State the different modes of $CO_2$ transport in blood.

(N/A) Carbon dioxide $(CO_2)$ is transported in the blood in three main forms:
$1$. As dissolved gas in plasma: About $7\%$ of $CO_2$ is carried in a dissolved state through the blood plasma.
$2$. As bicarbonate ions $(HCO_3^-)$: Approximately $70\%$ of $CO_2$ is transported as bicarbonate ions. Inside the red blood cells,$CO_2$ reacts with water to form carbonic acid $(H_2CO_3)$,which then dissociates into hydrogen ions $(H^+)$ and bicarbonate ions $(HCO_3^-)$.
$3$. As carbaminohemoglobin: About $20-25\%$ of $CO_2$ binds with the amino group of hemoglobin to form carbaminohemoglobin. This binding is reversible and depends on the partial pressure of $CO_2$ $(pCO_2)$.