Final answer:
When a foot is punctured by a dirty splinter, the body undergoes physiological and molecular changes as a defense response.
Step-by-step explanation:
When you step on a dirty splinter, the physiological and molecular changes that occur in your foot are a response to the injury and potential infection. The body's defense mechanisms are activated, starting with inflammation. Inflammatory cells such as neutrophils and macrophages are recruited to the site of injury.
These cells release chemical signals that attract more immune cells and increase blood flow to the area. The damaged cells and microbes are killed by these immune cells and enzymes, preventing the spread of infection.