Gas exchange

----------------Gas Exchange---------------

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definition......................................................................................................................

It is the diffusion of oxygen and carbon dioxide between the inside of the body and the external environment. Gas exchange takes place in accordance with the differential pressure of the partial (molecular) gases - always from HIGH to LOWER partial pressures.

TYPES OF GAS EXCHANGE GAS...................................................................................

EXTERNAL

>> it takes place in the lungs between the alveoli and blood >> it takes place according to the partial pressure difference of oxygen and carbon dioxide - it is passive transport >> thanks to the single-layer squamous epithelium that covers the alveoli, diffusion (passive transport) is very easy Carbon dioxide is transported from BLOOD TO ALVEOLI Oxygen is transported from ALVEOLI TO BLOOD

INTERNAL

• occurs in the tissues between cells and blood

• occurs according to the difference in partial pressures of oxygen and carbon dioxide - it is passive transport

Oxygen is transported from BLOOD TO CELLS

Carbon dioxide is transported from CELLS TO BLOOD

TRANSPORT OF OXYGEN.........................................................................................

The transport of respiratory gases in the body takes place with the participation of erythrocytes and blood plasma. The erythrocytes contain the HEMOGLOBIN protein whose main function is oxygen transport.

Oxygen which is not bound to hemoglobin dissolves in plasma.

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OTHER HEMOGLOBIN COMPOUNDS...................................................................

OXYhemoglobin - hemoglobin + oxygen

CARBOXYhemoglobin -> hemoglobin + carbon monoxide (II). It has 250/300 times greater affinity for hemoglobin than oxygen. By connecting it to hemoglobin, it leads to hypoxia in the body. Therefore, carbon monoxide poisoning can be fatal for humans.

CARBAMINOhemoglobin - hemoglobin + carbon dioxide

CARBON DIOXIDE TRANSPORT.................................................................................... The diffusion direction of carbon dioxide is opposite to that of oxygen. Carbon dioxide in the blood can be transported in a form: -> physically dissolved in plasma and in combination with plasma proteins - 10% -> related to hemoglobin - 20% -> HCO3- bicarbonate ions - 70%