[Biology Class Notes] on Difference Between Active and Passive Immunity Pdf

Immunity refers to a body’s ability to destroy foreign elements and pathogens in order to prevent infection. As a result, barriers such as skin, mucus, layers, and saliva serve as the human body’s first line of defence against viruses. In addition, we call this innate immunity. The second line of defence is phagocytes, which are produced only by innate immunity. After that, the third line of defence is adaptive immunity. 

Adaptive immunity is divided into two types: active and passive immunity. To comprehend it better, it’s crucial to understand the distinction between active and passive immunity. As a result, you’ll discover that antibodies produced outside the body and introduced into the body acquire passive immunity. Active immunity, on the other hand, arises when antibodies are created in the body.

What Does the Immune System do?

It works to prevent or restrict infection; when our immune system recognises pathogens, it responds to the situation. When the immune response is not stimulated, illnesses and diseases might arise. When such an immune system is awakened outside of an obvious threat or is not shut down after a threat has passed, problems such as allergic reactions and autoimmune diseases arise.

Active Immunity

The term “active immunity” refers to a person’s body’s immediate response to infections. When it is subjected to a foreign antigen, namely the antigen contained in bacteria, it is also triggered. It also refers to a person’s adaptive response in response to exposure to a certain illness or antigen. Furthermore, immunity does not develop immediately after a person is exposed to a disease. As a result, following the initial exposure, it might take days or weeks for it to appear. The protection it gives, however, can last a lifetime once it develops. Furthermore, it might arise spontaneously or as a result of immunisation. T cells, B cells, and antigen-presenting cells make up active immunity. It also includes antibody synthesis triggered by infection or an immunogen. It also leads to the creation of long-term memory cells.

Furthermore, the protection it provides is long-lasting. The protective response takes longer to build because of the lag period. Finally, a recurrence of infection or revaccination can reawaken it.

Passive Immunity

Passive immunity is immunity conferred by an individual through the transmission of serum or lymphocytes. They also catch it from a highly vaccinated person. It’s also a great approach to provide resistance without needing to await for an active immune response to emerge. Furthermore, passive immunity does not require prior exposure to the disease agent. It also works immediately and without delay. Furthermore, it is just temporary. To put it another way, it could only last a few months. In passive immunity, the antibody is created without the intervention of immune cells. Furthermore, there is no antibody development because it transmits directly. In addition, memory immune cells do not develop.

Furthermore, there is no other option available here. It must be re-administered on a routine basis to provide sustained protection. In circumstances of immunological deficiency, immunodeficiency, or severe combined immunodeficiency, it’s then beneficial.

Difference Between Active and Passive Immunity

Examples of Active Immunity

In active immunity, there are two types of immunity: natural and artificial. It creates antibodies in the natural world in response to harmful infections like measles. Furthermore, antibodies are produced artificially when they are produced in response to controlled exposure to an attenuated pathogen, which is vaccination.

Because the virus induces the immune system to develop antibodies that specifically recognise and kill the pathogen the next time it is encountered, an individual who recovers from a first episode of measles is resistant to further infection by the measles-causing virus.

Examples of Passive Immunity

Mothers and their children are one of the most common examples of passive immunity. Passive immunity is provided to babies by their mothers before they are born and for a length of time afterward. The maternal antibodies found in their mother’s placenta and breastmilk help them stay healthy. ‌

Pregnant women use their placentas and blood circulation to provide nutrition and protection for their newborns. Maternal antibodies and other immune defences pass through the bloodstream to the unborn kid. Although the infant is usually immune to bacteria and sickness before delivery, it becomes vulnerable to them once it leaves its mother’s body.

Some Interesting Facts of the Immune System

Understanding the basic structure of an immune system, it consists of three layers of defense to protect from infection

1. Barrier Immunity: Eg: Skin is a physical barrier as well as chemical and biological barrier as it produces antimicrobial proteins; Surface lining of the respiratory system has cilia for preventing pathogens an
   d building up of microorganisms; Stomach release strong acids with low pH and kills microorganisms that we accidentally ingest while eating; tears also is an example of barrier immunity as it protects our eyes from dust and pathogens.

2. Innate Immunity: When a microorganism is successful in crossing barrier immunity, innate immunity is activated. Innate immunity is non-specific and is present before birth. Neutrophils, mast cells, basophils, dendritic cells, eosinophils, natural killer cells, monocytes, and macrophages are different innate cells.

 

Acquired or Adaptive Immunity

It is the third line of defense and is produced in exposure to foreign substances. It is a specific immune system that consists of highly specialized systemic cells and processes that eliminate pathogens and prevent its growth. It adapts to the type of threat that we are exposed to; it produces lymphocytes and antibodies during second exposure which are specific to pathogens when exposed to the first exposure. It is slower in the process but more potent than innate immunity.

Immunological memory of the first encounter is produced while second exposure, thus lymphocytes, and antibodies are present to eliminate pathogens. SImilarly for subsequent exposures.

B lymphocytes and T lymphocytes are two kinds of lymphocytes.

1. Humoral immunity due to B-lymphocytes

2. Cellular immunity due to the T-lymphocytes

In Humoral immunity, B lymphocytes produce Antibodies that capture antigens present on the surface of bacteria or pathogens. Antigen-specific antibodies are produced on the second exposure.

T-lymphocytes consist of two major cells known as helper T cells that are known as CD4 cytotoxic and killer t cells known as CD8 cells.