The Lymphatic System

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.

Types of Immunity

The four types of immunity are natural/passive, natural/active, artificial/passive, and artificial/active. The following are examples of these types of immunities:

1. Natural/passive – Babies receive immunities from breastmilk.
2. Natural/active – The body produces antibodies to combat an illness when a person becomes sick.
3. Artificial/passive – This immunity is temporary and requires doses of serum to maintain the immunity.
4. Artificial/active – A vaccination provides artificial/active immunity.

Vaccination Prepares the Lymphatic System

Vaccination is the introduction into the body of a dead or disabled pathogen or of a harmless microbe with the protein of a pathogen on its surface. Vaccination triggers the lymphatic system response against the pathogen without an infection occurring. Afterward, the bloodstream of the vaccinated person contains memory cells that are directed against the pathogen. The vaccinated person is immunized against the disease. Vaccinations have dramatically reduced the incidence of many bacterial and viral diseases, including polio, tetanus, and diphtheria. An intensive vaccination program led to the elimination of the deadly disease smallpox in the 1970s.

Diseases and Disorders of the Lymphatic System

The ability of killer T cells and B cells to distinguish cells of the body from foreign cells is crucial to the fight against pathogens. In autoimmune diseases, this ability breaks down, causing the body to attack its own cells. The following chart gives examples of autoimmune conditions.

Age

As people age, their bodies produce fewer B and T cells. As a result, their bodies’ ability to defend themselves against viruses and bacteria lessens.

Allergies

Sometimes, the body’s immune system works too well and attacks itself. This is known as an allergy. Hay fever is an example.

Mast cells, attached to white blood cells, line entrances to the body. When they encounter matching antibodies, they initiate an inflammatory response, which releases histamines. Histamines cause capillaries to swell and increase mucous membrane production.

HIV/AIDS: Lymphatic System Collapse

HIV/AIDS is a result of a mutation that occurred in a virus that affects chimpanzees. It destroys macrophages and helper T cells.

How Is HIV Transmitted?

Because there is no cure for AIDS, prevention is key. HIV/AIDS can only survive in blood or body fluids because macrophages are located there. The primary means of transmission is through sexual intercourse.

HIV is not transmitted through the air, on toilet seats, or by any other medium where a macrophage cannot survive. It cannot be transmitted through shaking hands, sharing food, or drinking from a water fountain because macrophages cannot be transmitted through casual contact.

Let’s Review

• This lesson explored the lymphatic system’s keys components and the major disease and disorders of the system.
• The lymphatic system provides immunity against pathogens.
• Several organs work together to make the lymphatic system efficient.
• Killer T cells recognize and destroy body cells that have been infected with a virus.
• B cells do not directly attack pathogens or infected cells.
• B cells have receptor proteins on their surface called antibodies.
• Vaccination is the introduction into the body of a dead or disabled pathogen or of a harmless microbe with the protein of a pathogen on its surface.
• In autoimmune diseases, the ability to distinguish cells of the body from foreign cells breaks down, causing the body to attack its own cells.
• Age has a negative effect on the lymphatic system.

Lymphatic System Flashcards