2. Human Breathing Mechanisms  Breathing – gas exchange in lungs. Involves taking in and letting out air.

3. Human Breathing Mechanisms (cont’d)

5.  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)

6.  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.

7. 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

8. Human Breathing Mechanisms (cont’d)  Alveolus Large surface area for gas exchanges Thin walls for gas diffusion Moist inner surface A lot of blood cappilary to transport gases

9. Human Breathing Mechanisms (cont’d)  Breathing consists or two phases – inhalation and exhalation.

10. Human Breathing Mechanisms (cont’d) InhalationExhalation Contracts Flattens DiaphragmRelaxes Curves upwards Moves upwards and outwards Rib cageMoves downwards and inwards IncreaseVolumes of thoracic cavity Decrease Air pressureIncrease Air is pushed into the lungs Air movementsAir is pushed out of the lungs

11. Human Breathing Mechanisms (cont’d)  During inhalation Air movement : nostril → nasal cavity → trachea → bronchus → bronchiole → alveolus  During exhalation Air movement : alveolus → bronchiole → bronchus → trachea → nasal cavity → nostril

12. Human Breathing Mechanisms (cont’d)  Composition of air in respiration ContentInhaled airExhaled air Oxygen21%16% Carbon dioxide0.03%4% Nitrogen78% Water vapourlesssaturated Temperatureless34°C

13. The Importance of a Healthy Respiratory System Harmful substances and its effects on the respiratory system SubtancesEffects 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

14. The Importance of a Healthy Respiratory System (cont’d) Disease of the respiratory system Disease AsthmaNarrowing of the fine airways (bronchus and bronchioles) BronchitisInflammation of the lining of the bronchioles Lung cancerTumors inside the lungs 90% of lung cancer patients – heavy smoker EmphysemaThe broken down of alveoli structure Reduce the oxygen intake Heart diseaseCan cause heart attack and pressure