2 Breathing Mechanics Flashcards
What does Boyle’s law dictate?
Pressure exerted by gas is inversely proportional to its volume. ( P proportional to 1/V)
What is dalton’s law?
Total pressure of a gas mixture is the sum of the pressures of all individual gases (duh)
What is charles’ law?
Volume of a gas is proportional to temperature.
V proportional T
What is Henry’s law?
Amount of gas dissolved in a liquid depends on its solubility & pressure
What parts make up the upper respiratory system?
Mouth
Nasal Cavity
Pharynx
Larynx
What parts make up the lower respiratory tract?
Trachea
Bronhi
Lungs
What binds the lower respiratory system?
Ribs
Spine
Diaphragm
What is differnet about the external anatomy of the lungs?
The right lung has 3 lobes whereas the left only has 2
What are the lobes of the lung called?
Superior and inferior
The right lung also has a middle lobe
What encloses each lung?
Two pleural membranes seperated by a thin space of pleural fluid
What is the pericardial cavity?
The space around the heart
What is the inner pleural membrane called
The one around the lung (inner) is the visceral pleura
What is the outer pleural membrane called?
The one coating the inner rib surface (outer) is the Parietal pleura
What is inflammation of the pleura called?
Pleurisy
What do pleura do?
effectively stick the lungs to the ribs. This way the elastic recoil of the chess wall keeps the lung stretched open.
What is pneumothorax?
When air gets into the pleural cavity causing the lung to detach from the ribs and collapse
What muscles are involved in inspiration?
External intercostal muscles
diaphragm
Sternocleidomastoids
Scalenes
What muscles are involved in expiration?
Its passive at rest
But under heavy respiratory load the internal intercostal muscles & abdominal muscles are used.
What are the scalenes?
3 pairs of muscles in the lateral neck connecting the transverse processes of cervical vertebrae to the first 2 ribs
How does air enter the lungs?
- Muscles cause lung to expand increasing volume.
- Due to boyle’s law the pressure decreases.
- Air moves from higher pressure outside to lower pressure in lung
What abnormal action occurs during asthma?
Over-constriction of the bronchial smooth muscle
How does asthma cause breathing problems?
The over-constricted smooth muscle decreases the airway diameter
Thus the air flow resistance increases
Expiration becomes difficult
What are the 3 relevant pressures in breathing?
Intra-thoracic pressure (Alveolar) (Pa)
Intra-pleural pressure (Pip)
Transpulmonary pressure (Pt)
What is intra-thoracic (alveolar) pressure?
Pa:
Pressure inside the thoracic cavity (lungs).
-ve or +ve compared to atmospheric pressure
What is intra-pleural pressure?
Pip:
Pressure inside pleural cavity.
Always -ve
What is transpulmonary pressure?
Pt:
alveolar pressure - intra-pleural pressure.
Always +ve because Pip is always -ve.
Is Alveolar pressure +ve or -ve?
Either as compared to atmospheric pressure
Is intra-pleural pressure -ve or +ve?
Always -ve
How is transpulmonary pressure determined?
Pt = Pa - Pip
What is the measurment of pressure?
mm Hg
‘millimetres of mercury’
How does alveolar pressure change?
During inspiration it decreases then returns to normal
During expiration it increases then returns to normal
How does intrapleural pressure change?
It decreases during inspiration
Returns to normal during expiration
What effects bulk flow of air between atmosphere & alveoli?
Proportional to differnce between atmospheric & alveolar pressure.
Inversely proportional to airway resistance.
Equation for bulk flow of air?
F = (Patm - Pa)/R
When does Patm = Pa?
Between breaths at the end of unforced expiration
What factor determines how much air flows into the lungs?
- Airway resistance
- Pressure difference between atmosphere & alveoli
