| Answer | Crossword Clue |
|---|---|
| NIN | "The Four-Chambered Heart" author |
| NIN | "The Four-Chambered Heart" novelist |
| diplocardiac | of birds and mammals, having a four-chambered heart, which enables two separate circulations and prevents mixing of the arterial and venous blood |
| VALVE | One of four in the human heart |
| ATRIA | Two of the four chambers of the heart |
| ATNO | 79, for the chem. symbol at the heart of the four longest puzzle answers |
