Cardio-Respiratory Week Five Flashcards
What are the characteristic of type one respiraoty failure?
PaCO2 is normal or low and PaO2 is low. Examples include pneumonia or pulmonary oedema.
What are the characteristic of type two respiraoty failure?
PaCO2 is elevated and PaO2 is low. Example is COPD.
Name examples of short beta-2 agonists
Salbutamol, terbutaline
Name examples of short anti-muscarinic drugs
Ipratropium
Name examples of long beta-2 agonists
Salmeterol, formoterol, indocaterol
Name examples of long anti-muscarinic drugs
Tiotropium, glycopyronium
What kind of drug i beclometasone dipropinate?
Corticosteroids
What is ventilation?
Amount of gas going into the alveoli
What is perfusion?
Amount of blood flow into the alveoli
Describe V and Q in zone one of the lung
There is decreased perfusion due to gravity which causes waster ventilation. There is larger alveoli caused by more negative intrapleural pressure.
Describe V and Q in zone three of the lung
There is continuous blood flow due to gravity and there are smaller alveoli.
Where is the control centre for respiration?
The medullary rhythmicity centre in the medulla
What is the role of the dorsal respiraoty group?
This has inspiratory neurons. This is mainly responsible for normal inspiration. It sends impulses to external costals and diaphragm to contract at regular intervals. When it stops, expiration will occur passively.
What is the role of the ventral respiraoty group?
This has inspiratory and expiratory neurons. This initiates normal inspiration and expiration when it is forced. This is mostly in forced breathing.
Describe the control of Quiet breathing
The activity in the DRG increases over a period for about 2 seconds and this stimulates inspiratory muslces. Over this period, inhalation occurs. After around 2 second, the DRG neurons become inactive. They remain quiet for the next 3 second to allow inspiratory muslces to relax. Passive exhalation will then occur.
Describe the control of Forced breathing
There is increased activity of the DRG and this stimulates neurons in the VRG. This activates the accessory muscles for inhalation. After each inhalation, active exhalation takes place as neurons of the expiratory centre stimulate appropriate accessory muslces.
What is the function of the Pneumotaxic centre?
Transmits inhibitory impulses to DRG that help turn off inspiratory neurons, limiting duration of inspiration
What is the function of the Apneustic centre?
This stimulates inspiratory neurons in the DRG and VRG. Over stimulation from the apneustic centre results in apneustic breathing which is characterized by long gasping inspiration interrupted by occasional expirations.
What is the function of peripheral chemoreceptors?
These are located in the aortic body and carotid body. They detect oxygen, carbon dioxide and pH.
A decrease in oxygen, decrease in pH or increase CO2 will cause more signals to be sent up to respiratory centre and caused an increase in respiraoty rate.
What can sometimes happen when PCO2 remain chronically elevated?
Chemoreceptors will adapt and reset their values. They will lose their sensitivity to CO2.
What is the function of central chemoreceptors?
These are located in the Ventrolateral surface of the medullar oblongata. They respond to pH and PCO2.
What gases can cross the blood-brain barrier and what is the significance of this?
Carbon dioxide can. It will react and from hydrogen ions and bicarbonate. There will be a decrease in pH and this will cause more inhalation.
What is the function of mechanoreceptors?
Smooth muscle of trachea, bronchi and bronchioles have stretch recepotrs on them. When the lung is inflated, they send signals via the Vagus nerve to limit inflation. The Vagus nerve sends signals to the apneustic centre and this becomes inhibited. As exhalation begins, the signals are stopped and hence inspiration will begin again.
What is the Hering-Breuer reflex?
Shortens exhalation when lung is deflated.