Defence Against Disease Flashcards

All 14 cards in this deck

How does mucus protect the body from pathogens?

It traps pathogens.
It is produced by cells lining some surfaces of the body, e.g. the airways.

What do cilia do to defend the body against pathogens?

They move mucus (with trapped pathogens) across the cell surface, out of the lungs and into the throat.
Cilia are on the epithelial cells lining the respiratory system.

What are lysozymes and where are they found?

Enzymes that kill some bacteria, found in tears, saliva and mucus (and secreted by glands in the skin).

How does hydrochloric acid in the stomach defend against disease?

Its low pH destroys many pathogens in the stomach.

True or false? Hydrochloric acid in the stomach is a physical barrier to pathogens.

False. It is a chemical defence; skin, mucus and cilia are physical barriers.

What are the steps of the specific immune response?
e.g. bacteria enter the body through a cut

1. Antigens on the pathogen are detected — antigens on the bacteria.
2. Lymphocytes produce antibodies, leading to destruction of the pathogen — bacteria destroyed.
3. Memory lymphocytes are also produced and stay in the blood.

Which type of white blood cell produces antibodies?

Lymphocytes.

What is the role of memory lymphocytes in a secondary response?

They remain in the blood and, if the same pathogen returns, produce antibodies faster and in greater numbers, so the pathogen is destroyed before symptoms appear.

True or false? Antigens are made by white blood cells to destroy pathogens.

False. Antigens are found on the pathogen; white blood cells make antibodies.

What does a vaccine contain?

An inactive (dead or weakened) form of a pathogen, which still carries its antigens.

What are the steps by which vaccination protects against a disease?
e.g. the polio vaccine

1. The vaccine puts antigens from an inactive pathogen into the body — inactive polio virus.
2. Lymphocytes produce antibodies and memory lymphocytes.
3. If the live pathogen enters later, memory lymphocytes cause a secondary response, so the person is immune.

True or false? Each type of antibody is specific to one type of antigen.

True. An antibody only binds to the antigen that triggered lymphocytes to make it.

On a graph of antibody concentration in the blood after a first exposure to an antigen, why is there a delay of several days before the line rises?

Lymphocytes take time to detect the antigen and produce antibodies against it.

How does the skin protect the body against pathogens?

It is a physical barrier that stops pathogens getting into the body. If the skin is cut, blood clots form to seal the wound.