In this Article you will find, Introduction to basic concepts in immunology, components of immune system, principles of innate and adaptive immune system
Table of Contents
Immunology
Immunology is the study of the immune system and is the very important branch of the medical and biological sciences. The immune system protects us from infection through various lines of defence. If the immune system is not functioning as it should, it can result in diseases, such as autoimmunity, allergy and cancer. It is also now becoming clear that immune responses contribute to the development of many common disorders not traditionally viewed as immunologic, including metabolic, cardiovascular and neurodegenerative conditions such as Alzheimer's.
Components of immune system
The immune system is a complex system of structures and processes that has evolved to protect us from disease. Molecular and cellular components make up the immune system. The function of these components is divided up into nonspecific mechanisms, those which are innate to an organism, and responsive responses, which are adaptive to specific pathogens. Fundamental or classical immunology involves studying the components that make up the innate and adaptive immune system.
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Innate immunity is the first line of defence and is non - specific. That is, the responses are the same for all potential pathogens, no matter how different they may be. Innate immunity includes physical barriers e.g. Skin, saliva etc. and cells e.g. macrophages, neutrophils, basophils, mast cells etc. These components are ready to go and protect an organism for the fist few days of infection. In some cases, this enough to clear the pathogen, but in other instances the first defence becomes overwhelmed and a second line of defence kicks in.
Adaptive immunity is the second line of defence which involves building up memory of encountered infections so can mount an enhanced response specific to the pathogen or foreign substance. Adaptive immunity involves antibodies, which generally target foreign pathogens roaming free in the bloodstream. Also involved are T cells, which are directed especially towards pathogens that have colonised cells and can directly kill infected cells or help control the antibody response.
Difference between Adaptive immunity and innate immunity
| Innate Immunity | Adaptive Immunity |
|---|---|
| 1. It is general and non - specific, it is also the first line of defence against pathogens. | 1. It is also called acquired immunity, this type of immunity is built up as we are exposed to disease or get vaccinated. |
| 2. It is first line of defence. | 2. It is second line of defence. |
| 3. Their components are skin, mucous membranes, epithelial cells, phagocytes etc. | 3. Their components are Lymphoid organ that produce specialised cells called T cells and B cells. |
| 4. It can be inherited. | 4. It cannot be inherited. |
Immune system
The 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, parasites, and fungi.
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It can be broadly categorised into two main types:
- Innate immune system
- Adaptive immune system
Main elements of the innate immune system are -
a. Dendritic cells
b. Phagocytic leukocytes
c. Natural killer (NK) cells.
d. Physical epithelial barriers
e. Circulating plasma proteins
Pathogens
Pathogens are defined as microorganisms that cause infections in the body such as bacteria, fungi, viruses and protozoans.
Principles of innate and adaptive immune system
Principles of innate immune system.
1.Immediate Response: The innate immune system acts quickly, usually within minutes to hours of an infection. This rapid response is crucial in controlling the spread of pathogens.
2. Non - specific Defense: Unlike the adaptive immune system, the innate immune system does not target specific pathogens. Instead, it recognizes and responds to common features of pathogens known as pathogen - associated molecular patterns (PAMPs).
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3. Physical and chemical Barriers: The first layer of the innate immune system includes physical barriers like the skin and mucous membranes, and chemical barriers like stomach acid and antimicrobial enzymes.
4.Inflammation: Inflammation responses are initiated to recruit immune cells to inflection sites, promote pathogen destruction, and facilitate tissue repair. Key inflammatory mediators include cytokines and chemokines.
Principles of adaptive immune system
1. Specificity: The adaptive immune system is highly specific, meaning it can recognize and respond to particular antigens through receptors on B and T lymphocytes. Each lymphocyte has unique receptors that bind to specific antigens.
2. Clonal Expansion: When a lymphocyte recognizes its specific antigen, it undergoes clonal expansion, rapidly proliferating to produce many copies of itself. This increases the number of cells capable of responding to the antigen.
3. Regulation: The immune response is tightly regulated to prevent over reaction, which could damage the body's own tissues. Regulatory T cells and other mechanisms help modulate the immune response to maintain balance.
4. Antigen prevention: Dendritic cells, macrophages, and other antigen - presenting cells (APCs) process and present antigens on their surface to T cells. This is crucial for the activation of T cells and the subsequent adaptive immune response.
FAQs
What is immunology?
Immunology is the branch of biology that studies the immune system, which is responsible for defending the body against infections and foreign substances.
What are the main components of the immune system?
The main components of the immune system include -
White blood cells (leukocytes): Such as lymphocytes (B cells and T cells), macrophages, and dendritic cells.
Lymphoid organs: including the bone marrow, thymus, spleen, and lymph nodes.
Molecules: like antibodies, cytokines, and complement proteins.
What is the difference between innate and adaptive immunity?
Innate immunity is the body's first line of defense, providing immediate but non-specific protection against pathogens. It includes physical barriers (skin, mucous membranes), phagocytic cells (macrophages, neutrophils), and other mechanisms like inflammation and the complement system.
Adaptive immunity is a specific immune response that develops over time and has memory. It involves the activation of lymphocytes (B cells and T cells) which target specific antigens and provide long-lasting protection.
What is Pathogens ?
Pathogens are microorganisms or agents that cause disease in living organisms, including humans, animals, and plants. They can disrupt normal bodily functions, leading to a wide range of illnesses, from mild to life-threatening. Pathogens can exist in various forms, such as bacteria, viruses, fungi, parasites, and prions, each with unique characteristics and mechanisms of infection.
