Respiratory Physiology I Flashcards
What does the conducting zone of the respiratory system do to the air being breathed in?
Passes air to the site of gas exchange
Filters, humidifies, and warms the air
What does the respiratory zone do?
It is the site of gas exchange
What is the respiratory zone composed of?
Respiratory bronchioles
Alveolar ducts
Alveolar sacs
Why are alveoli so small and numerous?
To great a huge surface area for gas exchange.
What happens in the resiratory zone?
An “Air-blood barrier” creates a membrane for gas exchange through which oxygen diffuses from air into alveolus to blood in capillary.
Carbon dioxide diffuses from the blood in capillary to air in the alveolus
What percentage of alveolar surface is covered in capillaries?
80%
What percentage of cardiac output reaches the capillaries in alveoli?
100%
What lies between capillaries and alveoli?
Basal lamina which fuses them together
What pleurae cover the lungs?
Visceral and parietal pleurae.
What do pleurae do?
Reduce friction
Create suction
Compartmentalization (prevent infection)
How do pleurae reduce friction ?
They form a fluid rich layer over the lungs which allows them to slide on each other.
How do pleurae help with ventilation air intake?
They create a chamber for expansion of chamber
How do pleurae prevent infection?
They compartmentalize the lungs into separate chambers to prevent spread of infection
What does Boyle’s law state?
Gas pressure in closed container is inversely proportional to volume of the container.
Gas will flow from regions of high pressure to regions of low pressure.
There, to get air into alveoli their pressure must be lower than atmospheric pressure.
This is accompanied by increased chest volume.
What muscles are involved in quiet breathing inspiration?
Diaphragm only, intercostals are also active in inspiration
How does expiration occur?
It is mostly passive relying on the recoil of thoracic muscles
What muscles are incorporated in forced breathing inspiration?
Diaphragm, pectoral muscles, scalene, and sternocleidomastoid muscles.
What muscles are incorporated into forced expiration?
Internal intercostals, transverse thoracic muscles, rectus abdominus, external oblique transversus abdominus
Pelvic floor muscles must be active too to equalize pressure
How is pressure chainging in our alveoli?
Intrapleural pressure. When breathing in the lungs are being sucked out into the chest cage by the change in pressure. The pleura counter that by expanding all the way to the cage before the stage where the lung collapses in on itself.
Where must pressure always be maintained at negative pressure?
Transairway pressure and Intrapleural pressure
What pressure difference is maintained between the alveoli and the atmosphere?
About 4 - 5 mmHg
How does air flow into lungs?
Contraction of diaphragm causes pressure in ribcage to drop.
Dropping pressure in ribcage causes intraplueral pressur to drop
Dropping pressure in the intrapleural space moves the pleura away from the alveoli towards the ribcage thus causing the alveoli to expand and drop in pressure.
Low pressure in alveoli sucks air in
What does spirometry measure?
Volume of air entering and leaving the lungs during inspiration and expiration.
Forced expiration doesn’t bring lung volume to 0. What is the remaining volume of air called?
Residual Volume
