The Human Immune System

Components of the Immune System

White blood cells: These play a crucial role in the immune response, including neutrophils, lymphocytes and macrophages.
Antibodies: Proteins produced by the immune system to neutralise or destroy foreign substances or pathogens.
Lymphatic system: Composed of lymph nodes and lymph vessels that carry lymph, a clear fluid containing white blood cells.

Non-Specific Immune Responses

Physical barriers: Your skin and mucus membranes may stop pathogens from entering your body.
Inflammatory response: When cells are damaged, they release chemicals that cause blood vessels to leak fluid into the tissues, causing swelling.
Phagocytosis: This is a process where certain white blood cells engulf and destroy pathogens.

Specific Immune Responses

T cells: These cells recognise infected cells and coordinate the immune response.
B cells: These cells produce antibodies specific to the pathogen they encounter.
Memory cells: Created during an infection and remain in the body, ready to respond quickly if the same pathogen is encountered again.

Immune Responses to Viruses and Bacteria

Viral infections: T cells identify and destroy cells infected with the virus, while B cells produce antibodies to neutralise the virus.
Bacterial infections: Phagocytes engulf the bacteria while B cells produce antibodies to tag bacteria for destruction by other white blood cells.

Importance of Vaccination

Vaccines introduce a weakened or inactivated form of a pathogen to stimulate the immune system to produce an immune response.
The creation of memory cells means the immune system can respond faster and more effectively to any future invasion by the same pathogen.

Autoimmunity and Allergies

Autoimmune diseases: These occur when the immune system attacks the body’s own cells, mistaking them for foreign invaders.
Allergies: These are immune responses triggered by harmless substances, such as pollen or certain foods.

Understanding the human immune system and how it fights off diseases is key to understanding global health challenges, including the spread of diseases and the development of resistance to treatments. Vaccination plays a major role in combating these challenges, highlighting the importance of the immune response in global health efforts. These topics also touch on broader issues including autoimmunity, allergies, and the ethical implications of developing and distributing vaccines.