Mechanics of Breathing, Pressures and Work Flashcards
What does ventilation mean?
- movement of air in and out of the lungs
What does respiration mean?
- gas exchange - respiratory and circulatory systems working together
What is external respiration?
- gas exchange outside of the lungs - mouth for example
What is cellular respiration?
- gas exchange at a cellular level - capillaries for example
What is lung compliance?
- the ability of the lungs to stretch - aim is to increase lung volume
What is elastic recoil?
- the resistance of the lungs to stretch - aim to passively force air out of lungs
Are the lungs more elastic of compliant?
- roughly equal
What is the formula for compliance?
- 🔼 volume / 🔼 pressure
What is the relationship between compliance and volume and pressure?
- direct relationship between volume + compression - indirect relationship between pressure + compression
What is the formula for elasticity?
- 🔼 pressure / 🔼 volume
What is the relationship between elasticity and volume and pressure?
- direct relationship between pressure + elasticity - indirect relationship between volume + elasticity
What is pulmonary fibrosis?
- parenchymal tissue replaced by stiff fibrous tissue
What does pulmonary fibrosis do to compliance and elasticity?
- ⬇️ in compliance - ⬆️ in elasticity - difficult to get air in so restrictive disease
What may neuronmuscular disorders do to the respiratory tract?
- lack of innervation to diaphragm and/or intercostal muscles - ⬇️ in compliance - ⬆️ in elasticity
Cystic fibrosis and bronchitis causes a build up in mucus in the lungs making it difficult to get air out of the lungs, meaning they are obstructive diseases, what do these conditions do to compliance and elasticity of the lungs?
- ⬆️ in compliance - ⬇️ in elasticity - air can enter but not leave
In children born prematurely, a lack of surfactant secretion in the lungs can cause the lungs to collapse, this is called infant respiratory syndrome. What does this do to compliance and elasticity of the lungs?
- ⬇️ in compliance - ⬆️ in elasticity - difficult to get air in
What is transpulmonary pressure?
- difference in pressure between alveoli and intrapleural pressure in the pleural cavity
What is transthoracic pressure?
- difference in pressure between the intrapleural pressure in the pleural cavity and the pressure at the body surface
What does transthoracic pressure represent in breathing?
- total pressure required to expand or contract the lungs and chest wall
What happens to the diaphragm during inspiration and exhalation?
- inspiration = diaphragm flattens ⬆️ volume in lungs - expiration = diaphragm curves ⬇️ volume in lungs
What happens to the abdominal muscles during inspiration and exhalation?
- inspiration = relax ⬆️ volume in lungs - expiration = contract ⬇️ volume in lungs
What are the main muscles involves in inspiration?
- diaphragm (75% change in the volume) - external intercostals (bucket handle) - accessory muscles (forced inspiration)
What are the 2 main accessory muscle used during forced inspiration?
- sternomastoid - scalenus
Where are the sternomastoid muscles used during forced inspiration?
- insert at the mastoid of cranium (near ear)
- origin at munubrium of sternum and medial clavicle
Where are the scalenus muscles used during forced inspiration?
- scalenus = greek for ladder
- 3 muscles (anterior, medial, posterior)
- attach at C4-C6 and ribs 1 and 2
What does Boyles law say in relation to pressure and volume?
- if pressure ⬆️ then volume ⬇️
- if volume ⬆️ then pressure ⬇️
What is intrapulmonary pressure?
- the pressure within the pleural cavity - essentially the lungs
What is intrapleural pressure?
- the pressure within the pleural space - between visceral and parietal pleura
What is atmospheric measure?
- pressure at sea level
As we inhale and increase the volume in the lungs, what happens to the intrapleural pressure?
- volume in lungs ⬆️
- intrapleural pressure ⬇️
- Boyles law = ⬆️ volume = ⬇️ pressure
What is the calculation for transpulmonary pressure?
- intrapulmonary pressure (in lungs)
- intrapleural pressure (in pleural space)
- 760mmHg - 756mmHg = 4mmHg during normal breathing
What is the calculation for transthoracic pressure?
- intrapleural pressure (pleural space) - atmospheric pressure
- 756mmHg - 760mmHg = -4mmHg during normal breathing