Human Defence System 2.0

Question 1

What is immunity?

Answer 1

The resistance to an infection.

Question 2

What is a pathogen?

Answer 2

A disease causing organism.

Question 3

What are the two defence systems?

Answer 3

• General defence system
• Specific defence system

Question 4

What is the 1st line of the general defence system?

Answer 4

• Skin
• Clotting
• Sebum
• Lysozyme
• Mucus

Question 5

What is the role of skin in the general defence system?

Answer 5

Acts as a barrier & prevents pathogens from entering the body.

Question 6

What is the role of clotting in the general defence system?

Answer 6

Platelets in the blood form a clot, preventing the open wound from allowing pathogens.

Question 7

What is the role of sebum in the general defence system?

Answer 7

Skin produces sebum & the chemical in sebum kills pathogens.

Question 8

What is the role of lysozyme in the general defence system?

Answer 8

An enzyme in saliva and tears that helps destroy pathogens cell walls.

Question 9

What is the role of mucus in the general defence system?

Answer 9

Lungs & nose are lined with mucus. Traps pathogens in its sticky viscus.

Question 10

What is the role of cilia in the general defence system?

Answer 10

Tiny hairs in nose that trap pathogens & moves them out of the body by moving the hairs in an upward direction.

Question 11

What is the role of acid in the general defence system?

Answer 11

Found in stomach & vagina. They kill bacteria & enter due to low PH of these areas.

Question 12

What are the physical properties of humans related to immunity?

Answer 12

First line of the general defence system. If pathogens get past these barriers, the body can still destroy them via the second line of the general defence system.

Question 13

What is the second line of the general defence?

Answer 13

• White blood cells.
• Defence proteins.
• Inflammation.

Question 14

What are white blood cells?

Answer 14

• Phagocytes
• Macrophage

Question 15

What is the role of phagocytes?

Answer 15

Surround, engulf & destroy bacteria.

Question 16

What is the role of macrophages?

Answer 16

Is a large phagocyte that kills bacteria in the lymphatic system.

Question 17

What are defence proteins?

Answer 17

• Complement
• Interferons

Question 18

What are complement proteins?

Answer 18

A set of proteins that destroy bacteria.

Question 19

What are interferons?

Answer 19

A set of proteins that prevent viruses from reproducing & spreading.

Question 20

What is inflammation?

Answer 20

Chemicals released by damaged cells. Causes redness, heat & discomfort. Attracts more white blood cells to the site of the pathogen.

Question 21

What is the specific defence system?

Answer 21

Designed to attack particular pathogens.

Question 22

What are monocytes?

Answer 22

• Type of white blood cell, produced in the red bone marrow.
• Released into the bloodstream & lymphatic system. Surround & engulf pathogens to destroy them.

Question 23

What are lymphocytes?

Answer 23

• Produced in the red bone marrow & engulf infected body cells containing antigens on their surface.

Question 24

What are antigens?

Answer 24

Foreign molecule that stimulates production of antibodies.

Question 25

What are antibodies?

Answer 25

Proteins produced by white blood cells in response to the presence of antigens.

Question 26

What is the relationship between antigens and antibodies?

Answer 26

• An antigen is displayed on the surface of a pathogen. • This stimulates antibody production. • This antibody is specific to this antigen meaning, the antibody will only work on this particular antigen.

Question 27

How do antibodies work?

Answer 27

• Antigens present on the macrophages & prevent bacteria/viruses from entering. A new phagocyte then destroys the pathogen. • Antibodies cause the pathogens in a cell to clump together & phagocytes then destroy the pathogen. • Antibodies trigger the stimulation of the defence proteins, & complement proteins destroy the pathogen.

Question 28

What is induced immunity?

Answer 28

The stimulation of monocytes and lymphocytes to get rid of specific antigens present in the body.

Question 29

What is active immunity?

Answer 29

The production of antibodies by lymphocytes in response to a specific antigen.

Question 30

What is natural active immunity?

Answer 30

Occurs when lymphocytes produce antibodies in response to the body becoming infected by a pathogen from the environment. ## Footnote EG: resistance to a common cold. Longer lasting due to memory cells.

Question 31

What is artificial active immunity?

Answer 31

Occurs when lymphocytes produce antibodies in response to the pathogen being administered through vaccines. ## Footnote Antibodies are administered. Short-term immunity. EG: Breastfeeding.

Question 32

What is passive immunity?

Answer 32

Transfer of antibodies from one organism to another.

Question 33

What is natural passive immunity?

Answer 33

When a baby receives antibodies directly from its mother through the placenta before birth or via breast milk.

Question 34

What is artificial passive immunity?

Answer 34

When a person receives an injection of antibodies made in another organism.

Question 35

What is vaccination?

Answer 35

The administration of a non-disease-causing dose of the pathogen or part of a pathogen which stimulates and results in active immunity.

Question 36

What is immunisation?

Answer 36

The protection against pathogens by the injection of antibodies.

Question 37

What is the difference between artificial & natural immunity?

Answer 37

Artificial is the administration of antibodies & natural is the production of antibodies.

Question 38

What are B-lymphocytes?

Answer 38

• Mature in the bone marrow before moving to the lymph nodes. • Attack by producing antibodies.

Question 39

What are plasma B cells?

Answer 39

Produces antibody molecules which bind to the pathogens & mark them for destruction by monocytes.

Question 40

What are memory B cells?

Answer 40

They live in the body & respond if the same antigen enters again. - enable immunity.

Question 41

What are the functions of memory B cells?

Answer 41

• Produces more antibodies. • Quicker production of antibodies. • Produces antibodies in response to very little antigen.

Question 42

What are T lymphocytes (T cells)?

Answer 42

Move from the bone marrow & matures in the thymus gland. They attack cells by invading antigens on their cell membrane.

Question 43

What are the 4 types of T-lymphocytes?

Answer 43

• Helper T cells • Killer T cells • Suppressor T cells • Memory T cells

Question 44

What are helper T cells?

Answer 44

Recognise antigens & stimulate the production of B cells & Killer T cells.

Question 45

What are killer T cells?

Answer 45

Attacks cells containing a foreign antigen & secretes perforin which breaks down infected cell membranes allowing them to be flooded with water and causing them to burst. Pathogen-containing cells are destroyed.

Question 46

What are suppressor T cells?

Answer 46

Stops the immune response after the pathogen has been destroyed and are active when the antigen is gone. No more antibodies produced.

Question 47

What are memory T cells?

Answer 47

Triggers the production of B & T cells much quicker if a pathogen enters the body.

Question 48

Where do B lymphocytes mature?

Answer 48

Bone marrow.

Question 49

Where do T lymphocytes mature?

Answer 49

Thymus.

Question 50

Why does active immunity result in longer lasting immunity?

Answer 50

As memory T cells are produced and better able to respond.

Question 51

How do vaccines give immunity?

Answer 51

Stimulate antibody production.

Question 52

What are the two types of induced immunity?

Answer 52

Active and passive.

Question 53

What are the two organs specific to the immune system?

Answer 53

• Thymus • Lymph nodes

Question 54

Name a group of WBCs other than lymphocytes.

Answer 54

Monocytes.

Question 55

What WBCs produce antibodies?

Answer 55

B-lymphocytes.

Question 56

What part of a virus is recognised by antibodies?

Answer 56

Antigens.

Question 57

What is the function of antibodies?

Answer 57

Recognise antigens.

Question 58

What is the difference between active and passive immunity?

Answer 58

Active lasts longer than passive.