Alveoli is not associated with portal system .
Hence , OPTION D is correct .
A) Liver : it comes under hepatic portal system .
B) Nephrons : it comes under renal portal system .
C) pituitary : it comes under Hypophyseal portal system .
Portal system :
it can be defined as major venous system which carries capillary blood from esophagus , stomach ,small and large intestine , pancreas , gallbladder and spleen to liver .
there are three types of portal system ; hepatic portal system , renal portal system , and hypophyseal portal system .
Hypophyseal portal system :
It is a system of blood vessels in the microcirculation which connects the hypothalamus with the anterior pituitary . it helps in the quick transport and exchange of hormones between hypothalamus and anterior pituitary.
Hence , OPTION D is correct .
Learn more about hepatic portal system here :
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