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Respiration
Air
Ventilation
Gas exchange (alveoli)
Gas transport (blood)
Tissues
• Uptake O2
• Download CO2
for energy
Consumption of O2 and production of CO2
Determination by spirometry
Respiratory quotients for carbohydrates and fats
RQ =
CO2 produced
O2 consumed
200 ml / min
=
250 ml / min
Sugar + O2
= 0.8
CO2 + H2O
energy
Function of Upper Airways
• Warm
• Humidify
• Filter / clean
Air
/immune defense
• Maintain / provide airway
• Special functions: smell
taste
voice
Extensive vascular
mucous membrane
Pharnyx and Larnyx
1. Maintenance of airway
2. Pharnyx immune defense
Airway maintenance:
1. Intrinsic tone of pharngeal muscles, tongue
2. Relfexes:
swallowing reflex
cough reflex
Airway maintenance is compromised:
• muscle
floppy
• reflexes
1. Unconscious
face down and to side
gravity assists
2. Alcohol
3. Opiates, barbiturates, anaesthetic gases,
artificial airways
4. Sleep
From periphery
via R side of
heart
To periphery
via L side of
heart
Fig. shows envelopment of the alveoli by pulmonary capillaries.
Inspiration is active process: muscle contraction
Chest volume
Lung vol
Air pressure
Air in through mouth
and nose
Expiration (quiet) involves controlled muscle
relaxation
Chest volume
Lung vol
Air pressure
Air out through mouth
and nose
1 mmHg = 13.6 mm H2O
1 mmHg = 1.36 cm H2O
760 mmHg
Normal airflow achieved
Lungs
Mouth
• inspiration  1 mmHg
• 0 mmHg
• expiration + 1 mmHg
• Max inspir effort
 50 mmHg
• Max expir effort
+ 100 mmHg
Muscles of Respiration
Quiet breathing:
• Inspiration: diaphragm — phrenic N. C3,4,5
• Expiration: controlled relaxation, diaphragm
Heavy breathing:
• Accessory muscles
•Inspiration: external intercostals, neck muscles
•Expiration:
intercostals
abdominal
muscles,
internal
Summary
• Respiration
ventilation
perfusion
gas exchange
gas transport
cellular respiration
• CO2production,O2consumption–respir quotient
• Functions of upper airways
• Mechanism of inspiration & expiration
• Lung volumes