The Lymphatic System

The Key Players in the Lymphatic System


Anatomy of the Lymphatic System

Components of the lymphatic system are the spleen, tonsils, adenoids, appendix, thymus gland, and lymph nodes. The spleen helps fight certain types of bacteria. The tonsilsadenoids, and appendix were once believed to be vestigial organs, meaning they are remnants left over from human evolution. Now, scientists have found they have active functions. The thymus gland is located directly above the heart. It secretes hormones that stimulate the maturation of killer T cells. This gland is only active from birth through puberty. After puberty, it decreases in size and functionality.

The following images display components of the lymphatic system.

Lymph nodes assist the body by filtering lymph fluid to destroy harmful pathogens or foreign toxins.

The Immune Response

The body initiates a battle as soon as a pathogen, or a foreign body, enters. Two types of lymphocytes, B cells and T cells, are white blood cells that target the pathogen. Macrophages, another type of white blood cell, join in the invasion.

Killer T cells attack and kill infected cells. B cells label invaders for later destruction by macrophages. Helper T cells activate killer T cells and B cells. Macrophages consume pathogens and infected cells in a process known as phagocytosis. These four kinds of white blood cells exchange information and correlate their activities as an integrated system.

When someone comes down with the flu, influenza viruses enter the body in small water droplets inhaled into the respiratory system. If the mucous membranes do not ensnare them, they slip past patrolling macrophages and begin to infect and kill mucous membrane cells, which makes the person feel sick. Macrophages initiate an “alarm” signal that activates the helper T cells, which serve as the “generals” of the lymphatic system. Helper T cells activate killer T cells and B cells and produce defensive proteins.

The body now initiates a robust attack against the flu virus. Using a second chemical signal, the helper T cells call into action killer T cells, which recognize and destroy body cells that the virus has infected. The T cells have receptors that recognize tiny bits of the virus’s proteins and release enzymes into the infected cells that encourage the cells to destroy themselves, a process known as apoptosis. This is when macrophages are actively working during the immune response to consume pathogens and infected cells.”

The protein the helper T cells releases also activates the B cells. Like killer T cells, B cells have receptor proteins called antibodies on their surfaces. The B cells can release copies of these antibodies into the bloodstream or attach them directly to pathogens, marking pathogens for destruction. These B cells also secrete antibodies that attach to any invading pathogen into the bloodstream.

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