The Immune System - The Immune System and Phagocytosis (GCSE Biology)
The Immune System and Phagocytosis
The Immune System
- The immune system protects the body from pathogens. If a pathogen gets past the first line of defence (the non-specific defences), the immune system works to neutralise or destroy the pathogen, preventing or minimising infection.
- White blood cells are an important part of the immune system. White blood cells make up the immune system. There are two types of white blood cell that are important to us: lymphocytes and phagocytes.
- The immune system can also cause diseases. The immune system can target body cells and cause disease. For example, in Type 1 Diabetes, it can attack cells that produce insulin so insulin production is reduced and blood sugar levels aren’t controlled.
Types of Immunity
Active Immunity
- Active immunity is the body’s immune response against a pathogen through antibody production. The body must produce its own antibodies for it to be classed as active immunity.
- Active immunity can be gained after being infected by a pathogen or through vaccination. This is because both of these processes involve the body producing its own antibodies.
Passive Immunity
- Passive immunity is the body’s short term immune response against a pathogen through antibodies acquired from another person. The body doesn’t make its own antibodies but receives it from someone else. For example, a mother can pass on antibodies to her child during pregnancy and breastfeeding. This is important as the young child’s immune system may not be developed enough to produce its own antibodies so passive immunity protects them from infections.
- Memory cells are not made in passive immunity. Hence, there is no long term protection with passive immunity.
Phagocytosis
Phagocytes are non-specific white blood cells which engulf and digest pathogens.
- A phagocyte detects a pathogen. Phagocytes detect the presence of a pathogen.
- The phagocyte binds to the pathogen. The phagocyte is activated, and binds to the pathogen. The binding is non-specific.
- The phagocyte engulfs the pathogen. The membrane of the phagocyte engulfs the pathogen into the phagocyte cell, and encloses it into a vesicle called a phagosome.
- Lysosomes break down the pathogen. The phagosome vesicle then secretes digestive enzymes, called lysosomes, to break down the pathogen
- The debris is excreted. The phagocyte then excretes the digested pathogen and debris.
The immune system is a complex network of cells, tissues, and organs that work together to protect the body against harmful substances such as bacteria, viruses, and toxins. The immune system helps to identify and neutralize these substances, and also has the ability to remember previous encounters with specific substances, so that it can respond more quickly and effectively in the future.
Phagocytosis is a process where cells of the immune system, called phagocytes, engulf and destroy harmful substances, such as bacteria and viruses. Phagocytosis is an important component of the immune system, as it helps to eliminate harmful substances and prevent their spread.
Phagocytosis occurs in the body when a phagocyte encounters a harmful substance. The phagocyte will engulf the substance, forming a phagosome, which then fuses with a lysosome, containing enzymes that break down the harmful substance. This process effectively neutralizes the harmful substance and prevents it from causing harm to the body.
There are two main types of phagocytes involved in phagocytosis: neutrophils and macrophages. Neutrophils are the most abundant type of phagocyte and are responsible for eliminating bacteria and fungi.
Macrophages are a type of phagocyte that play a role in identifying and destroying foreign substances, as well as removing dead or damaged cells from the body.
The immune system recognizes harmful substances in the body through the use of specialized cells, such as T cells and B cells, which are capable of recognizing specific antigens, or foreign substances. When a harmful substance is encountered, the immune system activates a response that includes the production of specific antibodies that can neutralize the invader and prevent it from causing harm. The immune system also has the ability to remember previous encounters with specific antigens, allowing it to respond more quickly and effectively to subsequent exposures.
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