Dear student,
during jaundice, level of bilirubin rises in the body. Bilirubin is an end product of haem catabolism which under normal condition get converted as water soluble substance in liver and get excreted through faeces and some through kidney in urine. In jaundice, breakdown of red blood cells increases which obstruct the capability of liver to metabolize bilirubin and thus bilirubin remain in blood stream and results in yellowing of skin.
Regards