Which of the following statements best describes the primary function of the immune system?
A The immune system is responsible for regulating body temperature and blood pressure.
B The immune system is involved in digestion and absorption of nutrients from food.
C The immune system is responsible for recognizing and defending against foreign invaders, such as pathogens and toxins.
D The immune system is involved in producing hormones that control various bodily functions.
The Correct answer and Explanation is:
The correct answer is:
C. The immune system is responsible for recognizing and defending against foreign invaders, such as pathogens and toxins.
Explanation:
The primary function of the immune system is to protect the body from harmful substances, including pathogens (bacteria, viruses, fungi, and parasites), toxins, and other foreign invaders. This complex system of organs, cells, and proteins works together to detect and eliminate these threats, maintaining the body’s health and preventing disease.
Components of the Immune System
- White Blood Cells (Leukocytes): These are the primary cells involved in immune responses. They include various types such as neutrophils, lymphocytes (T-cells and B-cells), monocytes, and eosinophils, each playing distinct roles in identifying and destroying pathogens.
- Lymphatic System: This includes lymph nodes, spleen, and thymus. The lymph nodes filter lymph fluid, trapping pathogens and cancer cells. The spleen filters blood, removing old or damaged cells and pathogens. The thymus is where T-cells mature and learn to distinguish between the body’s own cells and foreign cells.
- Antibodies: Produced by B-cells, antibodies are proteins that specifically recognize and bind to antigens (foreign molecules) on pathogens, marking them for destruction or neutralization.
- Complement System: This is a group of proteins that work with antibodies to help destroy pathogens. They can directly kill bacteria or facilitate their removal by immune cells.
- Cytokines: These are signaling molecules that help regulate the intensity and duration of immune responses. They coordinate the activities of various immune cells and communicate between cells.
Immune Response Mechanism
When a pathogen enters the body, the immune system detects it through specialized receptors on immune cells. Once detected, the immune response is triggered. This includes the activation of innate immunity (immediate, non-specific defense mechanisms) and adaptive immunity (a more specific response involving memory cells). The innate immune system responds quickly but non-specifically, while the adaptive immune system provides a targeted response and creates memory cells for quicker responses to future infections by the same pathogen.
Overall, the immune system’s role is critical for maintaining health by identifying and eliminating threats before they can cause significant harm, thereby preventing infections and diseases.