Defence against disease

Created by

Mee Chan

Cards (13)

What are the 2 lines of defence
First line of defence -> prevents pathogens entering the body + non-specific
Second line of defence = protects body from pathogens that have entered body
What does the first line of defence include
Both physical + chemical barriers
Give some examples of the physical barriers from the 1st line of defence
Skin = prevents pathogens from entering + scabs form on cuts to prevent infections
Nose = hair + mucus traps pathogens
Trachea = produce mucus -> traps pathogens + cilia waft mucus up to throat to be swallowed into the stomach
Give some examples of the chemical barriers from the 1st line of defence
Stomach acid = kills pathogens
Lysosomes = lysosomes found in tears + other bodily fluids -> enzymes that destroy bacterial cells by breaking down cell wall
What fights the pathogens if they get past the 2nd line of defence
The immune system
What blood cells are in the immune system
White blood cells
What are the 2 types of white blood cells
Phagocytes
Lymphocytes
What do phagocytes do
Surround pathogens + engulf them
Enzymes found in the phagocytes -> break down pathogen to destroy it
What is the process of engulfing + breaking down pathogens
Phagocytosis
Are phagocytes specific or non-specific  
Non-specific
What do lymphocytes do
Pathogens enters the body with antigens on its surface
Antigens detected by lymphocytes + triggers immune response
Lymphocytes produces antibodies which bind to antigens so it sticks together
Easier for phagocytes to engulf them + destroy pathogens
Memory lymphocytes also produced
So if body infected again -> can make antibodies quicker
What is the 1st + 2nd time when your immune system responds, called
1ST = PRIMARY response
2ND = SECONDARY response
Why does the number of antibodies in the blood increase slowly during the primary infection
As there aren't many lymphocytes that can make the correct antibody for the pathogen