NCERT Class 11 Biology Chapter 19 Notes Excretory Products And Their Elimination- Download PDF Notes

Excretory Products and Their Elimination Class 11 notes state that Wastes are expelled in one of three forms in the animal kingdom: ammonia, urea, or uric acid. Class 11 Biology chapter 19 notes will teach you how living creatures expel waste products. The methods of removal of these compounds will be discussed in Excretory Products and Their Elimination Class 11 notes, with a focus on common nitrogenous wastes. Download the CBSE Notes for Class 11 Biology, Chapter 19, PDF to use offline anywhere. Students must go through each topic in the excretory products and their elimination in Class 11 Notes Biology in the easiest and most effective way possible with the help of NCERT Notes for Class 11.

According to CBSE Class 11 Biology Chapter 19 notes, undigested materials, and metabolic wastes must be removed from the body since all living organisms require a source of nourishment. Because accumulating these elements in the body can harm the organism's health. These Excretory Products and their Elimination Class 11 notes will give you more information on the subject, which will help you pass your tests. Students can now get the Excretory Products and Their Elimination Class 11 notes pdf download on the internet. Excretory Products and their Elimination NCERT Notes for Class 11 Biology help you revise these major concepts given in the NCERT Book in a short period of time during CBSE Board exam preparation. Having revision notes and NCERT Solutions for Class 11 Biology Chapter 19 handy is beneficial to save you time. The NCERT Class 11 notes pdf can be downloaded through the link given below.

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NCERT Class 11 Chapter 19 Class Notes

Excretory Products and their Elimination

Ammonia, urea, uric acid, carbon dioxide, water, and ions such as Na+, K+, Cl–, phosphate, sulphate, and others are all accumulated by animals, either by metabolic activities or through other mechanisms such as excessive intake. These compounds must be removed entirely or in part. The main nitrogenous wastes emitted by mammals are ammonia, urea, and uric acid.

The most harmful type, ammonia, necessitates a substantial amount of water for its removal, whereas uric acid, which is the least hazardous, can be eliminated with minimal water loss. Wastes are expelled in one of three forms in the animal kingdom: ammonia, urea, or uric acid. Ammonotelic creatures are animals that emit ammonia. Urea-producing organisms are known as ureotelic organisms. Uricotelic creatures are animals that manufacture uric acid. Humans are ureotelic organisms, which implies our excretory product is urea.

Human Excretory System

• A set of kidneys, one set of ureters, a urinary bladder, and a urethra make up the excretory system in humans.
• Kidneys are reddish-brown bean-shaped structures located near to the dorsal inner wall of the abdominal cavity, between the levels of the last thoracic and third lumbar vertebra. An adult human kidney is 10-12 cm long, 5-7 cm wide, and 2-3 cm thick, with a weight of 120-170 g on average.
• The ureter, blood vessels, and nerves enter the kidney through a notch called the hilum, which is located in the Centre of the inner concave surface. The renal pelvis is a large funnel-shaped area inside the hilum with projections called calyces.
• A strong capsule covers the kidney's outer layer. The kidney is divided into two zones: the outer cortex and the inner medulla. The medulla is separated into a few conical masses projecting into the calyces. Between the medullary pyramids, the cortex forms renal columns known as the Columns of Bertini.
• Nephrons are the functional units of each kidney, which have roughly one million complicated tubular structures. The glomerulus and renal tubule are two components of each nephron. The afferent arteriole, a fine branch of the renal artery, forms a tuft of capillaries called a glomerulus. An efferent arteriole carries blood away from the glomerulus.
• Bowman's capsule, a double-walled cup-like structure that encloses the glomerulus, is the beginning of the renal tubule.
• The Malpighian body, which includes the glomerulus and Bowman's capsule, is referred to as the renal corpuscle. The tubule continues to coil into a proximal convoluted tubule, which is a heavily coiled network.
• The next component of the tubule is a hairpin-shaped Henle's loop, which has a descending and ascending limb. The ascending limb continues as the distal convoluted tubule, a heavily coiled tubular area (DCT). Many nephrons' DCTs open into a straight tube known as a collecting duct and many of them converge and open into the renal pelvis via medullary pyramids in the calyces.

Urine Formation :

• The glomerulus filters blood, which is called glomerular filtration, and is the first stage in the formation of urine. The glomerular capillary blood pressure filters the endothelium of glomerular blood vessels, the epithelium of Bowman's capsule and a basement membrane between these two layers..
• Bowman's capsule epithelial cells, known as podocytes, are organized in such a way that filtration slits or slit holes are created.
• The blood is filtered so finely through these membranes that practically all of the plasma constituents, with the exception of proteins, enter into the Bowman's capsule lumen. As a result, it is classified as an ultrafiltration process.
• The glomerular filtration (GFR) rate is the amount of filtrate produced by the kidneys per minute. A healthy person's GFR is around 125 milliliters per minute, or 180 liters per day.
• When the volume of filtrate created per day (180 liters) is compared to the volume of urine discharged (1.5 liters), it appears that nearly all of the filtrate must be reabsorbed by the renal tubules. This is referred to as reabsorption.

Function of the Tubules

• Proximal Convoluted Tubule (PCT): Simple cuboidal brush border epithelium lines the PCT, increasing the reabsorption surface area. This segment reabsorbs nearly all-important nutrients, as well as 70-80% of electrolytes and water.
• Henle’s Loop: In its ascending limb, reabsorption is at a minimum. This area, on the other hand, is important for maintaining the high osmolarity of medullary interstitial fluid. The loop of Henle's descending limb is permeable to water but nearly impermeable to electrolytes. As the filtrate flows down, it becomes more concentrated.
• Distal Convoluted Tubule (DCT): This section involves the conditional reabsorption of Na+ and water. DCT can also reabsorb HCO3– and secrete hydrogen, potassium, and NH3 ions selectively to keep the blood pH and sodium-potassium balance in check.
• Collecting Duct: This lengthy duct connects the cortex of the kidney to the medulla's inner portions. This region could reabsorb a large amount of water, resulting in concentrated urine. To maintain osmolarity, this section allows modest amounts of urea to enter into the medullary interstitium.

Mechanism of Concentration of the Filtrate

• The vasa recta and Henle's loop both play a significant part. The filtrate flows in opposite directions in the two limbs of Henle's loop, forming a counter current. Blood also flows in a counter-current pattern through the two limbs of the vasa recta.
• The close proximity of the Henle's loop and the vasa recta, as well as the countercurrent in them, help to maintain a rising osmolarity towards the inner medullary interstitium, i.e., from 300 mOsmolL-1in the cortex to roughly 1200 mOsmolL-1 in the inner medulla. NaCl and urea are primarily to blame for this gradient.
• The ascending limb of Henle's loop transports NaCl, which is exchanged with the descending limb of the vasa recta. The ascending section of the vasa recta returns NaCl to the interstitium. Small amounts of urea enter the ascending limb of Henle's loop's thin segment, which is then carried back to the interstitium by the collecting tubule. The countercurrent mechanism is the above-described transport of chemicals assisted by the particular arrangement of Henle's loop and vasa recta.

Regulation of Kidney Function

• Hormonal feedback mechanisms involving the hypothalamus, JGA and to some extent, the heart efficiently monitor and regulate kidney function.
• Blood volume, bodily fluid volume, and ionic concentration variations activate osmoreceptors in the body. When the body loses too much fluid, the hypothalamus is stimulated to release antidiuretic hormone (ADH) or vasopressin from the neurohypophysis. ADH helps to prevent diuresis by allowing water to be reabsorbed from the tubule's later portions.
• To complete the feedback, an increase in body fluid volume can turn off the osmoreceptors and suppress ADH release. ADH's constrictor effects on blood vessels can also affect kidney function. Blood pressure rises as a result of this. An increase in blood pressure can result in an increase in glomerular blood flow and, as a result, in an increase in GFR.
• The JGA has a complicated regulatory role to perform. A decrease in glomerular blood flow, glomerular blood pressure, or GFR can activate JG cells, causing them to produce renin, Angiotensinogen in the blood is converted to angiotensin I, which is then converted to angiotensin II. Angiotensin II increases glomerular blood pressure and thus GFR since it is a powerful vasoconstrictor.

Micturition

• The urine produced by the nephrons is eventually delivered to the urinary bladder, where it is held until the central nervous system (CNS) sends a voluntary signal. The stretching of the urinary bladder as it fills with urine triggers this signal. Stretch receptors on the bladder walls respond by sending signals to the CNS. The CNS sends motor messages to the bladder's smooth muscles, prompting them to contract and the urethral sphincter to relax, causing urine to be released.
• Micturition is the process of releasing urine, and the micturition reflex is the neurological mechanism that causes it. On average, an adult human excretes 1 to 1.5 liters of urine every day. The urine produced is a light yellow-colored watery fluid with a characteristic odor. It is slightly acidic (pH-6.0). On a daily basis, 25-30 grams of urea are expelled.

Role of Other Organs in Excretion

• The lungs, liver, and skin, in addition to the kidneys, have a role in excretory waste removal.
• Lungs expel a considerable amount of CO2 (about 200mL/minute) as well as a significant amount of water. Bile-containing compounds such as bilirubin, biliverdin, cholesterol, degraded steroid hormones, vitamins, and medicines are secreted by the liver, the biggest gland in the body. The majority of these compounds are excreted with the wastes of digestion.
• Sweat and sebaceous glands in the skin are capable of removing certain substances through their secretions. Sweat is a watery fluid that contains sodium chloride, minor amounts of urea, lactic acid, and other substances. It is produced by sweat glands.

Disorders of The Excretory System

• Malfunctioning Kidneys can cause an accumulation of urea in the blood, a condition known as uremia, which is extremely dangerous and can lead to kidney failure. Hemodialysis can be used to eliminate urea in these patients. During hemodialysis, blood is drained from a handy artery and pumped into a dialyzing unit known as an artificial kidney.
• Kidney transplantation is the most effective treatment for acute renal failure (kidney failure). To reduce the odds of rejection by the host's immune system, a functioning kidney is transplanted from a donor, preferably a close family.
• Renal calculi: Within the kidney, a stone or insoluble mass of crystallized salts (oxalates, etc.) is formed.
• Glomerulonephritis: Inflammation of the kidney's glomeruli.

Chapter-Wise NCERT Class 11 Notes Biology

Significance of NCERT Class 11 Biology Chapter 19 Notes:

Excretory Products and Their Elimination class 11th notes will help you review the chapter and obtain a better understanding of the important points addressed. These Notes for Class 11 Biology Chapter 19 are also beneficial for covering the main themes of the CBSE Biology Syllabus in Class 11 as well as for competitive exams such as AIPMT, AIIMS, NEET, and others. The Class 11 Biology chapter 19 notes pdf download can be utilized for offline preparation.

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