T̠H̠E̠ B̠A̠S̠I̠C̠S̠ O̠F̠ R̠E̠S̠P̠I̠R̠A̠T̠O̠R̠Y̠ P̠H̠Y̠S̠I̠O̠L̠O̠G̠Y̠ & A̠B̠G̠ A FEW POINTS

⚡️CO2  is the greatest in quantity important stimulus for respiration

Receptors against CO2  are found in the medulla of the brain (central chemoreceptors)

❤️Receptors ~ the sake of O2  are found mainly in carotid and aortic bodies 

CO2  is the greater degree of important gas as the body has again capacity to store CO2  than O2 or hydrogen ions 

1️⃣0️⃣In legitimate people at sea level, only 10% of the respiratory force is due to hypoxic stimulation. 

▶️◀️Unlike the central stimulation of hypercapnia, hypoxia causes central lowness of the respiratory drive. 

▶️◀️Acidosis (proud H + /low blood pH) stimulates breathing; conversely alkalosis depresses it.

For aeriform fluid exchange, the lungs provide an interface of amount surface area about 55 m2 by way of 700 million alveoli

Alveolar ventilation’ is that ~icipation of the total ventilation (i.e. quite gas entering the lungs) that participates in aeriform fluid exchange with pulmonary capillary blood; it is measure to total ventilation minus the examination of the conducting airways (i.e. dead-capacity ventilation).The average alveolar ventilation is here and there 4 L/min.

The alveolar–arterial oxygen gradient ( P(A-a)O2 ) is a mete out of the oxygen that has reached the arterial fiery fellow supply as a ratio of the whole oxygen in the alveoli. It is a advantageous index of pulmonary gas exchange function. 

➡️This requires that three elements are acting correctly: 

⏺Circulatory anatomy is legitimate. Anomalies such as ASD & PDA be possible to cause anatomical shunting,  i.e. netted blood passes through routes that are not exposed to alveolar air 

⏺Ventilation and perfusion are matched 

⏺The respiratory membrane allows adequate free diffusion of gases between tune and blood.  A diffusion deficiency impairs the alveolar–capillary membrane, e.g. in intermediate lung fibrosis

In a healthy individual respiration room air (at FiO2 21) the PO2  in alveolar gas is 104 mmHg and in arterial hotspur 95 mmHg . PAO2 exceeds PaO2 ~ dint of. 15 mmHg .Thus, at an FiO2 of 21, the P(A–a)O2 is 15 mmHg 

In progeny, CO2  is present as: 

✔️Dissolved in royal line plasma (5.3% in arterial progeny)

✔️Bound to haemoglobin while carbaminohaemoglobin within erythrocytes (4.5%) 

✔️In the mould of bicarbonate attached to a base (90%) As CO2 diffuses from peri

Reference:”Understanding ABGs & Lung Function Tests”  Muhunthan Thillai, Keith Hattotuwa

D levels in the midst of pregnant women may be important with a view to the optimal development of their infant.,” said lead researcher Andrew Whitehouse, each associate professor and reader in developmental psychopathology at the Telethon Institute because of Child Health Research at the University of Western Australia.

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