Lung Physiology 3 Flashcards
3 Requirements of Respiration?
1) Ensure Hb as close to full sat w/ O2 as possible
2) Efficient use of energy resources
3) Regulate PaCO2 carefully
Where is pneumotaxic area found and function?
1) Upper Pons
2) Switches off inspiratory neurones –> Expiration
Where is apneustic centre found and function?
1) Lower pons
2) Activate inspiratory neurones –> NO EXP
What else regulates basic breathing rhythm? (Both in M.O)
1) Dorsal Respiratory Group (Mainly I)
2) Ventral Respiratory Group (I&E)
Briefly describe inspiration.
Inspiration is an active process. The external intercostal muscles and diaphragm contract. The volume of the thoracic cavity increases and you get a negative intra-thoracic pressure; air is drawn in.
Briefly describe expiration.
Expiration is usually passive. The ribs move down and in, the diaphragm relaxes. The intra-thoracic volume decreases and the pressure increases. Air is forced out.
Where are central chemoreceptors found and stimulation?
1) Medulla Oblongata
2) ^ [H+] in ECF (60% inf from PaCO2)
Where are peripheral chemoreceptors found and stimulation?
1) Carotid and aortic bodies
2) Decrease in PaCO2
What is the general rule for Minute ventilation? (MV)
Proportional to PaCO2 and 1/PaO2
What are the 3 Lung receptors?
Stretch, J and Irritant
Where are J receptors found, activation and response?
1) In Juxtapulmonary capillary (J and Bronchial C fibres)
2) Activated by ^ IF volume
3) Rapid shallow breathing, BC and CV depression
Where are irritant receptors found and role?
1) Larger conducting airways
2) Rapid adaption e.g. cough or gasp
Where are SASR found, activation and response?
1) Smooth muscle around airways
2) Lung distension
3) Promote expiration, as inhibit insp.
Where are RASR found, activation and response?
1) Between airway epithelial cells
2) Lung distension and irritants
3) Bronchoconstriction
What receptors are found in nose, nasopharynx and larynx and role?
1) Chemo and Mechano
2) Sense and monitor flow
