RESPIRATION Human Breathing Mechanisms Breathing gas exchange in

RESPIRATION

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) � Alveolus �Large surface area for gas exchanges �Thin walls for gas diffusion �Moist inner surface �A 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 • Contracts • Flattens Exhalation Diaphragm • Relaxes • Curves upwards Moves upwards and Rib cage outwards Moves downwards and inwards Increase Volumes of thoracic cavity 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 inhalation �Air movement : nostril → nasal cavity → trachea → bronchus → bronchiole → alveolus � During exhalation �Air 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% Water vapour less saturated Temperature less 34°C

The Importance of a Healthy Respiratory System Harmful substances and its effects on the respiratory system Subtances Effects Nicotine Cause rapid heartbeat, increase blood pressure Cause emphysema, heart disease, stroke Carcinogenic (cause cancer) Tar 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