Respiratory Flashcards
What are the four muscles of inspiration?
External Intercostals, Sternocleidomastoid, Serratus Anterior, Scalenus Muscles
What are the two muscles of Expiration?
Abdominal rectus, Internal Intercostals
What is the normal pressure of pleura at the beginning of inspiration?
Around -5cmH20
Inspiration causes more negative or positive pressure? And to what value?
More negative, -7.5 as chest cage pulls outwards on lungs.
Pressure when glottis is open/no air flowing?
0cmH20. Air pressure in aveoli are equal to atmospheric pressure.
Inward flow of air?
Pressure of alveoli vs outside?
Pressure of alveoli < atmohspheric pressure
~ -1cmH20
Outflow of air?
Pressure of alveoli vs outside?
Pressure of aveoli> atmospheric pressure.
~ 1cmH20
Forces about 0.5 liters of inspired air out of the lungs dring 2-3 seconds of expiration.
Transpulmonary Pressure
Difference between alveolar pressure and pleural pressure. A measure of elastic forces in lungs; recoil pressure. Pressure that keeps lungs inflated and prevents collapse.
Lung Compliance
Extend to which lungs will expand for each unit increase in transpulmonary pressure (Alveolar Pressure - Pleural Pressure); force that opposites the lung’s recoil (compliance wants to expand!).
Lung Compliance= Change in Volume/ Change in Pressure
In order for a lung to expand/be compliant, what has to be present?
Surface Tension (2/3 effect), Elasticity (1/3 effect) (recoil, elasin/collagen)
Which will have more compliance, air filled or saline filled lungs?
The lung with more surface tension. Example: saline filled lung (needs less pressure to change, so compliance is better), no surface tension. Only tissue elastic forces (recoil) present). So more transpleural pressure is neeed for air-filled lungs.
Total compliance of both lungs
200 mL
If the pressure inc by 1 cm, the lung volume inc to about 200 mL.
What has more compliance, expiration or inspiration?
Expiration
Surface Tension
An elastic force of lungs on the inner surfaces of alveoli, making them want to collapse/ pushes air out.
Surfactant
Greatly reduces alveolar surface tension and thus reduces effort required by respiratory muscle to expand lungs.
What is surfactant made from and out of?
Type 2 alveolar epithelial cells; a mix of dipalmitoyl-phosphtidylcholine, apoproteins, and Ca2+ ions.
Tidal Volume
Normal breath volume in/out
Inspiratory Reserve Volume
Volume of air that can be inspired over the normal tidal volume.
3L
Expiratory Reserve Volume
Max amout of air you can breathe out (after normal tidal expiration). 1.1L.
Residual Volume
Air remaining once youve maximally breathed out
Inspiratory Capacity
TV+ Inspiratory Reserve Volume
Vital Capacity
TV+ Expiratory Reserve Volume+ Inspiratory Reserve Volume
Functional Residual Capacity
Expiratory Reserve Volume + Residual Volume
Total Lung Capacity
Vital Capacity+ Residual Volume
Respiratory Distress Syndrome
Alveoli are not very big (smaller radius) so they have more tendency to collapse. Premature newborns at risk bc not high levels of surfactant yet.
What is dead space and it’s impact on alveolar ventilation?
Anatomical dead space is air inflow that’s not used in gas exchange; Physiological or functinoal dead space is from alveoli that are not functioning properly. If ventilation is impacted, o2 and co2 exchange is impacted.
Alveolar Ventilation Equation
VA= R(VT-VD)
Respiratory Rate per minute * (Tidal Volume - Physiologic Dead Space)
R is respiratory rate, VT is tidal volume, and VD is dead space volume.
When the pulmonary valve closes, how does the pressure in the pulmonary artery change compared to the right ventricle?
It drops.
Systolic pulmonary arterial pressure? Diastolic? Mean?
Systolic: 25 mmHg
Diastolic: 8 mmHg
Mean: 15 mmHg
Left atrial and pulmonary venous pressures
2-5 mmHg