19

19.1 INTRODUCTION

Every living organism needs air for burning fuel in the body to produce energy. Simultaneously, it must also throw out any ashes or gases formed in this process. Many other wastes are also produced in the body during cell activities and have to be removed from the body. In this lesson you will study about gaseous exchange for the release of energy and about the elimination of wastes.

19.2 OBJECTIVES

After completing this lesson you will be able to:

define respiration describe the respiratory organs in human body and make a labelled diagram there of.

differentiate between breathing and respiration, inspiration and expiration.

describe the exchange of respiratory gases in the lungs and their transport to and from the tissues.

describe briefly the gaseous exchange in amoeba, cockroach and fish.

define excretion and give its importance.

list organs of excretion in humans, amoeba, and earthworm.

explain ultra-filtration and urine formation.

define ammonotelism, ureotelism and uricotelism.

GASEOUS EXCHANGE

ACTIVITY

Take a deep breath, close your nostms and hold st for sometime. How long. I can you hold your breath in this way?

What made you stop from holding it any longer?

Did you feel uncomfortable towards the end?

Do you now realise the importance of breathing process?

The exchange of gases in our body is completed in two main steps

- Breathing and Cellular Respiration.

(i) Breathing is just inhaling and exhaling of ail-so that (X can be taken in and CO released sent out and

(ii) Cciiuiar Respiration is the oxidation of glucose molecules to release biochemical eaergy inside the cells.

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BREATHING	RESPIRATION
1.It is a physical process	It is a chemical process
2.Involves respiratory track and lungs.	Takes place in each cell
3.Involves inspiration and expiration of air	Oxidation of glucose to release energy takes place.

THREE COMMON BREATHING (LUNG) DISORDERS

ASTHMA

PNEUMONIA

TUBER- CULOSIS

Difficulty in breathing because of narrowing of bronchioles Sometimes caused due to certain factors present in the environment.

Lungs show inflammation due to bacterial infection. Visual symptoms are fever, pain and severe cough.

Lumps of tissue are formed in the lungs, caused by the bacteria. It is an infectious disease. In extreme cases blood may come out while coughing. BCG vaccination can prevent T.B.

NORMAL BREATHING RATES (PER MINUTE)
AT BIRTH	40-70
1 YEAR	35-40
5 YEARS	ABOUT 25
10 YEARS	ABOUT 20
25 YEARS	16-18
OLD AGE	MAY BE BEYOND 20

INTEXT QUESTIONS 19.2

1. Name the cell organelle where 0- is utilised during cellular respiration.

2. Complete the following equation:

? +6 0,——————-> 6 CO, + 6H,0 +38 ATP •"

3. Fill in the blanks:

(i) Alcohol or Lactic 'acid are produced during ..................

respiration,

(ii) Our body cells can use only the energy stored in .....................

molecules.

4. Match the following:

A B Cockroach Cell Membrane Amoeba trill lamellae Fish Tracheoles

19.12 NORMAL AND ABNORMAL COMPONENTS OF URINE

Normal	Components	Abnormal Components
Component	Amount/Day	Component	Cause
Water.	1200-1500 ml	Glucose	Diabetes mellitus
Urea	25-30 gms,
Uric Acid	0.7 gms.	Proteins	Kidney disease
Creatine	1.2 gms.	Acetone	Diabetes mellitus,
Ammonia	0.6 gms.		Starvation
NaCI	10-15 gms.	Erythrocytes	Infection in urinary
			system
KC1	2.5 gms.
Magnesium	0.2 gms.	Leucocytes	Large numbers indicate
		infection in urinary
			system
Phosphate	1.7 gms
Sulphate	2.0 gms
		Uric acid	Gout
		crystal.
Minute amounts of Fatty Acids,
Amino Acids, Pigments, Mucin,
Enzymes, Hormones, Vitamins.

Disorders of the Excretory System

Kidney Failure

An abnormal condition in which the kidneys fail to form urine. It may be caused by hypertension, injury, bacterial infection or exposure to toxins. In case of kidney failure the person can survive with a single kidney.

Kidney Stones

Accumulation of various mineral crystals in the pelvis of the kidneys and cause obstruction in urinary passage.

19.14 ARTIFICIAL KIDNEYS

Certain drugs taken over a long period of time, alcoholic drinks, nicotine from tobacco smoking, etc., may result in kidney failure. Body cannot tolerate high amount of nitrogenous toxic wastes above a certain level. An artificial kidney or dialysis machine can prolong life.

In an artificial kidney, a cellophane membrane is used to substitute for the glomerulus. The patient's blood is made to flow on one side of the membrane and the surrounding fluid on the other. Thus as both the fluids circulate through machine, wastes move from the blood into the surrounding fluid.

19.15 WHAT YOU HAVE LEARNT

Metabolic activities produce a number of waste products that need elimination from the body.

Breathing is a mechanical process of inhaling air (INSPIRATION) and giving out of CO₂ rich air (EXPIRATION)

Air passes through respiratory passage as follows -Nostrils —>Pharynx —> Trachea —>Bronchi—Bronchioles —> Alveoli (lungs).

Cellular respiration is a chemical process (taking place in a cell in mitochondria) associated with release of energy.

Haemoglobin is an iron containing pigment that easily combines with 0₂ and releases it.

Carbon dioxide in blood is transported in three ways; (i) Dissolved in plasma, (ii) as carbaminohaemoglobin, (iii) as bicarbonates.

Aerobic reactions take place in the presence of 0₂ and produces 38 molecules of ATP, CO₂ and water.

Anaerobic respiration takes place in the absence of 0₂ and produces 2 mols of ATP, CO₂ and alcohol or lactic acid.

EXCRETION is the removal of Nitous waste from the body.

Human excretory system consists of a pair of kidneys, a pair of ureters, urinary bladder and urethra.

Nephrons are the filtering units of kidneys.

Urine formation by nephrons is carried out in three steps:

(i) Ultrafiltration, (ii) Reabsorption and (iii) Tubular secretion.

Urine consists of water, urea, unwanted salts and bile pigments.

Depending upon the kind of excretory product, the animal may be classified as ammonotelic (NH₃ producing), ureotelic (Urea producing) and uricotelic (uric acid producing).

An artificial kidney or Dialysis machine may be needed in case of kidney failure.

Nephridia and contractile vacole are found in earthworm and amoeba respectively.

TERMINAL QUESTIONS

1. Discuss briefly the role of diaphragm in breathing.

2. Give any three differences between breathing and respiration.

3. How is carbon dioxide transported to lungs through blood?

4. What is cellular respiration? How much energy is released in the oxidation of one molecule of glucose.

5. What is meant by excretion? Why is it important?

6. Draw a labelled diagram of the filtering unit of the kidney.

7. What are the main steps involved in the formation of urine? What is the significance of the reabsorption step?

8. What is a dialysis machine? When is it needed?

CHECK YOUR ANSWERS

INTEXT QUESTIONS:

19.1

1. Breathing

2. Cellular respiration

3. Bronchioles

4. Trachea

5. Diaphragm

6. 500 ml., 4000 ml.

7. Oxy-haemoglobin, Carbaminohaemoglobin.

19.2

1. Mitochondrin

2. C₆H₁₂0₆ + 6 CO₂ Cellular mitochondria 6 CO₂ + 6 H₂O+38 ATP

Respiration

3. (i) Anaerobic respiration

(ii) ATP molecules

4. (i) Cockroach-Tracheoles,

(ii) Amoeba - Cell Memberane,

(iii) Fish- Gill lamellae.

19.3

1. Fish, man/frog

2. Protein or Amino Acids

3. 180 litres

4. Ultrafilteration, Reabsorption, and Tubular Secretion.

5. Earthworm and Amoeba.