Excretory System | Excretory Products and Their Elimination | Practice Mcqs | Part 2| MDCAT TEST

Excretory System | Excretory Products and Their Elimination | Practice Mcqs | Part 1| Important MCQS
What is Excretion?
Excretion is the physiological process of elimination of metabolic waste from the body. The excretory products include amino acids, urea, uric acid, carbon dioxide, water, and ammonia.
Some Molluscs and Echinoderms excrete waste products from the body in the form of amino acids. Ammonia is the primary excretory product in animals, it is derived from the proteins present in the food we eat. It is the most toxic nitrogenous waste and is excreted by diffusion by most of the amphibians and aquatic animals.
Mammals excrete nitrogenous waste as urea. It is less toxic and comparatively less soluble in water. Birds and reptiles excrete nitrogenous waste as uric acid.
Excretory Products in Different Organisms
The excretory products and organs of different organisms are mentioned below:
Organisms Excretory Products Excretory Organs
Paramecium, Ammonia Contractile vacuole
Amoeba Ammonia Contractile vacuole
Hydra Ammonia General body surface
Ascaris Ammonia Renette cells
Periplaneta Uric acid Malpighian tubule
Palaemon Uric acid Antennary gland
Pheretima Ammonia Nephridial system
Spider Uric acid Coxal glands, Malpighian tubule
Taenia Ammonia Protonephridia
Leucon Ammonia General body surface
Excretory Organs In Human
The human excretory system comprises of the following excretory organs:
A pair of kidneys
A pair of ureters
Urinary Bladder
Urethra
Also Read: Human Excretory System
Kidneys
These are the primary excretory organs in humans located on the left and right side of the spine, near the liver. They are divided into the renal cortex, renal medulla, and renal pelvis. Renal pelvis carries urine from the kidney to the ureter. A nephron is the functional unit of a kidney.
Also Refer: Regulation Of Kidney Function
Ureter
It is a thin tube that comes out of each kidney carrying urine to the urinary bladder.
Urinary Bladder
It is a sac-like structure that stores urine until micturition. The Process Of Urination or expelling urine from the body.
Urethra
It is a tube-like structure that extends from the urinary bladder and helps in expelling urine outside the body. It is usually shorter in females and longer in males.
Also Read: Disorders of the Excretory System
Other Excretory Organs
Besides the above mentioned excretory organs, humans have other excretory organs as well. These excretory organs include:
Skin
Skin is known to be the largest organ in the human body. It contains sweat glands and the sebaceous glands. The sweat glands produce sweat which contains sodium chloride, amino acids, water, and glucose. The sebaceous glands excrete excess fat such as sterol and wax.
Also Refer: Structure And Functions Of Skin
Lungs
Lungs facilitate gaseous exchange. They help in inhaling oxygen and eliminating carbon dioxide and water vapour from the body.
Around 18L of carbon dioxide per hour and 400ml water per day is eliminated from the body.
Salivary Glands
These glands participate in the excretion of heavy metal ions such as lead and mercury.
Gastrointestinal tract and Intestines
The intestines eliminate the nitrogenous waste in the form of faeces. salts, glucose, calcium, iron, fibre is
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