Respiration Physiology Part 2 Flashcards
What drives the ventilation cycle?
Movement of the thoracic wall by skeletal muscles.
What is pulmonary ventilation?
the
exchange of air
between the
atmosphere and the
lungs.
What are the main phases of pulmonary ventilation?
Inspiration and Expiration.
What is primary force?
Respiratory movement
What muscles are inspiratory muscles?
diaphragm
external intercostal muscle
What muscles are Expiratory muscles?
internal intercostal muscle
abdominal muscle
What muscles are Auxiliary inspiratory muscles?
• scalenes, sternocleidomastoid
What is Inspiration subdivided into?
Normal quiet breathing
Thoracic breathing:
What is the difference between normal quiet breathing and thoracic breathing ?
Normal quiet breathing (abdominal breathing ): movement of diaphragm
• Thoracic breathing: movement of external intercostal muscles
Describe the process of Inspiration
Contraction of the diaphragm lengthens the chest cavity, pulls down the lungs
• Causes the lung volume to increase
• Causes the decrease of intrapulmonary pressure
Flow of air into the lungs
Always an active process
Describe the process of expiration
Expiration is mainly caused by
• elastic recoil of the diaphragm
• relaxation of the external intercostal muscles
• relax diaphragm up and move ribs together
• Typically a passive process
What is forced breathing also known as?
Deep breathing
What inspiratory muscles can also help to expand the thoracic cavity?
sternocleidomastoid muscles
• pectoralis minor muscles
• what Other expiratory muscles can help with forced expiration?
Abdominal recti
> Internal intercostals
What is intrapulmonary pressure?
The pressure of air inside the lung alveoli
Air travels from?
regions of high air pressure to regions of low air pressure
When does air enter the lungs in terms of pressure?
When alveolar pressure (Pₐₗᵥ) is less than atmospheric pressure (Pₐₜₘ).
When does air exit the lungs in terms of pressure?
When alveolar pressure (Pₐₗᵥ) is greater than atmospheric pressure (Pₐₜₘ).
What is the formula for airflow (F)?
F = (Pₐₗᵥ - Pₐₜₘ) / R (resistance).
What causes airflow in the lungs?
The difference between intrapulmonary pressure and atmospheric pressure.
What is the difference between intrapulmonary pressure and atmospheric pressure called?
Direct Force
What causes changes in alveolar pressure?
Changes in the dimensions of the chest wall and lungs.
What is intrapleural pressure?
A: The pressure within the pleural cavity, which is always slightly negative than atmospheric pressure (around -5 mmHg or -5 to -7.5 cmH₂O). It is always negative.
Define transpulmonary pressure (Ptp).
Ptp=alveolar pressure (P alv)- intrapleural pressure (Pip)
What is the function of the ranspulmonary pressure (Ptp)?
holds the lungs open.
What happens during inspiration?
Diaphragm and intercostal muscles contract
• Thoracic cavity volume increases
• Intrapleural pressure becomes more negative
• Lungs expand
• Intrapulmonary pressure becomes negative
• Air flows into the lungs
What happens during expiration?
A:
• Muscles relax
• Thoracic volume decreases
• Intrapleural pressure becomes less negative
• Lungs recoil
• Intrapulmonary pressure rises above atmospheric pressure
• Air flows out of the lungs
What is the pressure difference across the chest wall?
P(atm) - P(ip) = 5 mmHg; this balances the chest wall’s tendency to move outward.
What is pleural pressure equal to?
Interpleural pressure, which is alveolar pressure minus elastic recoil pressure.
What is the diagnosis of a 14-year-old boy, tall and thin, chest tightness after 1000 meters?
Pneumothorax
What is pneumothorax?
Air escapes from the lungs or leaks through the chest wall into the pleural cavity, causing lung collapse.
What is the role of pleural pressure?
• Keeps the lungs inflated
• Promotes the return of venous blood and lymph
What are the key forces in pulmonary ventilation?
• Primary force: Respiratory muscle movement
• Direct force: Pressure differences
