On 10 October 1646, Ent married Sarah, the daughter of a former president of the Royal College, Dr. Othowell Meverell [Wikidata].

In 1665, his anatomy lectures at the Royal College of Physicians were observed by King Charles II, who knighted him in April of the same year.

Although born twenty-six years after him, Ent was a close friend of William Harvey, a man known best for his discovery of the circulation of blood.

Written in 1641, the Apologia pro circulatione sanguinis, Ent's most significant work on anatomy, defends the theories of William Harvey’s book de Motu Cordis (On the Circulation of the Blood), directly responding to the criticism of Emilius Parisianus.

This book is significant both on the merits of Ent's own anatomical theories and because it offered one of the first in-depth defenses of Harvey’s work.

In the Apologia, Ent elaborates on Harvey’s theories on circulation, suggesting that a “nutritive fluid” nourishes the body by passing through the nerves.

Ent draws on John Mayow’s theories on innate heat and respiration in his discussion of the nervous system.

The Sive animadversiones in Malachias Thrustoni contains Ent's analysis of Malachi Thruston’s theories on respiration.

The Grounds of Unity in Religion comments on the relationship of the English government and the Church of England, discussing the position of people of different faiths with the political and religious framework.