Human Breathing Mechanisms Breathing – gas exchange in lungs.

Involves taking in and letting out air.

Human Breathing Mechanisms (cont’d)

Human Breathing Mechanisms (cont’d)

Human Breathing Mechanisms (cont’d)

Air enters the respiratory system through the nasal cavity.Dust is trapped by the hairs.Air is warmed and moistened.

Then, air enters trachea.Wall of trachea is supported

by C-shaped rings of cartilage

The trachea branches into two bronchi. (singular:bronchus)

Each bronchus branches into smaller tubes called bronchioles.

The bronchioles end in millions of tiny air sacs called alveoli. (singular:alveolus)

The lungs are made up of alveoli, bronchioles and blood cappilaries.

Human Breathing Mechanisms (cont’d) The lungs:

are located in a space called the thoracic cavity.

protected by the rib cage which consists of ribs and intercostal muscles.

Diagraphm – sheet of muscle that separates the thoracic cavity from the abdomen

Human Breathing Mechanisms (cont’d)

AlveolusLarge surface area for

gas exchangesThin walls for gas

diffusionMoist inner surfaceA lot of blood cappilary to

transport gases

Human Breathing Mechanisms (cont’d)

Breathing consists or two phases – inhalation and exhalation.

Human Breathing Mechanisms (cont’d)

Inhalation Exhalation

•Contracts•Flattens

Diaphragm •Relaxes•Curves upwards

Moves upwards and outwards

Rib cage Moves downwards and inwards

Increase Volumes of thoracic cavity

Decrease

Decrease Air pressure Increase

Air is pushed into the lungs

Air movements Air is pushed out of the lungs

Human Breathing Mechanisms (cont’d)

During inhalationAir movement : nostril → nasal cavity →

trachea → bronchus → bronchiole → alveolus

During exhalationAir movement : alveolus → bronchiole →

bronchus → trachea → nasal cavity → nostril

Human Breathing Mechanisms (cont’d)

Composition of air in respiration

Content Inhaled air Exhaled air

Oxygen 21% 16%

Carbon dioxide 0.03% 4%

Nitrogen 78% 78%

Water vapour less saturated

Temperature less 34°C

The Importance of a Healthy Respiratory SystemHarmful substances and its effects on the respiratory

system

Subtances Effects

Nicotine Cause rapid heartbeat, increase blood pressure

Cause emphysema, heart disease, stroke

Tar Carcinogenic (cause cancer)

Sulphur Dioxide Irritation of the respiratory system Damage to the lungs

Carbon monoxide

Dizzines, headaches, fatigue, death Suffocation

The Importance of a Healthy Respiratory System (cont’d)Disease of the respiratory system

Disease

Asthma •Narrowing of the fine airways (bronchus and bronchioles)

Bronchitis •Inflammation of the lining of the bronchioles

Lung cancer •Tumors inside the lungs•90% of lung cancer patients – heavy smoker

Emphysema •The broken down of alveoli structure•Reduce the oxygen intake

Heart disease •Can cause heart attack and pressure