How Does The Immune System Work?

What is the immune system?

The immune system is a large and complex network of organs, white blood cells, proteins (antibodies), and chemicals that work together to help maintain a healthy state from foreign invaders. These foreign invaders could include bacteria, viruses, parasites, and fungi.

The main tasks of the immune system are to fight potential pathogens and recognize and neutralize harmful substances from the environment

INNATE VS. ADAPTIVE IMMUNE SYSTEMS 

There are two subsystems within the immune system:

1. The innate (nonspecific) immune system
2. The adaptive (specific) immune system. 

These systems are important for keeping you healthy and work together closely whenever a foreign invader triggers an immune response. 

What is the Innate immune system?

The innate immune system is the immune system you are born with and is active from the moment you’re born. It is the body’s first line of defence against germs entering your body. The innate immune system responds the same way to all foreign substances, which is why it is sometimes referred to as the “nonspecific immune system.”

It acts very quickly. If perhaps, you were to get a small cut on your finger, your innate immune system would work quickly to make sure that bacteria that have entered through the wound are detected and destroyed within a few hours

The innate immune system consists of two main types of immune barriers: the skin and mucous membranes, and by immune system cells and proteins.

Your skin is actually one of the most important parts of the innate immune system. The skin’s closed surface and mucous membranes already form a physical barrier against foreign invaders, protecting them from entering. Tear fluid, sweat, and urine also stop these invaders from settling in the body

If any invader gets past the skin and mucous membranes and enter the body, the innate immune system activates special cells and enzymes that contribute to the immune response.

However, the innate immune system has only limited power in stopping the spread of germs, which is why it needs help from its partner: the adaptive immune system

What is the adaptive immune system?

If the innate immune system cannot destroy these foreign invaders, the adaptive immune system takes over. The innate immune system specifically targets the type of invader, but first, it needs to identify what it is. That means that it does not respond as quickly as the innate immune system, but it is more accurate (hence why it is sometimes referred to as the “specific” immune system).

The adaptive immune system can also “remember” invaders, so the next time a known invader is encountered, the adaptive immune system can respond faster.

Main parts of the immune system 

White blood cells (Leukocytes)

White blood cells play an important role in the immune system. White blood cells serve as an army against unwanted invaders, and search for, attack, and destroy them to help keep you healthy.

There are two main types of white blood cells, phagocytes, and lymphocytes. Remember innate and adaptive immune systems? Phagocytes are the tools of the innate immune system, while lymphocytes are the tools of the adaptive immune system.

Two types of lymphocytes are B lymphocytes and T lymphocytes. B cells are sometimes compared to the body’s military intelligence system — they find the targets and send in defences — while T cells are the soldiers — they destroy the invaders the intelligence system (B cells) find.

Bone Marrow

The bone marrow is where all the cells of the immune system begin their development from stem cells. Your bone marrow makes billions of new blood cells every day.

Thymus

The thymus is an organ located in the upper chest. Immature lymphocytes travel from the bone marrow to the thymus where they “learn” how to become mature T-lymphocytes

Lymph Nodes

Lymph nodes are collections of T and B cells, which congregate to communicate with each other. These small glands filter and destroy invaders so they can’t spread to other parts of your body and make you sick. 

You have hundreds of lymph nodes all over your body, including in your neck, armpits, and groin. Swollen, tender lymph nodes are a sign that your body is fighting an infection

Spleen

The spleen stores white blood cells and filters your blood, destroying old and damaged red blood cells.

Tonsils

Because they are located in your throat and nasal passage, tonsils can trap foreign invaders as soon as they enter the body. Tonsils have immune cells that produce antibodies to help protect you from invaders that cause throat and lung infections.

Skin & Mucous membranes

Skin produces oils and secretes other protective immune system cells. Mucous membranes line the respiratory, digestive, urinary, and reproductive tracts and help support the immune system.