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Biology · Class 11 Science

Ch 17Excretory Products and their Elimination — Class 11 Biology, concept-first.

Every cell in the body is continuously carrying out metabolic reactions, and alongside the useful products these reactions yield, they also generate a stream of waste by-products that the cell cannot use and cannot safely retain.

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Key concepts

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Modes Of Nitrogenous Excretion

Ammonotelism, ureotelism and uricotelism based on excreted nitrogen form.

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Chapter contents

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17.1

Introduction to Excretion

Every cell in the body is continuously carrying out metabolic reactions, and alongside the useful products these reactions yield, they also generate a stream of waste by-products that the cell cannot…

17.2

Modes of Nitrogenous Excretion

The chemical form in which an animal excretes its nitrogenous waste is not a matter of chance; it reflects a direct trade-off between the metabolic energy needed to convert highly toxic ammonia into a…

17.3

Gross Structure of the Human Excretory System

The human excretory system is centred on a pair of kidneys — the principal organs responsible for forming urine — together with the ducts and single organ that carry that urine out of the body: the ur…

17.4

Structure of the Nephron

Each human kidney contains roughly one million tiny, densely packed tubular structures called nephrons, and it is within these nephrons, not in the kidney's gross anatomy as such, that urine is actual…

17.5

Urine Formation — Glomerular Filtration

Urine formation proceeds through three successive processes as filtrate moves along the nephron — glomerular filtration, tubular reabsorption and tubular secretion — of which glomerular filtration is…

17.6

Urine Formation — Tubular Reabsorption and Secretion

The roughly 180 litres of glomerular filtrate formed by the two kidneys each day is, apart from lacking large proteins and blood cells, very similar in composition to blood plasma — which means that i…

17.7

Osmoregulation and the Counter-current Mechanism

Osmoregulation is the maintenance, within a narrow and fairly constant range, of the osmotic concentration (the total concentration of dissolved solutes) of the body's fluids, despite the fact that th…

17.8

Regulation of Kidney Function

Glomerular filtration rate, blood volume, blood pressure and the concentration of the urine finally produced are not fixed quantities; they are continuously monitored and adjusted through a set of int…

17.9

Role of Other Organs in Excretion

Although the kidneys carry out the great bulk of the body's excretory work, several other organs also contribute to removing waste from the body, each specialising in a different class of by-product,…

17.10

Disorders of the Excretory System, Dialysis and Kidney Transplant

When the kidneys are damaged by disease, injury or long-term strain, or when the passages that carry urine out of the body become obstructed or inflamed, a range of disorders can result, several of wh…

17.11

Summary — Excretory Products and their Elimination

This chapter has traced excretion in humans from the underlying chemistry of nitrogenous waste through to the structure of the excretory system and the physiological mechanisms that keep it working co…

Very Short Answer Questions

+Show 8 questions8 questions
  1. Q11Define ammonotelism, and name one group of animals that excretes nitrogenous waste in this way.Free
  2. Q12What is the hilum of the kidney, and what three structures pass through it?Free
  3. Q13Name the two convoluted parts of the nephron tubule that lie within the cortex of the kidney.Free
  4. Q14What is meant by glomerular filtration rate (GFR)? State its approximate normal value in a healthy adult.Preview
  5. Q15Define osmoregulation.Preview
  6. Q16Name the hormone secreted by the walls of the atria of the heart that lowers blood pressure and opposes the renin-angiotensin-aldosterone sy…Preview
  7. Q17What is uremia?Preview
  8. Q18Name two organs, other than the kidneys, that assist the body in excretion, and state briefly what each removes.Preview

Short Answer Questions

+Show 8 questions8 questions
  1. Q19Differentiate between ammonotelism, ureotelism and uricotelism, naming one example organism or group for each.Free
  2. Q20Describe the structure of the Malpighian corpuscle, naming the glomerulus and Bowman's capsule and explaining how they are related.Free
  3. Q21Explain the process of tubular reabsorption, distinguishing clearly between obligatory reabsorption and facultative reabsorption.Free
  4. Q22What is the juxtaglomerular apparatus (JGA), and what role does it play in regulating glomerular filtration rate and blood pressure?Preview
  5. Q23Explain briefly the renin-angiotensin-aldosterone system (RAAS) and its overall effect on blood pressure and kidney function.Preview
  6. Q24Explain the role of ADH (vasopressin) in regulating the volume and concentration of urine, and describe what happens when its secretion is d…Preview
  7. Q25What is dialysis? Briefly describe the working principle of hemodialysis using an artificial kidney.Preview
  8. Q26Differentiate between renal calculi and nephritis as disorders of the human excretory system.Preview

Long Answer Questions

+Show 6 questions6 questions
  1. Q27Describe, with reference to their structure and function, the gross anatomy of the human excretory system, including the kidneys (external a…Free
  2. Q28Describe the detailed structure of a nephron, naming all its parts in order from the Malpighian corpuscle to the collecting duct and briefly…Free
  3. Q29Explain the mechanism of urine formation under the three successive headings of glomerular filtration, tubular reabsorption and tubular secr…Preview
  4. Q30Describe the counter-current mechanism operating in the loop of Henle and the vasa recta, and explain how it helps the kidney produce concen…Preview
  5. Q31Discuss the hormonal regulation of kidney function, covering the renin-angiotensin-aldosterone system, atrial natriuretic factor (ANF), and…Preview
  6. Q32Discuss the following disorders of the human excretory system — uremia, renal failure, renal calculi and nephritis — and describe dialysis (…Preview

More questions

+Show 10 questions10 questions
  1. Q1Most bony freshwater fish excrete their nitrogenous waste chiefly as which of the following, a substance that is highly toxic but extremely…Free
  2. Q2Mammals, most adult amphibians, and marine cartilaginous fish (elasmobranchs such as sharks) chiefly excrete nitrogenous waste as (a) Ammoni…Free
  3. Q3Birds, reptiles, land snails and many insects excrete nitrogenous waste chiefly as uric acid, a nearly insoluble semisolid paste. This mode…Free
  4. Q4The structural and functional unit of the human kidney, of which each kidney contains roughly a million, is the (a) Renal pyramid (b) Nephro…Preview
  5. Q5The double-walled, cup-shaped structure that surrounds the tuft of glomerular capillaries and collects the filtrate at the very start of the…Preview
  6. Q6The unusually high hydrostatic (blood) pressure inside the glomerular capillaries, which drives ultrafiltration, is chiefly maintained becau…Preview
  7. Q7Of the roughly 180 litres of glomerular filtrate formed by the two kidneys each day, approximately what percentage is normally reabsorbed by…Preview
  8. Q8The parallel, opposite-direction flow of filtrate through the loop of Henle and of blood through the vasa recta, which together build up and…Preview
  9. Q9The juxtaglomerular apparatus (JGA) releases the enzyme renin chiefly in response to (a) A fall in glomerular blood flow / blood pressure (b…Preview
  10. Q10Deficient secretion of ADH (vasopressin), or the kidney's failure to respond to it, results in the passage of a large volume of dilute urine…Preview