Excretory Products and their Elimination Class 11 Notes - Chapter 19

According to the CBSE Syllabus 2023-24, this chapter has been renumbered as Chapter 16.

Excretory Products and their elimination class 11 notes break down the concept of how living organisms discharge their waste products. All living organisms need a source of sustenance, and consequently, undigested materials and metabolic wastes need to be expelled from the body. Because if these materials are accumulated in the body, it can be detrimental to the health of the organism.

In the animal kingdom, wastes are excreted in one of three forms – ammonia, urea and uric acid. Animals that excrete ammonia are called ammonotelic organisms. Organisms that produce urea are termed ureotelic organisms. Animals that produce uric acid are termed urecotelic organisms. Humans are ureotelic organisms, which means we excrete urea as the excretory product.

Human Excretory System

Anatomically, the human excretory system consists of a pair of kidneys, a pair of ureters, a urinary bladder and the urethra. The kidneys contain tiny, numerous structures called nephrons. These are termed the functional unit of the kidneys and are responsible for the separation of water, filtering toxins and replenishing necessary elements back into the bloodstream.

Kidneys

Humans have a pair of kidneys on each side of the body. On average, the kidneys are between 10-12 cm in length and 5-7 cm in width. The kidneys weigh roughly 120 to 170 grams in a healthy adult human. The adrenal glands are found on the top of each kidney.

Nephron

The nephron is the most basic unit of the kidneys, with nearly a million found in each kidney. This structure is comprised of two parts – the glomerulus and the renal tubule. The glomerulus is a tuft of capillaries arising from the afferent arteriole. The renal tubule starts with a twin-walled cup-like structure called the Bowman’s Capsule (or glomerular capsule) which encloses the glomerulus.

Micturition

The process of release of urine is termed micturition, and the neural networks that cause this action are called the micturition reflex.

Read more, Micturition – The Process of Urination

Role of Other Organs in Excretion

Besides the kidneys, other organs help in ridding the wastes from the body. The various methods of excretion in humans can be categorized into two forms, namely:

1. Specific
2. Non-specific

Specific excretion mechanisms include the respiratory system, which expels metabolic waste products in the form of carbon dioxide. The alimentary canal breaks down harmful toxins and sends them to the blood and bile.

Disorders of the Excretory System

There are many potential causative factors for disorders of the excretory system. For instance, underlying illness, environmental factors, pathogenic microbes and even ingestion of certain substances can cause major functions of the excretory system to fail. Disorders can range from stones in the kidneys (called renal calculi), to much more life-threatening disorders such as chronic kidney disease.

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Further Reading:-

• Kidney Failure Symptoms
• Regulation Of Kidney Function