Mechanism of Respiration involves breathing mechanism and exchange of gases (Oxygen and Carbon Dioxide). Breathing mechanism will be continued with Inspiration (Inhalation) and Expiration (Exhalation) .

1. REPRESENTED BY WASIM AKRAM
BSC NURSING
ADWIKA INSTITUTE OF NURSING
MECHANISM OF
RESPIRATION

2. CONTENTS
• INTRODUCTION
• DEFINITION
• MECHANISM OF RESPIRATION
• MECHANISM OF BREATHING
• EXCHANGE OF GASES
• PRESSURE DIFFERENCES

3. INTRODUCTION
RESPIRATION IS THE MOVEMENT OF OXYGEN FROM
THE OUTSIDE ENVIRONMENT TO THE CELLS WITHIN
TISSUES , AND THE REMOVAL OF CARBON DIOXIDE IN
THE OPPOSITE DIRECTION THAT’S TO THE
ENVIRONMENT . THE MECHANISM OF RESPIRATION
INVOLVES BREATHING MECHANISM AND EXCHANGE
OF GASES .

4. RESPIRATION
• RESPIRATION IS DEFINED AS THE PROCESS OF
INHALING OF OXYGEN AND EXHALING OF CARBON
DIOXIDE BY THE LUNGS .
• THE PROCESS BY WHICH CELL USE OXYGEN TO BREAK
DOWN SUGAR AND OBTAIN ENERGY .
• THE NORMAL RESPIRATORY RATE IS 16 – 24
BREATHS/MIN .

5. MECHANISM OF RESPIRATION
THE MECHANISM OF RESPIRATION INVOLVES TWO PROCESS :
A. BREATHING
MECHANISM
B. EXCHANGE
OF GASES

6. A. BREATHING MECHANISM
• THE AIR WHICH WE BREATHE IN AND OUT OF THE LUNGS VARIES IN
ITS PRESSURE .
• SO BASICALLY WHEN THERE IS A FALL IN AIR PRESSURE THE
ALVEOLAR SPACES FALLS & THE AIR ENTERS THE LUNGS (
INSPIRATION ) AND AS THE PRESSURE OF THE ALVEOLAR WITHIN
EXCEEDS THE ATMOSPHERIC PRESSURE, THE AIR IS BLOWN FROM THE
LUNGS ( EXPIRATION ) .
• THE FLOW RATE OF AIR IS IN PROPORTION TO THE MAGNITUDE OF
THE PRESSURE DIFFERENCE .
• THE BREATHING MECHANISM INVOLVES TWO PROCESSES :
1. INSPIRATION

7. 1.MECHANISM OF INSPIRATION
• THE PROCESS OF INTAKE OF ATMOSPHERIC AIR IS KNOWN AS
INSPIRATION . IT IS AN ACTIVE PROCESS .
• WHEN THE VOLUME OF THE THORACIC CAVITY INCREASES AND THE AIR
PRESSURE DECREASES , INSPIRATION TAKES PLACE .
• CONTRACTION OF EXTERNAL INTERCOSTAL MUSCLES INCREASES THE
VOLUME OF THE THORACIC CAVITY .
• CONTRACTION OF THE DIAPHRAGM FURTHER INCREASES THE SIZE OF
THE THORACIC CAVITY . SIMULTANEOUSLY, THE LUNGS EXPAND .
• WITH THE EXPANSION OF THE LUNGS , THE AIR PRESSURE INSIDE THE
LUNGS DECREASES .
• THE PRESSURE EQUALIZES AND THE ATMOSPHERIC AIR RUSHES INSIDE
THE LUNGS.

8. 2. MECHANISM OF EXPIRATION
• THE EXPIRATION PROCESS IS CONSIDERED ONCE AFTER THE GASEOUS
EXCHANGE OCCURS IN THE LUNGS AND THE AIR IS EXPELLED OUT .
• THE PROCESS OF EXHALING CARBON DIOXIDE IS CALLED EXPIRATION . IT IS A
PASSIVE PROCESS .
• IT OCCURS WHEN THE SIZE OF THE THORACIC CAVITY DECREASES AND THE AIR
PRESSURE INCREASES .
• NOW THE EXTERNAL INTERCOSTAL MUSCLES RELAXED AND THE INTERNAL
INTERCOSTAL MUSCLES CONTRACTS .
• AS A RESULT, THE RIBS ARE PULLED INWARDS AND THE SIZE OF THE THORACIC
CAVITY REDUCED .
• THE DIAPHRAGM IS RELAXED AND THE LUNGS GET COMPRESSED .
• CONSEQUENTLY , THE PRESSURE INCREASES AND THE AIR IS FORCED OUTSIDE .

9. B. EXCHANGE OF GASES
THE EXCHANGE OF GASES TAKES PLACE IN THE ALVEOLI IN THE
FOLLOWING MANNER :
• TRANSPORT OF OXYGEN :
• OXYGEN IN THE BLOOD IS CARRIED TO THE TISSUES IN TWO FORMS
–
1. OXYHEMOGLOBIN IN RBC (97%) - CHEMICAL COMPOSITION OF
OXYGEN & HEMOGLOBIN .
2. SOLUTION OF OXYGEN IN THE BLOOD PLASMA (3%) .
• THE OXYGEN IN THE BLOOD COMBINES WITH HEMOGLOBIN WHEN
CONCENTRATION OF OXYGEN IS HIGH IN THE BLOOD .
• OXYHEMOGLOBIN , BEING UNSTABLE , DISSOCIATES TO RELEASE
OXYGEN . LOW OXYGEN, LOW PH AND HIGH TEMPERATURES
STIMULATE THE DISSOCIATION PROCESS .

10. EXCHANGE OF GASES
• INTERNAL RESPIRATION :
• THE GASEOUS EXCHANGE TAKING PLACE
IN THE TISSUES IS CALLED INTERNAL
RESPIRATION .
• HERE , THE OXYGEN IS CARRIED IN THE
FORM OF OXYHEMOGLOBIN GETS
DISSOCIATED TO RELEASE OXYGEN .
• THIS OXYGEN HELPS IN BREAK DOWN OF
GLUCOSE TO RELEASE CARBON DIOXIDE
, WATER AND ENERGY .
• THE ENERGY IS UTILIZED BY THE BODY ,
WHILE THE CARBON DIOXIDE IS
DIFFUSED OUT FROM THE TISSUES AND
MIXED WITH BLOOD .

11. EXCHANGE OF GASES
• TRANSPORT OF CARBON DIOXIDE :
• CARBON DIOXIDE IS TRANSPORTED FROM TISSUES TO THE LUNGS BY
THREE MECHANISMS :
1. SOME CARBON DIOXIDE DISSOLVED IN WATER OF THE BLOOD PLASMA TO
FORM CARBONIC ACID . => 7% .
2. CARBONIC ACID IONIZES TO FORM BICARBONATE IONS . THE HYDROGEN IONS
ARE CATALYZED BY THE ENZYME CARBONIC ANHYDRASE . BICARBONATE
IONS COMBINE WITH SODIUM AND POTASSIUM TO FORM SODIUM
BICARBONATE AND POTASSIUM BICARBONATE . => 70% .
3. SOME CARBON DIOXIDE COMBINES WITH HEMOGLOBIN FOR THE FORMATION
OF CARBAMINOHAEMOGLOBIN . => 20 – 25% .
• THESE THREE FORMS ARE FINALLY CARRIED TO THE LUNGS ( ALVEOLI –
SITE OF GASEOUS EXCHANGE ) AND RELEASED OUT OF THE BODY
THROUGH EXPIRATION .

12. -: PRESSURE DIFFERENCES :-
• ATMOSPHERIC –
• PARTIAL PRESSURE OF OXYGEN : 159
MM-HG
• PARTIAL PRESSURE OF CARBON DIOXIDE
: 0.3 MM-HG
• ALVEOLI –
• PARTIAL PRESSURE OF OXYGEN : 104
MM-HG
• PARTIAL PRESSURE OF CARBON DIOXIDE
: 40 MM-HG
• OXYGENATED BLOOD –
• PARTIAL PRESSURE OF OXYGEN : 95 MM
–HG
• PARTIAL PRESSURE OF CARBON DIOXIDE
: 40 MM-HG
• TISSUE –
• PARTIAL PRESSURE OF OXYGEN : 40 MM-HG
• PARTIAL PRESSURE OF CARBON DIOXIDE : 45
MM-HG
• DEOXYGENATED BLOOD –
• PARTIAL PRESSURE OF OXYGEN : 40 MM-HG
• PARTIAL PRESSURE OF CARBON DIOXIDE : 45
MM-HG

13. CONCLUSION
RESPIRATION IS THE PROCESS OF BREATHING AND EXCHANGE
OF GASES (OXYGEN AND CARBON DIOXIDE ) . THE BREATHING
MECHANISM INVOLVES INSPIRATION ( TAKING OXYGEN INSIDE THE
LUNGS ) AND EXPIRATION ( REMOVING CARBON DIOXIDE FROM
THE LUNGS TO THE ENVIRONMENT ) . THE GASEOUS EXCHANGE
TAKES PLACE IN THE ALVEOLAR WALL . IN THE ALVEOLAR
SURROUNDING CAPILLARIES , THE OXYGENATION OF BLOOD (
PURIFICATION OF BLOOD ) TAKES PLACE .