What is the main purpose of respiration?
To supply tissues with O2 and remove CO2 from the organism.
What are the four components of respiration?
Pulmonary ventilation, diffusion between alveoli and blood, transport in blood and fluids, and regulation of ventilation.
What is pulmonary ventilation?
The movement of air into and out of the lungs between atmosphere and alveoli.
What happens to the ribs during inspiration?
Inspiratory muscles elevate the ribs.
How does the diaphragm move during inspiration?
The diaphragm lowers during inspiration.
What effect does inspiration have on thoracic volume?
Thoracic volume increases during inspiration.
Which muscle contributes about 25% of lung volume change in quiet breathing?
External intercostal muscle contraction contributes about 25%.
Which muscle accounts for approximately 75% of air movement during quiet breathing?
Diaphragm contraction accounts for about 75%.
What muscles lower the ribs during active expiration?
Internal intercostals and transversus thoracis lower the ribs.
How do accessory expiratory muscles affect the diaphragm during active expiration?
They push the relaxed diaphragm upward into the thorax.
What is pleural pressure at rest?
Approximately -5 cmH₂O.
What is pleural pressure during inspiration?
Approximately -7.5 cmH₂O.
What is alveolar pressure without airflow?
0 cmH₂O.
How does alveolar pressure change during inspiration?
It falls to -1 cmH₂O.
How does alveolar pressure change during expiration?
+1 cmH₂O.
What is the formula for transpulmonary pressure?
.
What does lung compliance measure?
Increase in lung volume per unit increase in transpulmonary pressure.
What is the normal lung compliance value?
About 200 ml air per 1 cmH₂O increase.
What is a surfactant in alveoli?
A surface-active substance secreted by type II alveolar epithelial cells.
What are the main components of surfactant?
Phospholipids, proteins, and Ca++ ions.
What is the surface tension of alveolar fluid with surfactant?
Between 0.005 and 0.030 N/m.
What formula gives pressure from alveolar surface tension?
How does alveolar pressure change with radius?
Pressure increases as alveolar radius decreases.
What is the surface-tension pressure in a 100 µm alveolus with normal surfactant?
0.4 kPa
What is the surface-tension pressure in a 100 µm alveolus with pure water?
1.8 kPa
During normal breathing, which phase requires active work?
Inspiration requires active work.
What causes expiration during normal breathing?
Elastic forces of lungs and chest wall cause expiration.
Into which components is inspiratory work divided?
Work against elastic forces, tissue resistance, and airway resistance.
What percentage of total energy does pulmonary ventilation use during normal breathing?
3–5% of total energy expenditure.
By how much can the energy required for breathing increase during physical activity?
It can increase 50-fold.
What is spirometry?
The recording of air volume entering and leaving the lungs producing a spirogram.
What are the four pulmonary volumes?
Tidal volume, inspiratory reserve volume, expiratory reserve volume, and residual volume.
What is the tidal volume in milliliters?
500 ml
What is the inspiratory reserve volume in milliliters?
3000 ml
What is the expiratory reserve volume in milliliters?
1100 ml
What is the residual volume in milliliters?
1200 ml
What is the formula for inspiratory capacity (IC)?
What is the formula for total lung capacity (TLC)?
What is alveolar ventilation?
The amount of new air reaching gas-exchange areas per unit time.
What does anatomical dead space include?
Conducting airways without gas exchange.
What is the approximate volume of anatomical dead space?
About 150 ml.
What does physiological dead space include?
Anatomical dead space plus alveolar dead space from poorly perfused alveoli.
What forms alveolar dead space?
Alveoli with absent or insufficient perfusion.
What is the formula for minute alveolar ventilation?
Calculate minute alveolar ventilation with , ml, and ml.
4200 ml/min.
Where is cartilage present in the conducting airways?
From the trachea to the bronchi only.
Where is the main resistance to airflow located?
In the larger bronchi and bronchi near the trachea.
Approximately how many terminal bronchioles are there?
About 65,000 terminal bronchioles.
What effect does sympathetic stimulation have on the bronchi?
It dilates the bronchi via beta-adrenergic receptors.
What effect does parasympathetic vagal acetylcholine have on bronchioles?
It causes mild to moderate bronchiolar constriction.
Which substances released by mast cells constrict bronchioles during allergic reactions?
Histamine and the slow-reacting substance of anaphylaxis.
What is the function of mucus secreted by goblet cells and submucosal glands?
To trap particles in the airways.
How do cilia move mucus toward the pharynx?
By beating approximately 20 times per second.
Test your knowledge with 25 questions on Pulmonary Ventilation.
1. What is the primary purpose of respiration in the body?
2. Which sequence best represents the major processes included in respiration?
Review the complete course in the study sheet for Pulmonary Ventilation.
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