Life Sciences - Term 3 - Week 5

The human immune system is a complex network of cells, tissues, and organs that work together to defend the body against harmful invaders, such as bacteria, viruses, and parasites. It is divided into two main types: innate immunity, which provides immediate but non-specific defense, and adaptive immunity, which develops a targeted response to specific pathogens.

Key components of the immune system include white blood cells (leukocytes), antibodies, the lymphatic system, and various organs such as the spleen and thymus. Leukocytes are further categorized into phagocytes, which engulf pathogens, and lymphocytes, which are involved in the adaptive immune response. Antibodies are proteins produced by B cells that specifically target antigens on pathogens.

Consider a scenario where a person is exposed to a common cold virus. The innate immune response is activated first, with phagocytes attacking the virus immediately. If the virus persists, the adaptive immune system kicks in, producing specific antibodies against the virus. This example illustrates how both systems work together to eliminate pathogens.

In this activity, students will be given images of various immune cells, such as neutrophils, macrophages, and T cells. They will work in pairs to identify each cell type and discuss its function in the immune response. This collaborative effort will help reinforce their understanding of the different roles played by immune cells.

Students will choose a specific pathogen (e.g., HIV, influenza, or tuberculosis) and research how the immune system responds to it. They will prepare a short presentation that includes the pathogen's characteristics, the immune response it triggers, and any vaccines or treatments available. This assignment will encourage independent learning and application of knowledge.

• To digest food
• To protect the body from pathogens
• To circulate blood
• To regulate body temperature

Answer: To protect the body from pathogens

The immune system's main role is to defend against harmful invaders that can cause disease.

• Adaptive immunity
• Innate immunity
• Cell-mediated immunity
• Humoral immunity

Answer: Innate immunity

Innate immunity is the body's first line of defense and is present from birth, providing immediate but non-specific protection.

Answer: Neutrophils and lymphocytes

Neutrophils are phagocytes that engulf pathogens, while lymphocytes include B cells and T cells that are crucial for adaptive immunity.

• They destroy pathogens directly.
• They signal other immune cells to act.
• They bind to specific antigens on pathogens.
• They produce energy for immune cells.

Answer: They bind to specific antigens on pathogens.

Antibodies are proteins that specifically recognize and bind to antigens, marking pathogens for destruction.

• Spleen
• Thymus
• Bone marrow
• Liver

Answer: Thymus

The thymus is where T cells mature and differentiate before they enter the bloodstream to perform their immune functions.

Answer: Active immunity is developed through exposure to pathogens or vaccination, while passive immunity is acquired through the transfer of antibodies from another source.

Active immunity involves the body's own immune response, while passive immunity provides immediate protection without the body having to produce its own antibodies.