Life Sciences - Term 2 - Week 3

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, 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.

Innate immunity is the body's first line of defense and includes physical barriers like skin and mucous membranes, as well as immune cells that respond quickly to infections. In contrast, adaptive immunity involves a slower response that is specific to the pathogen encountered. For example, when a virus infects the body, B cells produce antibodies that specifically target that virus, providing long-term immunity.

In pairs, students will be given images of different types of immune cells, such as neutrophils, macrophages, and T cells. They will discuss the function of each cell type and how they contribute to the immune response. After the discussion, each pair will present their findings to the class, highlighting the role of each cell in fighting infections.

Students will choose a vaccine (e.g., measles, influenza, COVID-19) and research its development, how it works to stimulate the immune response, and its importance in public health. They will prepare a short presentation to share their findings with the class, focusing on how vaccines enhance adaptive immunity.

• To digest food
• To protect the body from pathogens
• To regulate body temperature
• To produce hormones

Answer: To protect the body from pathogens

The immune system's main role is to defend against harmful invaders like bacteria and viruses.

• Adaptive immunity
• Innate immunity
• Specific immunity
• Cell-mediated immunity

Answer: Innate immunity

Innate immunity is the body's first line of defense and is present from birth.

Answer: Neutrophils and lymphocytes

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

• To destroy pathogens directly
• To signal other immune cells
• To neutralize toxins
• To mark pathogens for destruction

Answer: To mark pathogens for destruction

Antibodies bind to specific antigens on pathogens, marking them for destruction by other immune cells.

• Spleen
• Thymus
• Bone marrow
• Liver

Answer: Thymus

The thymus is where T cells mature and become capable of responding to specific pathogens.

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 provides long-term protection, whereas passive immunity offers immediate but temporary protection.