinary bladder. The urethra is a canal that carries urine from the bladder and expels it outside the body.

Each kidney is enclosed in a thin, fibrous covering called the capsule. A renal artery brings blood into the kidney, along with nitrogenous waste materials. After filtration in the kidney, the purified blood leaves the kidney through a renal vein.

Structure and Function of a Nephron

A nephron consists of a long coiled tubule and the Malpighian corpuscle. The tubule of the nephron is differentiated into the proximal convoluted tubule, Henle’s loop and the distal convoluted tubule. The distal tubule opens into the collecting duct.  At the proximal end of the nephron is the Malpighian corpuscle, which consists of Bowman’s capsule and the glomerulus. Bowman’s capsule is a double-walled cuplike structure which surrounds the dense Network of blood capillaries called the glomerulus.

 

The process of excretion in nephron

The process of excretion may be divided into three stages- tubular secretion.

Filtration:  Filtration of blood occurs under high pressure in the nephrons of the kidney. Blood enters the glomerulus through the afferent arteriole (with a wider lumen) and leaves through the efferent arteriole (with a narrow lumen). Therefore, blood passes through the glomerulus under pressure. This results in filtration of blood.

Selective reabsorption:  Some Molecules of the glomerular filtrate are selectively reabsorbed into the blood. The glomerular filtrate flows through the proximal convoluted tubule, the U-shaped Henle’s loop and the distal convoluted tubule. It contains many useful substances such as glucose, amino acids and salts.

Tubular secretion:  Some nitrogenous waste products like creatinin and some other substances like potassium ions are removed from the blood by the distal convoluted tubule, and are then added to the urine. This is called tubular secretion.

 



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Excretion is the process by which the body gets rid of waste products. The main waste product produced by the body is urea, which is formed when the body breaks down proteins. Other waste products include ammonia, creatinine, and uric acid.

Urine formation

Urine is formed in the kidneys. The kidneys are two bean-shaped organs located in the lower back. They filter the blood to remove waste products and excess water. The filtered waste products and water are then excreted in the form of urine.

Urine composition

Urine is made up of water, urea, salts, and other waste products. The composition of urine can vary depending on a person’s diet, fluid intake, and Health status.

Urine transport

Urine is transported from the kidneys to the bladder through a system of tubes called ureters. The bladder is a muscular sac that stores urine until it is time to urinate.

Urine storage

The bladder can hold up to 1 cup of urine. When the bladder is full, it sends a signal to the brain that it is time to urinate.

Urine elimination

Urination is the process of expelling urine from the body. Urine is expelled from the bladder through a tube called the urethra.

Urinary tract infection

A urinary tract infection (UTI) is an infection of the urinary tract, which includes the kidneys, ureters, bladder, and urethra. UTIs are most common in Women, but they can also occur in men. The most common symptoms of a UTI are burning pain when urinating, frequent urination, and cloudy or bloody urine. UTIs are usually treated with antibiotics.

Kidney stones

Kidney stones are hard deposits that form in the kidneys. They can be caused by a number of factors, including dehydration, diet, and certain medications. Kidney stones can cause severe pain, nausea, and vomiting. They can also block the flow of urine, which can lead to kidney infection. Kidney stones are usually treated with medication or surgery.

Polycystic kidney disease

Polycystic kidney disease (PKD) is a genetic disorder that causes the kidneys to grow large and develop multiple cysts. PKD is the most common inherited kidney disease. It can cause kidney failure, high blood pressure, and other health problems. There is no cure for PKD, but treatment can help to manage the symptoms and prevent complications.

Glomerulonephritis

Glomerulonephritis is a kidney disease that affects the glomeruli, which are tiny filters in the kidneys. Glomerulonephritis can be caused by a number of factors, including infection, autoimmune disease, and certain medications. It can cause blood in the urine, high blood pressure, and swelling. Glomerulonephritis is usually treated with medication.

Nephrotic syndrome

Nephrotic syndrome is a kidney disease that causes the body to lose large amounts of protein in the urine. It can cause swelling, fatigue, and high blood pressure. Nephrotic syndrome is usually treated with medication.

Acute kidney injury

Acute kidney injury (AKI) is a sudden loss of kidney function. It can be caused by a number of factors, including infection, dehydration, and certain medications. AKI can cause a number of symptoms, including fatigue, nausea, and vomiting. It can also lead to more serious complications, such as heart failure and stroke. AKI is usually treated with medication and supportive care.

Chronic kidney disease

Chronic kidney disease (CKD) is a long-term condition that affects the kidneys. It can cause the kidneys to lose their ability to filter waste products from the blood. CKD can be caused by a number of factors, including diabetes, high blood pressure, and certain medications. It can cause a number of symptoms, including fatigue, nausea, and vomiting. It can also lead to more serious complications, such as heart failure and stroke. CKD is usually treated with medication and lifestyle changes.

End-stage renal disease

End-stage renal disease (ESRD) is the final stage of CKD. It occurs when the kidneys have lost so much function that they can no longer meet the body’s needs. ESRD can cause a number of serious complications, such as heart failure, stroke, and infection. Treatment for ESRD includes dialysis or kidney transplant.

Dialysis

Dialysis is a treatment that filters waste products and excess fluid from the blood when the kidneys can no longer do so. There are two types of dialysis: hemodialysis and peritoneal dialysis. Hemodialysis is performed in a hospital or dialysis center. Peritoneal dialysis is performed at home.

Kidney transplant

Kidney transplant is a surgical procedure that involves replacing a diseased kidney with a healthy kidney from a donor. Kidney transplant is the best treatment for ESRD. It can improve Quality Of Life and extend life expectancy.

1. What is the function of the excretory system?

The excretory system is responsible for removing waste products from the body. These waste products are produced as a result of metabolism, which is the process by which the body converts food into energy. The excretory system also helps to regulate the body’s fluid balance.

2. What are the organs of the excretory system?

The organs of the excretory system are the kidneys, ureters, bladder, and urethra. The kidneys are two bean-shaped organs that filter waste products from the blood. The ureters are two tubes that carry urine from the kidneys to the bladder. The bladder is a muscular sac that stores urine. The urethra is a tube that carries urine from the bladder out of the body.

3. How does the excretory system work?

The kidneys filter waste products from the blood and produce urine. Urine is a waste product that contains water, salts, and urea. The ureters carry urine from the kidneys to the bladder. The bladder stores urine until it is time to urinate. The urethra carries urine from the bladder out of the body.

4. What are some common problems with the excretory system?

Some common problems with the excretory system include kidney stones, urinary tract infections, and kidney failure. Kidney stones are hard deposits that form in the kidneys. Urinary tract infections are infections of the urinary tract, which includes the kidneys, ureters, bladder, and urethra. Kidney failure is a condition in which the kidneys cannot function properly.

5. How can I keep my excretory system healthy?

There are several things you can do to keep your excretory system healthy, including:

  • Drinking plenty of fluids
  • Eating a healthy diet
  • Exercising regularly
  • Getting enough sleep
  • Managing Stress
  • Avoiding smoking and excessive alcohol consumption
  • Getting regular check-ups with your doctor

  1. The main function of the kidneys is to:
    (a) filter the blood and remove waste products
    (b) produce urine
    (c) regulate blood pressure
    (d) all of the above

  2. The kidneys are located in the:
    (a) abdomen
    (b) chest
    (c) head
    (d) back

  3. The kidneys are made up of millions of tiny units called:
    (a) nephrons
    (b) ureters
    (c) bladder
    (d) urethra

  4. The nephron is responsible for:
    (a) filtering the blood
    (b) producing urine
    (c) reabsorbing nutrients
    (d) all of the above

  5. Urine is made up of:
    (a) water
    (b) waste products
    (c) salts
    (d) all of the above

  6. The kidneys are responsible for:
    (a) regulating blood pressure
    (b) producing red blood cells
    (c) breaking down Carbohydrates
    (d) none of the above

  7. The kidneys are connected to the bladder by the:
    (a) ureters
    (b) urethra
    (c) bladder
    (d) none of the above

  8. The bladder is a muscular sac that stores urine:
    (a) true
    (b) false

  9. The urethra is a tube that carries urine from the bladder to the outside of the body:
    (a) true
    (b) false

  10. The kidneys are responsible for:
    (a) producing urine
    (b) regulating blood pressure
    (c) both (a) and (b)
    (d) none of the above

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