Can anyone give some ideas on how to make a project on the process of excretion for class 10th
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Answer:
Human Excretory System Diagram
The diagram below represents the different parts of the human excretory system.
Human Excretory System
Excretion in Humans
Excretion is the process where all the metabolic wastes are removed from the body. Excretion in humans is carried through different body parts and internal organs in a series of processes.
Diffusion is the most common process of excretion in lower organisms. A human body is an exceptional machine, where different life-processes (respiration, circulation, digestion, etc.) take place simultaneously. As a result, many waste products produced in our body are in various forms that include carbon dioxide, water, and nitrogenous products like urea, ammonia, and uric acid.
In addition to these, the chemicals and other toxic compounds from medications and hormonal products are also produced. Simple diffusion is not sufficient to eliminate these wastes from our body. We need more complex and specific processes in order to eliminate waste products.
Blood contains both useful and harmful substances. Hence, we have kidneys which separate useful substances by reabsorption and toxic substances by producing urine.
Kidney has a structural filtration unit called nephron where the blood is filtered. Each kidney contains a million nephrons.
Capillaries of kidneys filter the blood and the essential substances like glucose, amino acids, salts, and the required amount of water get reabsorbed and the blood goes into circulation.
Excess water and nitrogenous waste in humans are converted to urine. Urine thus produced is passed to the urinary bladder via the ureters. The urinary bladder is under the control of the Central Nervous System. The brain signals the urinary bladder to contract and through the urinary opening called the urethra, we excrete the urine.
Mechanism of Excretion in Humans
The process of excretion in humans takes place in the following steps:
Urine Formation
The urine is formed in the nephrons and involves the following steps:
Glomerular Filtration
Tubular Reabsorption
Secretion
Glomerular Filtration
It is the primary step in urine formation. In this process, the excess fluid and waste products from the kidney are filtered out of the blood into the urine collection tubules of the kidney and eliminated out of the body.
The amount of filtrate produced by the kidneys every minute is known as Glomerular Filtration Rate (GFR).
Tubular Reabsorption
It is the absorption of ions and molecules such as sodium ions, glucose, amino acids, water etc. Water involves passive absorption, while glucose and sodium ions are absorbed by an active process.
Secretion
Potassium ions, hydrogen ions, and ammonia are secreted out to maintain the equilibrium between the body fluids.
The functions of the various tubules involved in the process are:
Glomerulus- filters the blood
Proximal Convoluted Tubules (PCT)- reabsorb water, ions and nutrients. They remove toxins and help in maintaining the ionic balance and pH of the body fluids by secretion of potassium, hydrogen and ammonia to filtrate and reabsorbing bicarbonate ions from the filtrate.
Descending Loop of Henle- is permeable to water and the filtrate gets concentrated as it is impermeable to electrolytes.
Ascending Loop of Henle- it is impermeable to water and permeable to electrolytes. The filtrate gets diluted due to the movement of electrolytes from the filtrate to the medullary fluid.
Distal Convoluted Tubule (DCT)- allows reabsorption of water and sodium ions. It also helps in maintaining pH and ionic balance by secretion and reabsorption of ions like PCT.
Collecting Duct- a large amount of water is reabsorbed from the filtrate by the collecting duct.
Micturition
The urinary bladder is stretched and gets filled with urine formed in the nephrons. The receptors present on the walls of the urinary bladder send signals to the Central Nervous System, thereby, allowing the relaxation of sphincter muscles to release urine. This is known as micturition.
Explore more: Micturition