knows this fact that it is not a simple deal for the students to grasp the excretory products along with their elimination concept. To pave the right way for this, we have formed this chapter section wise. By getting versed with the subject according to the sections divided by teachers, this will turn simpler for the students to learn all the related aspects of this chapter without having to face any sort of hassle.
So, students, this was a warmup about how is going to set up the entire curriculum for you. Now, you must be feeling much relaxed that it is not going to be a thing of burden for you but you are going to enjoy it with the real-time and interactive sessions with the tutors. Ending your excitement and multiplying your assurance of good preparation, we are going to start with the introduction. Here you are going to learn the first step of the chapter. If you feel that you can continue with the next session it is fine otherwise you can take a small break and let the introduction fix in your head before you start with the next sections.
All the living organisms eliminate their body waste and other toxic or excess waste in various ways that reside on the earth. Removal of nitrogenous waste products formed during metabolism from the body of a human is called excretion. Normally excretion means the release of nitrogenous excretory substances like urea Ammonia uric acid etc. Ammonia is excreted by some organisms called ammonotelic such as aquatic amphibians. Urea is excreted by some organisms called ureotelic such as terrestrial amphibians. While uric acid is excreted by some organisms called uricotelic such as reptiles. From all the excretory waste, urea is the least toxic and ammonia is the most toxic.
Excretory Products In Different Organisms
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Animals |
Excretory organs |
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Unicellular animals |
Contractile vacuole |
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Arthropods |
Malpighian tubules |
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Vertebrate |
Kidneys |
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Mollusca |
Urinary organ |
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Crustaceans |
Antennal gland |
Human Excretory System
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Kidney
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The main excretory organ in human and other mammals is a pair of kidneys which are bean-shaped and reddish-brown in color.
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It is an excretory and homeostatic organ which is mesodermal in origin.
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It is located between the last thoracic and lumbar vertebra. Its weight is 140 grams.
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There are two parts of the kidney. Cortex and medulla are the outer and inner parts respectively.
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Each kidney is made of approximately 1,30,00000 kidney ducts which are called nephrons.
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The functional and structural unit of the kidney is considered as Nephron. There is a notch on the inner side called hilum in each kidney through which ureters, blood vessels, and nerves enter.
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There is a cup-like structure in every nephron called Bowman’s capsule.
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The glomerulus is made up of thin blood vessels found in the Bowman’s capsule which is made up of two types of arterioles.
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Afferent arteriole: It takes blood to the glomerulus.
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Efferent arteriole: By which the blood is taken out of the glomerulus.
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The process of filtration of liquid into the cavity of the bowman’s capsule is called ultrafiltration.
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The main function of the kidney is the purification of blood plasma i.e to extract the unwanted nitrogenous waste substances through urination.
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The supply of blood to the kidney takes place in large quantities in comparison to other organs.
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In the Kidney average, 125 ml per minute blood is filtered i.e 180 liters per day.
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Out of it, 1.45 urine is formed daily and the remaining is absorbed back by the cells of the nephron and is mixed into the blood.
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Ureter
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A whitish and thin tube emerges from the hilum of each kidney which is known as the ureter. These tubes are about 28 cm long.
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Both the ureters open separately in the bladder but they are placed closely carrying urine to the urinary bladder.
Urinary Bladder
Urethra
Ammonia
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Excess amino acids are deaminated by most of the animals as these are the first metabolic waste of protein metabolism.
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These are degraded into their keto groups which are utilized in catabolism for generating ATP and ammonia groups which are excreted in other forms.
Urea
Uric Acid
Urine
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Urine is an aqueous solution in which 95% is water. Other constituents are urea, uric acid, chloride, sodium, potassium, organic and inorganic potassium.
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The color of urine is light yellow due to the presence of urochromes in it. Urochromes are formed by the disso
ciation of hemoglobin. -
Urine is acidic with a ph value of 6.
Other Excretory Organs in the Human Body
Skin: The oil gland and sweat glands found in the skin respectively secretes sebum and sweat.
Liver: Liver cells play the main role in excretion by converting more and more amino acids and ammonia of blood into urea.
Lungs: The lungs excrete two types of gaseous substance carbon dioxide and water vapor. The excretion of some substances like garlic, onion, and some species in which the vapor component is present is excreted by the lungs.
Conclusion
Hence, here you have ended up with the entire chapter. In our digital classroom, the mode of a learning experience is different from a physical class. We have refined everything according to the rising competition such as improved study resources, a better quality of teaching, tough test papers (to instill confidence within students), and we have shrunk the count of students in a single class so that more attention can be given to an individual student. With smaller batches, we are able to explore the strengths and weaknesses of the students in the best way possible. Plus, our classrooms are beyond the barriers of geographical locations and that is why students from different countries have already joined our learning journey.
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