Week 3: Mechanics of Respiration Flashcards
In what type of breathing is inspiration active?
Both quiet and deep
In what type of breathing is expiration passive?
Quiet
In what type of breathing is Expiration active?
Deep
When do the diaphragm and intercostal muscles contract?
Inspiration
When do the diaphragm and intercostal muscles relax
Expiration
How does thoracic cavity expand?
The intercostals pull against the rib expanding the cavity into three planes
What are the three planes the thoracic cavity is expanded into?
Anterior, lateral, inferior
What are the accessory muscles in laboured breathing?
- sternocleidomastoid
- scalene
- pectorals
In laboured breathing what type of process is expiration?
Active
Pressure and Size of a container are what to each other, if the temperature stays the same?
Directly proportional
As thoracic cavity increases, what happens to the pressure?
Pressure decreases
As thoracic cavity decreases, what happens to pressure?
Pressure increases
How much % of inspired air contains oxygen?
21%
How much of expired air contains nitrogen and rare gases?
78%
Which gas will have the same %, inspired and expired?
Nitrogen
How is partial pressure calculated?
The total partial pressure of a mixture is calculated by the sum of all the pressures (P’s)
What is the pressure of a specific gas in a mixture of gases called?
Partial Pressure (P)
What Law is linked to pressure?
Daltons Law
What is atmospheric air pressure at sea level?
760mmHg
How is alveolar air different to atmospheric air?
It has more CO2 and less O2 and it has water saturation
Where do the alveoli allow efficient gas exchange between?
Between the air and the bloodstream
What is the partial pressure of O2 in alveolar air?
104mmHg
What is the partial pressure of CO2 in alveolar air?
40mmHg
By what process does the exchange of gases occour when a difference in partial pressure exists across a semi-permeable membrane?
Diffusion
What is external respiration?
The exchange of gases between the alveoli and the blood
What is internal respiration?
The exchange of gases between the blood capillaries and the body cells
How is 98.5% of oxygen transported?
Carried in a chemical combination with haemoglobin , called oxyhemoglobin
How is 70% of CO2 transported?
In the form of bicarbonate ions (H2CO3)
What are the two areas of the PONS called?
Apneaustic and pneumotaxic
What does the apneustic centre do?
sends impulses from neurones to excite inspiratory area of medualla, prolonging inspiration, by flattening diaphragm and external intercostal muscles contracting
What does the Pneumatic centre do?
Sends inhibitory impulses to the medulla to stop inspiration and initiate expiration
What makes up the respiratory centre?
Medulla and the PONS
What are located in the medulla?
Inspiratory and expiratory neurones in the action of breathing in and out/transition between the two
What do chemoreceptors do?
Respond to changes in PO2 and PCO2 in the blood and cerebrospinal fluid
Where are the central chemoreceptors located?
Surface of the medulla oblongata
What do central chemoreceptors respond to?
Rises in arterial PCO2, to then stimulate the respiratory centre to increase the rate and depth of respirations
Where are peripheral chemoreceptors located?
Located in the arch of the aorta and carotid bodies
What are peripheral chemoreceptors more sensitive to?
Smalle rises in PCO2 than reductions in PO2, so sends nerve impulses from peripheral chemorectpros to repiratory centres
Where are stretch receptors located?
They are situated in the thoracic walls
What do stretch receptors do?
Stop over-inflation of the lungs by sending inhibitory impulses from the vagus nerve to the respiratory centre
What reflex stops over inflation?
Hering-Breuer Reflex
