Life Sciences - Term 4 - 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 can be divided into two main categories: 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. White blood cells are further categorized into phagocytes, which engulf pathogens, and lymphocytes, which are crucial for adaptive immunity. Antibodies are proteins produced by B cells that specifically target antigens on pathogens.

Consider a scenario where a person is exposed to a virus. The innate immune response is activated first, with phagocytes like macrophages engulfing the virus. If the virus persists, the adaptive immune response kicks in, involving T cells that destroy infected cells and B cells that produce antibodies. This example illustrates how both arms of the immune system work together to eliminate pathogens.

In pairs, students will classify various immune responses as either innate or adaptive. For example, the action of macrophages is innate, while the production of antibodies by B cells is adaptive. Discuss the importance of each response and how they complement each other in protecting the body.

Students will choose a specific immune cell type (e.g., T cells, B cells, or macrophages) and research its function, development, and role in diseases. They will prepare a short presentation to share their findings with the class, highlighting how their chosen cell contributes to the immune response.

• Transport oxygen
• Fight infections
• Regulate body temperature
• Digest food

Answer: Fight infections

White blood cells are essential for the immune response, as they identify and eliminate pathogens.

• Adaptive immunity
• Innate immunity
• Passive immunity
• Acquired immunity

Answer: Innate immunity

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

Answer: B cells and T cells

B cells produce antibodies, while T cells help destroy infected cells or assist other immune cells.

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

Answer: They bind to antigens on pathogens.

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

Answer: To engulf and digest pathogens.

Macrophages are phagocytes that play a crucial role in the innate immune response by engulfing and destroying pathogens.

• Spleen
• Thymus
• Bone marrow
• Liver

Answer: Thymus

The thymus is where T cells mature and learn to distinguish between self and non-self.

• Innate immunity is specific; adaptive is not.
• Adaptive immunity is immediate; innate is delayed.