Chapter 37: Human Defence System

Question 1

What is a pathogen?

Answer 1

a disease causing organism

Question 2

What is immunity?

Answer 2

the ability to resist disease

Question 3

What are the two defence systems called?

Answer 3

general defence system

specific defence system

Question 4

What does the general defence system do?

Answer 4

acts against all pathogens

Question 5

What is the first line of defence in the general defence system?

Answer 5

consists of skin, mucous membranes, secretion of skin

Question 6

What are the 3 possible 2nd line of defence in the general defence system?

Answer 6

white blood cells
defence proteins
inflammation

Question 7

explain how white blood cells act as a line of defence.

Answer 7

attracted to chemicals of invading micro organisms

surround and ingest pathogens

Question 8

What is a phagocyte?

Answer 8

a cell that ingests another cell

Question 9

What is a macrophage?

Answer 9

a large phagocyte

Question 10

What is phagocytosis?

Answer 10

when a cell surrounds and ingests another cell

Question 11

Explain how defence proteins work.

Answer 11

activated by infection

prevent multiplication and limit spread of viruses

Question 12

Explain how inflammation works.

Answer 12

infection causes blood capilleries to diallate
this brings more white blood cells to an area
those cells then fight infection

Question 13

What does the specific defence system do?

Answer 13

system attacks particular invaders

Question 14

How does the specific defence system work?

Answer 14

produces antibodies or white blood cells that engulf a particular pathogen

Question 15

What are monocytes?

Answer 15

white blood cells that become macrophages

they engulf invaders

Question 16

How do monocytes work?

Answer 16

they engulf invaders

once engulfed part of the invader remains on the surface of the macrophage

Question 17

What is an antigen?

Answer 17

a foreign molecule on the surface of a monocyte that stimulates the production of antibodies

Question 18

What are lymphocytes?

Answer 18

white blood cell that produces antibodies as a result of antigens

Question 19

How do allergies arise?

Answer 19

our bodies produce antibodies against non-invaders

the body perceives a harmless substance to be an invader

Question 20

What is induced immunity?

Answer 20

using antibodies to resist specific diseases

Question 21

What is active immunity?

Answer 21

antibodies produced in a persons body

Question 22

What is passive immunity?

Answer 22

antibodies from another organism enter a persons body

Question 23

What is natural active immunity?

Answer 23

pathogens enter in a natural manner and antibodies produced as a result of this e.g. catching a cold

Question 24

What is artificial active immunity?

Answer 24

pathogens are introduced into the body as a vaccine so that antibodies can be produced

Question 25

What is natural passive immunity?

Answer 25

getting antibodies from another organism in a natural way e.g. breast milk from mother to baby

Question 26

What is artificial passive immunity?

Answer 26

getting antibodies in a non natural way e.g. antibody injections

Question 27

What is an antibody?

Answer 27

proteins that are produced by lymphocytes in response to an antigen

Question 28

Why do adults have a greater number of antibodies than children?

Answer 28

they have been exposed to more pathogens

Question 29

Explain the antibody-antigen reaction.

Answer 29

there is a precise fit between the antigen and the antibody | each antibody is complimentary to the antigen

Question 30

How can lymphocytes be identified?

Answer 30

They have a large round nucleus

Question 31

Where are lymphocytes made?

Answer 31

Bone marrow

Question 32

What are the two types of lymphocytes?

Answer 32

B-cells | T-cells

Question 33

Where do b-cells mature?

Answer 33

Bone marrow

Question 34

What do b-cells do?

Answer 34

Recognize a specific antigen and produce the antibody to fight it

Question 35

What do b-cells usually attack?

Answer 35

Bacterial infections and some virus infections

Question 36

Explain how b-cells work.

Answer 36

Comes into contact with antigen Multiplies and produces large amount of antibodies Antibodies attach to antigens Cell engulfed by pathogen or cell complement system is activated

Question 37

What are memory b-cells?

Answer 37

The remaining b-cells that produce a specific antibody that have already overcome an infection

Question 38

What are the advantages of memory b-cells? (3)

Answer 38

Produces antibodies to small amount of antigens Produces antibodies faster Produces greater numbers of antibodies than first time

Question 39

How much faster do memory b-cells work than regular b-cells?

Answer 39

B-cells produce antibodies in about 14 day | Memory b-cells produce them in 5

Question 40

Where do t-cells mature?

Answer 40

Thymus gland

Question 41

What do t-cells do?

Answer 41

Fight off viruses and some bacteria

Question 42

What are the 4 types of t-cells?

Answer 42

Helper Killer Suppressor Memory t-cells

Question 43

What do helper t-cells do?

Answer 43

Recognize antigens and stimulate the multiplication of the correct b-cell Stimulates killer t-cells to reproduce

Question 44

What do killer t-cells do?

Answer 44

Attack and destroy abnormal body cells (cancer,virus)

Question 45

How do killer t-cells work?

Answer 45

Release a protein perforin Forms pores in the membrane of the cell Water enters and the cells burst

Question 46

What are suppressor t-cells?

Answer 46

Stimulated by specific antigens Slow growth They become active after the pathogen has been destroyed Inhibits other immune response

Question 47

What are memory t-cells?

Answer 47

Stimulate memory b-cells to produce large amounts of antibodies if the same pathogen reenters