Unit 1 Respiration

Science Form 3

1yschow@smkbpj(a)

Unit 1 Respiration

1.1 Human Breathing Mechanism

1.2 Transport of Oxygen in the Human Body

1.3 The Importance of a Healthy Respiratory

SystemSystem

2yschow@smkbpj(a)

HUMAN BREATHING MECHANISM

1.1

3yschow@smkbpj(a)

A. Human Respiratory System

1. Living organisms must be able to take oxygenfrom the air and get rid of carbon dioxide to the air.

2. Gas exchange takes place through a gas 2. Gas exchange takes place through a gas exchange surface, also known as a respiratory surface.

3. Breathing is also known as external respiration.

4yschow@smkbpj(a)

4. Breathing consists of two stages:

a. Inhalation - during which air is taken into the lungs.

b. Exhalation - during which air passes out of the lungs.

5. The breathing system or the human respiratory system consists of the following structures or organs:

a. The nasal cavity

b. Tracheab. Trachea

c. Bronchus (plural: bronchi)

d. Bronchiole

5yschow@smkbpj(a)

e. Lungs

i. Alveolus (plural: alveoli)

f. Rib cage

g. Diaphragm

h. The intercostal musclesh. The intercostal muscles

i. Internal intercostal muscles,

ii. External intercostal muscles.

6yschow@smkbpj(a)

6. Flow of air into the lungs

a. Air is breathed in through the nose and enters the nostrils.

b. The nostril leads to the nasal cavity where the air is warmed up and moistened. moistened.

b. The nostril leads to the nasal cavity where the air is warmed up and moistened. moistened.

i. Hairs and sticky mucus trap particles inside the nasal cavity.

c. The air then enters the trachea.

7yschow@smkbpj(a)

d. The trachea branches into two bronchi.

i. Each bronchus leads directly into a lung.

ii. The bronchus branches into many smaller

tubes called bronchioles

8yschow@smkbpj(a)

e. The air then passes through the bronchiole and comes to alveoli

i. The human lungs have millions of alveoli

ii. The wall of the alveolus is only one-cell thick.

iii. It is thin , moist and is surrounded by a network of

capillaries.

iv. The exchange of respiratory gases, oxygen and

carbon dioxide,

occurs between occurs between

the alveolus and

capillaries.

9yschow@smkbpj(a)

C. The Breathing Mechanism

1. The breathing mechanism is the physical changes which occur in the respiratory system during breathing.

2. This mechanism involves 2. This mechanism involves

a. inhalation

(breathing in),

b. exhalation

(breathing out).

10yschow@smkbpj(a)

3. During inhalationa. Both the intercostal muscles and

the diaphragm contract.

b. The diaphragm moves downwards , increasing the volume of the thoracic (chest) cavity.

c. The intercostal muscles pull the c. The intercostal muscles pull the ribs up , expanding the rib cage and further increasing the volume of the thoracic cavity.

d. These actions lower the air pressure in the alveoli.

e. Air from the outside then rushes in through the nasal cavities, trachea and lungs. The lungs expand. 11yschow@smkbpj(a)

4. During exhalation

a. the intercostal muscles relax causing the rib cage to move downwards and inwards.

b. the muscles of the diaphragm relax and the diaphragm curves upwards curves upwards and returns to its original dome shape.

c. These actions return the thoracic cavity c. These actions return the thoracic cavity to its original volume.

d. The air pressure inside the lungs is now higher than the atmospheric pressure outside.

e. The lungs contract and the air is forced out through the respiratory tract.

12yschow@smkbpj(a)

A model representing how diaphragm

works in the human respiratory system.

i. The bell jar -

represents the

thoracic cavity.

ii. The glass rod -

represents the trachea.

iii. The balloons The balloons -

represent the lungslungs.

iv. The rubber sheet -

represents the diaphragm.

13yschow@smkbpj(a)

When the rubber sheet is pulled downwards:

i. The volume of the bell jar increases.

ii. The air pressure inside becomes lower than the atmospheric pressure atmospheric pressure outside.

iii. This condition allows the air outside to enter the glass tube, causing the balloons to expand.

iv. This action represents the process of inhalation.inhalation.

14yschow@smkbpj(a)

When the rubber sheet is pushed upwards:

i. The volume of the bell jar decreases.

ii. The air pressure inside the bell jar becomes higher than the atmospheric pressure outside. pressure outside.

iii. The air inside the balloons is forced out through the glass tube. This causes the balloons to deflate.

iv. This action represents the process of exhalation. exhalation.

15yschow@smkbpj(a)

Composition of inhaled air and exhaled air:

21 16

0.03 4

78 78

less more

Variable 37 oC

16yschow@smkbpj(a)

Comparison between inhalation and exhalation:

17yschow@smkbpj(a)

TRANSPORT OF OXYGEN IN THE

HUMAN BODY

1.2

18yschow@smkbpj(a)

A. Diffusion of Oxygen from the Alveolus to the capillaries

1. Diffusion is the movement of molecules

from a region where they are highly

concentrated to a region where they are less

concentrated. concentrated.

19yschow@smkbpj(a)

2. The following characteristics enable oxygen to

diffuse through the walls of the alveoli easily and

efficiently.

a. The alveoli have very large surface areas and

thin walls (only one-cell thick).

b. The inner surfaces of the alveoli are always

moist. moist.

c. The outer surfaces of the alveoli are surrounded

by a network of blood capillaries. These

capillaries also have very thin walls

(only one-cell thick).

20yschow@smkbpj(a)

3. Inhaled air is rich in oxygen.

4. The oxygen concentration in the alveolus is therefore higher than the oxygen concentration in the deoxygenated blood in the capillaries.

5. The difference in oxygen concentration makes the oxygen diffuse easily into the blood capillaries.

a. Oxygen in the alveolus a. Oxygen in the alveolus

diffuses through the

wall into the blood.

b. Carbon dioxide and

water vapour diffuse from

the blood into the alveolus.

21yschow@smkbpj(a)

B. Oxygen Transport

1. Through the breathing process, oxygen from the air

flows into our bloodstream.

2. The heart then pumps the oxygenated blood to

supply oxygen to the body cells.

a. Body cells need oxygen for cell respiration.

b. Cell respiration is the oxidationoxidation of food to

release energy.

22yschow@smkbpj(a)

3. Heamoglobina. It is the special carrier and it transports oxygen

from the lungs to all parts of the body.

b. b. Haemoglobin is a blood pigment.

c. It contains haem (or heme) (the part which is made up of ferum )

and globinglobinand globinglobin

(the protein part).

d. As the oxygen

concentration is high

in the alveolus, oxygen

diffuses into the capillaries.

23yschow@smkbpj(a)

e. Oxygen then combines with haemoglobin in

the red blood cells and forms

oxyhaemoglobin.

f. Blood with oxyhaemoglobin is bright red in

colour.

g. It is carried to the heart to be distributed to g. It is carried to the heart to be distributed to

all the cells of the body.

24yschow@smkbpj(a)

C. Diffusion of Oxygen from the Capillaries

to the Body cells.

1. Oxygenated blood is sent to all the cells in the body by a vast network of blood vessels.

a. When blood reaches the body cells, oxyhaemoglobinis broken down into haemoglobin and oxygen.is broken down into haemoglobin and oxygen.

b. The oxygen then diffuses through the walls of the capillaries into the cells.

c. Oxygen is then used to oxidise food to release carbon carbon dioxide dioxide during cell respiration.

25yschow@smkbpj(a)

26yschow@smkbpj(a)

THE IMPORTANCE OF A HEALTHY

RESPIRATORY SYSTEM

1.3

27yschow@smkbpj(a)

A. Healthy Respiratory System

1. Our respiratory system is protected by a

layer of cilia and glands which secrete mucus.

2. Our lungs are in direct

contact with the air we contact with the air we

breathe.

3. The pollutants in the

air

can cause damage to our

respiratory system.28yschow@smkbpj(a)

B. Effects of Harmful Substances

1. Nicotine in cigarettes

a. Stimulates the production of cells in the

trachea and lungs and leads to lung cancer.

b. Narrows and hardens the blood vessels.

This affects bloodThis affects blood

flow and causes

heart attacks.

c. Leads to addiction

as nicotine is a drug.

29yschow@smkbpj(a)

2. Tar in tobacco

a. blackens the lungs.

b. The walls of the lungs thicken and this

makes respiration difficult.

c. Tar is carcinogenic and can cause lung

cancer.cancer.

30yschow@smkbpj(a)

3. Nitrogen dioxide in cigarette smoke and from

motor vehicles and industries

a. dissolves in the mucus layer on the walls of the trachea and alveolus.

b. It forms an acid which can destroy lung tissues. tissues.

c. In big towns, the reddish-brown layer in the

atmosphere is due to

the presence of

nitrogen dioxide.

31yschow@smkbpj(a)

Nitrogen dioxide, NO2, is a brownish-red gas at

room temperature.

Nitrogen dioxide is a poisonous gas

32yschow@smkbpj(a)

4. Sulphur dioxide

a. Sulphur dioxide is acidic.

b. It is released when fuels which contain sulphur are burnt.

c. Cigarette smoke and smoke from factories have a high sulphur dioxide content.

d. Sulphur dioxide is very soluble in the alveoli. It forms an acid which destroys the lungs.

33yschow@smkbpj(a)

5. Carbon monoxide

a. Carbon monoxide is a toxic gas which is produced

when organic fuels are burnt.

b. Most of the carbon monoxide in the atmosphere comes from vehicles and factories which use charcoal, petrol and diesel as fuel.

c. Carbon monoxide combines with

haemoglobin inthe red blood cells

and prevents oxygen from

combining with haemoglobin.

d. Our cells become deprived of

oxygen and this results in death.34yschow@smkbpj(a)

6. Dust and dirt

a. Dust and dirt are released to the atmosphere

by factories and motor vehicles.

b. The presence of dust and dirt in our lungs

hinders the exchange of gases.hinders the exchange of gases.

35yschow@smkbpj(a)

C. Diseases of the Respiratory System1. Asthma

a. The primary cause of asthma is due to airborne irritants such as pollutants and dust.

b. It may also caused by genetic factors and food allergy .

c. Asthma is a condition in which

the tubes of the lungs become

inflamed.

d. This is because the air tubes are

narrower and partially blocked.

e. More and thicker mucus is

secreted into the tubes.

36yschow@smkbpj(a)

2. Influenza

a. This disease is caused

b. by viruses which attack

the mucus membranes

in the respiratory system.

b. The influenza virus spreads through

tiny droplets in the air.

Blocked noses, teary eyes, giddiness,

headaches, aches in the limbs,

coughs and fever are some of

the symptoms of the disease.

Sneeze

37yschow@smkbpj(a)

3. Pneumonia

a. Pneumonia is caused by bacteria, viruses and chemical substances in polluted air.

b. The trachea and alveolus are attacked by bacteria or viruses.

The lungs are filled with

pus and fluid and the

patient will suffer from

chest pains, fever and

coughs.

38yschow@smkbpj(a)

4. Tuberculosis (TB)

a. This disease is caused by bacterial infection (Mycobacterium tuberculosis) which are carried by water droplets and dust in the air.

b. Infection occurs when the water droplets and dust are inhaled by dust are inhaled by

other people.

c. The patient suffers

prolonged coughs and

spits out blood in the

end stages.

39yschow@smkbpj(a)

5. Bronchitis

a. Bronchitis is caused

by viral infections.

b. Bronchitis makes a

person cough and

produce

a lot of mucus.

c. The bronchus becomes swollen and the patient feels pain in the chest. feels pain in the chest.

d. Bronchitis causes colds and phlegm.

e. This disease makes respiration and gaseous exchange difficult. Patients who smoke find it hard to recover.

40yschow@smkbpj(a)

6. Emphysema

a. This disease is linked to

smokers and people who

work in dusty areas such

as in mines and quarries.

b. The alveoli expand and burst. b. The alveoli expand and burst.

c. The lungs become less elastic.

d. The thickened layer of scar prevents oxygen from diffusing into the blood. As a result the patient experiences breathing difficulties.

41yschow@smkbpj(a)

7. Lung cancer

a. Many cancer cases are a result of smoking cigarettes.

b. Air polluted with carcinogens from factories and vehicle emissions, dust and asbestos also cause cancer.

c. Lung cancer is difficult to cure.

d. It is important that we keep

away from these pollutants.

e. Lung cancer is not contagious

and cannot spread from a patient

to other people.

42yschow@smkbpj(a)

D. Improving Air Quality

1. Pollution is mainly caused by irresponsible human behaviour and improperly planned activities.

2. We must be responsible for preserving and 2. We must be responsible for preserving and conserving air quality.

3. Air pollution interferes with the respiratory process. It can cause respiratory diseases which can be fatal.

43yschow@smkbpj(a)

Chemicals found in cigarette

44yschow@smkbpj(a)

HOW CAN YOU IMPROVE AIR QUALITY?

45yschow@smkbpj(a)

Walk or cycle instead of using your car.

Use public transport

instead of taking the car

Service your vehicle regularly - this can reduce

pollution and make it cheaper to run.

46yschow@smkbpj(a)

Don’t SmokeStop open burning Opening up the windows to

allow indoor air circulation

Car pool

Bring In Some Nature47yschow@smkbpj(a)