|
Excretion: Strategies Across Living Organisms
|
|
About
|
- Excretion is the biological process of removing harmful metabolic wastes from the body.
- Different organisms use varied strategies for excretion.
- Unicellular organisms often use simple diffusion from the body surface.
- Multicellular organisms, like humans and plants, use specialized organs or structures for excretion.
- Sometimes a person’s kidneys may stop working due to infection or injury.
- As a result of kidney failure. waste products start accumulating in the blood.
- Such persons cannot survive unless their blood is filtered periodically through an artificial kidney. This process is called dialysis.
|
|
The Human Excretory System
|
|
About
|
- The human body, a complex and intricate system, constantly produces waste.
- Managing this waste efficiently is crucial for maintaining health, and that’s where the excretory system comes into play.
|
|
The Kidneys: Filtration and Reabsorption
|
- Shape: The body possesses two bean-shaped kidneys that filter waste from the blood.
- Filtering Organ: These organs discerningly ensure that only waste is filtered out, retaining essential elements.
- Anatomy of Kidney:
- Bowman’s Capsule: Each capillary cluster in the kidney is associated with the cup-shaped end of a coiled tube called Bowman’s capsule that collects the filtrate.
- Unit of Kidney: Each kidney has large numbers of these filtration units called nephrons packed close together.
[Human excretory system]
- Selective Reabsorption: Some substances in the initial filtrate, such as glucose, amino acids, salts and a major amount of water, are selectively reabsorbed as the urine flows along the tube.
- Water Dependency: The amount of water re-absorbed depends on how much excess water there is in the body, and on how much dissolved waste there is to be excreted.
[Structure of a Nephron]
|
|
Ureters
|
- Ureters serve as transport channels, directing the filtered waste, now termed urine, from the kidneys to the bladder.
|
|
Urinary Bladder:
|
- The bladder functions as a reservoir, storing urine and signaling when evacuation is necessary.
|
|
Urethra
|
- The urethra signifies the final path through which urine exits the body.
- Waste Composition; Predominantly, urine comprises water, amounting to 95%.
- The residual 5% consists of urea and other waste materials.
- It’s noteworthy that an average adult expels about 1–1.8 L of urine daily.
|
|
Additional Excretory Mechanism
|
Beyond urine, the body also dispels waste via sweat, a concoction of water and salts. White marks on clothing after sweating can be attributed to these salts.
|
|
Green Exhalations: Exploring Plant Excretion Strategies and Waste Management
|
|
About
|
- Plants use different strategies.
- Oxygen, a byproduct of photosynthesis, is released during respiration.
- Excess water is eliminated through transpiration.
- Waste products may be stored in cellular vacuoles or in parts such as leaves that fall off.
- Resins, gums, and other waste substances are stored, especially in old xylem.
- Some waste substances are excreted into the soil surrounding the plant.
|
|
Nature’s Excretion: Comparison of Animal and Plant
|
- Animals, including humans, have specialized excretory organs for efficient waste removal.
- Plants utilize various structures, storage mechanisms, and shedding of parts for waste management.
- Both organisms employ strategies based on their physiological characteristics and environmental interactions.
|