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�

Prepared  by  Ms  Sue  Soh  

1.1 : Human Breathing Mechanism Structure of the Human Respiratory System

Prepared  by  Ms  Sue  Soh  

1.1 : Human Breathing Mechanism 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

Prepared  by  Ms  Sue  Soh  

1.1 : Human Breathing Mechanism 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

Prepared  by  Ms  Sue  Soh  

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

1.1 : Human Breathing Mechanism Breathing and Respiration

v Normally we breathe from 15 – 20 times per minute

v Rate of breathing increases during active work / exercise

Prepared  by  Ms  Sue  Soh  

1.1 : Human Breathing Mechanism 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

Prepared  by  Ms  Sue  Soh  

1.1 : Human Breathing Mechanism The Breathing Mechanism

Inhalation : Ø External

intercostal muscles contract

Ø Ribs are raised & the chest moves forwards

Ø Diaphragm muscles contract, is lowered & flattened

Ø Thoracic cavity expands

Ø Air pressure in the thoracic cavity decreases

Ø Air is rushed into the lungs

Prepared  by  Ms  Sue  Soh  

1.1 : Human Breathing Mechanism The Breathing Mechanism

Exhalation : Ø External

intercostal muscles relax

Ø Ribs are lowered & the chest moves inwards

Ø Diaphragm muscles relax & curves upwards

Ø Thoracic cavity becomes smaller

Ø Air is forced out from the lungs. Prepared  by  Ms  Sue  Soh  

1.1 : Human Breathing Mechanism Model to show the

Action of the Diaphragm

Prepared  by  Ms  Sue  Soh  

1.1 : Human Breathing Mechanism Model to show the Action of the Diaphram

INHALATION Ø When the sheet of

rubber (diaphragm) is pulled down, the volume in the bell jar (thoracic cavity) increases

Ø Air pressure in the bell jar (thoracic cavity) decreases

Ø Air from outside rushes into the balloons (lungs) via the Y-tube (trachea & bronchi)

Ø Balloons expand as filled with fresh air

EXHALATION Ø When the sheet of

rubber (diaphragm) is pushed upwards, the volume in the bell jar (thoracic cavity) decreases

Ø Air pressure in the bell jar (thoracic cavity) & in the balloons (lungs) increases

Ø Air is forced out through the Y-tube (bronchi & trachea)

Prepared  by  Ms  Sue  Soh  

1.1 : Human Breathing Mechanism Building Lungs

Model : 1.  Scissors/Blade 2.  3 balloons

(preferably 1 big 2 small) or clear plastic bag

3.  3 rubber bands 4.  Duct tape 5.  Clear Plastic

bottle/ Clear Plastic Cup

6.  Straws (at least 2 pc) Prepared  by  Ms  Sue  Soh  

Prepared  by  Ms  Sue  Soh