Respiratory SystemRespiratory System

trachea

bronchus (bronchi)

bronchioles

Bronchioles Bronchioles & Alveoli& Alveoli

bronchiole

alveoli

Nasal CavityNasal Cavity• Nasal cavity possess hairs for

trapping large dirt particles

• wall of nasal cavity lined with ciliated

epithelium and mucus-secreting cells

to trap dirt and bacteria

• near surface are numerous blood vessels

so incoming air are warmed, moistened

& filtered before entering lungs

Pharynx & LarynxPharynx & Larynx

• pharynx belongs to both

respiratory & digestive system

• glottis is the opening of larynx and it is

covered by epiglottis during swallowing

• larynx consists cartilage at the

entrance of trachea

• within the cartilage

are two membranes,

vocal cords to

produce sound waves

Trachea (Windpipe) Trachea (Windpipe) and Bronchiand Bronchi

• trachea lies in front of oesophagus

and extended into thoracic cavity

• at the lower end of trachea is

divided into two bronchi which

subdivides into many bronchioles

• each bronchiole terminates in

hollow, lobed air sacs called alveoli

• inner lining of the trachea

produces mucus and possess cilia

• mucus are used to trap the dirt &

germ while cilia are used to waft the

mucus towards the throat, it is then

either coughed out or swallowed.

Those coughed out are called phlegm

• wall of trachea strengthened by C-

shaped cartilages to keep trachea

open

Alveoli AdaptationsAlveoli Adaptations

• thin wall ( only one-cell thick)

– short diffusion distance for gases

• folding shape and numerous alveoli

– large surface area for diffusion of

gases

• lots of capillaries present– maintain high concentration

gradient of gases

• moist surface

– to dissolve gases for diffusion

Structure of LungStructure of Lung• lungs are protected by the thoracic

basket which is made up of

vertebrae, ribs and sternum

• each lung is surrounded by two

pleural membranes

• the inner membrane is in contact with the

lungs and the outer membrane lines against

the walls of the thorax and diaphragm

• between the two membranes is

pleural cavity which contains a pleural

fluid secreted by the membranes

• pleural fluid

lubricates the pleura

so to reduce friction

as the pleural

membranes rub

against each other

during breathing

rib

pleural membran

es

alveoli

pleural fluid

Intercostal

muscles

bronchiole

larynx

trachea -

have ring of

cartilageleft lungleft

bronchusheart

diaphragm

Thoracic Basket Thoracic Basket (rib cage)(rib cage)

vertebraesternum

ribspleural cavity- absorb shock

2 pleural membranes

Gaseous Gaseous Exchange in Exchange in

AlveoliAlveoli

tissue

Lungs(alveoli)CO2 (by

plasma and in form of

HCO3- )

O2 + haemoglobin

atmosphere

CO2O2

oxyhaemoglobin

(by red blood cell)

Heart

Deoxygenated blood

Oxygenated blood

Oxygenated blood

Lung Pulmonary artery

Pulmonary vein

Tissue

Gaseous Gaseous Exchange in Exchange in

AlveoliAlveoli

air moves out during

expiration

air moves in during

inspiration

O2

CO2

cell in capillary wall

plasma

cell in alveolar

wallmucus

red blood cell

deoxygenated blood

from pulmonary

artery

oxygenated blood to

pulmonary vein

Mechanism of BreathingMechanism of Breathing

• brought about by the action of diaphragm & intercostal muscles

• divided into two processes : inhalation (inspiration) & exhalation (expiration)

Inspiration (Inhalation)Inspiration (Inhalation)Diaphragm muscle- contract

Intercostal muscle - contract

Diaphragm- flattened

ribs & sternum - move upward

& outward

thoracic cavity expands (volume

increases)

air pressure in lung is lower than atmospheric pressure so air rushes

in

lungs inflated (expand)

Inspiration Inspiration (Inhalation)(Inhalation)

Expiration (Exhalation)Expiration (Exhalation)

intercostal muscles relax

diaphragm muscles relax

diaphragm becomes dome-shaped

ribs and sternum move downwards & inwards

thoracic cavity volume decreases

air pressure inside lungs increases

air forces out

lungs deflated

Walking & RunningWalking & Running

time (seconds)

205 10 150

1000

2000

3000

lun

g v

olu

me (

cm

)

3

at rest

lun

g v

olu

me (

cm

)

time (seconds)

5 10 150

1000

2000

30003

20

during exercise

Calculations of the Rate Calculations of the Rate and Depth of Breathingand Depth of Breathing

• From the graphs the volume of

air he breathed in per minute

at rest and during exercise can

be measured :

Rate ofbreathing

(breaths permin)

Depth ofbreathing

(cm3)

Volume of airbreathed in perminute (cm3)

At rest 6 x 60/20 = 18 2500 – 2000 =500

18 x 500 =9000

Duringexercise 9 x 60/20 = 27 3500 – 1500 =

2000

27 x 2000 =

54000

• If the percentage by volume of oxygen in atmospheric air is 21% and that in exhaled air is 16%. Then the volume of oxygen retained in the body per

minute can then be calculated : At rest : 18 x 500 x (21-16)% = 450cm3

During exercise : 27 x 2000 x (21-16)%

=2700cm3

COCO22 remains Constant remains Constant during Exerciseduring Exercise

CO2 concentration in blood remains

CONSTANT

muscles release CO2

ventilation rate increases

+

The graph of Lung capacities

Tidal Volume Tidal Volume

– amount of air entering & leaving the

lungs during normal breathing

– during exercise → can increase

volume

– during exercise → cannot increase

the capacity

– increase only after prolong training

– maximum air exhaled after taking

the deepest inhalation

Vital CapacityVital Capacity

– volume of air remaining in the lungs

which cannot be expelled even after

forced exhalation

Residual VolumeResidual Volume

Smoking & HealthSmoking & Health

• Effects on health :

(I) Tar :

(i) carcinogenic ( producing cancer )

(II) Nicotine :

(i) cause heart diseases

carbon monoxide

• Composition of a cigarette :

= cigarette+ tar+ nicotine

Smokers’ lung

(ii) dependence

(iii) retards growth of foetus

(III) Carbon Monoxide :

(i) combines irreversibly with haemoglobin and

prevents it from carrying oxygen

+ COhaemoglobin

(ii) decrease in physical fitness

(iii) cause air pollution

carboxyhaemoglobin

Smoking and Health Hazards

1.Lung Cancer

Smoking increase the risk of lung cancer

2.Heart disease

Nicotine increases the workload of heart

increase the rate of heart attack

Smoking and Health Hazards

3.Chronic bronchitis Smoking causes inflammation of trachea and

bronchitis The severe chronic bronchitis can cause death

4.Emphysema Causes of "smoker's cough" Smoker cough causes damage of alveolar wall

in lungs

Passive SmokingPassive Smoking• process of breathing in smoke from

cigarette smokers

• causes nose, throat & eye irritations

Warning

DO NOT SMOKE !!!!!