2. Functions of lungs
Stages of respiration:
1.Pulmonary ventilation
2. Gases exchange in lungs
3. Transport of gases by blood
4. Gases exchange in tissues
5. Intracellular breathing
3. Respiration
Pulmonary ventilation. Factors, necessary
for it:
1. Hermeticity of the thorax and changing of its
volume due to respiratory muscles;
2. Negative intrapleural pressure;
3. Elasticity of the lungs;
4. Free connection of the air with the alveoli
4.
5. Respiratory muscles
Muscles of inspiration:
Diaphragm. (C3-C5); external intercostal
muscles and internal intercartilaginous
muscles.
Accessory inspiratory muscles are used during
exersises.
Muscles of expiration: Passive expiration due to
relaxation of inspiratory muscles and elasticity
of lungs and chest (in rest).
Internal intercostal muscles, abdominal muscles
10. Elasticity of lungs. Surfactant
Elastic tension of lungs:
1. Surface tension of liquid molecules inside of
alveoli (70%)
2. Elastic fibres of alveoli tension (30%)
3. Tone of small bronchi and bronchioles
Sufractant reduces surface tension. Includes
lipids and proteins (dipalmityl phosphatidyl
choline).
Functions of surfactant.
Control of surfactant synthesys.
11. Functions of surfactant.
Control of surfactant synthesys
It provides stable shape of alveoli.
Defense function. Cleaning of lungs.
Newproduced surfactant increases O2
diffusion.
Stimulate: parasympathetic n.s., deep
inspiration, food, including plant oils.
Inhibits: sympathetic n.s., stress, nicotine,
acetone, washing powders (detergents).
12. Biomechanic of inspiration and
expiration
ET + IPP = IAP (during pause)
ET + IPP < IAP (during inspiration)
ET + IPP > IAP (during expiration)
Donders’ model
Passive role of lungs in pulmonary ventilation
15. Lung volumes
Tidal volume (TV) 0,5 l; quite breathing
Inspiratory reserve volume (IRV) 2,5-3 l max.
vol., can be inspired after quite inspiration
Expiratory reserve volume (ERV) 1-1,5 l max.
vol., can be expired after quite expiration
Vital capacity of lungs (VCL) 3,5-5 l for men
and 3-4 l for women; VCLm=height (cm)x25
VCL = TV+IRV+ERV; VCLw=height (cm)x20
Residul volume (RV) can not be expired (1 l)
Total capacity of lungs VCL+RV
16. Dynamic indexes of pulmonary
ventilation
Minute pulmonary ventilation
(MPV) = TV*breath. rate/min; 0,5*16=8 l/min
Minute Alveolar ventilation (MAV)
MAV= (TV-DS) *breath.rate/min
Dead space air conduct ways (150ml)
Coefficient of pulmonary ventilation:
CPV = (TV-DS):FRC; FRC=RV+ERV
CPV= (500-150):2500= 1/7 or 14% part of air