CHAPTER 1 : RESPIRATION 1.1:The Human Breathing Mechanism 1.2:Transport of Oxygen 1.3:Cell Respiration 1.4:Importance of a Healthy Respiratory System

Structure of the Human Respiratory System

Nose : Always moist with fine hairs to filter the air Trachea : Strong muscular tube; has rings of cartilage Bronchi : Each bronchus branches into bronchioles Bronchioles : Fine air tubes; Ends in cluster of air sacs (alveoli) Alveoli : Surrounded by blood capillaries

Structure of the Human Respiratory System Rib muscles : Called intercostal muscles – contract / relax and caused the ribs move upwards / downwards Causes thoracic cavity (chest cavity) to expand or contract allowing breathing in & out Ribs : Works together with breastbone (sternum) to protect the lungs Diaphragms : Large sheet of muscle that can contract and or relax

Breathing : Mechanical process which alternately draws & expels air into & out of the lungs Respiration : Chemical process that takes place in the cells of the body Aka internal or cell respiration Breathing and Respiration  Normally we breathe from 15 – 20 times per minute  Rate of breathing increases during active work / exercise

The Breathing Mechanism Inhalation : Breathing in air Exhalation : Breathing out air Pathway of inhalation : Nose – trachea – bronchi – bronchioles – alveoli Passing through the nose, the air is : filtered; Warmed to body temperature Moistened by mucus

The Breathing Mechanism Inhalation :  External intercostal muscles contract  Ribs are raised & the chest moves forwards  Diaphragm muscles contract, is lowered & flattened  Thoracic cavity expands  Air pressure in the thoracic cavity decreases  Air is rushed into the lungs

The Breathing Mechanism Exhalation :  External intercostal muscles relax  Ribs are lowered & the chest moves inwards  Diaphragm muscles relax & curves upwards  Thoracic cavity becomes smaller  Air is forced out from the lungs.

Model to show the Action of the Diaphragm

Model to show the Action of the Diaphram INHALATION  When the sheet of rubber (diaphragm) is pulled down, the volume in the bell jar (thoracic cavity) increases  Air pressure in the bell jar (thoracic cavity) decreases  Air from outside rushes into the balloons (lungs) via the Y-tube (trachea & bronchi)  Balloons expand as filled with fresh air EXHALATION  When the sheet of rubber (diaphragm) is pushed upwards, the volume in the bell jar (thoracic cavity) decreases  Air pressure in the bell jar (thoracic cavity) & in the balloons (lungs) increases  Air is forced out through the Y-tube (bronchi & trachea)