Week 3 - Breathing mechanics & physiology Flashcards
Muscles primarily involved in tidal inspiration and how do they affect the lungs?
Diaphragm and external intercostals
Contraction of the diaphragm increases the thoracic cavity’s volume, decreasing internal pressure and allowing air to flow into the lungs. The effect is general lung expansion but significantly impacts the lower parts due to diaphragmatic movement.
What is the attachments for the diaphragm and innvervated by?
Lower ribs, sternum and lumbar vertebrae through central tendon
Phrenic nerve C3-5
Forced inspiration muscles
Scalenes and sternocleidomastoid
Elevate ribs and sternum increasing thoracic volume
Pump / bucket handle
Attachments for scalenes and sterno and innervation
Scalenes - C3-7 to first two ribs
Sterno - mastoid process and super nuch. line to sternum and clavicle
Anterior rami of spinal nerves
Why is tidal expiration passive?
Due to the elastic recoil of the lungs and chest wall.
Boyle’s Law
States that the pressure of a gas in a closed container is inversely proportional to the volume of the container.
Boyle’s Law applied to breathing
As the thoracic cavity’s volume increases due to muscle contraction, pressure in lungs decrease compared to atmospheric pressure, causing air to flow in down the pressure gradient. During tidal expiration, recoil occurs, increasing pressure in lungs, which decreases volume by pushing out air.
Medulla and breathing
Controls the basic rhythm of respiration
Pons and breathing
Modulates the rate and depth of breathing
How does the body detect pH changes in the body?
Chemoreceptors in aortic arch and carotid arteries detect blood pH changes due to CO2 levels. Drop in CO2 lowers blood pH. They signal the cardiorespiratory centre (medulla and pons). Respond by adjusting rate and depth of breathing to rid the body of CO2 and get more O2 in.
