Understanding the Immune System - The Basics
- Paulina Hupka
- Jan 27
- 6 min read
The immune system consists of a complex network of proteins, cells, and organs that work in harmony to protect the body. Understanding the basics of the immune system can be helpful when we get ill and want to support the healing process naturally.
Important parts of this network:
Physical Barriers: Skin and mucous membranes form the first layer of defence by blocking the entry of pathogens.
Fluids: Tears, saliva, sweat, and urine help flush out harmful microorganisms.
Lymphatic System: Organs like the spleen and thymus, along with lymph nodes and vessels, play a critical role in producing and housing immune cells.
Together, these components perform vital tasks such as neutralizing harmful substances, destroying pathogens like bacteria and viruses, and targeting abnormal cells, including cancerous ones.
The Two Mechanisms of the Immune System
1. Innate Immune System: The First Line of Defense
The innate immune system is the body’s general defence mechanism, responding immediately to invaders without distinguishing between specific pathogens. It can be divided into two key lines of defence:
First Line of Defense (External Barriers):
Skin: Acts as a mechanical shield against
pathogens.
Mucous Membranes: Trap microorganisms entering through the digestive and respiratory tracts.
Fluids: Enzymes in saliva and tears (e.g., lysozyme) destroy bacteria. Sweat and urine wash out pathogens.
Stomach Acid: Destroys pathogens ingested with food.
Movement: Cilia (hair-like structures) in the bronchi and bowel movements help expel pathogens.
Second Line of Defense (Internal Response):
When pathogens bypass external barriers, the second line of defence is activated:
Inflammatory Response: Injuries or infections prompt immune cells, such as mast cells, to release histamine, which dilates blood vessels, increases blood flow, and causes redness, swelling, and heat. This process improves the delivery of nutrients and white blood cells to the affected area.
Phagocytosis: Specialized white blood cells like macrophages engulf and digest pathogens. This process involves scavenger cells consuming invaders and presenting their fragments on their surface.
Natural Killer (NK) Cells: These cells patrol the blood and lymph, destroying infected or abnormal cells by releasing cell toxins.
Antimicrobial Proteins: Enzymes mark pathogens for destruction, attract other immune cells, and break down microbial structures.
2. Adaptive Immune System: The Second Line of Defense
When the innate immune system fails to heal an infection, the adaptive immune system takes over. Technically, we are all familiar with this basic mechanism of the immune system. This process is slower but highly specific since the pathogen's structure is being stored and remembered for faster responses in the future. It employs two main strategies: Humoral Immunity and Cellular Immunity.
Humoral Immunity:
B Lymphocytes (B Cells): These white blood cells originate in the bone marrow and patrol the body, binding to specific antigens. When activated, they produce antibodies that mark pathogens for destruction. B cells differentiate into:
B Effector Cells: Produce and release large quantities of antibodies.
B Memory Cells: Remember information about specific antigens for faster responses.
Antibodies: These proteins attack pathogens by binding to their surface, preventing them from infecting healthy cells and marking them for destruction by phagocytes.
Cellular Immunity:
T Lymphocytes (T Cells): Produced in the bone marrow and matured in the thymus, T cells identify infected cells and regulate the immune response. They include:
T Helper Cells: Activate other immune cells and release cytokines to coordinate the immune response.
Cytotoxic T Cells: Destroy infected cells by releasing enzymes that trigger cell death (apoptosis).
Memory T Cells: Store information about pathogens to ensure a faster response to future infections.
Key Players to Understand the Basics of the Immune System
Phagocytes: Cells that engulf and digest
pathogens. Subtypes include:
Neutrophils: Most abundant white blood cells, responsible for initial responses.
Macrophages: Large cells that consume pathogens repeatedly.
Natural Killer Cells: Destroy infected or abnormal cells.
Dendritic Cells: Bridge the innate and adaptive systems by presenting antigens to T cells.
Cytokines: Protein messengers that facilitate communication between immune cells.
Antibodies: Produced by B cells, these proteins neutralize pathogens and facilitate their destruction.
How the Immune System Learns and Adapts
The immune system’s ability to learn and remember pathogens is central to its effectiveness!
This "immunological memory" is why some diseases, like chickenpox, usually occur only once. Adaptive immunity stores information about specific pathogens, enabling faster and more efficient responses when infected with the same pathogen.
Why Understanding the Immune System Matters
A strong immune system is essential for fighting infections, preventing chronic diseases and maintaining overall health. However, malfunctions can lead to autoimmune conditions, increased vulnerability to infections, or chronic illnesses.
"Understanding how the immune system works and how to nourish it effectively empowers us to make healthy choices."
Support of proper immune function can look like:
Balanced Nutrition: Providing essential nutrients for immune cell production and reducing inflammation-promoting foods.
Regular Exercise: Increasing circulation and immune cell activity.
Stress Management: Reducing the negative impact of chronic stress on immunity.
Adequate Sleep: Supporting recovery and immune regulation.
Here is a list of important nutrients that support the basic function of the immune system.
Nutrient | Selected Foods |
Vitamin A | Beef liver, fish liver oil, egg yolk, milk products; asparagus, broccoli, pumpkin, carrots, sweet potato, cantaloupe, cherries, mango, papaya, peaches contain beta carotene, squash, yellow maize, dark leafy greens |
Vitamin C | Citrus fruits, rosehip, acerola cherries, strawberries, tomatoes, dark leafy greens, sprouted grains, broccoli, asparagus, apple, red pepper, orange, kiwi, broccoli, grapefruit, green peas |
Vitamin D | Liver, fish, shellfish, mushrooms, fortified milk and cereals, some cheeses, salmon, trout, cod liver oil |
Vitamin E | Coconut oil, olive oil, peanut oil, whole grains, leafy greens, asparagus, what germ oil, sunflower seeds, almonds, hazelnuts, peanut butter, spinach boiled, broccoli, kiwi |
Vitamin B6 | Poultry, fish, organ meats, potatoes, starchy vegetables, fruits (other than citrus fruit), chickpeas, tuna, salmon, turkey |
Vitamin B12 | Beef liver, clams, oysters, tuna, salmon, plain yogurt, some cheeses |
Folate | Beef liver, spinach boiled, black-eyed peas, white rice, asparagus, Brussels sprouts, avocado, eggs, nuts, seeds |
Iron | Oysters, white beans, beef liver, lentils, spinach, tofu, kidney beans, sardines |
Zinc | Oysters, beef, blue crab, pumpkin seeds, pork, turkey, some cheeses, shrimp, lentils, sardines, plain yogurt |
Copper | Liver, nuts, seeds, grain products, meats, dried fruits, mushrooms, tomatoes, bananas, potatoes (8) beef liver, oysters, shiitake, cashew nuts, sunflower seeds, salmon, avocado |
Selenium | Brazil nuts, tuna, halibut, sardines, shrimp, beef liver, cottage cheese, brown rice, eggs |
Magnesium | Pumpkin seeds, chia seeds, almonds, spinach, cashews, peanuts, soymilk, black beans, edamame, baked potatoes with skin, plain yogurt, kidney beans, salmon |
Conclusion
The immune system is a sophisticated defence network that protects the body against countless threats daily.
From its innate barriers to the adaptive mechanisms, every component works in concert to maintain health and resilience.
By understanding and supporting this system, individuals can optimize their body’s natural defences and improve their overall well-being.
Are you curious to find out how sugar and binging influence your immune system? The next blog posts will cover more information. For now, take care of your immune system so that it can take care of you.
InformedHealth.org [Internet]. Cologne, Germany: Institute for Quality and Efficiency in Health Care (IQWiG); 2006-. In brief: What are the organs of the immune system? [Updated 2023 Aug 14]. Available from: https://www.ncbi.nlm.nih.gov/books/NBK279395/
InformedHealth.org [Internet]. Cologne, Germany: Institute for Quality and Efficiency in Health Care (IQWiG); 2006-. How does the immune system work? [Updated 2020 Apr 23].Available from: https://www.ncbi.nlm.nih.gov/books/NBK279364/
Branco, A. C. C. C., Yoshikawa, F. S. Y., Pietrobon, A. J., & Sato, M. N. (2018). Role of Histamine in Modulating the Immune Response and Inflammation. Mediators of inflammation, 2018, 9524075. https://doi.org/10.1155/2018/9524075
Golias, C.h, Charalabopoulos, A., Stagikas, D., Charalabopoulos, K., & Batistatou, A. (2007). The kinin system--bradykinin: biological effects and clinical implications. Multiple role of the kinin system--bradykinin. Hippokratia, 11(3), 124–128.
InformedHealth.org [Internet]. Cologne, Germany: Institute for Quality and Efficiency in Health Care (IQWiG); 2006-. The innate and adaptive immune systems. [Updated 2020 Jul 30].Available from: https://www.ncbi.nlm.nih.gov/books/NBK279396/
CrashCourse. (2015, August 12). Immune System, Part 1: Crash Course Anatomy & Physiology #45 [Video]. YouTube. https://www.youtube.com/watch?v=GIJK3dwCWCw
CrashCourse. (2015, December 14). Immune System, Part 2: Crash Course Anatomy & Physiology #46 [Video]. YouTube. https://www.youtube.com/watch?v=2DFN4IBZ3rI
CrashCourse (2015, December 21). Immune System, Part 2: Crash Course Anatomy & Physiology #467 [Video]. YouTube. https://www.youtube.com/watch?v=rd2cf5hValM&t=368s
Mellman I. (2013). Dendritic cells: master regulators of the immune response. Cancer immunology research, 1(3), 145–149. https://doi.org/10.1158/2326-6066.CIR-13-0102
