Response:

When a student scrapes his knee while climbing a tree, the body system that responds by transporting white blood cells to the wound is the circulatory system.

Circulatory System:
The circulatory system is responsible for the transportation of blood and nutrients throughout the body. It consists of the heart, blood vessels, and blood. The main function of the circulatory system is to deliver oxygen, nutrients, hormones, and immune cells to various parts of the body while removing waste products.

Response to Injury:
When an injury occurs, such as a scraped knee, the body's immune system responds to protect against infection and aid in the healing process. White blood cells, also known as leukocytes, are a vital component of the immune system and play a crucial role in fighting off harmful bacteria and viruses.

Process:
When the skin is scraped, it breaks the barrier and exposes the underlying tissues to potential pathogens. The damaged blood vessels in the area release chemicals that trigger a response from the immune system. The white blood cells are then mobilized and transported to the site of injury through the circulatory system.

Transportation of White Blood Cells:
The circulatory system carries white blood cells to the wound site using the blood vessels. The blood vessels expand in the injured area, allowing more blood flow to the site. This increased blood flow brings more white blood cells to the wound, helping to fight off any potential infection.

Role of White Blood Cells:
White blood cells have various types, including neutrophils, lymphocytes, monocytes, eosinophils, and basophils. Each type of white blood cell has a specific function in the immune response. Neutrophils are the first responders and are responsible for engulfing and destroying bacteria. Lymphocytes produce antibodies and help coordinate the immune response. Monocytes transform into macrophages, which also engulf and destroy bacteria. Together, these white blood cells work to protect the body from infection and aid in the healing process.

Conclusion:
In summary, when a student scrapes his knee while climbing a tree, the circulatory system responds by transporting white blood cells to the wound. This immune response is crucial for protecting against infection and promoting healing.