Mechanisms of breathing* Flashcards
What does the pons do?
2 centers in the pons send stimuli to the medulla to regulate the rate and depth of breathing.
What does the pneumotaxic centre do?
It increases the rate by shortening inspirations.
What does the apneustic centre do?
Aphneustic centre increases the depth and reduces the rate by prolonging inspirations.
What is the hering-bruer reflex?
A reflex is triggered to prevent over inflation. Stretch receptors in airway smooth muscle respond to excessive stretching of the lung during large inspiration. It sends signals back to the medulla to limit inspiration and prevent over inflation.
Explain quiet inspiration.
It involves the primary muscles of inspiration (the diaphragm and external intercostals).
It will then increase thoracic and lung volume.
Explain forced inspiration.
Primary and secondary muscles of inspiration are used (scalenes, sternocleidomastoids, neck and back muscles and upper respiratory tract muscles).
Explain what quiet expiration is?
It is a passive process using elastic recoil. There are no primary muscles of expiration.
Relaxation of external intercostal muscles, recoil of the lungs and the diaphragm relaxes.
What muscles are involved in forced expiration?
Accessory, internal intercostals, abdominal and neck/back muscles.
What does the pleura do?
The pleural cavity filled with secretions and prevents the lungs from sticking to the chest wall.
It enables free expansion and collapse of the lungs.
Explain surface tension.
Due to the differences in the forces on water molecules at the air/water surface tension will develop.
In a gas bubble, there is a balance between the pressure exerted by the gas and the surface tension at the gas/water border.
In the lungs, air sacs of different volumes. The pressure in the larger sacs is lower than in smaller sacs. Air flow from smaller alveoli to larger leading to their collapse.
What is anatomical dead space?
the volume of conducting airways, the volume of air in the parts of the respiratory tract responsible for conducting air to the alveoli and respiratory bronchioles but do not take part in the process of gas exchange itself.
What is Physiological dead space?
Volume of lungs not participating in gas exchange.
