Final answer:
Negative marital relationships can have negative effects on physical health due to stress. Chronic stress from negative interactions can lead to the development and progression of physical illnesses and diseases.
Step-by-step explanation:
When marital relationships have negative effects on physical health, the physiological mechanism at work is stress. Stress from negative interactions in a relationship can have a toll both emotionally and physically. Research has shown that individuals who experience higher levels of negative interactions in their closest relationships are more likely to experience serious heart problems over time. The physiological response to chronic stress can lead to the development and progression of physical illnesses and diseases such as heart disease.