Simplify the following text for a Grade 10 native English-speaking person.
Original: Henry John Heinz III ( October 23 , 1938 â `` April 4 , 1991 ) was an American politician from Pennsylvania , a Republican member of the United States House of Representatives ( 1971 â `` 1977 ) and the United States Senate ( 1977 â `` 1991 ) .
Simplified: Henry John Heinz III ( October 23 , 1938 â `` April 4 , 1991 ) was an American politician from Pennsylvania and the great-grandson of the founder of H. J. Heinz Company . He was a member of the United States House of Representatives from 1971 to 1977 and was a US senator from 1977-1991 .