CHAPTER 1 : RESPIRATION1.1 : The Human Breathing

Mechanism1.2 : Transport of Oxygen1.3 : Cell Respiration1.4 : Importance of a

Healthy

RespiratorySystem

1.1 : Human Breathing MechanismStructure of the Human Respiratory System

1.1 : Human Breathing MechanismStructure 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

1.1 : Human Breathing MechanismStructure 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

1.1 : Human Breathing MechanismBreathing and Respiration

Normally we breathe from 15 – 20 times per minute

Rate of breathing increases during active work / exercise

1.1 : Human Breathing MechanismThe Breathing Mechanism

Inhalation :• Breathing in airExhalation : • Breathing out airPathway of inhalation :• Nose – trachea –

bronchi – bronchioles – alveoli

Passing through the nose, the air is :• filtered;• Warmed to body

temperature• Moistened by mucus

1.1 : Human Breathing MechanismThe 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

1.1 : Human Breathing MechanismThe 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.

1.1 : Human Breathing Mechanism

Model to show the

Action of the Diaphragm

1.1 : Human Breathing MechanismModel 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

EXHALATIONWhen 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)